UNIVERSITY OF CALIFORNIA AT LOS ANGELES GIFT OF R. W. Webb H.H.WEBB ROBERT W. WEBB GEOLOGY DEPT., U.C.LA THE PRACTICAL ENGINEER'S HAND-BOOK, COMPRISING A TREATISE ON MODERN ENGINES AND BOILERS MARINE, LOCOMOTIVE, AND STATIONARY. PRACTICAL WORKS BY THE SAME AUTHOR. (Uniform with the Present Volume.} Second Edition. Medium 8vo, 448 pages, and 314 Illustrations, i8.r. cloth. STEAM-BOILER CONSTRUCTION: A PRACTICAL HAND-BOOK FOR ENGINEERS, BOILER-MAKERS, AND STEAM-USERS, CONTAINING A LARGE COLLECTION OF RULES AND DATA RELATING TO RECENT PRACTICE IN THE DESIGN, CONSTRUCTION, AND WORKING OF ALL KINDS OF STATIONARY, LOCOMOTIVE, AND MARINE STEAM-BOILERS. Ij^ OPINIONS OF THE PRESS. The Engineer. "There has long been room for a modern hand-book on steam boilers; there is not that room now, because Mr. Hutton has filled it. He has followed the lines of his' WORKS' MANAGER'S HAND-BOOK,' and 'PRACTICAL ENGINEER'S HAND-BOOK,' and has produced a book which is made for, and will be useful to, engineers in practice. It is a thoroughly practical book for those who are occupied in the construction, design, selection, or use of boilers." Marine Engineer. "Mr. Hutton's new work on the impoitant subject of steam-boilers fill be welcomed by a large circle of readers who have benefited by the results of his previous labours. The book teems with information and statistics. Every detail, both in boiler design and management, is clearly laid before the reader It is of the utmost value fin de sitcle engineer and works' manager." Iron. "The practical nature of the information contained in these hand-books has been much appreciated by engineers. The present volume is concisely packed with carefully selected information on steam-boiler construction and will be as fully and deservedly appreciated as Mr. Hutton's previous works have been." Colliery Guardian. " The value of this book can hardly be over-estimated. The author's rules, formulae, &c., are all very fresh, and it is impossible to turn to the work and not find what you want. No practical engineer should be without it." Medium 8vo, 426 pp., and 150 Illustrations, 155. Cloth. THE WORKS' MANAGER'S HAND-BOOK OF MODERN RULES, TABLES, & DATA FOR CIVIL AND MECHANICAL ENGINEERS, MILLWRIGHTS, AND BOILER MAKERS; TOOL MAKERS, MACHINISTS, AND METAL WORKERS ; IRON AND BRASS FOUNDERS, ETC., ETC. .tfiftfi edition, KrutsrtJ. umf) attritions. Ij^" OPINIONS OF THE PRESS. Marine Engineer.-" This work is essentially what it professes to be a book ot reference lor practical men. We can cordially recommend its perusal, for we are sure it will prove both of great service and interest 10 all seeking information on the subjects embraced by it." The Engineer. " The author treats every subject from the point of view of one who has collected workshop notes for application in workshop practice, rather than from the theoretical or literary aspect, and the work contains a great deal of that kind of information which is gained only by practical experience, and is seldom written in books." Mechanical World." An exceedingly useful volume, brimful with notes, memoranda, and rules, and well worthy of being on every mechanical engineer's bookshelf. .... There is valuable information on every page." Mining Journal.'- l n the volume before ustheauthor supplies data constantly required in the usual course of business, and of the utmost importance. , . . Mr. Hutton has performed his task adm.rably . The information is precisely that likely to be required in practice. . . . 1 he work forms a desirable addition to the library, not only of the works' manager but of anyone connected with general engineering." Ryland' Iron Trades Circular.-" A formidable mass of facts and figures readily ac- cessible through an elaborate index. It will be found absolutely necessary as a look of reference in all sorts of ' works ' connected with the metal trades. Any ordinary foreman or workman can find all he wants in the crowded pages of this useful work." CROSBY LOCKWOOD & SON, 7, STATIONERS' HALL COURT, LONDON, E.C. H.H.WEBB TRIPLE-EXPANSION MARINE-ENGINES OF 1200 I H.P. Bv PALMER & Co., LIMITED, JARROW-ON-TYNB. [For Description see page 415, COMPANION TO " THE WORKS' MANAGER'S HAND-BOOK!' THE PRACTICAL ENGINEER'S HAND-BOOK COMPRISING A TREATISE ON MODERN ENGINES AND BOILERS MARINE, LOCOMOTIVE, AND STATIONARY. AND CONTAINING A LARGE COLLECTION OF RULES AND PRACTICAL DATA RELATING TO RECENT PRACTICE IM DESIGNING AND CONSTRUCTING ALL KINDS OF ENGINES, BOILERS, AND OTHER ENGINEERING WORK. THE WHOLE CONSTITUTING A COMPREHENSIVE KEY TO THE BOARD OF TRADE AND OTHER EXAMINATIONS FOR CERTIFICATES OF COMPETENCY IN MODERN MECHANICAL ENGINEERING. BY WALTER S. HUTTON, CIVIL AND MECHANICAL ENGINEER, AUTHOR OF "THE WORKS' MANAGER'S HANDBOOK FOR ENGINEERS/ 5 "STEAM BOILER CONSTRUCTION," ETC. Witfr apfarar&s of 370 illustrations. FIFTH EDITION, CAREFULLY REVISED, WITH ADDITIONS. LONDON- CROSBY LOCKWOOD AND SON, 7, STATIONERS' HALL COURT, LUDGATE HILL. LONDON : BRADBURY, AGNEW, & CO. LD., PRINTERS, WH] PREFACE. THIS volume is designed as a companion to the Author's book, " THE WORKS' MANAGER'S HAND-BOOK," and, like that work, contains a quantity of matter not originally intended for publication, but collected for the Author's own use in " the practical construction of a variety of modern engineering work. The Author has endeavoured to give in simple lan- ^ guage, bereft of complex mathematical formulae, and in a concise and condensed form, the most useful practical ^ information, freely illustrated by well-executed engravings, v* which elucidate and shorten description ; and to explain ^\the true principles of, and give the principal rules for, the construction of engines and boilers, and the economical production of steam-power. The whole comprises the results of recent researches and experiments in various branches of engineering, and contains a large collection of Tables and practical data ^invaluable to all engaged in designing, constructing estimating for, engines, boilers, and other engineering The principal subjects treated are as follows : Air, gas, and water ; air-motors, gas-engines, and water-motors ; fuel ; combustion, products of combustion ; heating-power and evaporative-power of fuel, evaporation .of water to steam ; heat and heat-energy ; methods of burning liquid-fuel and refuse-fuels. Evaporative effect of natural draught and forced draught in the furnaces of steam-boilers , 296237 VI PREFACE. Propulsion of modern steam-ships, with description of, and rules for various propellers. Evaporative-performance of various kinds of modern steam-boilers. Boiler-explosions, their causes : and the usual manner in which boilers explode. Rules and practical data for the construction of modern locomotive, stationary, and marine engines and boilers. Rules and practical data for triple-expansion and quad- ruple-expansion engines. Strength and specific gravity of a variety of materials, collated from careful experimental data. It is hoped the volume will be found to be con- siderably in advance of any work of a similar description, and that, besides being a useful reference-book for engineers, it will prove extremely valuable to. those who, having had the necessary practice, aspire to hold a Board of Trade Certificate for Competency in Mechanical Engineering. PREFACE TO THE FIFTH EDITION. THIS new Edition has been carefully revised, and improved by the addition of a little new matter to some of the sections. W. S. HUTTON. J:ine, 1896. CONTENTS. SECTION I. AIR, WIND, AND WIND-MOTORS; WATER AND WATER- MOTORS; HEAT AND FUEL; GAS AND GAS-ENGINES', COMBUSTION, ETC, PAGE Atmospheric-air .... 3 Nitrogen, oxygen . . 3 Weight and volume of air . 3, 4 Compression of air . . . 4 6 Volume of air due to increased tem- perature ..... 6, 7 Temperature and pressure of air . . 6 8 Atmospheric resistance ... 8 Barometers ..... 8, 9 Pressure of air at different heights of the barometer .... 9 Pressure and velocity of wind . 10, n Windmills . . . . 12, 13 Pantanemone . . . . . 13 Weight and volume of water . 14, 15 Expansion of water by heat . . . 15 Composition of sea- water . . . 16 Quantity of salt ir sea- water . 16, 17 Boiling-points of sea-water . 17, 18 Hydronometers or salinometers . 18, 19 Blowing-off sea-water . . 19, 20 Loss of fuel and heat by blowing-off 21, 22 Measurement of flowing-water . 23, 25 Driving-power of flowing-water . 25 Turbines . . . . 26 Efficiency and regulation of tur- bines ..... 27, 29 Jonval and Girard turbines . . 30 34 Pelton's water-wheel . . 34 3 Thermometers . . . 3 6 > 37 Temperatures beyond the range of thermometers .... 37 Standard temperatures of water . . 37 PAGE Notable temperatures ... 38 Temperature of rivers, seas and lakes 38, 39 Underground tempeiatures . -39 Temperature of hot and deep mines 39, 40 British unit of heat . . . . 40 Specific heat .... 40 42 Calorimeters . . . . 42, 43 Latent heat . . . . 43, 44 Temperatures resulting from a mixture of hot and cold liquids . .44-46 Laws of expansions of metals by heat 46 Expansions of substances by heat 46 49 Contraction of wrought-iron on cool- ing 49 Coals, varieties of . . . 50 Composition and weight of coal . 51 Heating-power of coal . ..52 Patent fuels 52 Stowage-capacity of fuels . 53 Coal-bunkers, rules for . . . 54 Practical analysis of coal . . , r 4, 55 Combustion ... 56 Carbon and hydrogen . . . . 56 Effect of heat on coal ... 56 Chemical composition of combustibles 57 Heating-power of fuels . . 57, 58 Heating-power of liquid fuel . 58, 59 Gaseous fuel 59 Heating-power of coal-gas . . 59 Quantity of gas obtained from coal . 59 Pintsch-gas and other oil-gas . . 60 Gas-engines .... 6062 CONTENTS. PAGE Water-gas 62 Pressure produced by the explosion of air and inflammable gases . . 63 Hot-air engines .... 63 65 Heat evolved by combustibles . 65, 66 Liquid-fuel, petroleum and creo- sote 67 Weight of petroleum-refuse . . . 67 Liquid-fuel injectors . . 68, 69 Combustion-chambers for burning liquid-fuel .... 6974 Petroleum-engine . . . 74 7^ Burning vegetable-refuse fuel . . Straw-burning apparatus . Furnace for burning coal-dust, breeze and similar refuse-fuels . . . Composition and evaporative-power of coal-dust Results of tests of a furnace burning coal-dust Hand-firing for boilers Mechanical stoker . . . i Air required for combustion Products of combustion . . . Vitiation of the air by combustion . Smoke Furnace-front Air in boiler-furnaces . . . . Hot-air evolved by combustion Weight of gases and vapours . PAGE Loss of fuel due to a high tempera- ture in a steam-boiler chimney or funnel . . . .86 Consumption of coal in marine- boilers 8789 Consumption of coal by locomotives on various railways ... 89 Composition, heating-power and evaporation of petroleum-oil . . 90 Results of trials of a locomotive burn- ing petroleum, coal, and wood . 91 Average rate of combustion of coal in different kinds of steam-boilers . . 91 Force developed by combustion . 92 Consumption of coal by different kinds of engines . . . . 92 Action of flame in boiler-tubes and boiler-furnaces 93, 94 Temperature of the products of com- bustion in chimneys of different kinds of boilers . . . . 94 Temperature of the products of com- bustion at different stages between the fire and the chimney of a steam-boiler . 94 96 Absorption, conduction and radiation of heat .... 9698 Non-conductors of heat . . . 97 Loss of heat by radiation from steam- pipes 98,99 Convection, effect of heat on water ; and circulation . . . 100 SECTION II. EVAPORATION; BOILER-SHELLS, BOILER-FURNACE-TUBES; BOARD OF TRADE, LLOYD'S, AND OTHER RULES AND DATA FOR STEAM-BOILERS; BOILER-CONSTRUCTION; BOILER EXPLOSIONS, ETC. PAGE Evaporative efficiency . . . 103 Total, latent, and sensible heat of steam 103, 104 Volume and pressure of steam . . 104 Efficiency of steam-boilers . . . 105 Evaporative-power of fuel . 105,106 Theoretical evaporative power of various kinds of fuels . . . 106 Actual evaporative-power of fuels . 107 Effect of blast-pressure in a chimney . 108 Evaporative-performance and effi- ciency of steam-boilers . . .108 CONTENTS. IX PAGE Evaporative-performance of loco- motive-boilers .... 109, 1 10 Rate of evaporation of various coals . 1 1 1 Evaporative-performance of various kinds of steam-boilers . . 1 1 1 Evaporative-performance of torpedo- boat boilers 112 Evaporative- tests of boilers of modi- fied locomotive type . . .113 Fire-grate-surface and heating-surface of steam-boilers . . ..114 Indicated horse-power developed by marine-engines from a given area of fire-grate and heating-surface 115, 116 Heating-surface of locomotive-boilers 117 Standard proportions of heating-sur- face of fire box and tubes of loco- motives on various railways . . 117 Transmission of heat . . .117,118 Grate-surface and heating-surface . 118 Efficiency of heating-surface . 119, 120 Forced -draught . . .120 Natural-draught experiments on a steam-boiler . . . 121, 122 Forced-draught experiments on a steam-boiler 122 Performance of steam-ships with natural-draught and with forced - draught in their boiler-furnaces 123 125 Forced-draught with warm-air . .126 Evaporative-performance of steam- boilers with Howden's system of forced-draught . . . 127, 128 Forced - combustion by induced- draught .... 128, 129 Arrangement of boiler-plates . . 129 Strength of boiler-plates . . 129, 130 Strength and proportions of riveted- joints 130, 131 Lloyd's proportions for riveted - joints 132, 133 Board of Trade proportions for riveted - joints 133, 134 Riveted-joints in soft steel plates, Professor Kennedy's rules and data for I35H2 Strength of boiler-shells . . . 142 Diameter and thickness of the plates of boiler-shells . . . 142, 143 Bursting-pressure of boiler-shells . 143 PAGE Collapsing-pressure of furnace-tubes, various rules for the . . . 144, 145 Board of Trade Rules for steam- boilers I45IS5 Illustrations of the Board of Trade Rules for steam-boilers . 1 56 1 60 Lloyd's Rules for steam-boilers 161 165 Illustrations of Lloyd's Rules for steam-boilers . . . 166 168 Corrugated furnace-tubes, strength of 167, 168 Ribbed furnace-tubes . . . 169, 170 Fire-box roof-stays of locomotives 171, 172 Cast-steel roof-stays . . . .172 Thickness of plates for the flat-sur- faces of steam-boilers . . . 1 73 Thickness of tube-plates and furnace- tubes 173, 174 Boiler- tubes 174 Heating-surface of boiler-tubes . 175, 176 Steam-space of marine-boilers . . 1 76 Quantity of steam used by an engine 177 Quantity of water evaporated in, and efficiency of steam-boilers . 1 77 Efficiency of various kinds of steam- boilers 178 Horse- power of steam-boilers . 178 180 Safety-valves for steam-boilers . . 180 Flow of steam through safety- valves 180, 181 Safety-valves loaded with lever and weight, rules and data for . 182185 Safety-valve-spring, diagram of .186 Board of Trade Rules for safety- valves .... 186188 Spring-loaded safety-valves . 188 190 Lloyd's regulations for safety-valves . 190 Spring-loaded safety - valves for marine-boilers 191 Spring-loaded safety - valves for locomotive-boilers . . 192, 193 Safety-valve-area . . 194 196 Dead-weighted safety-valves . 197, 198 Feed-water consumption in steam- boilers 199 Feed-pumps for steam-boileis . .199 Feed back-pressure-valves . . . 200 Action of an injector . . . 200 Rules for injectors . . . 2OI Automatic re-starting injector . 201, 202 CONTENTS. i PAGE Automatic exhaust-steam injector, rules and data for . . 202207 Position of the feed-discharge in steam-boilers .... 207 Unequal expansion and contraction, strains due to, in boilers fed with cold water . . . .207, 208 Feed-water-heaters, rules and data for 208 210 Scale-forming substance in feed- water 211 Prevention of scale in steam-boilers 21 1,212 Softening and purifying feed- water . 212 Construction of steam-boilers . . 213 Cornish boilers .... 213, 214 Lancashire boilers . . . 214, 215 Strengthening-rings, and expansion- . 215 . . 216 216, 217 . . 217 218, 219 220224 . 224 224,225 hoops for furnace-tubes Boiler-setting Galloway-boilers Vertical boilers . Locomotive-boilers . Marine-boilers, various Blow-off cocks and fusible-plugs Directions for getting-up steam . PAGii Water-tube boilers . . 226228 Velocity of hot gases . . .128 Chimneys for steam-boilers, rules for 228 230 Boiler-explosions . . . . 230 Causes of explosions of various kinds of steam-boilers .... 230 Explosions of vertical boilers . . 23 1 Sources of boiler- explosions . . 232 Improper setting of steam-boilers . 233 Corrosion of steam-boilers . 232 234 Zinc-remedy for corrosion . . 234 Pitting and grooving . . . . 235 Effect of pouring water on hot plates 236 Overheating .... 236, 237 Temperature of fractured-plates . 237 Shortness of water and over-pres- sure . . . . . 237, 238 Weak furnace-tubes and boiler-shells 238 Fractured plates, defects in the de- sign of boilers, defective workman- ship and materials : and preserva- tion of boilers when not in use . 239 Method of testing a steam-boiler . 240 SECTION III. STEAM, CONDENSATION, CONDENSERS, AIR-PUMPS, WATER- PUMPS; SLIDE-VALVES, PISTON-VALVES, CORLISS AND OTHER VALVES; LINK-MOTION AND OTHER VALVE- GEARS, ETC. PAGE Pressure of steam . . . . 243 Volume, pressure, and density of steam 243, 244 Advantage of high-pressure steam . 244 Temperature and volume of saturated steam, table of . . 245, 246 ' Weight, volume, total heat, and latent heat of steam, table of . 246 250 I Flow of steam through an orifice . 250 Superheated steam . . 251252 Separator, steam drier . . 252, 253 Condensation of steam, rules for 253 255 Efficiency of steam in an engine . 256 Final temperature of steam in a cylinder or condenser . 256, 257 Vacuum ...... 257 Power obtained by using a condenser 258 Water required for condensation in condensing-engines . . . . Hot-well Jet condensers . . . 259, 260 Air- valve for condensing-engines . 261 Ejector-condenser . . . .261 Surface-condensers . . . 261 Cooling-water and cooling-surface of surface-condensers . . . 262 258 259 CONTENTS. xi PAGE Quantity of steam condensed by cold surfaces 262 Weight of steam condensed by tube- surface of condensers . . . 263 Cooling surface and water required for surface-condensers . . . 264 Circulating-pumps and condenser- tubes 264, 265 Packings of various kinds for con- denser-tubes .... 265, 266 Air-pumps, condensers and air-pump valves .... 266 272 Heat carried off in condensing water 272 Method of measuring water flowing from the air-pump of a condensing engine 273, 274 PAGE Mode of carrying out an engine-test 275277 Water-pumps 8 nd tanks, rules for 277 283 Slide-valves 284 Lap, lead, and travel of slide-valves, rules for . . . . 285289 Trick-valve and expansion slide- valves .... 289293 Diagrams of slide-valves . . 292, 293 Slide-valve, relief-frames . 295 297 Piston-valves, double-beat valves and Corliss valves . . . 299 302 Link-motion . . . 303 305 Eccentrics and eccentric-straps 306 308 Joy's valve-gear . . . 308310 Bremme's valve-gear . . 310312 SECTION IV. CONNECTING - RODS, CO UP LING - RODS, CRA NK - SHAFTS, CRANK -AXLES; SCREW - PROPELLER- SHAFTING AND BEARINGS, SCREW-PROPELLERS, PADDLE-WHEELS, AND JET-PROPELLERS, ETC. PAGE Connecting-rods of various kinds for marine-engines . . . 315, 316 Connecting-rods for stationary-engine 317 Connecting-rods, rules for . 317, 318 Connecting-rods for locomotive- engines . . . . . 319 Coupling-rods, or side-rods, for loco- motive-engines . . 320, 321 Crank-shafts 322 Crank-shafts, built-up. . . . 322 Crank-shaft for triple-expansion en- gines 322, 323 Crank- shafts for marine-engines 322 324 Crank-shafts, proportions and weight of 324 Crank-shafts, rules for . . 325, 326 Crank-shafts, bearings and bushes for 326 Strain on a crank-pin . ... 327 Counter-balancing cranks . . 327 Crank-axles, locomotive . 328, 329 Causes of crank-shafts being strained 329 Crank-axles, usual manner of failure of 329 PAGK 330 330 33<> 333 333 Analysis of steel for crank-shafts Bent-cranks Cranks for large pumps Strength of shafts to resist bending . Strength of shafts to resist torsion . Screw-propeller-shafting and bear- ings, rules and data for . 331 336 Stern-shaft and stern-tube . . 336 Plummer-blocks and thrust-bearings of various kinds . . . 337,338 Screw-propellers . . . . 338 Delineation of a screw-propeller 339 341 Pitch of screw-propellers . . . 342 Rules and data for screw-propellers and propulsion . . . 342 356 Twin screw-propellers . . . 356 Pitchometer 357 Screw-steering-propeller . . . 358 Paddle-wheels . . . 358362 Feathering paddle-wheel, rules for . 561 Speed of a paddle-steamer, rules for 361 Jet-propellers .... 361, 362 CONTENTS. SECTION V. HORSE-POWER; EXPANSION OF STEAM IN A CYLINDER,- PROPORTIONS OF THE CYLINDERS OF STEAM-ENGINES; PISTONS, PISTON-RODS AND CROSS -HEADS; MILL- ENGINES; DOUBLE - EXPANSION, TRIPLE - EXPANSION, AND QUADRUPLE-EXPANSION MARINE-ENGINES, ETC. PAGE Heat, the source of power of steam . 365 Mechanical value of heat . 365, 366 Horse-power 366 Nominal horse-power of condensing engines 367 Nominal horse-power of non-con- densing engines . . 368 370 Effective mean-pressure of steam re- quired for a given nominal horse- power 370 Nominal horse-power of compound or double-expansion engines . 371 373 Nominal horse-power of triple-expan- sion and quadruple - expansion engines .... 374, 375 Actual or indicated horse-power 375, 376 Friction of engines . . . . 377 Expansion of steam in a cylinder . 377 Terminal-pressure . . . . 377 Average pressure of steam through- out the stroke . . . .378 Saving effected by working expansively 378 Maximum economy in working steam 379 Steam-jacket ..... 379 Mean-pressure of steam in a cylinder, rules and data for . . 380, 381, 382 Table showing the mean-pressure of steam in a cylinder, with various grades of expansion . . . 383 Diameter of cylinders, rules for 384, 385 Compound-engines . . . . 385 Proportions of cylinders of compound or double-expansion engines 385, 386 Proportions of the cylinders of triple- expansion engines . . 386, 387 Best arrangement of cranks . . 387 Economy of triple-expansion and quadruple-expansion engines . . 387 Proportions of the cylinders of quad- ruple-expansion engines . . 388 Metal for cylinder-liners . . . 389 Rules for cylinder-liners . . . 389 Rule for the thickness of marine- engine-cylinders . . . . 390 PAGE 390, 39i 391 Locomotive-engine-cylinders Stationary-engine-cylinders . Proportions of the cylinders of non condensing engines, table of . 392 Proportions of the cylinders of com- pound or double-expansion marine- engines, table of . . 392 Cylinders of triple-expansion engines 393 Velocity of steam through the cylin- ders of triple-expansion engines . 393 Proportions of the cylinders of triple- expansion engines of various steam- ships, table of .... 394 Bolts for cylinder-covers . . . 395 Piston-speed and piston-displace- ment . . . ... . 396 Pistons 397 Piston of a locomotive-engine . . 397 Pistons and piston-rings, various 398, 400 Piston-rods .... 400 401 Metallic packing for glands . . 402 Cross-head of a locomotive-engine . 403 Cross-head of stationary engine . 404 Cross-heads, various, of marine- engines 405, 406 Mill-engines 406 Stationary non-condensing engines . 407 Corliss engine . . . 408, 409 Barring-engine . . . . . 410 Vertical tandem compound mill- engine ..... 410 Non-condensing compound engine, with automatic expansion-gear 410 414 Marine-engines . . . -414 Compound surface-condensing screw- engines 415 Triple-expansion engines . 415 418 Conversion of compound or double- expansion-engines to triple-expan- sion engines. . . . .418 Quadruple-expansion engines . . 420 Oscillating paddle-engines . . 422 Marine-engine governors . 423? 424 Initial condensation of steam . . 424 CONTENTS. SECTION VI. STRENGTH AND SPECIFIC GRAVITY OF STEEL AND WROUGHT-IRON PLATES AND BARS; CAST-IRON, GUN- METAL, SRASS AND OTHER ALLOYS; TIMBER AND OTHER MATERIALS, ETC. PAGE 427 Definition of strains Modulus of elasticity of metals and woods 428 Elastic limit of steel and wrought- iron . . . . , . 429 Factor of safety 429 Test-strips of wrought-iron and steel 429 Table of the tensile strength, elonga- tion, and contraction of area of fracture of steel plates, wrought- iron plates and bars . . . 430 Mild steel-plates for fire-boxes . . 430 Table of strength of \vrought-iron and steel bars and plates, culled from the test-books of several noted manufacturers . . 431 4 Table of the breaking strength of steel-plates and bars, crank-shafts, tyres, axles, rails, steel-wire, &c., by various authorities . 435 437 Table of the breaking strength of iron-wire, wrought-iron bars and plates, and forgings : giving also the effect of cold-rolling, and the loss of strength in screwing and welding, by various authorities 437 440 Table of the tensile strength and compressive strength of cast-iron, by various authorities . 440, 441 Table of the breaking strength of metals and alloys, by various authorities . , . 442, 4-3 443 444 j Table of the tensile strength and resistance to torsion of wires of various metals .... Table of the tensile strength and conductivity of silicium-bronze and phosphor-bronze wire Table of the tensile strength, electri- cal resistance and relative conduc- tivity of wires of various metals . Table of the tensile and compressive strength of timber, by various authorities .... 444447 Table of specific gravity of timber 447, 448 Table of the specific gravity of cast- iron, wrought-iron, steel, bronze, brass, tin, lead, zinc, and other metals 449 Table of the specific gravity of vari- ous materials and liquids . 450, 451 Table of specific gravity of gases and vapours ..... Rules for specific gravity . . . Table giving the weight of a cubic foot of various metals . Aluminium Table giving the weight of a cubic foot of stone and mineral substances . Table giving the weight and bulk of stone 454 Table giving the weight of a cubic foot of timber . . . 454 456 Table giving the weight of liquids . 456 45 * 452 452 453 453 INDEX . *,.*. 457478 ALPHABETICAL LIST OF ILLUSTRATIONS. Air-pump valves -- valve PACK ! ... 272 261 Apparatus for measuring condensing- water in engine-tests . . .273 Application of heat to the surface of water ...... 100 Back -pressure valves . . . 200 Balanced slide-valves, various 295 298 Barring-engine . . . .410 Bent crank ...... 330 Blow-off cock ..... 225 Boiler explosions . . . 231 239 Boss of screw-propeller . . . 345 ; Bremme's valve-gear . . 311,312 Circulating-pump and air-pump . 265 Coal-bunker ..... 53 Combustion-chambers for burning liquid-fuel .... 70 73 < Compound marine-engine . . . 417 Connecting-rods for locomotives 318 320 - for marine-engines . . . 315 for stationary-engines . 316,318 Corliss engine-cylinder and valves . 408 - valve-gear .... 301 Cornish-boilers . . . 213 Coupling of propeller-shafting . . 332 -- rods for locomotives . . . 321 | Crank-shafts for marine-engines 322, 323 | Cranks and eccentrics . . . . 285 Cross-heads of various kinds 402 406 PAGE Lancashire-boilers . . . 214, 215 Lever safety-valve . . . 182 Link-motion, of various kinds 393 395 Liquid -fuel injector . . .68, 69 Locomotive and stationary engine- cylinders .... 389391 boiler .... 218, 219 crank-axles . . . 328, 329 Marine-boilers . . 165, 167, 220224 -engine-governor . . 4 2 3 Mechanical stoker . . 81 Metallic-picking for glands . . 402 Method of measuring flowing water . 23 of setting boilers . . .216 Models of slide-valves . . . 284 Non-condensing compound-engine . 413 Oscillating paddle-engine . .421 Packings for condenser-tubes - 265, 266 Pelton's water-wheel 35 Petroleum -engines Piston-valves, various . Pistons of various kinds Pitchometer Dead weighted safety-valve . Delineation of a screw-propeller Diagrams of slide-valves of steam-pressure 197 340 292, 293 378, 380 Eccentrics and eccentric-straps of various kinds . . . 306 308 Egg-ended boiler and setting . . 95 Ejector-condenser . . . .261 Expansion slide-valves . 290 294 Feathering paddle-wheel . . . 359 Feed-pumps for boilers . . . 199 -water heater .... 210 Fire-box of locomotive-boiler 170, 171 roof-stays . . . .173 Fire-boxes, or combustion-chambers 157 Furnace-front ..... 84 for burning dust-fuel . . . 78 Fusible-plug 225 Gas-engine . . . . . . 61 Hot-air engine .... 64 Howden's system of forced draught . 126 Injectors .... 202 204 . 362 309, 310 Jet-propeller . Joy's valve-geai 75- 7" 299, 303 397 4 357 Quadruple-expansion marine- engines 419 Return-tube marine-boiler . .156 Ribbed furnace-tubes . . . . 169 Safety-valve springs . . 186, 189 Safety-valves for locomotive and other boilers . . . 182, 185, 192, 193 for marine-boilers . . . 191 Screw-propeller .... 338 -- propeller-shafting . . . 331 -- steering-propeller . . . 358 Separator ...... 253 Slide-valves, various . . 285290 Stationar non-condensin-enine . 407 176 253 336 77 251 Thrust -bearings, various . . 337, 338 Triple-expansion engine-cylinders . 393 Triple-expansion engines . (Frontispiece) Turbines, various . . 26, 28, 30 33 Twin screw-propeller . . . . 356 Vertical and horizontal air-pumps and condensers . . . 267 269 Vertical boilers . . . .217 - jet condenser . . . . 260 pumps . . . -278, 280 tandem mill-engine . . . 411 Water-tube boiler .... 2?6 Windmills ..... 12, 13 , . . nary non-condensing-engin collecting-pipe . . - -dryer Stern-tube and stern-shaft Straw-burning apparatus Superheater SECTION I. AIR, WIND, AND WIND-MOTORS ; WATER AND WATER-MOTORS; HEAT AND FUEL; GAS AND GAS-ENGINES; COMBUSTION, ETC. H.H.WEBB THE PRACTICAL ENGINEER'S HAND-BOOK. SECTION I. MR, WIND, AND WIND-MOTORS ; WATER AND WATER-MOTORS; HEAT AND FUEL; GAS AND GAS-ENGINES; COMBUSTION, ETC. ATMOSPHERIC AIR AND COMPRESSED AIR. Atmospheric Air is a transparent invisible fluid surrounding the earth to a height of about 45 miles. Air is a very slow conductor of heat. The Air is composed of nitrogen 78-5 parts; oxygen, 20-6; aqueous vapour, -86 ; and carbonic acid, -04 parts. Air contains about 4 grains of moisture per cubic foot. Nitrogen does not support combustion or respiration, and has no taste or smell. It is lighter than common air; its specific gravity being -9736. Oxygen is essential to the support of animal life and combustion. It is one-tenth heavier than common air; its specific gravity being 1-1056. Carbonic Acid is produced by the fermentation of animal and vegetable substances, the respiration of animals and the processes of combustion. Carbonic Acid is composed of 2 atoms of oxygen and i of carbon. Its specific gravity is 1-529. The Effect of Carbonic Acid is to destroy animal life and extinguish flame. When the atmosphere contains 8 per cent, of carbonic acid there is danger of suffocation, and air mixed with 10 per cent, of this gas will extinguish lights. Carbonic Acid Gas is frequently found in mines, where it is called choke-damp, or black-damp. The Weights and Volumes of the two principal Gases of which the air is composed, under the pressure, of one atmosphere at 32 Fahr., are as follows: The weight of one cubic foot of nitrogen = '07859 Ib. or 1-258 ounces, do. do. oxygen = '08926 Ib. or 1-428 do. The volume of one pound weight of nitrogen = 12-727 cubic feet. do. do. oxygen = 11-205 do - B 2 4 THE PRACTICAL ENGINEER'S HAND-BOOK. The Weight of Atmospheric Air is '08072 lb., or i'2gi6 ounces, or 565 grains, per cubic foot, at 32 Fahr., under the pressure of one atmosphere. At 62 Fahr. the weight of one cubic foot is 32 grains less or 533 grains, or i'2iji ounces or '076098 lb. The Weight of Air under the pressure of one atmosphere at 32 Fahr. is 773 times lighter than that of water of the same temperature, and at 62 Fahr. it is 820 times lighter than water of the same temperature. For ordinary calculations air is frequently taken as 770 times lighter than water. The Weight of Air is about two-thirds more than that of gaseous steam, and about fourteen times greater than that of hydrogen. The Weight of Air decreases with the height above the surface of the earth, its weight at a height of 3! miles being only one-half ; at 7 miles, one-fourth; at io| miles, one-eighth; and at a height of 14 miles, one-sixteenth of its weight on the surface of the earth. The Volume of one pound of Air under the pressure of one atmo- sphere at 32 Fahr. is 12-386 cubic feet, and at 62 Fahr. it is 13-14 cubic feet. Compression of Air. The power, independent of friction, leakage, and resistance of valves, necessary to compress a given volume of air by isothermal compression is theoretically obtained by the formula* : where W t = the work performed by isothermal compression. R = the ratio of compression = absolute end-pressure divided by the absolute pressure of the atmosphere. P = the pressure in the receiver = end-pressure in compressing- cylinder. Y!= volume traversed by the compressing-piston. A = the back pressure of the atmosphere = 14-7 Ibs. per square inch. Example : Required the amount of power expended in compressing one cubic foot of air of 45 Ibs. pressure per square inch above the atmosphere = 597 Ibs. total pressure? Then R = 597 = 4-0612. H7 log. e R, or the hyperbolic log. R = 1-4015. P= 59-7 Ibs. per square inch = 597 x 144=8596*8 Ibs. per square foot. V t is, for isothermal compression, inversely as the pressure and = R x the number of cubic feet of compressed air produced, = 4-0612 x i cubic foot = 4*0612 cubic feet. A = 14-7 Ibs. pressure per square inch = 14-7 x I44 = 2ii6'8 Ibs. pressure per square foot. * The Author is indebted for the above formulae to the Articles on Compressed Air in "The Engineer," of Feb. 6 and 13, 1885. COMPRESSION OF AIR. -l ~ 2Il6-8 lbs - x 4'o6 1 2 cub. ft = [('59*3 x 8596-8) 2IJ.6-8] x 4-0612 cubic feet. = 2966-7 Ibs. x 4'o6i2 cubic feet. Therefore W t = 12048 foot-pounds. To find the amount of steam power necessary to compress a given amount of air, it is necessary to consider the losses caused by friction, leakage, and heating of the air. The theoretical power may be taken as that due to adiabatic compression, but friction and leakage as due to isothermal compression. By adiabatic compression the mean forward pressure is found by Professor Cotterills* formula, where for adiabatic compression of air n = y = 1-41. p _. 7 v P t _J_yP A m - - ^ - - - * ^> -to y I r 7-1 Where P m = the mean forward pressure per square inch, absolute. P, = the pressure resulting from compression = 597 Ibs. per square inch = 8596*8 Ibs. per square foot. P 2 = the pressure of the atmosphere =147 Ibs. per square inch = 2116-8 Ibs. per square foot. 7=1-41 (a number on which the velocity of sound depends, irre- spective of any special theory of heat, found by experiment to have this value for air and other simple gases). _ specific heat of airjit constant pressure _ 183-4 _ ~ specific heat of air at constant volume ~~ 130-2 ~~ y = ratio of compression, the volume of air to be compressed at 14-7 Ibs. pressure and 60 deg. F. being, as in the former case, 4-0612 cubic feet: the resulting volume is found in the following way : Temperature due to compression = T x = /ultimatepressurey 29 x absolute .^ t ature . V initial pressure / s=f5ZY i *52i deg. =4 -0612 -29 x 521. Log. T! = -29 x log. 4'o6i2 + log. 521 deg. ; and temperature = 782-3 deg. F. Rise of temperature = 782-3 521 = 261-3 deg. F. and 261-3 + 60 == 321 deg. F. ... . 14-7 Ibs. 4-0612 cub. ft. (782-3-28)* Re sul tins' volume ^r. X --- w OQ J -- -- 59-7 Ibs. 521 28 = -246 x 6-213 = i 53 cubic feet. Ratio of compression = 4 '-- - 1 = 2*654. * If the standard volume of these calculations were taken at 32 deg. F. the changes of volume would be proportional to the absolute temperature, but if taken at 60 deg. F., 60 deg. -32 deg. = 28 deg. has to be deducted from all the absolute temperatures. THE PRACTICAL ENGINEER'S HAND-BOOK. Therefore P m = (i^lx-57W_l_ x 147 l ' ' = (3-439 x 22-49) - (2-439 x i47 lbs -) = 77-346 35-843 = 41-498 lbs. per square inch. Mean effective pressure = 41-498 14-700 = 26-798 lbs. per square inch = 26798 X 144 = 3859 lbs. per square foot. Total power exerted in compressing 4-0612 cubic feet of air adiabatically = 4-0612 cubic feet x 3859 lbs. per square foot= 15,672 ft.-lbs. Assuming friction, leakage, and resistance of valves to be about 24 per cent., in addition to the load, then each foot- pound in the compressor requires 1*24 foot-pounds steam- pressure, and the friction due to 12048 foot-pounds will 12048 x -24 . . . . . . . 2892 ft.-lbs. Total power required for i cubic foot of compressed air .18564 ft.-lbs. The Temperature of the Atmosphere is greatest at the surface of the earth, and decreases with the height above the surface ; the decrease being at the rate of i Fahr. for every 340 feet of vertical height. The atmosphere receives scarcely any of its warmth directly from the sun's rays, but is heated almost entirely by the ground on which it rests, and it is therefore in the condition of the water in a boiler where the heat is applied from below. The Temperature of the Air on the surface of the Earth varies with the height above the level of the sea, and with local circumstances. It decreases from the Equator to the Poles. The greatest Heat in the Air seldom exceeds 150 Fahr., and the greatest cold is seldom more than 74 Fahr. below freezing point. Air is increased in Volume by Elevation of Temperature: the volume varies as the absolute temperature when the pressure is constant. Absolute temperature is measured from absolute zero, which is 461 below zero of Fahrenheit's scale, at which point air has no elasticity, therefore it has been adopted as that of absolute zero. The absolute temperature is found by adding 461 to the temperature indicated by a Fahrenheit- thermometer. The increasad volume of a constant weight of air of which the initial volume = i taken at 32 Fahr., heated to a given temperature under atmospheric pressure, or 14-7 lbs. per square inch, may be found by this Rule : Increased volume of Air = Gjven temperature + 461 32 + 461 If the temperature be taken at 62 instead of 32, the divisor is 62 + 461 = 523- Example : Required the increased volume of a constant weight of air al 75 Fahr., of which the initial volume = i at 32 Fahr. Then 7 -^ Q = 1-087, the increased volume of air by expansion. 32 -j- 401 Table No. i has been calculated by this rule. PRESSURE OF AIR. The volume of a constant weight of air for any pressure, when the volume at a given pressure is known, the temperature remaining constant, may be found by this Rule : New volume of Air = Given volume x given pressure New pressure The product of the pressure and volume of air is proportional to the absolute temperature. The pressure of air varies directly as the absolute temperature when the volume is constant, and inversely as the volume when the temperature is constant. The pressure of a constant weight of air for any other volume and temperature, when the pressure is known for a given volume and tempera- ture, may be found by this Rule : New pressure of Air = Given pressure x Given volume x New absolute temperature. New volume x Given absolute temperature. Table i. INCREASED VOLUME OF ATMOSPHERIC AIR BY EXPANSION DUE TO ELEVATION OF TEMPERATURE. At 32 Fahr. vol. ^qual i -ooo 1 U; 100 Fahr. vol. equal 137 35 i -006 , uo I 5 8 40 1-018 , 120 178 45 I-O26 , 130 I 9 8 50 1-036 , 140 219 55 1-046 , 150 239 ,, 60 , 1-056 , 160 259 65 I -066 , jyo , 279 70 1-077 , i 80 300 ;: 75 1-087 , 190 320 80 1-097 , 200 '341 8 5 1-107 , 210 361 9 o 1-117 , 212 365 95 1-127 . 230 402 The Mean Pressure of the Atmosphere at the level of the sea is equal to 14-7 Ibs. per square inch, being the weight of a column of air one inch square, of the height of 27,800 feet at 32 Fahr. of uniform density equal to that of air at the level of the sea. This is called one atmosphere of pressure, and it is taken in round numbers at 15 Ibs. pressure per square inch. The Atmospheric Pressure is equal to 144 square inches x 14-7 Ibs. = 2116-8 Ibs. per square foot. A Column of Mercury 29-922 inches high or in round numbers 30 inches high at 32 Fahr. will equal or balance the pressure of the atmo- sphere, at the mean level of the sea. A Column of Water at 62 Fahr. i inch square and 33-947 feet high or in round numbers 34 feet high will equal or balance the pressure of the atmosphere. 8 THE PRACTICAL ENGINEER'S HAND-BOOK. A Column of A 2 ' = 1893 feet high, at 32 Fahr. of uniform density equal to that of air at the level of the sea, will equal a pressure of i Ib. per square inch. A Column of Mercury ?2!S2*_ = 2*035 inches high at 32 Fahr. .will equal a pressure of i Ib. per square inch. A Column of Water 33 947 _ 3-309 feet high or in round numbers H'7 2-31 feet high; or 2-31 x 12 = 27-72 inches high at 62 Fahr. will equal a pressure of i Ib. per square inch. The Atmospheric Resistance to moving bodies increases as the square of the velocity of the body : and the atmospheric resistance in Ibs. per square foot of frontage of a moving body increases as the square of the velocity in feet per second multiplied by '0017. Example: W'hat amount- of atmospheric resistance is opposed to the front of a locomotive engine having a frontage-area of 30 square feet, at a speed of 40 miles an hour ? 1 760 yards x 3 feet x 40 miles Then 60 minutes X 60 seconds = 58 ' 66 ' &nd 5 8 ' 662 * '0017 x 30 feet area = 175*49 Ibs. atmospheric resistance opposed to the front of the locomotive engine. The Atmospheric Resistance on Railways, independent of side winds, at ordinary speeds, is equal to about one-half the gross resistance, or from 3 Ibs. to 4 Ibs. per ton of the weight of the engine, tender and train. With average side winds a constant total resistance of 8 Ibs. per ton of the weight of the engine, tender and train, is usually adopted in calculations of this kind. The Weather-Barometer is an instrument for measuring the atmos- pheric pressure, the pressure being measured by a column of mercury which rises or falls as the weight of the atmosphere increases or diminishes. It consists of a straight glass tube, 33 inches long, closed at the top, containing mercury ; the lower end dips into a cup of mercury placed at the bottom of the tube. There is a space at the top of the tube, free from air and moisture, and the mercury is raised in the tube by the atmospheric pressure on the mercury in the cup ; the level of the mercury in the tube varies with the heaviness or lightness of the atmosphere. The graduations on the instru- ment indicate weather as follows : Height of the Mercury in Inches. 28 indicates Stormy weather. 28*5 , Much rain. 29 29-5 3 3'5 Rain. Change of weather. Fair weather. Set fair. Very dry. ATMOSPHERIC PRESSURE. 9 A Barometer has sometimes been used instead of a vacuum-gauge, but it differs in construction from the weather barometer, and consists of a glass tube bent in the form of an inverted syphon. One leg of the syphon- shaped tube is open to the atmosphere and contains mercury ; the end of the other syphon-leg is connected by a pipe to the condenser, and the mercury rises in this leg according to the amount of vacuum and falls according to the amount of vapour. When not in operation the mercury will stand at the same level in both legs of the syphon. If there were a perfect vacuum in the condenser, as each pound of vacuum represents 2 inches of mercury, the pressure of the atmosphere in one leg would cause the mercury to rise in the other leg of the syphon connected to the con- denser to a height of 30 inches, when it would balance the atmospheric pressure and indicate 15 Ibs. of vacuum; if the mercury rose to 26 inches it would be 13 Ibs of vacuum, and so on, the indicated pressures being those below atmospheric pressure. The Ordinary Weather-Barometer can be used for ascertaining the heights of mountains. The mercury falls on being taken to a height above the ground at the rate, approximately, of one-tenth of an inch for every hundred feet of vertical height, because the atmospheric pressure decreases with the height above the surface of the ground. The Aneroid-Barometer is the best instrument for ascertaining heights, because it is extremely sensitive and contains no liquid. It consists of a round metal box, exhausted of air, in the top of which a very thin and flexible sheet-metal plate is placed, which yields to the pressure of the atmosphere, and actuates a system of multiplying levers and a spring connected to an index, which moves on a scale. The Pressure of the Atmosphere in Ibs. per square inch cor- responding to the Height of a Barometer may be found by mul- tiplying the weight of a cubic inch of mercury, =-4908 lb., by the height of the barometer in inches. The following Table has been calculated by this rule. Table 2. PRESSURE OF ATMOSPHERIC AIR AT DIFFERENT HEIGHTS OF THE BAROMETER. Height of the Barometer. Pressure of the Air in Ibs. per Square Inch. Pressure c f the Air in Ibs. per Square Foot. Height of the Barometer. Pressure of the Air in Ibs. per Square Inch. Pressure of the Air in Ibs. per Square Foot. Inches. Inches. 27 i3 >2 5 1908-23 29-25 U'35 2067-24 27-25 3"37 1925-89 29-50 i4'47 2084-92 27 50 2775 3'49 13-61 i943'5 6 1961-23 29-75 30 14-60 14-70 2IO2'58 2116-80 28 i3'74 1978-90 30-25 14-84 2I37-92 28-25 13-86 1996-56 30-50 14-96 2i55'59 28-50 13-98 20I4-24 3075 15-09 2173-26 28-75 2 9 14-11 14-23 2031-9! 2049-58 3 1 31-5 15-22 15-46 2190-94 2226-27 10 THE PRACTICAL ENGINEER'S HAND-BOOK. PRESSURE AND VELOCITY OF WIND. Wind is air in motion, due to the disturbance of the equilibrium in some part of the atmosphere, caused by a difference in temperature of adjacent countries ; the air in one part having become heated expands, and being lighter, rises, and the motion of the cooler air in rushing in to supply its place produces a current, the velocity of which depends upon the difference between the temperatures. The Velocity of the Wind increases with altitude. The velocity at different altitudes may be calculated by the following Rule: V 4 /H = A / - in which V, v, H, h, are the velocities and heights at the lower v V h and upper levels respectively. The Force of Wind increases as the square of its velocity. The ratio of the different forces exerted by two winds of different velocity is found approximately by squaring the ratio of their velocities. Thus, a wind blowing at the rate of 60 miles an hour has a velocity three times greater than that of another wind moving at the rate of 20 miles an hour, and the former will exert a force approximately equal to 3x3 = 9 times greater than that of the latter. Pressure and Velocity of Wind. The force or pressure of wind may be found by the following Rule, deduced from the results of recent experiments. Pressure of Wind in Ibs. per square foot= (velocity in feet per second) 2 X'0017. Example : Required the pressure of the wind in Ibs. per square foot when its velocity is 42 feet per second. Then 42X42X '0017=3 Ibs. pressure per square foot. The Velocity of the Wind in feet per second may be found by the following Rule : Velocity of wind in feet per second = ^/Pressure m lb^e7sqlIa7e"fobT: V -0017 Example : Required the velocity of the wind in feet per second when its pressure is 40 Ibs. per square foot, then A / 4 = 154, the wind's V -0017 velocity in feet per second, and its velocity in miles per hour = 154 feet per second x 60 seconds x 60 minutes T = 105 miles per hour, the 1 760 yards x 3 feet wind's velocity. A column of water i inch high exerts a pressure on the base of 5' 196 Ibs. per square foot, therefore a pressure of i Ib. per square foot would equal ' = '192 inch of water pressure. Table 3 has been calculated by these rules. It will be found useful in making calculations of the pressure of wind on structures ; the power of fans and blowers, and of natural draught and forced draught in chimneys. PRESSURE AND VELOCITY OF WIND. I I Table 3. PRESSURE AND VELOCITY OF WIND. WIND-PRESSURE. WIND'S VELOCITY. Description of Wind. Pressure in Ibs. per Square Foot. Pressure in Inches of Water. Velocity in Feet per Second. Velocity in Miles per Hour. Bu. Inches. 1 048 12-13 8-2 7 Gentle wind. 2 096 I7-I5 11-69 Pleasant wind. 144 21 I4'3I Fresh breeze. I 192 24-25 16-53 Strong breeze. It 288 29-71 20'O2 If -311 32-08 2I-87 Gale. 2 384 34-3 23-38 4 4 80 26-14 Brisk gale. 3 '577 42-OO 28-63 si 45'37 3'93 Strong wind. 4 769 49 33-60 5 962 54 36-81 Moderately high wind. 6 154 59 40-22 High wind. 7 347 64 43-63 8 '539 69 47-04 9 731 73 49-81 10 924 77 52-50 Very high wind. ii 2'Il6 80 54-55 12 2-309 84 57-27 13 2-501 88 60-00 Storm. H 2-693 9i 62-04 15 2-886 94 64-09 16 3-078 97 66-13 Great storm. 17 3-271 loo 68-18 18 3-463 103 70-22 19 3-655 106 72-27 . 20 3-850 109 75-26 Very great storm. 2 5 4-810 122 83-18 Tempest. 30 5-772 J 33 90-68 Hurricane. 35 6-734 144 98-56 40 7-696 105-00 Great hurricane. 45 8-658 163 iirai 50 9-620 172 117-27 Violent hurricane. 55 10-582 1 80 122-72 60 11-544 1 88 128-03 Very violent hurricane. 65 12-506 196 133-63 70 13-468 203 138-41 75 14-430 210 143-18 80 15-392 217 147-95 Tornado. 85 i6-354 224 152-72 90 17-316 2 3 156-81 95 18-278 237 161-39 IOO 19-240 245 167-04 12 THE PRACTICAL ENGINEER'S HAND-BOOK. WIND-MOTORS. Windmills are efficient and economical motors for intermittent work, or where the nature of the work admits of its being suspended during a calm, which seldom lasts more than two days at a time. Taking the average of the running of windmills for a year, it has been found that they may be depended upon working constantly for at least one-third of the time, or 8 hours out of 24. The average velocity of the wind being 1 5 miles an hour. Windmills, shown in Fig. i, may be applied to working pumps, for supplying water for domestic use, irrigation, drainage, compression of air, or driving dynamo machines. They are fitted with self- adjusting sails and self-winding tackle to keep the mill always in wind, and require no attention except filling the lu- bricators, which are arranged to hold a supply of lubricant to last one or two months. The Length of the Whip, or radial arms of the sails of a windmill, depends upon the power, situation, and velocity required ; the sails are frequently made rectangular, and the length is equal to five times the breadth. The Whip is divided into seven equal parts, six of those parts, from the ex- tremity, being the length of the sails. The weather-board, or wind-board, is equal to one-fifth of the sail's breadth. The Shaft on which the sails are fixed may have an angle with the horizon between 10 and 15. The Total amount of Sail-Surface should not exceed one-fourth of the whole disc-surface described by the whip or radial arms of the sail. In order to gain the greatest amount of the wind's impulsive effect to produce circular motion by the sails of a windmill, the total surface of sails presented to the wind should be about seven-eighths of the circle's surface which is formed by their motion, and each sail should be angled to the plane of motion as follows, the whip or back being divided into six equal parts : Distance from the centre of motion .12345 Angle with the plane of motion . . 24 21 18 14 9 The Horse-power of a Windmill, H. P., may be found Rule : TT p _ ('Total area of sauVv /Velocity of the wind \ 3 ~~ V in square feet ) \'m feet per second ) 1,100,000 Fig. i.-WindnulL 6 by this WIND-MOTORS. The total area, A, in square feet of the sails of a windmill may be found by this Rule : Horse-power x 1,100,000 A = (wind-velocity in feet per second) Table 4. EFFICIENCY OF WINDMILLS TURNING 8 HOURS A DAY AT A SPEED OF 15 MILES AN HOUR WHEN USED FOR WORKING PUMPS. Diameter of Windmill. Number of Revolutions per Minute. Actual Horse -power developed. Quantity of Water raised daily to a Height of 25 Feet. Quantity of Water raised daily to a Height of 50 Feet. Quantity of Water raised daily to a Height of zoo Feet Feet 12 15 18 55 5 45 i 1 fl 1 Gallons. 13500 20OOO 4OOOD Gallons. 6750 IOOOC 200OO Gallons. 3375 5000 IOOOO 20 22 24 40 36 t I || 5OOOO 60000 80000 25000 3OOOO 40000 12500 15000 20000 3 2 36 24 if I 1 0000 1 60000 55000 8OOOO 27500 40OOO 40 22 2 2OOOOO IOOOOO 5OOCO The Fantanemone or Universal- Win dm ill, shown at Fig. 2, is a recent continental invention in wind-motors. Two plane surfaces in the form of semi-circles are mounted at right angles to each other upon a horizontal shaft, and at an angle of 45 with respect to the latter. These motors it is said work satisfactorily whatever may be the direction of the wind. One of them has been working in the vicinity of Poissy for several years, where it lifts about 40,000 litres of water to a height of 20 metres every 24 hours, in a wind of a velocity of from 7 to 8 metres per second. Another one raises about 150,000 litres of water to the Villejuif Reservoir at a height of 10 metres every 24 hours, in a wind of a velocity of 5 to 6 metres per second. The Horse-power, H. P., of the Fantanemone may be found by this Rule : /Total area of sails^ V in square feet ) H. P. = Fig. 2. Pantanemone. /Velocity of the windy ^ in feet per second ) 1,200,000 14 THE PRACTICAL ENGINEER'S HAND-BOOK. The total Area, A, in square feet, of the sails of the Pantanemone, may be found by this Rule : . _ Horse-power x 1,200,000 ~~ (wind-velocity in feet per second) 3 . WATER AND WATER-MOTORS. Water is composed of two gases, hydrogen and oxygen, in the propor- tion of one part of hydrogen and eight parts of oxygen. Water dissolves more substances than any other agent : it freezes at a temperature of 32 Fahr. The Weight of a cubic foot of Ice is from 57-5 to 58 Ibs., its specific gravity being about '922. Water in freezing expands about -^ih of its original volume as water, its expansive force at the moment of freezing being estimated at about 32,000 Ibs. per square inch. A cubic foot of ice floating in water has about -f^ths of its volume under water, and -^th of its volume above water, and a square foot of ice of any thickness requires a weight equal to xV-h of its weight to sink it to the surface of the water. The compressive strength of hard pure block-ice is about 20 tons per square foot. The specific heat of ice is -504. Snow weighs 6 Ibs. per cubic foot when freshly fallen, and averages 12 Ibs. per cubic foot when moderately saturated with rain.- Snow has 12 times the bulk of water, and its specific gravity is '084. The Standard Measures of water are as follows : The weight of one cubic inch of pure water at 62 Fahr. = 252-505 grains. 32 ,, = -03612^. 39 -I = -036125 Ib. 62 = -03608 Ib. 212 = -03451 Ib. The Weight of one cylindrical inch of pure Water at 62 Fahr. =. 4533 ounce or -02883 Ib. The Weight of one cubic foot of pure Water at 32 Fahr. =62-418 Ibs. ,, 39'i =62-425 Ibs. 62 =62-355 lbs - ,, ,, 212 ,, =59-640 lbs. The weight of a cubic foot of water is usually taken at 62-4 lbs. per cubic foot for ordinary calculations. A cubic foot of water at the temperature of maximum density weighs 998-8 ounces it is usually taken at 1000 ounces. One Gallon of pure Water at 62 Fahr. weighs 10 lbs., and its volume is 277-123 cubic inches, or -160372 cubic foot. The Volume of 1 Ib. of pure Water at 32 Fahr. = 27-684 cubic inches. 39-1 = 27-680 62 = 27-712 212 = 28-978 The volume of one ton of pure water = 35-9 cubic feet. EXPANSION OF WATER BY HEAT. 15 The volume of pure water at 62 in cubic inches x -0036 = capacity in gallons. The pressure of a column of water i foot high = I = -433 lb., or 6-928 ounces, per square inch pressure. The pressure of a column of water 33-947 feet, or say 34 feet high = the pressure of the atmosphere, or 147 Ibs. The pressure of a column of water 33'947 feet high =2-309 feet high, or say 2-31 feet high=i lb. per square inch pressure. 'Expansion of Water by Heat. Water expands as the temperature rises above the temperature of maximum density, 39'iFahr., it also expands in nearly an equal ratio, as the temperature falls below this point, down to the freezing point. Table 5. TEMPERATURE AND VOLUME OF WATER. Temperature. At 40 Fahrenheit, its volume i -ooooo M 55 1-00054 65 ?> I-OOI37 75 > j> 1-00255 85 )> ?> I -00404 95 ?> > 1-00583 105 I -OOSOO ,, 115 J 3> I-OII2I 125 5> .'3 I-OI275 135 j> ;> I-OI55I 145 ?> 1-01847 . i55 j> I-02I62 165 I-O250O i75 1-02845 185 > 1-03209 i95 J> 5> 1*03590 ,, 205 1-03984 212 " I-04600 The Evaporation from the Surface of Water in Lakes, Canals and Rivers in this country probably averages a total of 8 inches in spring, 1 2 inches in summer, 7 inches in autumn, and 4 inches in winter : equal to 31 inches per annum. The annual evaporation in some districts has been found to average 75 per cent, of the annual rainfall, and in others it has been found to exceed the annual rainfall. Weight of Sea-water. The weight of one cubic foot of sea-water at 62 = 64 Ibs.: 35 cubic feet of sea-water = i ton. The weight of a cubic yard of sea-water =15 cwt. i qr. 20 Ibs., or nearly 15^ cwt. Itf THE PRACTICAL ENGINEERS HAND-BOOK. The weight of fresh water compared with that of sea-water is as i to 1-026, or as 39 to 40. The Mean Specific Gravity of Sea-water is 1-026 : in the Black Sea it is i'oi6 : in the Indian Ocean, 1-0264 : in the North Atlantic Ocean, 1-0267: in the South Atlantic Ocean, 1-0268: in the Red Sea, 1-0286: and in the Mediterranean Sea 1*029. The Composition of Average Sea-water is as follows : Water . Chloride of Sodium . Chloride of Magnesia Sulphate of Soda Carbonate of Lime Sulphate of Lime 96-6 parts. 2-6 "4 '37 .-, 02 01 1 00 '00 Table 6. COMPONENTS OF THE SALTS OF SEA- WATER. Ingredients. PER 100 PARTS OF TOTAL SALTS. PER TOO PARTS OF HALOGE j CALCULATED AS CHLORINE. Dittmar. Dittmar. Forchammer. Chlorine .... Bromine . . . . Sulphuric Acid (S O 3 ) . Carbonic Acid (C O 2 ) . . Lime (Ca O) . Magnesia (Mg O) . . Potash (K 2 O) . Soda (Na 2 O) Basic equivalents to the Halogens Total Salts . 55-2 9 2 1884 6-410 152 1-676 6'209 r 33 2 41*234 12-493 99-848 3402 II-576 2742 3-026 11*212 2-505 74-464 Not determined. " n-88 " Not determined. 2-93 11-03 r 93 Not determined. IOO 180-584 181-1 The mean quantity of solid substances chiefly salt held in solution by sea-waiter is 3-4 per cent., three-fourths of which is common salt. The Quantity of Salt in Sea-water varies in different seas. The waters of the White Sea, the Baltic Sea, and the Polar Seas contain very little salt, but the Red Sea contains a large quantity of salt. The Red Sea contains 4-32 per cent, of salt: the Baltic Sea, 5 per cent. : and the sea at Cronstadt contains 2 per cent, of salt. The Ice of Sea-water contains no salt, because water in freezing parts with all its impurities. Ordinary Sea-water contains -^ part of its weight of salt, called i degree of saltness. BOILING POINTS OF SEA-WATER. The weight of Salt in a Gallon of Sea- water may be ascertained as follows : If thirty-three pounds weight of sea-water be evaporated, it will leave one Ib. of salt or ^rd of its weight. One gallon of sea- water weighs io|- Ibs., T Vd part of which is salt, therefore the quantity of salt contained in one gallon is *g^5 Ibs. x 16 ounces = ^ ^^ or . Q round numbers 5 ounces of salt per gallon of sea-water. Sea- water Boils at 2i3'2 Fahr. under the pressure of one atmosphere, or when the mercury in the weather-barometer stands at 30 inches/ The boiling point of sea-water varies with the quantity of salt held in solution, and rises in proportion to its concentration as brine ; it also varies with the rise and fall of the weather-barometer. Saturated Brine boils under the pressure of one atmosphere at 226- 4 Fahr. The point of Saturation of ordinary Sea-water is if of its weight, when the water is so full of salt that it will hold no more, and it is therefore rapidly precipitated. The Boiling Point of Sea-water may be calculated from its density as follows : It is found that -J^-rd part of salt increases the boiling point to the extent of i'2 Fahr. ; the boiling point of fresh water being 212 Fahr., that of ordinary sea-water will equal 212 + i - 2 = 2I3'2 Fahr. at atmospheric pressure, or when the weather-barometer stands at 30 inches. The following Table has been calculated in this way, each degree of salt representing 5 ounces of salt per gallon of sea-water. Table 7. BOILING POINTS OF SEA-WATER OF VARIOUS DENSITIES UNDER ONE ATMOSPHERE OF PRESSURE. Part of Salt. Degrees of Salt. Ounces of S 22\ 2I 7'5 W 25 2l8 o ~/3 ,, 6 ,, ,, ... 30 219 '2 7 "33" ,,7 . 35 220'4 8 ... 40 22I'6 -Ts ,,9 M ' . 45 222 C '8 TT 10 ., ... 50 224 H ii ,, . . 55 225'2 if 12 Saturated brine . . . 60 226'4 1 8 THE PRACTICAL ENGINEER'S HAND-BOOK. The above Table gives the boiling points when the mercury in the weather barometer stands at 30 inches or atmospheric pressure, and in using the Table an allowance must be made when the barometer stands above or below that point. As i degree of salt increases the boiling point to the extent of i'2, it will be sufficiently near in most cases to deduct two- thirds of i '2 or '8 from the boiling point for every | inch the barometer registers below 30 inches, or to add the same for every | inch the mercury stands above 30 inches. Example : The boiling point given in the Table is 215-1 for 2\ degrees of salt when the barometer stands at 30 inches, required the boiling point when the barometer stands at 30! inches, or | inch higher. Then 215'! -f '8 = 215*9, t^ 6 boiling point of water containing 2\ degrees of salt when the mercury in the barometer stands at 30^ inches. DENSITY OF SEA-WATER. SALINOMETERS. BLOWING-OFF. The Working Density or Saltness of Water, when sea-water is used in marine boilers, is from i| to 2 degrees of saltness, or from \\ to ^V^s its weight of salt : the maximum density seldom exceeds -gV^s. A Boiler is said to be Salted when there is an accumulation of salt on the tubes and heating surface. Four degrees of saltness, or -gVcIs, deposits salt rapidly. Salting is prevented by scumming and by frequently and regularly blowing off a portion of the boiler-water. Scum-Cocks. The salt and dirt floating on the surface of the water in a marine-boiler can be blown into the sea by means of the scum-cocks. These cocks are fixed on the shell of the boiler, and are connected to a cock fixed on the ship's side by a pipe. From each scum-cock a pipe is carried inside the boiler, having a dished end placed a little below the working level of the boiler, which collects the refuse from the surface of the water. The scum-cocks are used whenever the surface of the water is considered to be dirty, or when the limit of density is reached. They must be shut before the water level has fallen too low. Neglect of the cocks leads to their sticking fast, and renders the boiler liable to become salted and the tubes to become burnt. A Hydrometer or Salinometer is an instrument for measuring the density or degree of saturation of the water when sea-water is used in a marine-boiler. It consists of a bulb of glass or metal having a graduated stem at the top, and a stem at the bottom filled with mercury to make the instrument swim upright. It acts by sinking into the water more or less according to the degree of saltness of the water, the salter the water the less will it sink. The salinometer is graduated into 33rds, representing 5 ounces of salt per gallon of water. To graduate the stem, the zero point is marked at which the instrument floats in fresh water, it is also marked at the level at which it floats in sea-water of the average degree of saltness. The space between these two fixed points is divided into ten parts or degrees of the salinometer, and the graduations are extended to 35. Every 10 represents -g^rd of saltness ; 10 represents the density of sea- BLOWING-OFF SEA-WATER. 19 water: 15 = i| the density: 20 = twice the density: 25 = 2\ times the density, and 30 = tnree times the density of sea-water. A Hydrometer or Salinometer cannot be used at any temperature indiscriminately, because it is graduated for a fixed temperature, and it should only be used in water of the temperature for which it was marked ; therefore it is necessary to test the water with a thermometer before using the instrument, when accuracy is required. Hydrometers or Salinometers are usually marked to suit a temperature of 200 Fahr., this being about the temperature of the boiler-water immediately after being drawn off for testing ; therefore it is only necessary to use a thermometer with the instrument when great accuracy is required. To test the boiler-water in the absence of a salinometer, draw off and boil a small quantity of the water, and test it with a thermometer to ascertain its boiling point in the open air, from which the degree of saltness corresponding to its boiling point may be ascertained from Table 7. Blowing-off is practised in marine boilers which are fed with sea-water, to prevent the degree of saltness of the water exceeding a particular density, the supersalted water being got rid of by blowing off a portion of the boiler-water into the sea, which is replaced with sea-water of ordinary density. The Quantity of Peed- Water required when blowing-off is practised, is equal to the sum of the quantity of water evaporated to steam and the quantity blown off. The Quantity to be Blown Off to maintain a constant density, may be found by dividing the number of cubic feet of feed-water by the number of degrees of saltness. Example : A marine boiler is to be kept at two degrees of saltness. How much water must be blown off? Then if i = the quantity of feed- water, i -r- 2 = "5, or one-half the quantity of feed-water must be blown off to prevent the degree of saltness rising above -%> or IO ounces per gallon. The Quantity to be Blown Off may be calculated from the water evaporated, by this Rule : Subtract i from the number of degrees of saltness, and by the remainder divide the quantity of water evaporated. Example: if 1200 gallons of water be evaporated to steam, what quantity of brine must be blown off, that the water in the boiler may be maintained at -/-$, or three degrees of saltness. Then = 600 gallons must be blown off. The Quantity of Water Evaporated may be calculated from the quantity blown off, by this Rule : Subtract i from the number of degrees of saltness, and multiply the remainder by the quantity of water blown off. Example : If 600 gallons be blown off, what number of gallons have been evaporated to steam, the water in the boiler being maintained at T "y, or three degrees of saltness ? Then 31 = 2 x 600 = 1200 gallons, the quantity of water evaporated. The Quantity of Water Blown Off maybe calculated from the weight of salt per gallon, by this Rule : Divide the number of ounces of salt per gallon of feed-water by the number of ounces per gallon of boiler-water, and the quotient will give the proportion of feed-water to be blown off. Example i : The feed-water contains 4-2 ounces of salt per gallon, and C 2 2O THE PRACTICAL ENGINEER'S HAND-BOOK. the water in the boiler contains 1 2 ounces of salt per gallon. What pro- portion of the quantity of the feed-water should be continuously blown off ? Then 4-2 ounces of salt per gallon of feed-water^ a ^ mQre 12 ounces of salt per gallon of boiler-water than one-third of the feed-water should be blown off. Example 2 : If the feed-water from a surface condenser has only a trace of salt, say '04 ounce per gallon, and it is required to work the boiler at '8 ounce of salt per gallon, what percentage of the feed-water must be blown off after the water in the boiler has reached this degree of saltness ? rp, IOQ x '04 ounce of salt per gallon of feed-water _ _ er n v t 8 ounce of salt per gallon of boiler-water The Saltness of the Water in the boiler may be calculated from the weight of salt per gallon of feed-water, by this Rule : Divide the number of ounces of salt per gallon of feed-water by the fraction of the feed con- tinuously blown off, the quotient will be the number of ounces of salt per gallon of the water in the boiler. Example : The feed-water contains 4-2 ounces of salt per gallon, and 35 of the feed is continuously blown off. What quantity of salt does the water in the boiler contain ? Then 4^ounces of saltj pergallcmof feed-water_ = ^ ^^ Qf ^ '35 proportion of feed-water blown off per gallon contained in the water of the boiler. The Saltness of the Feed-water may be calculated from the quantity of salt in the boiler-water, and the quantity of feed-water blown off, by this Rule : Multiply the quantity of salt in ounces per gallon of water in the boiler, by the proportion of feed-water blown off. The product will be the quantity of salt in ounces per gallon of feed water. Example: If the water in the boiler contains 9 ounces of salt per gallon, and one-eighth of the feed-water is continuously blown off, what quantity of salt is contained in the feed- water ? Then 9 ounces per gallon of boiler- water x '125 blow-off = ri25 ounces of salt per gallon, is contained in the feed-water. It may also be ascertained as follows : i : 9 : : '125 = 1-125 ounces per gallon of feed-water. The pressure of Steam required to expel the Brine at a depth below the surface of the sea, may be ascertained as follows : A pressure of I Ib. per square inch is equal to a column of sea-water = 2-3 1 height of a column of fresh water = ^ ^ ^ ^ 1*020 specific gravity 01 sea-water hence the Rule: Divide the depth in feet of the level of the water in the boiler, below the surface of the sea, by 2-251, the quotient will be the force or pressure in pounds per square inch required to expel the brine. It may also be ascertained as follows: the pressure of the atmosphere= 14-7 Ibs. being balanced by a column of sea-water = 34 feet height of a column of fresh water '~T^6lpecific gravity of sea-water As 33-128 feet : depth in feet below sea-surface : : 14-7 Ibs. = the pres- LOSS OF HEAT BY BLOWING-OFF. 21 sure of the water in Ibs. per square inch ; and pressure ot water + 14-7 = the total pressure at the given depth. Example i : What pressure of steam is required to expel the brine,. the level of the water in a marine boiler being 12 feet below the surface of the sea ? Then 12 -h 2-251 = 5-33 Ibs. pressure, or as 33*138 : 12 : : 147 = 5-32 Ibs. pressure. Example 2 : What pressure of steam is required to expel the brine from a marine boiler having its water-level 1 1 feet below the surface of the sea, the pressure of steam being 25 Ibs. per square inch? Then - = 4'88 Ibs. pressure of water, and 4-88 + 14*7 = iy'58 Ibs. total pressure at u feet, and the force available to expel the brine is 25 19'58 = 5'42 Ibs. per square inch. The Loss of Fuel and Heat by Blowing-off may be found as follows : Let N = the number of times the density of the boiler-water is greater than that of the feed-water. ,, T = the temperature of the water in the boiler in degrees Fahr. ,, t = the temperature of the feed-water in degrees Fahr. Then, the loss per cent, of the fuel used= T-t (N- The loss per cent, of the total heat in the boiler= lOoxT t (N-i) Example: The density of the water in a marine boiler is i'8 times greater than that of the feed-water, the temperature of the boiler-water is 245 Fahr., and that of the feed-water 45 Fahr. Required the loss per cent, of the fuel used by blowing off, and also the loss per cent, of the total heat in the boiler ? Then - 2*tlL= - = i-8-i='8, and (r8- 1) 245 x -3 = 73-5 + iii5 = n88-5-45 = ii43 < 5 x ' 1114-8 and 245 45 = 200, then - 2 ='178, the loss per cent, of the fuel 1 1 140 used. The loss per cent, of the total heat in the boiler will be ^- X ._ 2 45:z45 ------ 8 C ent. of heat lost by - (i-8- 1) (1115. ;--3X2 4 5- 4 5)-r- 245-45 blowing off. The Loss of Fuel and Heat by Blowing-off may also be found as follows: Let B = the number of cubic feet of water blown off every 3 hours. E = the number of cubic feet of water evaporated every 3 hours. ,. T = the temperature of the water in the boiler in degrees Fahr. ,, t = the temperature of the feed- water in degrees Fahr. 22 THE PRACTICAL ENGINEER'S HAND-BOOK. The number of cubic feet of water entering the boiler every 3 hours will equal B + E. The total units of heat in steam of 212 Fahr. = 1115+ -3 x 212 = 1115 + 63-6 = 1178*6 units total heat. To evaporate E cubic feet of water to steam will require (1178-61) E units of heat. To boil the B feet of water blown off will require (T 1) B units of heat. The total loss will be (T-t) B. The total quantity of heat used will be (1178-6-1) E + (T-t) B, as out of (1178-6-1) E + (T-t) B there is lost (T-t) B. Thelossof heatby blowing-off= - Thelossper cent.of thetotalheat in the boiler ^^--- Example : A marine boiler is blown out every hour: 140 gallons being expelled each time, and 420 gallons are evaporated in the same time. The temperature of the water in the boiler is 242 c- 8 Fahr., and that of the feed-water is 42'8 Fahr. Required the loss per cent, of the total heat in the boiler ? Then 140 gallons blown off per hour equal 140 x 3 = 420 gallons, or 420 -=- 6-25 = 67-2 cubic feet of water blown off every 3 hours. 420 gallons of water evaporated per hour = 420 x 3 = 1260 gallons, or 1260 -;- 6*25 = 201-6 cubic feet of water evaporated every 3 hours. ioox(2 4 2 -8- 4 2 -8)x67-2 ; =:I178 ( ^~^ = _ (ii 7 8-6-42-8)X20i-6-K242 -8-42 -8)x6 7 - 2 1135-8 x 201-6 = 228, 977'28 + (242-8 42-8) x 67-2 = 242, 417.28 units, the loss of heat by blowing-off : and 100 x (242-8 42-8) x 67-2= icox 200 x 67-2 = i, 344,000, then I ' 344 ' =5'54 per cent, of the total heat in the 242,417-28 boiler lost by blowing off. When the temperatures are expressed in degrees Centigrade, the same rule can be used as the last, by changing the constant 1178-6 Fahr. in the last rule, to 637-2 C., that being the number of units of heat in i Ib. of steam at 100 C., or 212 Fahr. The Density of the Water in the Boiler may be calculated from the quantity blown off by the following Rule : where L=loss per cent, of the fuel used. The density of the boiler-water above that of the feed= T-t 5 + - 3 T-t) Example: If the loss by blowing off is equal to th or 'iz'-j of the fuel used, the temperature of the steam being 248 Fahr., and that of the feed-water 108 Fahr., at what density should the boiler- water be main- tained above that of the feed-water ? 248-108 125 Then MEASUREMENT OF FLOWING WATER. and and 248 io8=i4O, then -4=n89-4 io8=io8i'4X-i25 = . = 1-4 +1 = 2 -4, the amount 140 the density of the boiler-water should exceed that of the feed-water. MEASUREMENT OF FLOWING WATER, The Height of the Pall should be measured from the level of the ivater in the head-race to the level of the water in the tail-race. Measurement of Flowing Water by a Notched-Board. The quantity of water in a stream, available for driving a turbine, may be measured by means of a notched board as shown in Fig. 3, with which proceed as follows : Fig. 3. Notched-board for measuring flowing water. Place a board across the stream at a point where the water flows very slowly ; cut a notch in the board sufficient in depth to pass all the water to be measured, and not more than two-thirds of the width of the stream in length. The edges of the notch on the bottom and sides must be bevelled to almost a sharp edge towards the downstream side as shown, and the surface of the water below the notch should not be less than one foot. About 3 feet behind the notch drive a stake into the bottom of the water-course, the top of the stake being level with the notch. When the water has reached its greatest depth, measure the depth, marked h in figure 3, from the surface to the top of the stake, by a thin-edged rule. The following Table will show the quantity of water in cubic feet per minute for weirs from one inch to twenty-five inches in depth. The number in the Table corresponding to the depth h when multiplied by the 24 THE PRACTICAL ENGINEER'S HAND-BOOK. length of the notch in inches, will give the quantity of water in cubic feet per minute. For instance, if the depth of the notch be 5 inches and its length 40 inches, the multiplier given in Table 8 is 4-5 ; and the quantity of water delivered in cubic feet per minute is = 4*5 x 40 = iCo cubic feet. Table 8. MULTIPLIERS FOR FINDING THE QUANTITY OF WATER FLOWING OVER A NOTCHED-BOARD OR WEIR. Depth of Weir (AX Multiplier. Deoth of Weir (AX Multiplier. Depth of Weir (k). Multiplier. Depth of Weir (h). Multiplier. I 40 ? L 7-84 I 3 1 19-42 i9i 33'94 I* '55 7\ 8-25 13! 19-97 I9 34-60 If '74 7f 8-66 J 3f 20-52 I 9r 35-27 If '93 8 9-10 14 21*09 20" 35-94 2 1-14 8i Q'52 X 4l 2I-65 20| 36-60 2 4 1-36 8 i 9-96 : 4| 22'22 20| 37-28 2\ i '59 8| 10-40 144 22'79 2O| 37*96 2| 1-83 9 10-86 15 2 3'38 21 38-65 3 2-09 9i 11-31 !5i 23-97 21 4 39-34 3i 2-36 9f 11-77 15^ 24-56 2\\ 40-04 31 2-63 9f 12-23 15! 25-16 2lf 40-73 3f 2-92 10 12-71 16 25-76 22 - 4i'43 4 3'22 10* 13-19 16^ 26-36 22\ 42-13 13-67 i6| 26-97 22\ 42-84 3-83 i of 14*16 i6| 27-58 22\ t4 4-16 II 14-67 1 7 28-20 23 1 44-28 5 4-50 Ilj 15-18 17! 28-82 45-00 4-84 III 15-67 17^ 29-45 23! 45-7i 5f 5-18 Ilf l6'2O 17! 30-08 2 3f 5f 5'54 12 16-73 18 30-70 24 47" 1 8 6 5'9 \2\ 17-26 185- 3 r 34 2 4r 47'9 X 11 6-29 6-65 I2 I 17-78 18-32 l8 t 31-98 32-63 24| 48-65 49'39 6f 7'5 1 3 18-87 J 9 33' 2 9 25 50-13 7 7'44 Measurement of Flowing-water by the Velocity of the Water and Sections of the Stream. Choose a length of the stream, say about 50 or 100 feet, along which the section is as uniform as possible, and find the area of the section by multiplying the width by the average depth. It is advisable to take several sections in the chosen length, from which to find the average section. A stake should be fixed at each end of the measured length, and a float, consisting of a bottle, cork, or piece of wood, must be thrown into the middle of the stream a little above the first stake, and the time noted which it takes to pass from the one stake to the other. This should be DRIVING POWER OF FLOWING WATER. 2$ several times repeated, and the average time taken, so as to get a more accurate result. From these data the quantity of water passing can be found, as illus- trated in the following example : The sectional area of a stream is 20 square feet, and a float passes over a measured length of 90 feet in 36 seconds. To find the quantity of water pissing, multinly the area of the stream by the measured length, and also by 60. and divide the product by the time in seconds taken by the float in passing over the chosen length. Thus, 20 x 90 x 60-^-36=3000 cubic feet per minute. From this a deduction (amounting to about 20 per cent, for earthen banks) must be made to allow for loss of velocity at the sides and bottom through friction. In the above example, 20 per cent, of 3000 is equal to 600, and the true quantity passing will be 3000 600=2,400 cubic feet per minute. Measurement of Flowing-water by Discharge through an Orifice. This method may often be used in situations where a sluice already exists. The sluice must be raised, so that all the water coming down just passes through, and the length and depth of the opening carefully measured, together with the depth from the surface of the water in the head-race to the centre of the orifice, and from these data the quantity of water may be calculated by the following rule for the discharge through an orifice under a given head. Rule: Multiply the area of the aperture in square feet by the square root of the head in feet and by 5*1, the product will be the quantity discharged in cubic feet per second. Example : Required the quantity of water in cubic feet per second dis- charged through an orifice or sluice, 15 inches wide and i foot 6 inches high, the head, or depth from the surface of the water in the head-race to the centre of the orifice, being 16 feet. Then A/ 16=4 and 1-25 foot wide xi '5 foot highx 4X 5'i = 38'25 cubic feet of water discharged per second. The velocity of the water is A/ 16=4 x 5'i = 2O'4 feet per second. The Driving Power of Flowing-water being gravity, the power of a stream of water depends upon the height of the fall and the quantity of water flowing per minute. The theoretical horse-power of a stream of water may be found by this Rule : Theoretical horse-power of stream= cubic feet of water falling per minute x 62*5 Ibs. xfall in feet. ~" 33000 A deduction of 25 per cent, must be made from the result obtained by this rule to allow for the power absorbed by friction and for leakage, the remainder will be the actual power which should be developed by a good water-motor. Example: Required the horse-power of a stream of water, passing 1600 cubic feet of water per minute over a fall of 33 feet, the height being measured from the level of the water in the head-race to the level of the water in the tail-race. 26 THE PRACTICAL ENGINEER'S HAND-BOOK. Then, 1600 cubic feet x 62-5 Ibs. x 33 feet height of fall_ 33000 Ibs. the theoretical power of the stream and 100x75 = 75 horse-power the actual power which should be obtained from the stream by a good water-motor. WATER-MOTORS. A Turbine, when correctly designed and constructed, is the best and most efficient motor for the utilization of water power. The chief types of turbines and their modes of action may be briefly described as follows : Classes of Turbines. There are two classes of turbines, called respectively Pressure and Impulse turbines, the difference between them being that whereas in the former the water acts in part by impulse and in part by pressure, in the latter the water acts entirely by its impulse. Whitelaw's Re-action Wheel is the simplest form of turbine. It has two arms formed in the shape of an Archimedean spiral, like Figs. 4 and 5. The water is supplied from the underside of the wheel, as shown in Fig. 5, through the centre of the arms, and flows horizontally outwards Figs. 4 and 5. Whitelaw's re-action wheel. through the arms towards the periphery, and leaves the motor in a direction tangential and opposite to the direction of rotation. The water acts by re-action, and the most efficient speed of the wheel, at the discharging orifices at the extremity of the arms, is equal to the velocity due to the height of the fall. When the wheel is running at this speed there is a loss of efficiency of at least 16 per cent, arising from the backward velocity of the water as it leaves the wheel. The horse-power of this turbine may be found by the following Rule: Multiply the effective quantity of the water flowing through the wheel in cubic feet per minute by the height of the fall in feet and divide the product by 700. Example : Required the horse-power of a Whitelaw-turbine, produced by looo cubic feet of water with a fall of 21 feet. r looo cubic feet x 21 feet fall = 30 horse power. EFFICIENCY AND VELOCITY OF TURBINES. 2/ The following are the rules for proportioning this turbine, with two pro- perly formed jets : Width of each discharging orifice W. vy_ /i 35 x number of horse-power. " V " 1000 H v/H Where H=the height of the fall or head of water. Width of each arm =4 W. Diameter of machine=5O W. Diameter of central opening=io W. TIT I ^ 7 ; J 49'44 A/H JM umber of revolutions per minute = -vr: -~-~r r^ Diameter ot the machine The efficiency of this turbine in practice seldom exceeds 55 per cent. It is seldom used now on account of its low efficiency, imperfect regulation and unstable speed, and it has been superseded by more efficient motors. Causes of Loss of Efficiency of Turbines. No turbine, however good and perfect in its action, can utilize all the power in a stream of falling water, as there are various losses of efficiency common, in a greater or less degree, to every turbine. These losses of efficiency arise from : (i.) Shocks and collisions due to changes of section and curvature, and collision of the water on the tips of the guide and wheel-vanes. In a good turbine the changes of section and curvature have little or no effect, as all parts of the motor would be designed so as to secure gradual changes of section and curvature, but in faultily constructed ones their influence may be considerable. The loss arising from collision of the water on the tips of the guide-vanes should be inappreciable, but that due to collision on the tips of the wheel-vanes cannot in practice be quite eliminated, but should not exceed from \\ to 3 per cent.; (2.) Friction of the moving water on the surfaces of the motor. This is generally the most important source of loss in a turbine, indeed were it not for skin friction, a turbine might easily be made to give an efficiency of 90 or 95 per cent.; (3.) The energy carried away by the water as it leaves the wheel ; (4.) Friction of the footstep or bearing of the turbine. Guide-vanes of Turbines. Fourneyron conceived the idea of giving the water an initial forward velocity before it entered the wheel or moving part of the turbine, and he effected this by means of fixed guide-vanes, which now form one of the fundamental parts of every turbine. Water-paths and Velocities of a Turbine. In Fig. 6, A repre- sents the fixed part of a parallel flow turbine containing the guide-vanes, and B the moving part or wheel of the turbine ; C D and E F are the centre lines of a guide-cell and wheel-bucket respectively. In this figure the water enters the guide-ports from the head-race or turbine-case in a direction parallel to the axis or shaft of the turbine, flows along the curved guide- blades, and is by them directed into the wheel with its proper velocity and direction. If c be the velocity and direction of the water as it leaves the guide-ports, on entering the moving wheel, this velocity is resolved into two components, viz., u lt the velocity of the wheel at its receiving circum- ference, and c^ the velocity of the water relatively to the moving wheel ; 28 THE PRACTICAL ENGINEERS HAND-BOOK. c and c 1 are generally known as the absolute and relative velocities of the water as it enters the wheel, and in order that the water may enter the wheel with as little collision as possible, the first portion of the wheel-vanes must be tangential to the direction of the velocity c r . The discharge portion of the wheel-vane is straight so as to guide the water clear away from the turbine, and to secure a high efficiency the absolute direction of the water as it leaves the wheel must be at right angles to the direction of motion. The velocity of the wheel on its discharging circumference being known, in a parallel-flow turbine the velocity of the wheel is neces- sarily the same on both the receiving and discharging circumferences and GUIDE PORTS Fig. 6. Diagram showing ports and buckets of a Jonval turbine, with water paths and velocities. ths direction of rotation and also the absolute direction of the water as it leaves the wheel, it will be found that the smaller the discharging angles of the vanes the smaller becomes the loss of velocity and conse- quently of efficiency, as the absolute velocity (c 3 ) of the water as it leaves the wheel represents a loss of fall. The choice of the discharge angle depends upon various circumstances. In some cases this angle may be comparatively large, so that the turbine will pass a large quantity of water with a small diameter of wheel. A large angle, however, means an increased loss of efficiency, and should therefore only be adopted in cases where the water supply is abundant and a high efficiency is not necessary. Where a high efficiency is required, the angle must be made as small as possible. In Figure 6, u l is the velocity of the wheel at its discharging circum- ference, and c 2 and c 3 the relative and absolute velocities respectively of the water as it leaves the wheel : but the velocities and angles differ to a greater or less extent in almost every turbine. In Pressure-Turbines the proportions between the velocities and angles are such that the water leaves the guides with a velocity due to about REGULATION OF TURBINES. 29 one-half the head or fall, the remaining portion of the fall acting by pressure. In order to keep up the correct distribution of pressure and velocity in the turbine, and thus maintain the efficiency, there must be a definite rate of flow through the wheel, the water must be admitted continuously over the entire circumference, and the wheel-buckets are necessarily filled with water unuer pressure. Pressure-turbines may very conveniently be divided into inward, out- ward, and parallel-floiv turbines, accordingly as the water enters and leaves the motor. Regulation of Turbines. As it frequently happens that the water available for driving a turbine varies considerably, often sinking down in summer to one-half or one-fourth of the usual supply, it becomes necessary to provide some means of regulating a turbine so that it will give a good efficiency not only with a full, but also with a very reduced supply. Many turbines will yield a high efficiency when fully supplied with water, but become almost useless when the supply sinks down to one-half or less, and hence the subject of regulation becomes of very great practical importance. In cases where the supply remains constant, or nearly so, but the power required varies, the turbins may be constructed to pass the water requisite for the maximum power required, and a stop, sluice, ring, or throttle-valve used to regulate the speed. These methods of regulation are not economical, but are often sufficient if the water supply is abundant, and are generally much cheaper than an efficient regulator applied to the turbine itself. A proper regulation should always be applied if the water supply varies. Regulation of Inward- Flow Turbines. In inward-flow wheels the water enters the guide ports on their outer circumference, flows towards the axis of the turbine, and leaves the wheel along its inner circumference. There are various methods of regulating inward-flow turbines, the commonest being by making the guide blades movable, so that by slightly turning them the discharge angle is altered and more or less water dis- charged as the case may be. This mode of regulation is often convenient, but is open to many objections, the chief one being, that although the dis- charge area of the guide- ports is altered, that of the wheel is in no way lessened, and this necessarily causes a loss of efficiency. Another objec- tion is, that the speed of maximum efficiency of the wheel varies with the inclination of the guide blades, and thus for good working, the wheel should run at a different speed when the opening of the guide blades is altered. Regulation of Outward- Flow Turbines. In outward-flow wheels, the water enters the wheel on its inner, and leaves it on its outer circum- ference, and the regulation consists of a cylindrical sluice working between the guides and wheel. This manner of regulation is very imperfect and far from economical, as when the turbine is using the reduced supply, only the area of the guides is altered, that of the wheel remaining the same. Great contraction takes place as the water leaves the guides, and the water on passing into the wheel has to enter a space much larger that it can fill with the velocity it has attained. A great loss of efficiency thus takes place, and in order to diminish this, in the better forms of the Fourneyron turbine, the wheel and guides are divided into two or more tiers, and by shutting off one or more of these tiers to suit the decreased supply a fair 30 THE PRACTICAL ENGINEER'S HAND-BOOK. efficiency is obtained, provided that the open tiers are fully supplied with water. The chief objections to this regulation are, that the skin friction is much increased, and the turbine is rendered very liable to be choked by leaves. The efficiency of the best Fourneyron turbine is a little lower than that of an inward or parallel-flow turbine. The Jonval or Parallel-Flow Turbine is in many respects simpler than either of the preceding types. In this turbine, the water enters the guides parallel to the axis of the shaft, and after passing through the motor leaves the wheel in the same direction. Figs. 7 and 8 are sections of the ports and buckets of a Jonval turbine. For low falls this turbine is much Figs. 7 and 8. Sections of the ports and buckets of the Jonval turbine. cheaper than any other, both in the cost of the motor itself and in its erection. As the water passes parallel to the axis of the motor, a smaller turbine case, where one is necessary, is required for a given diameter of wheel than would be requisite for an inward-flow turbine. The Jonval, in common with all other pressure-turbines, does not admit of a perfect adjustment for a reduced water supply, but it frequently admits of a better one than either of the other types. On low falls it may be provided with vertical slides fitted into the guide ports, one slide to each port. These slides are raised and lowered by suitable mechanism, either singly, or three together. When the turbine is applied to medium falls, a slide may be constructed so as to close two guide ports simultaneously. The efficiency of a Jonval turbine is as high or perhaps higher than any other pressure-turbine, a well-constructed wheel will yield an efficiency of from 75 to 78 per cent. Most pressure-turbines work equally well whether totally immersed or free from the tail-water, consequently they are especially suitable for situations where considerable fluctuation takes place in the levels of head or tail-water. They are also capable of being arranged so that part of the fall, provided the portion so used does not exceed 25 to 30 feet, acts by suction. In such a case the turbine can be arranged with its shaft either vertical or horizontal ; the suction pipe must be perfectly air tight, and with its lower end always below the surface of the tail-water. A Jonval turbine with horizontal shaft and adjustment is shown in Fig. 9. Excellent as pressure turbines are for low or medium falls with constant or nearly IMPULSE TURBINES. 3! constant water supplies, they should not be applied to high falls, as under such circumstances their speed of rotation becomes very great, and the wear, tear, and repairs are much increased. Impulse-Turbines differ from pressure-turbines, inasmuch as in the former the water leaves the guides with the velocity due to the entire head or fall, and thus acts entirely by impulse. Since the water acts by impulse alone, the wheel-buckets do not require to be filled with water, and the turbine may consequently be so constructed that the water glides along the concave surfaces of the wheel-vanes without touching the convex sides, as shown in Fig. n. As the Girard turbine is now the only impulse-turbine Fig. 9. Jonval turbine, with horizontal shaft. of importance, it is only necessary to refer to the various forms of this motor. The Girard- Turbine, of which Figs. 10 and n are sections of the ports and buckets, should be placed so that the bottom of the wheel is just clear of the tail-water when the turbine is working; the object of this being to secure a perfectly free discharge for the water as it leaves the wheel. An inch or two of clearance between the bottom of wheel and top of tail- water is ample. In the Girard-turbine, it is not necessary that the water should enter the wheel over its entire circumference, consequently the injection may take place over only a small portion, and the turbine will still retain its high efficiency. This property is of great advantage, as it enables a perfect regulation to be applied to the motor, for if the turbine is constructed for the maximum quantity of water available it can be adjusted for decreased supplies by merely closing some of the guide ports. This turbine may be applied to any fall, from about 6 feet upwards, and for high falls it is the only one capable of giving a high efficiency. One of the best known turbine-makers, Mr. W. Gunther, of the Central Works, Oldham, recommends this turbine for low and medium falls with variable supplies of water, for medium falls with small varying quantities of water, and for high falls. For low and medium falls with constant or 32 THE PRACTICAL ENGINEER'S HAND-BOOK. nearly constant water supplies, and for situations where the rivers are subject to frequent floods, he adopts the Jonval turbine. Figs. 10 and ii. Sections of ports and buckets of the Girard-turbine. Axial and Radial Girard- Turbines. There are two chief types of the Girard-turbine, known respectively as the axial and radial. In the former the water enters and leaves the motor in a direction parallel to the axis, as in the Jonval turbine, while in the latter it enters the wheel on its inner and leaves on its outer circumference. The axial type may be used for low, medium, and high falls, and is invariably constructed with the shaft vertical. For low falls this turbine is made with full injection, that is, injection over the entire circumference of the wheel, and the regu- lation consists of vertical slides fitted to each guide port, the slides being raised or lowered by suitable gearing worked from the turbine-house or other convenient place. For medium falls, full or half injection, according to circumstances, is used, and the regulation is effected by a slide arranged so as to close two guide ports simultaneously. For high falls and small quantities of water this turbine is made with partial injection, that is, the water is only admitted on a fraction of the cir- cumference, and the diameter of the wheel is increased so as to secure a moderate number of revolutions. A high-fall Girard turbine with partial injection is necessarily more expensive than a turbine of small diameter with full injection, but as the former runs at a much s'ower speed it is not subject to the wear, tear, and friction of a quick running motor, it gives a higher efficiency, and is much more durable. The Radial Girard- Turbine is generally only used for high falls, and is then constructed with a horizontal shaft. Partial injection is always applied, and the method of regulating the turbine generally consists of a slide closing the guide ports one after the other. Turbines of the horizontal type have frequently been constructed for falls exceeding 500 feet, and worked with perfect success, thus testifying to the adaptability of this motor to high falls. It is scarcely necessary to add that under such high heads a pressure turbine would run at such a high speed as to become almost unmanage- able. G1RARD-TURBINES. 33 A Girard-turbine arranged with a vertical shaft, for a medium fall and variable water supply, is shown in Fig. 12. In this arrangement the guide- channels are on the whole circumference, and the adjustment for varying the supply is so arranged that the turbine can work with either full or partial Fig. 12. Girard-turbine with vertical shaft for medium falls. Fig. 13. Girard-turbine with vertical shaft for high falls. injection. For low falls the outer case is dispensed with, and the guide- channel cylinder is fixed direct to the bottom of the head-race. A Girard-turbine arranged with a vertical shaft for high fails and varying water supplies, partial injection being employed in this case, is shown in Fig. 13. Another Girard-turbine for high falls and variable supplies, is shown in Fig. 14. In this arrangement the shaft is placed horizontally, and the water enters the wheel on the inner circumference, and leaves it on the outer circumference. The wheel is protected by a wrought-iron case, which is not shown in the wood- cut. This arrangement is especially adapted for large powers under very high falls, and partial injection is always used. The proportions of a Turbine should be adapted to the fall, quantity of water, location, and cir- cumstances under which it has to work. The following general rules for the Jonval-turbine may be modi- fied as circumstances require. Rules for Proportioning Jonval's Turbine. To find the Diameter at the Centre of the Buckets, or Centre of Motion D. Rule : Multiply the square root of the height of fall in feet by 1000, and divide the product by the number of the revolu- tions of the turbine per minute. Fig. i : with horizontal shaft for Cover removed. 34 THE PRACTICAL ENGINEER'S HAND-BOOK. Number of buckets in the turbine wheel = six times the square root of the diameter of the centre of motion D. Number of guides=5 times the square root of D. Depth of buckets = one-eighth of D. Radius of the curved portion of the bucket = depth of bucket x 1-25. Depth of guides = one-sixth of D. Radius of the curved portion of guides = depth of guide x 175. To find the total horse-power of a fall of water delivered on a Turbine. Rule : Multiply the quantity of water passed through the turbine in cubic feet per second by the height of the fall in feet, and multiply the product by '1134. These wheels, as previously stated, yield as high as 78 per cent, of the total power expended, when well constructed. Example: Required the horse-power of a fall of water 28 feet high, discharging 15 cubic feet of water per second, taking the efficiency at 65 per cent., a very low estimate. 15 x 28 x "1 134=47-628 total horse-power, of which 47-628 x '65 modulus=3O'958, or say 31 horse-power would be available as actual horse-power in a Jonval-turbine, and this fall would require a turbine, making say 190 revolutions per minute = (1000 ^28 feet fall)-4-(i9O revolutions)= 27-85 inches diameter. Water-Jet Motors. The application of a jet of water to a number of cups or buckets attached to the rim of a wheel is a simple and excellent method of producing motive power. It is, however, essential to economy and efficiency that the formation of the buckets shall not permit the lodg- ment and carrying-over of water which has lost its impelling power, termed dt ad-water, and that the water shall be received without shock and dis- charged without velocity. It is also necessary that the buckets be small in area and number, because the loss by friction is proportional to the area of the wetted surface. The wheel should be driven by the impulse of the jet, or by a uniform and continuous pushing-action of the water. When it is driven by the impact of the jet, or by a succession of blows of the water, such as result from variations in the angle of the impingement of the jet, there is a considerable loss of efficiency. The velocity of the bucket should be equal to one-half the velocity of the impelling jet. Buckets of Water-Jet Motors. The action of a jet of water in striking a flat plate at right angles is shown in Fig. I4A. The water divides and forms a wedge of dead-water, and the direction of the discharge precludes a complete stoppage of the water. The action of a jet of water in striking a curve- shaped bucket is shown in Fig. 143. The same wedge-shaped formation of dead-water F! fcttriklijSftrt exists as in tne preceding case, but there is Fig. i 4 B. T w a ter- piate. a reversal of the stream which allows it to iurve^s'hf ed be almost completely checked and ex- bucket, hausted of its energy. The Felton Water-Wheel. In the double-curve or wedge-centre bucket, designed by Pelton, shown in Fig. 140, the loss due to water- wedge is avoided, because a piece of metal projects into the middle of the THE PELTON WATER-WHEEL. 35 stream and occupies the space of the water-wedge. The jet is applied tangentially, and becomes divided into two parts, one turning to the right and the other to the left ; the direction of both being almost completely reversed before the water leaves the bucket. The wheel revolves vertically, and is highly efficient, as will be seen from the following table. To facilitate the escape of the spent-water, and to utilize all of the head of water, the stream is usually applied to the lower side of the wheel. Fig. i 4 c.-Water- jet striking a Pe ton-bucket. Table 9. RESULTS OF TESTS OF A PELTON WATER-WHEEL. Size jet. Inch. Running pressure. Revolu- tions. Actual water used. Actual Horse- power developed. Theoretical Horse-power possible. Efficiency pcrcenage. A IOO 775 1478 5*349 6-422 83-30 1 103 780 I5-00 5'563 6-715 82-90 4 I2 5 880 23-05 IO-730 12-520 85-69 102 775 20-82 7^45 9-226 : 85-02 IOO 775 2O'6l 7-756 8'957 86-59 I 125 ; 900 23-05 10*670 I2-52O 85-16 \ 100 i 780 2O'6l 7717 8-957 86-15 The power of the Pelton-wheel is independent of its diameter, and depends upon the head and volume of the water. The Peltori-wheel with a single nozzle may be employed for heads of water as low as 30 feet, if the power required is small. When large power ?ig. 140. Pelton Water-wheel with multiple nozzles. By the Pelton Water-wheel Co., San Francisco. Fig. 15. Pelton Water-wheel. By the Pelton Water-wheel Co., San Francisco. is required from a comparatively low head of water, a wheel with multiple nozzles is employed, as shown in Fig. 140. The Pelton-wheel, shown in Fig. 15, is especially adapted for heads above 50 feet ; and there is no limit to the height of head of water under which it will efficiently work. For instance, a Pelton water-wheel of 36 inches diameter, formed of a solid steel disc, with phosphor-bronze 36 THE PRACTICAL ENGINEER'S HAND-BOOK. buckets riveted to the rim, as shown in Fig. I5A, is working under a vertical head of 2100 feet, equivalent to a pressure of 2100 x '433 = 910 pounds per square inch. The wheel makes 1150 revolutions per minute; the peripheral velocity is 10,804 ^ eet P er minute, or about 1 20 miles an hour. At an electric light works, there are eight Pelton-wheels of 24 inches diameter, each weighing 90 pounds, and capable of developing 175 horse-power, or nearly two horse -power for each pound weight of the wheel. The speed is looo revolutions per minute, and the head of Fig. ISA. Peiton Water-wheel water is 820 feet, equal to a pressure of 820 formed of a solid disc. J- , x '433 = 355 pounds per square inch. Other Pelton-wheels are working under pressure of from 700 to 1000 pounds per square inch. The latter is equal to a head of 1000 x 2-31 = 2310 feet, under which a wheel of 18 inches diameter, weighing 30 pounds, will develop 2 1 horse-power, with a nozzle-tip of y inch diameter. Considerably more power is stored in the rivers and streams of the world than is sufficient for all the industrial purposes of mankind. It is astonishing that only a small percentage of the available power has hitherto been utilized, considering that efficient motors are obtainable, adapted to all heads and purposes, for the economical utilization of water-power. HEAT AND FUEL. A Thermometer is an instrument for measuring temperatures. It consists of a glass-tube having a bulb at the foot, containing either mercury or alcohol : mercury being used for ordinary temperatures, and alcohol for very low temperatures, because it remains fluid and does not solidify at the greatest known cold. A scale is placed at the side of the tube, graduated into degrees, which indicates the expansion of the fluid in the tube, from which the temperature is read off. The temperature of melting ice being constant at all temperatures, it is used for marking the zero point of centi- grade and Reaumur thermometers: in Fahrenheit thermometers the zero point is placed 32 below this, at about the temperature of a mixture of salt and snow. As distilled water under the same pressure, in a vessel of the same kind, always boils at the same temperature, it is used for marking the boiling point of thermometers. After the mercury is introduced, it is boiled to expel air and moisture, and the tube is hermetically sealed. The action of the thermometer is due to the change of bulk or volume to which bodies are subject with a change of temperature ; they expand with heat, and contract with cold, thus indicating a high or low temperature. The Fahrenheit Thermometer is used in this country and in America. The number o on its scale represents the greatest degree of artificial cold that could be produced at the time the thermometer was invented. The number 32 represents the freezing point, or temperature of melting ice, and 212 the temperature of boiling water, in both cases under atmospheric pressure. From the freezing-point to the boiling- point there are 180 degrees. The Centigrade Thermometer is used in France and other parts of TEMPERATURE. 37 tne continent ; number o on its scale represents the temperature of melting ice, and 100 the temperature of boiling water. From the freezing-point to the boiling-point there are 100 degrees. The Reaumur Thermometer is used in Russia and Turkey, &c. Number o on its scale represents the temperature of melting ice, and 80 the temperature of boiling-water. From the freezing-point to the boiling-point there are 80 degrees. To convert Degrees Fahrenheit into Degrees Centigrade. Rule: Subtract 32, multiply the remainder by 5, and divide the product by 9. To convert degrees Centigrade into Degrees Fahrenheit. Rule : Multiply by 9, divide the product by 5, and add 32 to the quotient. To convert Degrees of Centigrade into Degrees Reaumur. Rule: Multiply by 4 and divide the product by 5. To convert Degrees of Reaumur into Centigrade. Rule: Multiply by 5 and divide the product by 4. To convert Degrees of Fahrenheit into Degrees of Reaumur. Rule : Subtract 32, multiply the remainder by 4, and divide the product by 9. To convert Degrees of Reaumur into Degrees of Fahrenheit. Rule : Multiply by 9, divide the product by 4, and add 32 to the quotient. A Thermometer is used by marine engineers with the salinometer to test the temperature of the water drawn from the boiler for the purpose. of ascertaining its density, and to test the temperature of the feed-water, and of the air in the engine-room. High Temperatures beyond the range of a Thermometer may be ascertained approximately, by heating a bar of wrought-iron to the tem- perature required to be ascertained, and then quenching it in cold water, when the rise of temperature of the water will enable the unknown tempera- ture required, to be calculated by the following rule, which assumes the specific heat of wrought-iron to be one-ninth that of water : Let T = the temperature of the water produced by quenching the iron. t = the original temperature of the cooling-water. W = the weight of the cooling-water i-n Ibs. w = the weight of the bar of wrought-iron in Ibs. X = the unknown temperature required. -(T-t)xWx 9 -| + T x=[( Example : A bar of wrought-iron weighing 20 Ibs. was inserted in the chimney of a steam boiler, and when heated, was quenched in 30 Ibs. of water at 55 Fahr., thereby raising the temperature of the water to 93 Fahr. Required the temperature of the chimney. Then (93 - 55) x 30 Ibs. of water x 9 _ . Fah and 20 Ibs. weight of wrought-iron 93 = 606 Fahr., the temperature of the chimney. The Standard Temperatures of Water are as follows : The freezing-point under one atmosphere is 32 Fahr. or o Cent. The point of maximum density . . . 39' i ,, ,, 4 The British standard temperature . . 62 0< o ,, i6'66 The boiling-point under one atmosphere .212 ,, 100 29G237 38 THE PRACTICAL ENGINEER'S HAND-BOOK. The temperature used in calculating the specific gravity of bodies is usually 62 Fahr. Notable Temperatures. Melting ice, 32 Fahr. ; boiling water, 212 / ? ahr., under the pressure of one atmosphere or in the open air ; steam at 60 Ibs. pressure per square inch by the steam-gauge, 3O7'5 Fahr. ; super- heated steam 380 to 400 Fahr. Smoke in the funnel of a marine-boiler, 552 to 600 Fahr.; water in the hot-well, 100 to 120 Fahr.; boiler- furnaces, 2500 to 3000 Fahr. Dull cherry-red heat, 1470 Fahr.; full cherry-red, 1700 Fahr.; orange-colour, 2000 Fahr.; white-heat, 2370 Fahr.; bright white-heat, 2500 Fahr. The Mean Temperature of a place is the mean of its annual tem- perature averaged for a number of years. The mean daily temperature is obtained by dividing the sum of 24 hourly observations by 24 the temperature being taken of the air and not of the ground. The mean temperature of 24 successive hours is approximately equal to the tempera- ture at 9 o'clock A.M., and the mean temperature of the day from 9 o'clock, A.M., to 5 o'clock, P.M. is approximately equal to the temperature at 1 2 o'clock noon. Temperature of the River Thames. Sir C. B. Airy found from observations of the temperature of the Thames extending over many years, that on the average of thirty-three years the temperature of the Thames 517 is higher than the air at the Royal Observatory 5O 0> 2 by i| degrees. During the seven months, May to November, this difference averages 2 ; and during the winter, December to April, only 07. On the average of the thirty-three years, July gives the highest monthly mean river tempera- ture 657 and January the lowest 39'4. The high temperature of 73*1 was recorded as the average for June, 1846, and of 75*4 on July 2oth, 1859. Temperature of Seas and Lakes. The temperature of the surface of the sea varies with the seasons and with the direction of the ocean currents. The surface temperature of tropical seas is generally the same as that of the air, but that of polar seas is higher than that of the air. The average winter temperature of the sea round the coast of England is higher than that of the land. The mean annual temperature of the surface of the sea round England is 49 Fahr. ; the mean surface temperature of the Indian Ocean is 89 Fahr. ; and of the Red Sea 94 Fahr. The temperature of maritime land is influenced by the winds which come from the sea, as Ihe air resting upon the surface of the sea acquires its temperature, and is distributed over the land. The Temperature of Deep-Sea-Water is considerably less than that of the surface water ; the temperature decreases as the depth increases. The temperature of the bottom of the sea in both temperate and tropical climates averages 36 Fahr. The temperature of the bottom of lakes averages 39 Fahr. The surface water is the warmest part of the sea, its temperature extends to different depths in different seas, forming a stratum generally from 100 to 300 fathoms deep, below which the water becomes colder towards the bottom, as will be seen from Table 10, which contains the results of observations in various parts of the world. UNDERGROUND TEMPERATURES. 39 Table 10. TEMPERATURE OF SEAS AND LAKES AT VARIOUS DEPTHS. surface 1 tu empera- re. Fahr. Fthms. Fahr. North Pacific Ocean South Pacific Ocean 70 Temperature at a depth of 67 2500=34 1950=31 North Atlantic Ocean . South Atlantic Ocean . Equatorial Ocean 40 $ :: : 3000 = 34 300 = 33 300 = 39 ,, 78 600 = 35 ,, 78 900=32 Lake of Geneva 78 950=42 Lake Sabatino, Rome . 77 490=44 Loch Lomond, Scotland 50 500 = 42 Springs of Water assume the temperature of the ground through which they pass. Shallow springs have the same temperature as the air, but deep springs assume the temperature of the stratum of constant tem- perature, or the mean annual temperature of the place. Warm Springs of water rise from a depth below the stratum of constant temperature. Treir temperature is due to the internal heat of the earth, and is an approximate indication of the depth from which the water rises. Warm or thermal springs are largely impregnated with mineral matter, such as magnesia, soda, iron, lime, manganese, potash, bromine, lithia, iodine, and other substances. The maximum temperatures of a few noted thermal springs are: Great Geyser, Iceland, 261 Fahr. ; Chandes-Aignes, 180 Fahr.; Wiesbaden, 160 Fahr.; Baden-Baden, 155 Fahr.; Lucca, 130 Fahr. ; Bath, 120 Fahr., and Buxton, 82 Fahr. The Temperature of the Earth at the surface nearly equals that of the air, but below the surface the temperature varies greatly at different localities and in different geological formations. Limestone is the coolest formation. The two coolest mines or tunnels are in limestone, viz., Chanarcillo Mines and Mont Cenis Tunnel. Underground Temperatures. The normal temperature of the earth at a depth of about 30 feet in this country, and at a depth of 55 feet in warm climates, is constant, and equal to the mean annual temperature of the air at that place. Below that depth the temperature gradually increases with the depth, and although it varies in amount in different kinds of rock, its average rate of increase is i Fahr. for every 55 feet in depth, except in exceptionally hot mines, where it sometimes increases i Fahr. for every 30 feet in depth. In a deep bore-hole near Schladebach, Germany, the temperature at a depth of 4567 feet was 120 Fahr. In a deep artesian- well at Pesth, the temperature at a depth of 3120 feet was 158 Fahr. In a deep bore-hole at the Waterworks, Richmond, Surrey, the temperature at a depth of 1447 feet was found to be 765 Fahr. in a shaft in the Aberdare Valley the temperature was found to be : At a depth of 546 feet = 56 Fahr. ; 780 feet = 59^ Fahr.; 1020 feet = 63 Fahr., and at 1272 feet deep = 66 Fahr. At the Denton Colliery the temperature at a depth of 1317 feet was 66 Fahr. Hot Mines. The mines on the Cumstock Vein, Nevada, are extremely 40 THE PRACTICAL ENGINEER'S HAND-BOOK. hot ; at depths of from 1 500 to 2000 feet the thermometer placed in a freshly-drilled hole will register 130 Fahr., and small bodies of water run for years at 170 Fahr., and large bodies of water at 155 Fahr. The tem- perature of the air is kept down to 110 Fahr. by forcing in fresh air cooled over ice. In one of the mines the temperature increased as follows : 100 to 1000 feet deep increase i Fahr. in 20 feet. jootoiSoo ., 30-5 feet. 100 to 2300 ,, 30-3 feet. Iced water is drunk by the miners in these hot mines, with apparently no bad results. Deep Mines. The high temperature of deep mines forms an obstacle to their working. At the Comstock Mines, Nevada, some years ago, the miners could only work a few minutes at a time on account of the great heat. At the New Almaden Silver Mine, California, the temperature at a depth of 600 feet was 115 Fahr. A coal mine in Durham, 1814 feet deep, has a temperature at the bottom of 78 Fahr. ; at another, near Manchester, 2150 feet deep, the temperature is 75 Fahr. ; at a copper mine in Cornwall, 2100 feet deep, the temperature is 88 Fahr. ; and water is obtained from a well at Grenoble, France, 1797 feet deep, at a temperature of 817 Fahr. The Internal Heat of the earth may be seen from the following examples, taking in each case the surface temperature at 42 Fahr., and the rate of increase of temperature at i Fahr. for every 60 feet in depth: Water will boil at a depth of 212 boiling point 42 x 60 feet - ~ = ''93 miles > and ' Brass will melt at a depth of 1650 melting point 42 x 60 feet -776o yards x 3 feet ~ = '8-27 miles. Quantities of Heat are expressed in units of weight of water heated one degree. The British Unit of Heat, or Thermal Unit, is the quantity of heat necessary to raise the temperature of one pound of water at 32 Fahr. one degree Fahr. that is, from 32 to 33. Dr. Joule found that by the expenditure of one unit of heat, 772 Ibs. weight could be raised one foot high. The mechanical measure of heat is, therefore, taken at 772 foot- pounds for one unit of heat. Heat and mechanical energy are mutually convertible, and heat requires for its production, or produces by its disappearance, mechanical energy, in the proportion of 772 foot-pounds for each unit of heat. The Specific Heat of a body means its capacity for heat, or its power of storing heat ; or the quantity of heat required to raise the temperature of the body one degree Fahr., compared with that required to raise the temperature of an equal weight of water one degree. Water is taken as the standard for comparison of specific heat, and its specific heat exceeds that of nearly all other bodies. The specific heat of all colid and liquid substances is nearly constant for temperatures up to 21 2 Fahr. ; but above that point the specific heat increases as the temperature rises. The specific heats of solid and liquid substances at ordinary temperatures, are given in the following table : SPECIFIC HEAT. Table n. SPECIFIC HEAT OF SOLID AND LIQUID BODIES, AND OF GASES, FROM THE EXPERIMENTS OF REGNAULT, POUILLET, PF.TIT, AND DULONG, DALTON, DESPRETZ, AND LAPLACE. Water at 32 Fahr. . = I 'OOOO Chloride of calciuo. . . 1642 Iridium . . . . 1886 Zinc, 32572 F. . 1015 Manganese 1442 Lead, '0314 : Gold . . 0325 Cast-iron . . . . 1299 Silver 0570 Steel, soft, '1166 : hard . 1185 Antimony, 32 572 F. 0547 Wrought iron, 32 212 F. 1099 Bismuth .... 0308 32-392 F. 1152 Cadmium . . . . 0567 32662 F. 1256 Platinum at 212 F. '335 Copper, 32 212 F. 0952 572 F. . . 03*3 32-572 F. . . 1014 2192 F. 0381 Brass, '0940 : Tin . 0569 Mercury, solid . . . 0320 Zinc, '0955 : Cobalt . . 1069 liquid 0334 Molybdenum . 0721 32572 F. . . 0350 Palladium . . . 0593 Nickel . . . . 1087 Uranium .... Tungsten . . . . 0619 0364 Sulphate of potash . . 1901 0873 Quicklime 2170 Protochloride of mercury . 0689 Magnesian limestone . 2175 Perchloride of tin 1016 Chalk . 2149 Diamond . . . . 1469 White marble . . . . 2159 Sapphire .... 2174 Stonework 1972 Bromine, '0840 : Iodine . 0542 Brickwork . . . . 1918 Tellurium . . . 0516 Glass, 32 212 F. . 1770 Oak, '5710 : Fir . . . 6510 32-572 F. . . 1900 Pear tree .... 5020 Coke, -2030 : Coal . 2412 Olive oil . . 3010 Anthracite . . . 2017 Turpentine 4700 Graphite, natural 2019 Acetic acid, concentrated . 6580 ,, from blast fur- Vinegar, "9200 : Alcohol . 6590 naces . . . . 4970 Essence of orange . 4890 Magnesia . 2216 lemon . , 4880 Ice, -5040: Soda. . . 2 3 H ,, juniper - 4770 Animal black . 2609 Benzine, 59 68 F. . . 3932 Charcoal . . . . 2415 Ether, oxalic . '4555 Phosphorus, 52 212 F, . 2504 sulphuric, density Sulphur . . . . 2026 76 . . . ". 6600 ,, recently cast 1845 Chloride of calcium, solu- Nitrate of silver . I 43 6 tion .... 6448 , potass 2388 Wood spirit, 5968 F. . 6010 , soda . . . 2783 Sulphuric acid . 6613 , barytes 1523 Water from 32 212 F. . 1-0052 Chlor de of lead . . . 0665 Air 2380 tin % -.- 1476 Nitrogen, '2445 : Oxygen. 2190 zinc . . : . 1362 Hydrogen . . . . 3-4050 magnesium . 1946 Gaseous steam . '4757 manganese 1426 Ammoniacal gas . 5086 sodium . *22OO Olefiant gas . . 3706 I 42 THE PRACTICAL ENGINEER'S HAND-BOOK. The Specific Heat of Bodies varies considerably, as may be seen from the previous table. Woods average one-half of the specific heat of water ; coal averages one-fourth, and coke, stone, brick, glass and sulphur each average one-fifth the specific heat of water. The metals have the least specific heat. The specific heat of bismuth is '03084, therefore, the quantity of heat that would raise a given weight of bismuth through one degree Fahr. would only raise the temperature of the same weight of water through 03084 of a degree. The specific heat of mercury is -033, and the quantity of heat that would raise the temperature of mercury one degree, would only raise the temperature of the same quantity of water "033 of a degree ; hence the same quantity of heat that would raise i Ib. of water i degree, would raise the temperature of 30 Ibs. of mercury i degree. The specific heat of iron is only about one-ninth that of water, therefore nearly 9 Ibs. of iron would be raised to a given temperature, by the same quantity of heat which would be required to raise i Ib. of water tp the same temperature. The specific heat of the same body is less in the solid than in the liquid state, for instance : The specific heat of water is 1*000 liquid and '504 solid. Ditto mercury '0333 '3 1 9 The specific heat of water in a gaseous state, or steam, is '662. Capacity for Heat means the quantity of heat required to raise the same weight of different bodies through the same number of degrees of temperature. If the same weight of several different substances be heated to the same degree of temperature and tested in an ice-calorimeter, their capacity for heat will be determined by the quantity of ice melted by each substance. Water has a greater capacity for heat than any other substance. The Calorimeter is an instrument for determining the total amount of heat in a body, or its specific heat. The ice-calorimeter consists of three concentric vessels of tin, in the central one is placed the heated substance to be tested, and the other two are filled with pounded ice. The ice sur- rounding the central vessel is melted by the heated substance, and the ice in the outer vessel excludes the heating influence of the external air. Each compartment is fitted with a cock to draw off the water produced from the liquefaction of the ice. The water from the melted ice in the compartment surrounding the central vessel will be proportional to the heat stored in the substance in the calorimeter ; and if the weight of melted ice be divided by the number of degrees through which the substance has fallen, it will give the quantity of ice which the substance would melt by falling through one degree. A substance in cooling from a given temperature to zero, gives out as much heat as it absorbs in being heated from zero to the given temperature. The Calorimeter used in Boiler- Tests, in its simplest form, consists of a barrel provided with a stirring-arm revolving on a vertical shaft foi mixing hot and cold water, The barrel is placed upon a weighing machine, and is supplied with a certain weight of cold water, into which steam is discharged from a pipe connected to the boiler. The rise of temperature of the mixture of water and steam is indicated by a thermo- CALORIMETER USED IN BOILER-TESTS. 43 meter, and when the temperature fixed as a basis of calculation is reached, the weight of the water is taken. The difference between the weight of the barrel of water before and after the addition of the steam, gives the weight of condensed water received as steam from the boiler. If \V = the original weight of water in the calorimeter, w = the weight of condensed water, or water added by heating with steam, / = the temperature of the original water in the calorimeter, /! = the temperature of the water after the admission of steam to the calorimeter, T = the temperature of the steam admitted to the calorimeter, / = the latent heat in the steam of boiler-pressure : then the heat imparted to the water by the steam will = \V (t l /). The sensible heat imparted to the water by the steam = w (T /J. If the portion w (T /J representing the sensible heat of the water added by the condensation of the steam from the boiler, be subtracted from W (/ 1 /), representing the total heat given to the water in the calorimeter, the remainder will be the heat-units used for evaporation in the steam at boiler- pressure, which divided by the latent heat of steam, /, will give the weight of water in Ibs. which the heat of steam of that pressure will evaporate. Representing the weight of water in Ibs. by x, then If E = the heating efficiency of the steam supplied, compared with saturated steam between the same limits of temperature, H = the total heat of the steam at the observed pressure, and Q = the quality or dryness of the steam : Then Then when Q is less than i, the percentage of moisture in the steam is = 100 (i Q). When Q is greater than i, the number of degrees that the steam is superheated = 2 '083 3 / (Q i). Latent Heat. When a solid body is heated and ultimately passes into the liquid state under the influence of heat, the temperature of the body rises until it reaches the melting point, when the temperature remains constant whatever the intensity of the heat may be, and the heat thus absorbed by the body in changing its condition becomes latent, and is not sensible to the thermometer, its only effect being to maintain the body in its liquid state. This is called the latent heat of fusion or liquefaction, and 44 THE PRACTICAL ENGINEER'S HAND-BOOK. represents the number of units of heat absorbed by i Ib. of the solid in passing to the liquid state ; when, on the contrary, the liquid passes into the solid state, the latent heat is disengaged or restored. Every body, under the same pressure, solidifies at a fixed temperature, which is the same as that of fusion or liquefaction, and the temperature remains constant during solidification. The Latent Heat of a Non-Metallic Substance may be found by M. Person's Rule : Subtract the specific heat of the substance in its solid state from the specific heat in its liquid state, and multiply the remainder by the number of the degrees Fahrenheit of the melting point, plus 256. The product is the latent heat of fusion or liquefaction in heat units. Table 12. LATENT HEAT OF FUSION OR LIQUEFACTION OF SOLID BODIES. Description of Substance. Latent Heat in Units of Heat. Authority. Ice I42'6 Person. Chloride of calcium 73' Phosphate of soda ..... I2O'O Phosphorus 9'O Spermaceti I48-0 Wax I75-0 . Sulphur IJ-O Nitrate of soda 113-0 Nitrate of potass . 85-0 Tin 2 5 -6 Cadmium 2 5 -6 Bismuth ....... 22'7 Lead ....... 9'86 Zinc ...... 50*60 Silver 37'9 Cast-iron ....... 233*00 Clement. Platinum 46-00 Mercury 36-00 The latent heat of water is 142-6, or in round numbers 143 units of heat, being the number of units of heat absorbed by ice during the process of melting ; the amount of heat thus absorbed would have raised the same weight of water 143 degrees. Hence to melt one pound of ice requires as much heat as would raise 143 Ibs. of water i degree Fahr. The Temperature resulting from a Mixture of Water of different Temperatures may be found by this Rule : Divide the sum of the products of the weight in Ibs.of each quantity of water by its temperature, by the weight of the mixture in Ibs. Example : If 30 Ibs. of water at 32*- TEMPERATURE OF A MIXTURE OF ICE AND WATER. 45 Fahr. be added to 40 Ibs. of water at 212, what will be the temperature of \he mixture ? Then 30 Ibs. x 32 = 960 Thermal units in the ist quantity of water. 40 Ibs. X 212 = 8480 Thermal units in the 2nd quantity of water. 9440 -^ 40 Ibs. + 30 Ibs. = i4L_ i34'85 Fahr., the temperature of the mixture. The Temperature resulting from a mixture of Ice and Water may be found as follows : To melt one pound of ice will absorb 143 thermal units, that being the latent heat of water. Then let I = the weight of ice in Ibs. W = the weight of water in Ibs. T = the temperature of the water. The resulting temperature s Example : If 10 Ibs. of ice be mixed with 10 Ibs. of water at 212 Fahr.^ what is the resulting temperature? Then 143 32 = 111 x 10=1110 and 212 x 10=2120 1 1 10= 1010^20 Ibs. = 5O 0- 5 Fahr., the temperature of the water. The Weight of Ice to be added to Water to Cool or lower its Temperature may be found as follows : Let T=the temperature of the water to be cooled. t=the temperature the water requires to be cooled down to. W=the weight of water in Ibs. to be cooled. Weight of ice = -CT = t)KW_ (143-32)4-1. Example : How many pounds of ice must be mixed with 10 Ibs. of water at 2 12 Fahr., to obtain water at a temperature of 5O'5 Fahr.? Then 2i2-5o -5 = i6r 5 and=- __ =io Ibs. of ice. (143- 3 2 ) + 5'5 161-5 The Temperature resulting from mixing Mercury with water may be found as follows, when the temperature of the mercury is less than that of the water : The specific heat of water is i . The specific heat of mercury is '033. T=the temperature of the water. t^the temperature of the mercury. T t The temperature of the mixture will be= - -\- t. i + '033 Example: If i Ib. of mercury at 52 Fahr. be placed with i Ib. of water 46 THE PRACTICAL ENGINEER'S HAND-BOOK. 212 Fahr., what is the resulting temperature ? Then - 12 ~ 52 =-i-^- = i + -033 1-033 154-8+ 52= 206-8 Fahr., the temperature of the mixture. When the temperature of the mercury is greater than that of the water, the temperature of the mixture may be found as follows : Every 30*3 degrees given up by the mercury will only heat the water i degree, and the difference of the temperatures of the mercury and the water divided by 30-3 + 1, and added to the temperature of the water, will give the tempera- ture of the mixture. Example i : If i Ib. of mercury at 212 Fahr. be placed with i Ib. of water at 52 Fahr., what is the resulting temperature ? Then 212 52 = 160, and =5ii + 52-=57 c -ii Fahr., the tempera- ture of the mixture. Example 2 : If i Ib. of mercury at 212 Fahr. be placed with 10 Ibs. of water at 42 Fahr., what is the resulting temperature ? Then 212 42 = 170, and ^-rr- - = t 54 + 42=42-54Fahr.,thetem- 3 1*3 x 10 IDS. perature of the mixture. Exampte 3 : How much mercury at a temperature of 212 Fahr. will be required to melt 20 Ibs. of ice ? Then 143 latent heat of water x 20 lbs. = 286o, and 2i2x-o33specffic\eatofmercury = ^ 8 ' 8 l bs - f mercuiy. Laws ef Expansion of Metals by Heat. Metals expand equally in all directions, only when of uniform homogeneous texture, free from laminations and impurities. The rate of expansion is not constant for each metal, but varies with its mixture ; for instance, four different mixtures of gun-metal, heated to the same temperature, were found to expand respectively per degree of heat = -000010461, -000010576, 000010645, "000010783. The expansion of a metal is greatest when it is pure and homogeneous, less when it is fibrous or porous, and least when it is either in a burnt or rotten state. When a metal has coarse fibres, the expansion will be greater along than across its fibres. Expansion is increased by rolling, or compressing the metal, as it closes the pores and makes the texture of the metal more uniform. The amount of force exerted by heat and cold in the expansion and contraction of a metal, is equal to that which would be required to stretch or compress it to the same extent by mechanical means. The Expansion of Metals for every degree Fahr., of increase of temperature, is frequently taken at six parts in one million parts for cast iron, that is 6 inches in a length of one million inches : at 7 for wrought iron : 8 for steel not tempered : 9 for brass : 10 for tempered steel : 12 for tin and lead. Example: If a bar of wrought iron, 10 feet long, be heated from 62 Fahr. to 212 Fahr. required the length due to expansion by heat. EXPANSION OF SUBSTANCES BV HEAT. 47 Then 212 62 = 150 degrees increase of temperature, and 150 x 7 = 1050 inches increase of length due to expansion in a length of one million inches, and IO 5 x IO feet X " inches = .^ inch ^ additional IOOOOOO length of the bar due to expansion by heat. Example 2 : A multitubular boiler is 10 feet long, the plates are wrought- iron, the temperature of the bottom of the shell is 238 Fahr., and that of the remainder of the shell 308 Fahr. If the difference between the expan- sion of the top and bottom of the shell be apportioned at th for compression on the top of the shell and f for tensile strain on the bottom of the shell : How much will the elongation be, in parts of the length of the boiler ? Then taking the temperature of the air outside the boiler at 58 Fahr. The expansion of the top of the boiler will be _ (308 - 58) x 7 x 120 inches long _ . 21Qoinch ICOOOOO The expansion of the bottom of the boiler will be - (238 - 58) x 7 x 120 inches long _ . inch IOOOOOO Leaving a difference of -2100 '1512 . . = -0588 inch. Then '0588 -f- 4 '0147, the allowance for the compression of the top- plates, and '0147 x 3 = '0441, the allowance for the tensile strain on the bottom-plates. Then "0441 -f '1512, the expansion of the bottom plates = '1953, the total expansion, and '1953 -f- 120 inches length of boiler = -00162. The expansion of a metal-pipe is sometimes employed as a means of automatically working the valve of a drain-pipe for draining condensation- water from steam-pipes. The valve-seat is placed at the bottom of the drain-pipe, and the valve is held by iron rods connected to a. crossbar fixed on the drain-pipe above the valve. When the drain pipe contains steam, it expands and closes the valve ; when it contains water, the pipe cools and recedes from the valve, and the water escapes. Taking steam at 212 Fahr., and condensation-water at 112= 100 difference of temperature, a wrought-iron pipe 10 feet long would expand = 120 inches x 100 X 00000658 = "0789 inch. Average Expansion of Substances by Heat in length and volume. The results of experiments by various authorities are given in Table 13, the use of which may be illustrated by the following examples : Example i : How much will a bar of average quality wrought-iron, 20 feet long, expand in length when heated 150 degrees ? Then 20 feet x 12 = 240 inches x '00000658 x 150 degrees = 23688 inch, or nearly \ inch, making the bar 20 feet o| inches long. Example 2 : How much will 64 cubic feet of oil expand when heated 100 degrees, and what would the volume of the oil be ? Then 64 cubic feet x -00044445 x 100 degrees = 2*8444 cubic feet the expansion, and the volume of the oil would be 64 + 2 '8444. =: 66-8444 cubic feet. 4 8 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 13. LINEAR, SUPERFICIAL, AND CUBICAL EXPANSION OF SUBSTANCES, &c., BY HEAT, PER DEGREE FAHRENHEIT, FROM 32 FAHRENHEIT. Superficial expansion, or expansion in length and breadth, is twice the linear expansion ; and cubical expansion or expansion in length, breadth, and depth, is three times the linear expansion. Description of Substance. Temperature. Fahr. Linear Expansion. Superficial Expansion. Cubical Expansion. Permanent gases . 32 212 '00069417 00138834 -00208251 Water .... 392572 00018905 OO0378IO -00056715 Water .... 212392 OOOI7067 00034134 ; -00051201 Water .... 32 212 OOOO8807 00017614 ; -00026421 Alcohol and nitric acid . 32 212 OOOI5I53 00030306 -00045459 Oil 32 212 '00014815 00029630 00044445 Turpentine and ether . 32 212 00012967 00025934 00038901 Sulphuric acid . . . 32 212 OOOIIII2 OOO22224 00033336 Salt solution 32 212 00009252 00018504 00027756 Zinc, hammered 32 212 OOOOI728 00003456 00051840 Zinc, cast 32 212 00001636 OOOO3272 00049080 Lead .... 32 212 OOOOI586 00003172 00004758 Tin, hammered 32 212 OOOOI5O8 OOOO3OI6 OOOO4524 Hard solder . . . 32 212 00001436 O0002872 OOO04308 White-metal . 32 212 00001325 OOO0265O 00003975 Tin, cast . . . 32 212 'OOOOI2IO OOOO242O 00003630 Compressed gun-metal . 32 212 OOOOII3O OOOO226O, 00003390 Silver, hammered . 32212 ooooiiiS OOOO2226 00003354 Silver, pure . . . 32 212 00001063 OOOO2I20 00003189 Copper 32572 00001095 'OOOO2 I 90 00003285 Copper . . . . 32 212 00000958 coooiSio OO002874 Brass-sheets and plates . 32 212 00001078 OOOO2I56 00003234 Brass, cast . . . 32 212 00001047 OOOO2094 OOO03I4I Phosphor-bronze . . . 32 212 00001067 00002134 OOOO32OI Gun-metal . 32 212 00001062 OOOO2I24 OO003I86 Gold, hammered 32 212 00000837 00001674 OO0025II Gold, pure . 32 212 00000821 OOOOI642 OOOO2463 Wrought-iron . . . 32572 00000892 00001784 OOOO2676 Wrought-iron, average . 32 212 00000658 OOOOI3I6 OOOOI974 Wrought-iron, best . . 32 212 00000685 OOOOI37O OO002O55 Cast-iron 32 212 00000630 OOOOI26O OOOOlSgO Malleable cast-iron . . 32 212 00000636 OOOOI272 OOOOI908 Cast-steel . . . 32 212 00000615 OOOOI230 OOOOI845 Cast-steel castings 32 212 00000621 00001242 OOOOI863 Hardened steel 32 212 00000695 OOOOI39O OOOO2085 Compressed-steel . . 32 212 00000650 OOOOI3OO OOOOI95O Mild-steel boiler-plates . 32 212 00000672 00001344 OOOO2OI6 Mild-steel boiler-plates ") Siemens-Martin, best ) 3 2 450 00000700 OOOOI4OO 'OOOO2IOO Roman cement . . 32 212 00000800 OOOOI6OO OOOO240O Bismuth 32 212 00000780 00001560 OOOO234O EXPANSION AND CONTRACTION OF SUBSTANCES. Table 13 continued. EXPANSION OF SUBSTANCES, &c. 49 Description of Substance. Temperature. Fahr." Linear Expansion. Superficial Expansion. Cubical Expansion. Wire, brass. . . 32 212 00001074 COOO2 I 48 OOOO3222 Wire, iron . . . 32212 00000745 00001490 00002235 Mercury . . . 32 212 00003334 00006668 OOOIOO02 Glass . . . . I 392 572 00000665 OOOOI33O OOOOT995 Glass . . . . 1 212 392 00000550 oooonoo '00001650 Glass . . . . 32 212 00000482 00000964 OOOOI446 Antimony . . ] 32 212 00000610 OOOOI220 -00001830 Palladium . . . j 32 212 00000560 OOOOII20 ,'OOOOl68o Platinum . . . I 32 572 00000525 OOOOIO50 | '00001575 Platinum . . . 32 212 00000500 ooooiooo OOOOI500 Marble . . . 32 212 00000620 OOOOI240 OOOOl86o Granite . . . . 32 212 00000440 00000880 '00001320 Kentish rag-stone . j 32 212 00000452 000009O4 OOOOI356 Bath stone . . . 32 212 00000405 'OOOOoSlO OOOOI2I5 Stock-bricks . . ! 32 212 00000306 OOOOO6l2 '00000918 Fire-bricks . . . j 32 212 00000235 OOOOO47O '00000705 Slate .... 32 212 00000577 OOOOII54 | '00001731 Gutta percha . . . 25 6O 00008450 00016900 -00025350 Ice . . . 17 + 30 00002857 00005714 -00008571 1 Table 14. CONTRACTION OF WROUGHT-!RON ON SUDDEN COOLING, FROM THE EXPERIMENTS OF WRIGHTSON, HOWE, AND OTHERS. Size of Bar or Wire Initial length of Bar or Wire. Number of times quenched. Percentage of Contraction. Inches. Times. Per c- nt. Bar, i^ inches square 3'5 5 7 6 Bar, i~ inches square 30-05 15 2-26 Hoop, ii inches wide 5770 5 61 Hoop, i|- inches wide . . .' 5770 20 2-25 Wire, -022 inch thick . 7i'oo 2O '3 1 Wire, -012 inch thick . . . 7275 2O 09 Wire, -009 inch thick . 9275 5 06 Bar, i inch square . . . . 36-00 i ooi Bar, i inch square 36-00 6 005 Bar, i inch square . ' . 36-00 12 008 Bar, i inch square Tire, 6 feet diameter . ... 36*00 226-25 20 5 'OI2 009 Tire, 6 feet diameter . 226-25 10 015 Tire, 6 feet diameter . . . 226-25 15 O2 2 Contraction of Wrought-iron by Sudden Cooling. If a bar of wrought-iron be suddenly cooled from a bright-red heat, the contraction which occurs is considerably greater than the expansion previously caused by heating the bar, so that its final length is considerably less than its 5O THE PRACTICAL ENGINEER'S HAND-BOOK. initial length. If the heating and cooling of the bar be repeated, say 30 times, a further permanent contraction occurs at each successive cooling. Thick bars contract considerably more than thin ones, as will be seen from the results of experiments given in the previous Table, showing that bars i^- inch square contracted about seven times as much as wire of less than ^ inch in thickness. COAL AND OTHER FUELS. Coal is the product of the decomposition of vegetable matter, and is composed of carbon, hydrogen, oxygen, nitrogen, and sulphur. Its impurities consist of silica, alumina, magnesia, lime, oxide of iron and earthy matter. The more carbon the coal contains the more heat it will yield. Coal deteriorates rapidly by exposure to the atmosphere, owing to the gradual escape of the constituent gases. Weight of Coal. Coal in its natural bed weighs about 80 Ibs. per cubic foot, and in its broken or loose state it averages 48 Ibs. per cubic foot, small or screened coals weigh 43 Ibs. per cubic foot. Hard coals contain from 5 to 9 per cent, of volatile matter, and soft coals from 15 to 35 per cent, of volatile matter. Those coals contain the most volatile matter which swell up and present a volcanic appearance in burning. All coals contain a certain percentage of water; and they yield in burning from i| to 10 per cent, of ash. Anthracite Coal is of homogeneous structure and jet-bJack colour. It yields intense heat, and contains from 90 to 95 per cent, of carbon, and from 5 to 9 per cent, of volatile matters. It ignites with difficulty, makes hardly any smoke, and emits no sulphurous fumes ; it burns with a short feeble flame, falls to pieces much in burning, and does not cake ; specific gravity, 1-36 to i'6o. Bituminous Coals are lighter than anthracite, and consist of several kinds, viz., clear-burning, flaming, and fuliginous coals. Clear-burning Coals are fragile, ignite with difficulty, and burn slowly with a short, clear, bluish flame, and contain from 15 to 25 per cent, of volatile matter. Some bituminous coals, on being heated, cake, and others swell up and fuse. Flaming Coals are black and glossy, ignite with difficulty, and burn away rapidly with a long whits flame ; they contain from 20 to 35 per cent, of volatile matter. Fuliginous Coals ignite easily, and burn away rapidly with a long yellow smoky flame, and contain upwards of 35 per cent, of volatile matter. Semi-bituminous Coals are of dull-black colour, with from 10 to 20 per cent, of volatile matter, do not cake, and burn with greater flame than anthracite. Bituminous or Gaseous Coals are hard and strong, of dull lustre and brownish-black colour. Newcastle Coal is a flaming coal, it burns faster and makes more smoke than Welsh coal. In order to obtain the same evaporative economy, shorter fire-grates are required in burning Newcastle or long flaming coal thin for a coal containing a less quantity of volatile ingredients, such as Welsh coal, because the generation of heat is spread over a greater length COMPOSITION AND WEIGHT OF COAL. of surface by the long flame of the flaming coal, than the short flame of Welsh coal. The furnace-bars should be spaced wider apart for Welsh coal than for Newcastle coal, as it requires more air. Composition of Coal. The average composition of several kinds of coal is given in the following Table : Table 15. COMPOSITION, WEIGHT, &c , OF COAL. Constituents, &c. Anthra- cite Coal. Aber- dare Coal. Welsh Coal. New- castle Coal. Lanca- shire Coal. Derby- shire Coal. York- shire Coal. Scotch Coal. Carbon, per cent. . 92-00 88*28 86*26 83*60 80*70 So'00 1 7Q-QO 79-50 Hydrogen . . . . 3'8o 4-24 4*66 5*28 5*5o 4-85 4-83 S-58 Oxygen .... I'OO 1*65 2*60 4-65 8.48 9-90 8-33 Nitrogen I'OO 1-66 J "45 1*12 I- 35 1*40 1-14 Sulphur .... 70 -91 1-77 1*25 I '50 J "45 Ash 1-50 3-26 3-26 2*70 2*30 2*77 4*00 Specific gravity . Weight of a cubic foot in 1- 37 1*32 1-31 1-25 I*2 7 1-30 1*29 1*26 ' Ibs. in solid state . . . 85*60 82-50 81*90 78*10 79-40 81*20 80-60 78*70 Weight of a cubic yard in tons, in solid state . . j 1*031 '994 987 941 957 978 972 * 94 8 Average bulk of one ton, heaped, in cubic feet . . 1 41 42 43 46 45 44 44'5 45'5 ( With Quickly How it burns . . .-< diffi- Slowly. Slowly. Quickly Quickly Quickly and Quickly < cultv. cakes. Draught required . j Quick. Quick. Quick. Ordi- nary. Ordi- nary. Ordi- nary. Brisk. Ordi- nary. Quantity of smoke . . [ | None. Scarcely any. Very little. Large. Large. Large. Large. Very large. 1 The Specific Gravity of Coal may be ascertained as follows : suspend from the under side of the pan of a weighing-balance a piece of coal by means of a horse hair, and weigh it both in and out of water, divide its weight in the air by the loss of weight when in the water, and the quotient will be the specific gravity. Example: A piece of coal weighs . . . .561 grains Its loss of weight when weighed in water is . . . 445 grains Then 561 -^445= 1-26 specific gravity of the coal compared with water. Table 16. WEIGHT OF COAL. WEIGHT OF A CUBIC FOOT OF LOOSE Specific Gravity. Weight of Coal in the Natural Bed, per Inch thick per Acre. COAL. Large Coal. Small Coal. Tons Ibs. Ibs. 10 III-25 43 38 '1C I l6"53 45 39 20 121-76 47 41 25 126-84 40 43 3 131-92 51 44 '35 136-59 53 46 40 I4I-95 55 48 '45 I46-75 57 49 50 I52-00 59 51 52 THE PRACTICAL ENGINEER'S HAND-BOOK. The Weight of Coal in its natural bed, per inch in depth per acre- allowing for loss in working available in a given area of seam is approxi- mately equal to the weight of the same surface and depth of rainfall, or about 100 tons per acre ; and the weight in tons of an acre of coal i inch thick is approximately equal to 100 times its specific gravity. The Heating Power of Coals, or their average evaporative power in pounds of water from 212 converted into steam by i lb. of coal, is as fellows : Anthracite coal 9'io Bituminous clear-burning coal . . . . 9'i6 Bituminous flaming coal . . . . . . 8'io Bituminous fuliginous coal 8'io Semi-bituminous coal 9 oo Gaseous coal 6-20 Warlich's Patent Fuel is a mixture of small coal I ton, tar 10 gallons, or 242 Ibs., moulded into blocks and baked at a temperature of 800 Fahr. for ten hours ; the blocks in baking lose 5 per cent, of their weight. Wylam's Fuel is a mixture of small coal or slack 92 parts, finely ground dry pitch 8 parts. The mixture is forced with an Archimedean screw through a retort maintained at a dull red heat, and afterwards moulded under pressure into blocks. Mezaline's Fuel is a mixture of finely ground small coal and pitch ; during the process of grinding it is softened by superheated steam. Fuel prepared in this way loses 4 per cent, of its weight when exposed to a high temperature. Barker's Fuel is a mixture of one ton of small coal, thirty gallons of farina-mucilage consisting of farina i part, water 4 parts, and a small quantity of carbolic acid and a small quantity of powdered pitch. The mixture is baked for 9 hours at a temperature of 300 Fahr. Holland's Fuel is a mixture of small coal, lime and cement ; hence it makes when burnt a considerable quantity of ash. Penrose and Richard's Patent Coke is a mixture of 60 per cent, of anthracite, 35 per cent, of bituminous coal, and 5 per cent, of pitch, ground and mixed together ; the yield of coke is 80 per cent, of the weight of the charge. This coke is very hard, of steel-grey colour, and is about 23 per cent, heavier than Welsh coke. Weight and Bulk of Coal. The weight of a cubic foot of heaped coal varies from 44 to 58 Ibs. The average weight of a variety of different coals was found to be 50 Ibs. per cubic foot. Weight of Coke. The weight of a cubic foot of heaped coke is 30 Ibs. The Bulk of one ton of Heaped Coal varies from 37 to 50 cubic feet. The average bulk is 45 cubic feet per ton. Coal of medium density averages if cubic yards per ton heaped. Peat of medium density averages 8 cubic yards per ton heaped. The bulk of one ton of heaped coke averages 80 cubic feet. The Admiralty allowance for the Bulk of Coal equals 40 cubic feet per ton of 2240 Ibs., and 48 cubic feet per ton of 2700 Ibs. Patent Fuels are lighter than coal. The average weight is 74 Ibs. per cubic foot solid, and 65 Ibs. per cubic foot heaped. The bulk of one ton of patent fuel heaped averages 35 cubic feet. STOWAGE OF FUEL AND STORES. 53 Petroleum-Refuse Fuel requires a space of 41 cubic feet to contain one ton. The stowage-capacity of Patent Fuels, Liquid Fuels, and Stores is given in the following table : Table 17. WEIGHT AND SPECIFIC GRAVITY OF PATENT FUELS, LIQUID FUELS, AND STORES. Description. Weight per Cubic Foot. Weight per Cubic Yard. Specific Gravity. Lbs. Tons. Wylam's patent fuel . 68-8 .820 '10 Lyon's 70*6 8 5 I ' J 3 Bell's .... 71-2 858 'H Livingstone's 71-2 858 "14 Warlich's 71-9 86 7 -I 5 Holland & Green's . . . 81-2 978 30 Vinegar distilled weighs 68 009 Milk 64-3 030 Fresh water .... 62-425 coo Wine 62 ... 993 Tallow 59 950 Linseed oil 58-7 940 Ice 58 '93 Rape seed oil and whale oil . 57'4 ... 920 Alcohol, proof strength 57'4 920 Olive oil 57*i 915 Gunpowder, average . 56-7 910 Petroleum . . . . . 54*9 880 Turpentine .... 54'2 870 Naphtha S3'' 850 Cotton waste . . . . ii 170 Dry Fine Wood requires no cubic feet to stow one ton, and weij 21 Ibs. per cubic foot. Bulk of Gunpowder, cubical contents of 100 Ibs. weight of gunpowder=i'774 cubic feet, or 3064 cubic inches. The Quantity of Coal a Bunker will contain may be found by this Rule : Multiply the length, width, and depth, in feet together, and the product will be the contents of the bunker in cubic feet, then divide by 45, the number of cubic feet in a ton of coal of average bulk, and the quotient will be the quantity in tons which the bunker will contain. The section of a coal-bunker is shown in Fig. 16. When the cubical contents in feet and two dimensions only are given to find the third The Length of a Bunker may be found by dividing the cubical contents in feet by the product of the breadth and height in feet. The Width of a Bunker may be found by dividing the cubical contents in feet by the product of the length and height in feet. fig. 16. Coal- bunker. 54 THE PRACTICAL ENGINEER'S HAND-BOOK. The Height of a Bunker may be found by dividing the cubical contents in feet by the product of the length and width in feet. The Cubical Contents or Space required in Cubic Feet to contain Coal may be found by multiplying the number of tons by 45. Example i : Required the quantity of coals contained in a coal bunker 1 6 feet long, 8 feet wide, and 7 feet 6 inches high. Then 16 x 8 x 7-5 = 960 -h 45 = 21 tons, 6 cwt., 2 qr., 12 Ib. of coal. Example 2 : Required the quantity of coals contained in a coal-bunker 20 feet long, 10 feet deep, 7 feet wide at the top, and 5 feet wide at the bottom. First find the mean width by adding the two widths together and dividing by two. Then 7 + 5 = 124-2 = 6 the mean width and 20 x 10 x 6 = 1200 -f- 45 = 26 tons, 13 cwt., o qr., 23 Ibs. of coal. Example 3 : A coal-bunker is required 8 feet wide and 6 feet deep, what length should it be to hold 20 tons of coal ? To find the length divide the cubical contents by the product of the width and height. Then 8 x 6 = 48, and 20 tons x 45 cubic feet = 900 4-48 = 18 feet 9 inches, the length required. Practical Analysis of Coal.* The sample should represent an average of the whole quantity no less than one pound can be used. This must first be ground in an iron mortar and sifted through a fine sieve. What remains must again be ground and sifted until all passes through. Estimation of Water. Weigh off three grammes of the powdered sample, and heat in an air-bath at I2OC. for twenty minutes; then weigh (after cooling). Afterwards heat up again, weighing every ten minutes until the weight is constant. Then the loss in weight = water. Bituminous coals increase in weight by oxidation during the heating, so too great care cannot be exercised in this part of the analysis. Unless the percentage of water is specially desired it need not be re- garded. Under all circumstances it is best to calculate all results in the dry material, for which purpose heat up the sample for forty minutes and place in a desiccator to cool. Volatile and Combustible Material. Place the dry sample in a weighing flask. Deliver from it o^oog. coal into a porcelain crucible, and heat for ten minutes over the strongest Bunsen burner, the crucible being kept covered all the time. Cool and weigh. Loss = volatile and combustible material -+- \ the sulphur of the FeS 2 . Fixed Carbon. Take from the weighing flask about O'5oogr. and place it in a tarred, open platinum dish. Heat gently at first over Bunsen burner, then more strongly, and finally at highest heat, until all the carbon is burned off. Loss = volatile matter + | S + F. carbon. The difference is the fixed carbon. The residue = ash. Examine ash closely as to colour and texture. Sulphur. Oxidize 2g. of coal with 2oc. c. fuming nitric acid and |g. chlorate of potash in a porcelain dish. Cover with inverted funnel for two hours at a very low heat, bring on to a filter, wash with boiling water, and precipitate with BaCl 2 . Wash the precipitate in acetate of ammonia by * See an article by Mr. A. K. Glover, in the " Scientific American." PRACTICAL ANALYSIS OF COAL. 55 boiling up with it and decanting several times. From the BaSo 4 calculate the sulphur. Estimation of Total Carbon and Available Hydrogen. Employ a hard, infusible glass combustion tube 4ocm. long and about i5mm. in diameter, drawn to a point. Fill one-third the length with dry fused chromate of lead finely powdered. Then by means of a small delivery tube insert o - 2oog. of coal into the combustion tube. Mix well the coal and chromate by means of a wire stirrer, and finally add more chromate, stirring still, until the tube is filled to the extent of 35011. At the anterior end place a thick coil of copper gauze, to decompose the nitrous oxide that may be formed. Then attach a chloride of calcium tube, carrying two bulbs, to the tube by rubber cork. To the chloride of calcium tube attach a U tube containing nitrate of lead, to catch the sulphurous acid formed, and lastly the potash bulbs filled with strong caustic potash. Proceed carefully as in any other delicate organic analysis, keeping the copper gauze at a bright red heat. The posterior part of the chromate should be heated the hottest. From the increase in weight of the potash bulbs calculate the total carbon (fixed and volatile) and from the CaCl 2 tube the hydrogen. Never use more than o'25Og. of coal. In coals carrying as high as 20 per cent, of volatile material o'loog. is sufficient. Too much care in using dry chromate of lead cannot be exercised, otherwise too much hydrogen will be set down for the coal. Heating Power of Carbon and Hydrogen. Taking as a heat-unit the heat necessary to raise the temperature of one pound of water through one degree centigrade, ond pound of carbon (C) in burning to carbonic acid (CO 2 ) disengages 8080 thermal-units: and one pou^d of hydrogen (H) in burning to water (H 2 O) disengages 34,460 thermal-units. Hence the following approximate Rule for finding the heating power. For a more exact Rule see p. 57. Valuation in Heating Power. Multiply the percentage of total carbon by 8080, and the available hydrogen by 34,460. Divide each result by 100, and add together. Example : Required the heating power of coal containing 80 per cent. carbon and 5 per cent, hydrogen. Then (80 x 8080) + (5 x 34,460) 100 6464-00 1723-00 8187-00 = calorific or heating power. If the English unit of heat, or the heat necessary to raise the temperature of one pound of water through one degree Fahr., be taken as the heat unit instead of that given above, then the multiplier for the above Rule will be 14,500 for the carbon, and 62,535 f r tne hydrogen As a further means of comparison, it is often advisable to record the amount of coke yielded by a given sample. The coke is the difference between 100 per cent, and the volatile matter. Beyond the above analysis nothing is wanted to enable a right judgment to be formed as to the value of a sample of coal. 56 THE PRACTICAL ENGINEER'S HAND-BOOK. COMBUSTION. ^Combustion is the chemical combination of substances principally carbon and hydrogen with oxygen, the supporter of combustion, attended with the evolution of heat and light. The chief constituents of coal are carbon and hydrogen, neither of which can be consumed while they remain united, the carbon or carbonaceous portion is combustible only in its solid state, and the hydrogen, or bitumi- nous portion is combustible only in the gaseous state. Carbon is perfectly consumed when combined with 2'666 parts of oxygen to form carbonic acid gas, and partly consumed when combined with one- half that quantity of oxygen to form carbonic oxide gas or smoke. Hydrogen is the lightest body known : it is 14^ times lighter than air. It is the main element in the gas evolved from burning coal, and its com- bustion produces flame. Hydrogen in burning combines with eight parts of oxygen to form nine parts of water. Bituminous coal contains from 5 to 6 per cent, of hydrogen, and as each pound of hydrogen in combustion combines with 8 Ibs. of atmospheric oxygen, it produces 9 Ibs. of water in the form of steam ; and each hundred-weight of coal produces about 50 Ibs. of water. The gaseous products of the complete combustion of i Ib. of fuel, are as follows : i Ib. of carbon unites with 2*66 Ibs. of oxygen to form 3-66 Ibs. of carbonic acid. i Ib. of hydrogen unites with 8 Ibs. of oxygen 'to form 9 Ibs. of steam. i Ib. of sulphur unites with i Ib. of oxygen to form 2 Ibs. of sulphurous acid. The sulphur may be omitted in ordinary calculations. When Heat is applied to Bituminous Coal the first result is its absorption by the coal and the disengagement of gas, from which flame is exclusively derivable. The constituents of this gas are hydrogen and carbon, and the unions form two gases, viz., carburetted hydrogen, and bi-carbu- retted hydrogen commonly called olefiant gas. These inflammable gases require certain quantities of atmospheric air to effect their combustion, and they are only combustible in proportion to the degree of mixture and union which is effected between them and the oxygen of the air. The chemical assimilation of the volatilised coal-elements is retarded by contact with cold surfaces, and assisted by hot surfaces. Air can be heated instan- taneously, and when the heating-surfaces of a combustion-chamber are highly heated, the air is instantaneously heated to the same degree of tenuity as the hot gases, they therefore instantly unite and produce intense heat. When a sufficient supply of air is not provided to the furnace, the result is waste of fuel from the escape of unconsumed fuel, in the gaseous and smoky state, to the chimney. If the supply of air be correctly regulated, there will be perfect combustion producing carbonic acid ; but if the supply of air be deficient, the combustion will be imperfect and carbonic oxide will be produced. The Heat developed by Fuels in burning, may be ascertained by calculation when their chemical composition is known. The chemical composition of various combustibles is given in the following Table. COMPOSITION AND HEATING-POWER OF COMBUSTIBLES. 57 Table 18. CHEMICAL COMPOSITION OF COMBUSTIBLES. Description. Carbon. Hydrogen. Oxygen. Ash. Coke, average of 25 analyses . '935 06 5 Charcoal, from wood, average . 925 075 Oil of turpentine . . . 882 i is Pine-wood oil . . . . 867 106 027 Paraffin, or petroleum-oil 8 55 '145 ... Petroleum, average . . v . . 840 no 050 Creosote, or tar-refuse . . 825 ico 075 Spermaceti 817 123 'O6o Beeswax . . . . . 815 '39 046 Coal, average . . . 8o 4 052 079 041 Schist oil . . . . '. 800 117 08 3 Resin . . . . . 791 IO2 107 Asphalte 790 095 087 028 Tallow . . . ; . 788 118 094 Sperm oil 787 110 103 Olive oil .... 770 -I 34 096 Lignite, bituminous . . . 749 075 130 j "046 Lignite, perfect 690 050 202 058 Lignite, imperfect . . . 602 053 2 9 055 Peat, perfectly dry . 600 060 300 O4O I Peat, dry, average 570 060 3 20 050 Peat, dry, medium quality 460 050 437 053 Alcohol . . . . . 520 **35 '345 Wood-pimps, or bundles of twigs, dry .... 510 060 400 030 Wood, perfectly dry, average . 500 060 418 O2 2 Wood-bark, dry . 477 063 43 2 028 Wood, pine, dry . . . 445 055 485 015 Wood, oak, dry ... '43 053 496 021 Sawdust, dry . . . . 410 043 '53 1 016 Straw, barley, dry . 380 054 510 056 Straw, wheat, dry . . ". . 360 050 540 050 Straw, oats, dry 348 050 557 045 Heating-Power of Carbon. One Ib. of carbon burning to carbonic acid develops 14500 units of heat according to Peclet, and 12906 units of heat according to Dulong. One Ib. of hydrogen develops 62535 units of heat; the heat developed by hydrogen is 62535 -f- 14500 = 4-31 times as great as that of carbon. One Ib. of hydrogen requires 8 Ibs. of oxygen. Atmospheric air contains 20 per cent, of oxygen. The Heat developed by a Combustible, or its Calorific Power, may be calculated from its chemical constituents by this formula : Units of heat = (14500 x percentage of carbon J + j 62535 hydrogen 58 THE PRACTICAL ENGINEER'S HAND-BOOK. Coke contains -935 carbon, but no hydrogen or oxygen as will be seen from Table 18. Therefore coke in burning will develop 14500 X -935 = I 3557 units of heat per Ib. of coke; this is its maximum calorific power. The Effect of Oxygen in a Combustible containing hydrogen, is to diminish its heating power. The oxygen is combined with the hydrogen in the ratio of 8 to i forming water instead of leaving free the heat which the hydrogen gives off in burning. When the quantity of oxygen in a combustible is less than that ratio, it combines with one-eighth of its weight, and the excess of hydrogen, above that neutralized by the oxygen, yields its proportion of heat, which may be calculated in the following manner : Heating Power of Feat. As oxygen requires one-eighth part of its weight of hydrogen, the oxygen in peat will require one-eighth of its hydro- gen or -320-^8 = '04 hydrogen, the hydrogen in the peat is '06 ; therefore, the excess of hydrogen available for yielding heat will be - o6 -04 = '02, and the heat this fuel will yield will be as follows : Peat average, carbon = -570 X 14500 = 8265 units Hydrogen in excess = '02 x 62535 = 1250 units 9515 units of heat per Ib. of peat. Heating Power of Coal. Coal composed of '804 carbon: '052 hydrogen : '079 oxygen, will yield Carbon '804 x 14500=11658 units Hydrogen. Oxygen. Hydrogen ('052 ?^2_ J='O422 x 62535= 2639 units 14297 units of heat per Ib. of coal : its maximum calorific power. Heating Power of Sawdust. Sawdust in burning requires large fire-grate surface, the grate-bars should be placed low, and thin grate-bars, having narrow spaces between them, should be used. A thick layer of saw- dust should be kept on the bars which will develop the following quantity of heat : Sawdust when in a dry state, on an average is composed of '410 carbon; and i Ib. of hydrogen for each 8 Ibs. of oxygen ; and as the hydrogen is thus neutralised by the oxygen, it develops no heat. Hence sawdust will yield: carbon -410 x 14500 = 5945 units of heat per Ib. of sawdust, its maximum calorific power. Heating Power of Liquid Fuel. Petroleum-oil is largely used for this purpose. Paraffin or petroleum-oil, composed of '885 carbon and '145 hydrogen, will yield Carbon '885 x 14500 = 12832 units Hydrogen -145 x 62535 = 9067 units 21899 um 'ts of heat per Ib. of oil, its maximum calorific power. HEATING-POWER OF COAL-GAS. 59 The heating power of petroleum, it will be seen from the above, is more than 50 per cent, greater than that of coal. Creosote-oil, or residue from the distillation of tar, is also used as liquid fuel. Its composition is given in Table 18; its calorific power is less than that of petroleum-oil. Creosote-oil is liable to crystallize at tempera- tures below 120 Fahr., and it is necessary to place a small steam-pipe inside the pipe through which the oil flows when using it as liquid fuel. Gaseous Fuel. The composition of average coal-gas is as follows : Hydrogen SI'GO Marsh-gas 35'3 Carbon oxide ......... 7'58 defines 3'55 Nitrogen 2-27 Oxygen -30 The Maximum Heating-Power of Average Coal-Gas has been found by experiment to be 700 heat-units per cubic foot of gas. The heating power of ordinary i6-candle-power coal-gas is 630 units of heat per cubic foot. As 30 cubic feet of coal-gas at 62 Fahr. = i lb., the maximum heating power of i lb. of coal-gas is 700 x 30 = 21000 heat-units, or more than 50 per cent, greater than that of coal of average quality. Table 19. QUANTITY OF GAS IN CUBIC FEET OBTAINED FROM COAL. Description of Coal. Specific gravity of Gas. Cubic feet of Gas obtained per ton of Coal. Weight in Ihs. of Gas per ton of Coal. Boghead .... 752 I5OOO 866 Capeldrae . . . . '577 14400 638 Lesmahago .... 618 I32OO 627 Arniston 626 I26OO 606 Newcastle .... '475 11648 423 Welsh 737 II424 645 Pelaw "444 II424 389 Pelton '437 II424 387 Bickerstaff, Liverpool '475 II424 415 Wigan 528 II40O 461 Garesfieid .... 398 I050O 321 Powell '459 10165 357 Forest of Dean 360 IOI33 279 South Staffordshire . . . '320 9600 2 35 Derby's Deep Main . . '424 9400 308 Derby's Soft Coal . . . -528 7500 303 Leeds '530 6500 264 The volume of gas in cubic feet may be reduced to weight in Ibs. by multiplying the volume by the specific gravity of the gas and by the constant number '076. 60 THE PRACTICAL ENGINEER'S HAND-BOOK. One Ton of Crude Petroleum will yield 21000 cubic feet of good gas. Pintsch-Gas, or Gas from Oil, is successfully used for lighting railway carriages and for purposes where coal-gas is not available.* It is made bi decomposing petroleum or shale-oil, and is compressed to about 10 atmospheres. During compression, liquid is deposited in a chamber im- mediately attached to the pumps, and to a much larger extent in the reservoir in which the gas is stored, and from which it is delivered into the iron recipients (drums) attached to the railway carriages. This liquid is commonly called " hydrocarbon," and for convenience it is designated " pump hydrocarbon " and " reservoir hydrocarbon." Notwithstanding the nature of the material used in making oil-gas, the " hydrocarbon " is practically free from paraffins, containing but traces of hydrocarbons in- soluble in sulphuric acid ; it essentially consists of benzene and toluene, mixed with hydrocarbons of the C n H 2n and C n H 2n 2 series. The " reservoir hydrocarbon " especially is saturated with gas, and on passing this into bromine, a solid bromide, of the composition C 4 H 6 Br 4 , is obtained, which melts at 116 C, and is but slightly volatile. It seldom contains less than about 50 per cent, of benzene and toluene. The " pump hydro- carbon " differs from that deposited in the reservoir, only in being richer in the less volatile constituents. In the Piutsch System of Manufacturing Oil-Gas, two cast-iron D-shaped retorts are set one above the other; the largest size used being 6 feet 4 inches long, 10 inches wide, and QJ inches deep. The oil is run into the upper retort at one end, falling upon an iron-tray, which is loosely fitted into the retort ; and to complete the decomposition, the vapours are passed through the second lower retort. The temperature at which the retorts are worked is very high a bright cherry-red. The oil is run in at the rate of about \2\ gallons per hour, and about 80 cubic feet of gas is yielded per gallon of oil. In the Keith System of Manufacturing Oil-Gas, the retort is generally 6 feet long, 5 inches broad, and 10 inches deep, and is constricted in the middle ; it is made shallower in the middle and proportionally broader, so that the sectional area is the same as at the end. The oil is caused to flow down an inclined trough, so that it strikes the retort near the constriction where the temperature is highest. It is stated that from 100 to 150 cubic feet of gas may be obtained from i gallon of oil, according to the quality of the latter ; and with 1 2 retorts 2000 cubic feet of gas can be pro- duced per hour, of 5o-candle-power. The results depend upon the quality of the oil, and the manner in which the decomposition is effected. GAS ENGINES AND HOT-AIR ENGINES. Gas Engines possess many advantages over small steam engines, and compare favourably with them as regards the cost of fuel. The " Otto " gas engine, shown in Fig. 17, is single-acting, the cylinder being open at the front end. The first forward stroke of the engine draws an explosive * See a Paper by Professor Armstrong, in the " Journal of the Society of Chemical Industry." GAS ENGINES. mixture of air and gas into the cylinder, which, on the return of the piston, or first inward stroke, is compressed to about one-third its volume. At the beginning of the second out-stroke, the compressed charge is ignited, and the expanding gases propel the piston to the end of the stroke, the products of combustion being expelled at the second in-stroke. The tested con- sumption of coal gas by the "Otto" gas engine, when new, may be averaged; Fig. 17. " Otto" horizontal gas-engine. at from 18 to 22 cubic feet per indicated horse-power per hour for the large sizes, to 25 cubic feet per indicated horse-power per hour for the smaller sizes. At intermittent hoisting work, using coal-gas costing 3.?. per 1000 cubic feet, the cost of working a 3! horse-power engine, taking an average of three months' consumption of gas, has been found to be as low as tenpence per day. The cylinder of the " Otto " gas engine is shown in section at Fig. 18. The slide is shown in the position when it is about. Fig. 18. Section of a cylinder of an "Otto" gas-engine. to ignite the charge in the cylinder through passage A ; the slide has carried the light B from the light c, which is always burning when the engine is working ; the light B is extinguished after every explosion. The light B is fed with gas through a small passage in the slide. This passage will be closed just before light B reaches chamber A, and it ignites the charge. 62 THE PRACTICAL ENGINEER'S HAND-BOOK. In careful tests of a single " Otto " gas engine of 30 indicated horse- power, the total consumption of fuel was found to be only i'2 Ib. per indi- cated horse-power, and 1-5 Ib. per brake horse-power per hour. Dowson's Water-gas is used for large gas engines. It is very much cheaper than coal-gas, its cost being only about three pence per thousand cubic feet ; in an " Otto" gas engine using this gas, the consumption is as low as i '3 Ib. of anthracite coal per indicated horse-power per hour. An analysis of this gas by Professor Foster is given in the following Table, which also contains for comparison an analysis of ordinary coal-gas of 16 candle- power, from which it will be seen that coal-gas has nearly four times the calorific power of the other, the comparative explosive force of the two gases in atmospheric air being as 3-8 : i, that is, the coal-gas has 3-8 times the energy of the other. Table 20. COMPOSITION AND CALORIFIC POWER OF DOWSON'S WATER- GAS, AND OF ORDINARY 1 6 CANDLE-POWER COAL-GAS. ORDINARY COAL-GAS, 16 CANDLE- DOWSON'S GENERA TOR-GAS, POWER. OR WATEK-GAS. Composition of the Gas. Volume per Cent, at Weieht in Calorific Volume per Cent, at Weight in Calorific o deg. Cent. Grammes of Power of o deg. Cent. Grammes ol Power of and 760 100 Litres. 100 Litres. and 760 100 Litres. 100 Litres. mm. mm. Hydrogen . 5I-8l 4-63 I 59>559 I8-73 I-6 7 ' 57,689 Marsh gas . . 35-25 25-20 329,187 0-3I 0'22 2,899 Olefiant gas . 3-53 4-4I 52,664 0-38 4,633 Carbonic oxide . 8-95 II'20 27,854 25-07 31-36 77,992 ,, acid 6-57 12-91 Oxygen . . . 0-08 O'H 0'04 Nitrogen . 0-38 0-47 48-98 6l-27 lOO'OO 46-02 569,264 lOO'OO 107-85 >3 Water-gas is now used for a great variety of purposes, such as singeing yarns and fabrics, type-founding, varnish making, heating water, cooking, baking bread, &c., and in all cases it is found that by allowing about four volumes of the generator gas for one of coal gas, the same heating effect is obtained. The above theoretical calculations of the calorific power are therefore confirmed in practice. The Pressure produced by the Explosion of Gaseous Mixtures has been determined by experiments made by Mr. D. Clerk,* the results of which afford useful data for gas engines, and are given in the following Table. In no case did the heat accounted for by the explosion-pressure amount to more than 77 per cent, of the total heat present as inflammable gas ; in the majority of cases it was a little over 50 per cent. * See a Paper read before the Institution of Civil Engineers, by Mr. D. Clerk, F.C.S., "On the Explosion of Homogeneous Gaseous Mixtures." HOT-AIR ENGINES. Table 21. PRESSURES PRODUCED BY THE EXPLOSION OF MIXTURES o? INFLAMMABLE GASES WITH ATMOSPHERIC AIR. OLDHAM COAL-GAS AND AIR MIXTURES. Average Temperature of Gases before Ignition taken at 17 degrees Centigrade. Pressure, atmospheric (14*7 Ibs.). GLASGOW COAL-GAS AND AIR MIXTURES. Temperature of Gas before Ignition 18 degrees Centigrade. Pressure, atmospheric (i^y Ibs.). Proportion of Gas by Volume. Maximum pressure in Ibs. per Square Inch above the Atmosphere. Maximum Tempera- ture, Centigrade. Time of Explo- Proportion of Gas by Volume. Mean pressure in Ibs. per Square Inch above the Atmosphere. Maximum Tempera- ture, Centigrade. Time of Explo- sions. TV TV TV TV t i Ibs. 40 5''5 60 61 78 7 90 9 1 80 Degrees. 806 '033 I2O2 1220 1557 1733 1792 1812 1505 Seconds. '45 31 24 '17 08 06 04 05 16 TV TV I Ibs. S 2 ^ 6 9 8 9 9 6 Degrees. 1047 1265 1384 1780 IQiS Seconds. 28 18 13 07 05 Hydrogen and Air Mixtures. Temperature of Gases before Ignition, 16 degrees Lee tigrade. Pressure, atmospheric (14*7 Ibs.). * i t Maximum. 41 68 80 826 to got 358,, i53< 615 I92( ) '15 j "026 ) -01 The Highest Temperature in a Gas Engine has been estimated at 3444 Fahr. absolute, the temperature of the exhaust gases being estimated 3444 1230 at 1230 Fahr.; the highest theoretical efficiency being = = 64-2 per cent. Such a high efficiency is not lealised in practice, the loss of heat through the sides of the cylinder being very great, owing to its having to be kept cool in order to enable the piston to work properly. The practical efficiency of gas engines is from 12 to 22 per cent. Hot-Air Engines are used to a limited extent for the development of small power. In these engines heat is applied to air enclosed in a cylinder, the air expands and drives a piston. The air in doing work loses heat, and the efficiency of the engine depends upon the difference of temperature through which it works ; the greater the fall from the higher to the lower temperature, the greater the power developed. The efficiency cannot be greater than Higher absolute temperature lower absolute temperature Higher absolute temperature. The best hot-air engines consume about 8 Ibs. of coke per horse-power per hour ; a ^-horse power engine consumes about 40 Ibs. of coke in working ten hours. 6 4 THE PRACTICAL ENGINEER'S HAND-BOOK. The " Bider" Hot-Air Engine, shown in Fig. 19, is a simple and efficient small motor. It has two single-acting cylinders placed vertically ; there are two plungers, marke:! c and D, which are coupled by means of connecting rods j to cranks keyed at right angles to each other on a crank- shaft common to both ; one plunger D, called the power plunger, works in a cylinder kept permanently hot by means of a fire, while the other c, called the compression plunger, works in a cylinder surrounded by a water-jacket E. The two cylinders are connected by a wide passage H, fitted with plates, and constituting the re- generator. There is no change < f air in this engine, but the relative motions of the two plungers cause a constant al- teration in volume and move- ment of the air between the two cylinders. Any leakage is made good through the inlet valve shown at the bottom of the cool cylinder c. The work- ing of the engine includes four operations :* i. A small com- pressed bulk of air has heat restored to it by the regene- rator, the pressure rising during the process ; the back pressure in c counterbalances the for- ward pressure in D, so that this is a period of displacement, t?king place during the first quarter of a revolution as the plunger D moves up from the bottom centre. 2. The small bulk of air receives a fresh supply of heat at the highest temperature, expands, doing useful work by pressure on D, and subsequently on c to a less extent. This takes place during the second quarter of a revolution, the piston D arriving at the top centre. 3. A large expanded bulk of air is transferred from B to A, and its heat abstracted and stored in the generator. The pressure falls, and the forward pressure on c during the last half of the upward stroke counter-balances the pressure in D. This is a period of displacement, which takes place during the third quarter of the revolution. 4. The large bulk of air is compressed into the small space c. The back pressure against c is not counterbalanced by the for- Fig. 19. - Rider's hot-air engine. * See article on this engine in the "Mechanical World." HEAT EVOLVED BY COMBUSTIBLE*. 6$ ward pressure in D ; hence during this period work is required from the fly-wheel to compress the air, but at the same time heat is withdrawn while the fluid is at the lowest temperature, and the work required to com- press the fluid while cold, and losing heat, in the fourth pariod is con- siderably less than the work given out by the fluid while expanding when hot, and receiving heat, in the second period. The Effective Power of this Engine represents the difference be- tween that given out in the second revolution and that required to compress the air in the fourth. The engines made of this type are of , |, and i horse-power, the number of revolutions being from 100 to 150 per minute, and the indicated maximum pressure from 20 Ib. to 22 Ib. The regenerator consists of cast-iron plates about | in. thick, with a space between of -^ inch ; in the % horse-power engine, it measures about 1 1 inches by 4 inches by 4^ inches. The heaters run good, if used with care, from two to five years ; the cost of a new heater is about 23-5-., and the labour of one man for a day to put it in place. The air appears to get heated to the temperature correspond- ing to dull-red heat of cast-iron, or about 1000 Fahr. At one test of a \ horse- power engine, when working a pump, about 675 gallons of water were raised per hour to a height of 90 feet with 4 Ibs. of coal. This performance is equal to, say 10.128 ft. Ib. per minute, or '307 horse-power; and the consumption of coal per effective horse-power was 13 Ib. At another trial, 4 Ibs. of coal were sufficient for \ horse-power duty in the water, or 8 Ibs. per horse-power. The mean effective pressure in the working cylinder was i6'8, and in the cooling cylinder (making allowance for the difference in strokes) 6-47, giving 10-33 'bs. per square inch nett. The i horse-power engine has plungers 10 in. in diameter, and 13 in. stroke, and occupies a floor space of 4 ft. 4 in. by 2 ft. 8 in., and measures to the top of the fly-wheel 7 ft. 6 inch. The weight complete is about 28 cwt. 2 qr., and it gives out about one effective horse-power. The power cylinder has an iron jacket for about half its length, so formed that the entering air passes well round the cylinder and between the jacket, and then impinges directly on the hot heater bottom F, thus getting thoroughly heated in its passage, and at the same time the cylinder remains relatively cool. The packing round the plungers consists of leather collars held in position by a ring. HEAT EVOLVED BY COMBUSTIBLES. The Total Quantities of Heat evolved by the Combustion of Different Combustibles, the results of experiments by MM. Favre and Silbermann and others, are given in the following Table. Table 22. HEATING POWER OF VARIOUS COMBUSTIBLES. Heat in degrees Fahr. to which i Ib. of water will be raised by i Ib. of combustible. Acetate, C 6 , H 6 , O 4 ..... . 9616 ,, of Alcohol, Valeric, C 20 , H 20 , O 4 . . . . 14349 Acetone, C 6 , H 6 + O 2 ....... 13149 Acid, acetic, O 4 + C 4 ,H 4 , 6310; butyric acid, O 4 + C 8 , H 8 . 10122 ethalic, O 4 + C 32 , H 2 ...... 16956 66 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 22 continued. HEATING POWER OF VARIOUS COMBUSTIBLES. Acid, formic, O 4 + C 2 , H 2 ,, phrenic, C 12 , H 6 , O 2 stearic, O 4 + C 38 , H 38 . valeric, O 4 + C 10 , H 10 .... Alcohol, H O 2 + C 4 , H 4 ethalic, HO, + C 38 , H 32 . valeric, HO 2 + C; o , H 10 Aldehyde, ethalic, C 32 , H 32 , O 2 ,, stearic, C 38 , H 38 , O 2 . Amylene, C 20 , H 20 , 20347; C 22 , H 22 Aragonite, combined, gives ,, separated, absorbs .... ,, separated after combination, absorbs Butyrate of methylene, C 50 , H 10 , O 4 Carbon burnt with peroxide of azote at 10 from C to C O 2 ,, ,, gas retorts . ,, ,, sugar from C to C O 2 . Cetine, C 32 , H 32 Decomposition of oxide of silver absorbs . ,, of peroxide of azote ,, of water oxygenated i gr. oxygen Diamond, 13987; Diamond, heated Essence of citron, C 20 , H 16 .... ,, ,, turpentine, C 20 , H 16 . . . Ether, acetic, C 8 , H 8 , O 4 butyric, C 12 , H 12 , O 4 . sulphuric, H O 2 + C 8 , H s ,, valeramilic. C 20 , H 20 , O 4 . valeric, H0 2 + C 20 ,H 20 . . . Formiate of alcohol, C 6 , H 6 , O 4 . methylene, C 4 , H 4 , O 4 . Gas, marsh, C 2 , H 4 , 23514; Gas, olefiant, C 4 , H Graphite from high mines, 14014; No. 2 . Graphite, natural, No. i, 14061 ; No. 2 Hydrogen at 59 Iceland spar for C O 2 and C to O absorbs . Metamylene, C 40 , H 40 Oxide from carbon, C O 2 Paramylene, C 10 , H 10 Spirit of wood, H O 2 +C 2 , H 2 . Sulphur at instant of crystallization native melted, 3998 : Sulphur of carbon TeVebene, C 20 , H 16 . Valeriate of alcohol, C 14 , H 14 . methylene, C 14 , H 14 , O 4 it in degrees Fahr. to which i Ib. of water will be raised by i Ib. of combustible. . . 3600 . I4H7 . . 17676 . II59I . . 12932 18616 18893 20279 +68-9 -554-6 -485-6 12238 20085 H545 14486 14472 19942 -39'8 19963 2346 14182 1 97 2 7 19534 11327 12764 16249 15379 18339 9503 7556 21344 13927 14007 62032 -554'6 19672 43 2 5 20684 9543 4066 6121 19194 14103 13277 SPECIFIC GRAVITY AND WEIGHT OF PETROLEUM-REFUSE. 67 LIQUID-FUEL. Petroleum-Refuse and Creosote-Oil are used as liquid-fuel. They are usually burnt upon a fire-grate covered with fire-bricks, and the liquid- fuel is blown into the furnace from below, by spray-injectors, steam being used for injecting the spray. The spray-injectors have long narrow orifices, the usual width being from -02 inch to "08 inch. The air for combustion is generally forced into the furnace, partly above and partly under the fire- grate, by fans or blowers, and the fire-box has frequently two combustion- chambers, constructed with brick-work, which offers a slight resistance to the free exit of the ignited gases, and retains them as long as possible in the combustion chambers, thus ensuring complete admixture with the air. Weight of Petroleum-Refuse.* As the quality of petroleum varies considerably, it is necessary to employ a hydrometer and thermometer for testing the specific gravity and temperature of petroleum-refuse ; the specific gravity varying with the temperature. The following Table contains the specific gravity and weight per cubic foot of petroleum-refuse; the heaviest petroleum-refuse has a specific gravity of '921, or a weight of 57*412 Ibs. per cubic foot when at freezing-point, thus requiring a space of 39 cubic feet to contain a ton. The lightest at a temperature of 95 Fahr. has a specific gravity of -889, or a weight of 55*24 Ibs. per cubic foot, requiring a space of 40^ cubic feet to contain a ton. *Table 23. SPECIFIC GRAVITY AND WEIGHT PER CUBIC FOOT OF PETRO- LEUM-REFUSE AT VARIOUS TEMPERATURES. WATER=I'OOOO SPECIFIC GRAVITY, AT ij\ CENTIGRADE OR 63^ FAHRENHEIT. TEMPERATURE. Weight Specific in Ibs. Gravity, per Cubic Foot. T Specific Gravity. Weight in Ibs. per Cubic Foot. Cent!- grade. Reaumur. Fahren- heit. Centi- grade. Reaumur. Fahren- heit. Ibs. Ibs. O O'O 3 2 9IIO 56-6I 18 I4-4 64-4 8997 55^4 I 0-8 33-8 9103 56-55 19 I5-2 66-2 8991 55-84 2 r6 35-6 9097 56-50 20 irro 68-0 8984 55'8l 3 2-4 37*4 9091 56-50 21 16-8 69-8 8978 55-74 4 3-2 39-2 9085 56-42 22 17-6 71-6 8972 5574 5 4-0 41*0 9078 56-36 23 18-4 73'4 8965 55-68 6 4-8 42-8 9072 56-36 24 19-2 75-2 8959 55-62 7 5-6 44'6 9066 56-30 25 2O'O 77-0 8953 55-62 8 6-4 46-4 9060 56-30 26 20-8 78-8 8947 55'55 9 7-2 48-2 9 53 56-2O 27 21-6 80-6 8940 55*55 10 8-0 50-0 9047 5 6 -i4 28 22-4 82-4 8934 55-48 ii 8-8 5 l-8 9041 56-14 2 9 23-2 84-2 8928 55-43 12 9-6 53-6 9034 56-11 3 24-0 86-0 8922 55-43 13 10-4 55'4 9028 56-05 3i 24-8 87-8 8915 55-37 H II'2 57-2 9O22 56-05 3 2 25-6 89-6 8 9 09 55-30 '5 I2'0 59' 9016 55"99 33 26-4 91-4 8903 55-3 16 12-8 60-8 9009 55-92 34 27-2 93-2 8896 55-24 17 I 3 -6 62-6 9 003 55-92 35 28-0 95-0 88 9 55-24 * See a Paper read before the Institution of Mechanical Engineers, by Mr. Thos. Urquhart. F 2 68 THE PRACTICAL ENGINEER'S HAND-BOOK. I Fig. 21 Liquid-Fuel is very much used in Russia. On one line of railway about one hundred and fifty locomotives and a number of stationary boilers are burning this description of fuel, with the most satisfactory results, in special furnaces or combustion-chambers constructed on .Mr. Urquhart's system of burning liquid- Fig. 20. fuel. The following is a brief description of the apparatus used for feed- ing the furnaces and of the construction of several varieties of com- bustion - chambers by which the efficient and economical combustion of petroleum-refuse is satisfactorily obtained. The dimensions given in the woodcuts are French measures. Urquhart's Liquid- Fuel Injector,* or pul- veriser, is shown in Figs. 20 to 23. The orifice through which the petro- leum flows, is adjustable, and can be swept out by the steam, so that if the outlet becomes choked, the opening can be en- larged, and this can be thoroughly cleansed without interfering with the working, otherwise than by increasing the flow of oil for a few moments. A tube is fixed through the double walls of the fire-box to admit the nose of the injector, around which a space is left for air to be carried in by the jet. The oil runs down a pipe, which ends in the external nozzle of the injector, while the steam passes through the inner nozzle, which it enters through a ring of holes, the steam and oil cavities being separated by a stuffing-box packed with asbestos. This packing is renewed once a month. The steam supply is regulated by a valve on the pipe and independent of the injector, while the oil supply is increased or diminished by screwing the steam nozzle backwards and forwards in the external nozzle, and varying the section of the annular passage. This is effected by a worm and wormwheel, the latter of which is connected to the steam nozzle by a feather-key, while the former is on a shaft which terminates in a convenient position close to the fireman's * The Author is indebted to " Engineering" for the above description and drawings. of Mr. Urquhart's Patent Apparatus for Burning Liquid Fuel. Figs. 20 and 21. Urquhart's liquid-fuel injictor. BURNING LIQUID-FUEL. 6 9 hand. Skill and care in regulation are two most important points in the use of this fuel on railways, in order to avoid smoke, and, at the same time, not to admit an excessive quantity of cold air. Every change in the opening of the regulator or the position of the link requires a corresponding alteration of the oil admission, while when the engine is at rest or running clown an incline with the steam off, the flame must be exiinguished, and the firebox sbut up by closing the dampers. Even under these conditions the steam will continue to rise from the gradual emission of the heat stored in the brickwork of the firebox. When the stoppage is ended, or the incline passed, the flame is lighted again by first turning on the steam, and then gradually admitting the oil, which catches fire from the hot bricks without any explosion. The dampers can then be opened and the full supply of oil turned on, according to the load and the character of the road. Spocket Fig. 22 Figs. 22 and 23. Urquhart's liquid-fuel injector. wheels and pitched chains convey the motion of the regulating wheel from the cab to the injector. Mr. Urquhart's apparatus is entirely outside the firebox, and is screened from the radiant heat of the flame, while the earlier injectors were more or less inside the furnace and exposed to the fierce temperature which carbonised the oil on the outlet of the jet, and contributed even more than the dirt to the choking of the nozzle. Special Combustion-Chamber. Important as is the construction of the injector, however, the arrangement of the firebox or combustion- chamber is more so, particularly in a locomotive with its infinite capacity for leakage at numberless tubes, stays, and rivets. The experience of forced draught on torpedo boats has shown that there is a decided limit to the temperature which a tube-plate can bear, and that if very highly heated flame be driven against it, there will be continual trouble. In the case of petroleum the flame is so hot that the sight-hole through which it is observed has to be covered with coloured glass, to protect the eyes of the fireman, and in the early experiments, it was found that the nuts on the inside of the fire-box crown dropped off, so great was the heat brought to bear upon them. Further, while the direct impact of flame is detrimental to 70 THE PRACTICAL ENGINEER'S HAND-BOOK. the plates, it is also unfavourable to perfect combustion of the gases. In the most recent types of the Siemens furnace a great advantage has been Fig. 24. Fig. Fig. 26. Figs. 24- 26. Combustion-chamber fjr liquid-fuel. found in keeping the flame free both of the brick-work and of the objects to be heated, and although this of course cannot be followed in a boiler furnace, yet it is possible to let the principal part of the combustion take Fig. 27. Fig. 28. "Fig. 29. Figs. 27 29. Combustion-chamber used in winter for liquid-fuel. place in an area inclosed by glowing walls, which exercise no check upon the complete oxidation of the gases, but allow them to attain the full tem- perature before they meet the comparatively cold metal plates. Several Forms of Combustion-Chambers are used by Mr. Urquhart, according to the class of engine to which they are to be applied, and to the teachings of experience. Five varieties are illustrated in Figs. 24 to 41. Figs. 24 to 26 show the fire-box as used in passenger and six-wheeled goods engines. Opposite the lower part of the fire-box there is built a COMBUSTION-CHAMBERS FOR LIQUID-FUEL. stout wall, which is continued along each side (Fig. 26), terminating at the top with a skewback. An arch is thrown from side to side, and Forms a top to this combustion-chamber which is entirely open at the front. The Figs. 30 and 31. Combustion-chamber for liquid-fuel. jet plays on to the back wall, while the flames turn up under the arch above, filling the box and entering the tubes in tongues of fire. There are three ashpit doors, one at the trailing end and one at each side, and these can be opened to any extent by a chain and notched lever. Sufficient air to commence the combustion enters with the spray, which is protected by a brick- work screen from the main draught, until it reaches the mouth of the com- bustion-chamber. Figs. 27, 28, 29 represent a modified arrangement for use during the severe frosts which prevail in Russia. The difference between the two is not great ; the latter, however, has the back wall carried up to the roof of the box, and perforated with numerous openings which" are set at an angle, as shown in Fig. 28, and diffuse the heat over the tube-plate with great uniformity. The side of the box is partially pro- tected, but the midfeather, shown in Fig. 26, is wanting. Figs. 30, 31, 32, show another and more recent construction of combustion-chamber, in which no side-doors are cut in the ash-pan, the original front and back doors being utilised. The air which enters through the front door is passed up through a thin brick-channel A, and becomes heated before it comes in contact with the gases. Two cast-iron boxes, BB, are built into Fig. 32.- Combustion-chamber for liquid-fuel. J2 THE PRACTICAL ENGINEER'S HAND-BOOK. the brick-work, in order to let a small quantity of flame gain access to that part of the tube-plate below the tubes. The entire heating surface of the sides of the box is likewise utilised by keeping the walls of the chamber a short Fig 33- Fig. 34- Fig. 35- Figs. 3335. Combustion-chamber for liquid-fuel. distance from them, and allowing the flame to play between the two. The spray injector is placed in the ash-pit, as shown in Fig. 31, which is made very deep, and the hollow stay shown in Fig. 21, is not used. Figs. 33, 34, and 35, illustrate another modification in which there is preliminary Fig. 36 Fig. 37- Fig. FigF. 36 38. Combustion-chnmber for liquid-fuel. heating of the air, while Figs. 36, 37 and 38, are engravings of the combus- tion-chamber of an eight-wheeled locomotive engine weighing 48 tons. The Brick-work of the Combustion-Chambers acts as a reservoir of heat, tending to keep the furnace at a uniform temperature, and to maintain the combustion under the most favourable conditions. It COMBUSTION-CHAMBERS FOR LIQUID-FUEL. 73 likewise serves to light the spray when it has been turned out during a stoppage. When the boiler is cold the jet cannot be used, of course, as there is no steam to propel the oil forwards. Under such conditions it is customary to raise the steam by a temporary attachment to a stationary boiler, and then to create a draught by turning on a blower in the chimney. A handful of burning waste is then placed in the combustion-chamber, and the steam and oil are turned on in succession. Mr. Urquhart has also applied brick combustion-chambers to all the stationary boilers, twenty-five in number, under his control; the method adopted with Cornish boilers is shown in Figs. 39, 40, and 41. The Petroleum is carried in a tank in the tender of the locomotive, Fig. 40. Figs. 39 41. Combustion-chamber for burning liquid-fuel in Cornish-boilers. formed by placing a bulkhead at the head of the coal-space, and a cover over the top of it. There is a pocket made in the bottom to receive the water, which the oil picks up in its transit in barges, and the separation is aided by the heat which is received from the feed-water tanks on the tender, and from a special steam-coil. When the temperature falls 12 degrees below freezing-point the use of artificial heat is imperative. For a six-wheel locomotive the capacity of the tank is 3^ tons, a quantity sufficient for 250 miles, with a train of 480 tons gross, exclusive of engine and tender. Creosote-oil is the residue from the distillation of tar in the production of anthracene, quinone, and alizarin. The heating-power of creosote-oil has been found in practice to be double that of ordinary good steam-coal, that is, one ton of oil is equal to two tons of coal. It costs about twenty- five shillings per ton, makes very little smoke in burning, and when used 74 THE PRACTICAL ENGINEER'S HAND-BOOK. in a well-arranged furnace requires little attention. In Sadler's system of burning creosote-oil as liquid fuel in a circular furnace, the furnace-tube is lined with fire-brick for a portion of its length so as to form a brickwork- tube, the end of which is closed by a baffle-wall perforated with holes 3 inches square. The oil is forced into the furnace by a jet of steam, by means of a nozzle similar in construction to that of a Giffard's injector. The draught produced by the jet of steam is checked by the baffle-wall at the end of the furnace, and by an ordinary damper. Fig. 42. Priestman's Oil-engine. PETROLEUM-ENGINES. Oil-Engines occupy small space, require little attention, are readily started, and work economically with ordinary mineral oil. There arc several forms of these engines, some of which may be briefly described as follows : The Priestman Oil-Engine. This engine, shown in Fig. 42, is mounted on a hollow bed-plate forming a tank of sufficient capacity to contain a supply of oil to run the engine a day. Air is pumped into the tank. The oil is delivered in a state of fine spray to a vapourising chamber, where it is converted into vapour by heat supplied by a lamp on starting the engine, and afterwards by exhaust vapour which envelopes the chamber. The engine has a four-cycle movement, that is, the piston on its first or forward stroke draws in a charge of vapour through an inlet-valve. This charge is compressed on the second stroke, and at the moment of com- pression an electric spark, from a small battery, explodes the charge and drives the piston out, thus making the third stroke. The fourth stroke drives the spent vapour out of the cylinder through an exhaust-valve. PETROLEUM-ENGINES. 75 The engine works satisfactorily with common mineral oil. The quantity of oil consumed is about one pint per brake-horse-power per hour. When Jl Fig. 43. Hornsby's Oil-engine. using oil costing fivepence per gallon, the cost of a horse-power is from one-halfpenny to three farthings per hour. Fig. 44. Crossley's Oil-engine. Hornsby's Oil-Engine. This engine, shown in Fig. 43, has a tank in the bed-plate containing oil. At each stroke a small quantity of oil is 76 THE PRACTICAL ENGINEER'S HAND-BOOK. pumped into a vapourising chamber, connected by a short pipe to the back of the cylinder. This chamber is heated by a lamp on starting the engine, and afterwards by the heat of the explosion. There is one explosion in four strokes, or two revolutions. A mixture of air and oil-vapour is drawn into the cylinder on the first stroke of the piston, and compressed on its back- ward stroke. The compressed charge is ignited by the hot metal, and explosion takes place in the vapouriser. Crossley's Oil-Engine. This engine, shown in Fig. 44, resembles a gas-engine in general appearance. The oil is pumped into a vapouriser, which is heated by a lamp. The firing is effected by a horizontal hct tube. Fig. 45. Spiel's Oil-engine. Spiel's Oil-Engine. This engine, shown in Fig. 45, has a four-cycle movement. The piston on its out-stroke draws in a charge of air and petroleum ; it then returns compressing this mixture, which is exploded as the crank passes the back centre ; in the next stroke the combustion and expansion of the charge takes place, while the fourth and last stroke of the cycle expels the products of combustion. Thus there is one acting stroke in every four, the energy stored up in the fly-wheel carrying it through the other three. VEGETABLE-REFUSE FUEL. In countries where coal is dear and vegetable-refuse abundant, it is important to utilise the latter as fuel for steam boilers. Vegetable sub- stances, such as sugar-cane refuse, cotton-stalks, reeds, dry-grass, fibrous plants, peat, and brushwood make excellent fuel, and although greatly in- ferior to coal, can compare favourably with wood, as regards calorific power, when burnt as fuel in steam boilers properly constructed for burning this description of fuel. BURNING VEGETABLE-REFUSE FUEL. 77 Boilers using Vegetable-Refuse as Fuel require to have the furnace or fire-box twice as large as that required for coal, and the total heating surface at least one-half larger than that required for coal-burning. The fire-bars should be thin and spaced about six inches apart ; and they should be placed diagonally across the furnace. The fuel should be fed continu- ously in a thin layer to the fire, and a large supply of atmospheric air must be admitted to the furnace to produce perfect and continuous combustion. Heating-power of Vegetable -Refuse Fuel. The vegetable sub- stances above-mentioned, when in a perfectly dry state, on an average are composed of '34 carbon, -5 hydrogen, and '40 oxygen. As the hydrogen Fig. 46. Ruston's straw-burning apparatus. and oxygen are in the combining proportions for forming water they develop no heat. Hence these vegetable substances will yield : Carbon 34 x 14500 = 4930 units of heat per Ib. of fuel : its maximum calorific power. Taking the maximum units of heat in i Ib. of coal at 14297, the weight of straw required to develop the same heat as i Ib. of coal will be 14297 -4- 4930 = 2'94 Ibs., or nearly 3 Ibs. In practice rather more than this is required, and 4 Ibs. of straw are equal to i Ib. of coal. Ruston's Straw-burning Apparatus applied to a portable-engine is shown in Fig. 46. The straw is fed into a hopper attached to the fire-box r and is ignited on entering the furnace : as the fire is fed from the bottom of the furnace it burns like a torch, the fire not being damped down when fed, as would be the case if the straw were put upon the top of the fire. The combustion is forced by a steam-jet, and complete combustion of the fuel is obtained. The apparatus is simple and effective, and it can be used for burning other kinds of vegetable-refuse fuel as well as straw. 78 THE PRACTICAL ENGINEER'S HAND-BOOK. Coal-dust, Coke-dust, Breeze, and similar Refuse-Fuels which are of no value as fuel in ordinary furnaces, may be efficiently and economically burnt in Ferret's Furnace, with water-cased grate, as shown Fig- 47- Figs. 47 and 48. Perrett's furnace for burning dust-fuel. BURNING COAL-DUST FUEL. 79 in Figs. 47 and 48. The ash-pit of this furnace is closed, and is worked under pressure supplied either by a fan or steam-jet. The fire-bars are spaced only about T ^th of an inch apart ; they are made very deep, and the bottoms of the bars are immersed in water as shown. An air blast of a pressure of from one-half inch to one inch of water is admitted above the surface of the water in the troughs, and underneath the fire-bars, and passes through the fuel. From 20 Ibs. to 30 Ibs. of fuel can be burnt in this furnace per square foot of fire-grate per hour. The evaporative power of coal-dust and breeze are given in the following Table : Table 24. COMPARATIVE TRIALS OF COAL-DUST AND BREEZE IN FERRET'S FURNACE. Fuel Fuel Consumed. Water Evaporated Pounds of Water Evaporated per Pound of Fuel. Cost per looo Gallons Evaporated. Ibs. Ibs. Ibs. s. d. i. Breeze . 2800 14,300 5' 1 4 4 2. Equal weights of breeze and coal dust . . . 3008 17,400 5-8 5 9 3. Coal dust 20l6 I5.300 7-6 5 io| 4. Washed coal dust . 2 35I I5,82O 7-i 6 3* Test of Ferret's Furnace. A Lancashire boiler, fitted with Ferret's furnace burning coal-dust, was carefully tested for eleven hours. The boiler was 2 1 feet long x 7 feet diameter, with a total heating surface of 582 square feet : fire-grates 4 feet long, and i foot lof inches wide, each equal j\ square feet of surface, or 15 square feet in all. The coal burnt during the trial was 2231 Ibs. ; equal 14' 8 Ibs. per square foot of grate per hour, and '383 Ibs. burnt per square foot of heating surface per hour. Thickness of fuel on the bars, 5 inches : water in fuel, 4-17 per cent.: air used per Ib. of fuel, 14' 3 7 Ibs. : average pressure of blast = f inch of water : pressure of steam, 46-2 Ibs. per square inch. Ashes, 58 Ibs.: clinkers, 176 Ibs. : or a total waste of 234 Ibs. = io'5 per cent. Useful coal consumed, 1902 Ibs. Temperature of smoke at exit from the boiler, 3 76' 5 Fahr. The coal-dust was analyzed and found to contain as follows : Table 25. COMPOSITION OF RADFORD'S NAVIGATION COAL-DUST, USED IN- THE TEST OF FERRET'S FURNACE. Carbon. . 8479 or 1^92 Ib- of the day's consumption of 2231 Ib. Hydrogen . 4-55 ,, 102 ,, Oxygen . 2-17 ,, 48 ,, Nitrogen . . 0^96 ,, 21 ,, Sulphur . 0-57 ,, 13 ,, Ash . . . 2-79 ,, 62 Water . . 4*17 ,, 95 8o THE PRACTICAL ENGINEERS HAND-BOOK. Results of the Test.* The evaporative power was 12-8 Ib. at 212 Fahr. Air-blast velocity was 2248 feet per minute through a tube of 297 feet sectional area. Taking the weight of i cubic foot of air at 58 Fahr. to be '0767 Ibs., the weight of air passed during the eleven hours was (2248 x '297) x '0767 (60 x n) = 33798 Ibs. The carbon in the O day's charge required 1892 x - = 5045 Ibs. of oxygen to form 6937 Ibs. of carbon dioxide, and the hydrogen in the day's charge required 1 02 x 8 = 816 Ibs. of oxygen to form 918 Ibs. of water, so that the total oxygen required to burn the coal was 5861 Ibs. But the charge of fuel itself contained 48 Ibs. ; hence the oxygen required for the air was 5813 Ibs. But the air actually supplied contained 33,798 x 2- = 7773 Ibs. of oxygen. Deducting that absolutely required for combustion, viz., 5813 Ibs., the excess of oxygen supplied was 1960 Ibs., and this is equivalent to 1960 x 1 = 8522 Ibs. of air, whilst the nitrogen present in the air, whose oxygen was used, was 5813 x Z_= 19461 Ibs. The proportion in which the heat of the fuel was used and wasted in the above test is shown by the following balance sheet : Table 26. BALANCE SHEET OF HEAT UNITS (FAHR.). Per Ce.it. I 5 -8 Heat Absorbed. Heat Units. By feed water evaporated, 1582 gallons at 46*2 Ibs. gauge pressure. Total heat from 32 deg. in steam at 46-2 lbs.= 1 167-5. Tem- perature of feed=93 deg.; hence j 1167 (93-3 2 )} x 15,820 ....". Furnace Gases. Excess air=&522 Ibs. x -238, specific heat x (376-5 58 = 318-5) . . . Nitrogen with consumed oxygen= 19,461 Ibs. X 244 (sp. ht.)x 318-5 Carbon dioxide formed = 6937 Ibs. x. -2164 (sp. ht.)X3i8'5 Water from H in coal=9i8 Ibs. x [(212 58) x 5'3 .-,--, ^ Jf - j j ,, -~~.jj Water in coal = 95 x [(212 60) x 1 + 966 + (376-5 212) x -4805] Evaporation from troughs under grate 416-06 x [(212 60) X I + 966 + (376-5 212) X -4805]. Loss by radiation (say=night) 133,647 x n Unaccounted for : Heat in cinders, carbon in smoke, cinders unconsumed 17.504,830 6 45.993 1,512,392 478,122 1,100,682 H3.7I5 498,031 1,470,117 4,261,987 27,585,869 * Kindly given to the Author by Messrs. B. Donkin & Co., London. FIRING STEAM BOILERS. Heat evolved : 2231 Ibs. of coal, evolving 12-8 pound, will give during combustion 2231 " " units. Si X 12 x 966 heat units per x 966 = 27,585,869 COMBUSTION AND CONSUMPTION OF FUEL IN STEAM BOILER FURNACES. Firing. The fire should be as thick as the quality of the coals will allow; a thin fire is wasteful, because parts of the grate are liable to become uncovered and permit air to pass through the furnace unconsumed. The shape of the fire should be concave, that is much thicker at the sides than the middle, which ensures proper admixture of the gases and economical Fig. 49. Proctor's Mechanical-Stoker. combustion of the fuel with the least smoke. Side firing is best in most cases, that is, the coal is thrown on each side of the fire alternately, leaving one side of the fire always bright, by which means the temperature of the furnace is reduced as little as possible. It is better to fire frequently, putting a little coal on at a time, than to put large charges of coal on the 82 THE PRACTICAL ENGINEER'S HAND-BOOK. fire at long intervals. Hand-firing is preferable for round coal, but for burning slack in the most economical way, mechanical-firing gives the best results in many cases. A Mechanical Stoker provides a steady evaporation, although it is frequently not so rapid as in hand-firing: it produces a steady supply of steam, and is an excellent preventer of smoke. It dispenses with the frequent opening of the furnace door, thereby preventing large volumes of cold air impinging upon the hot plates. The Mechanical-Stoker, shown in Fig. 49. is a very good imitation of hand-firing, it being so arranged that it delivers the coal upon the fire with varied lorces, by means of a radial shovel actuated by a shaft making a partial rotary motion. The machine is very simple, has few working parts, and provides an evaporation nearly as rapid as hand-firing; in one case 9*41 Ibs. of water were evaporated per Ib. of coal from feed water of 1 10 Fahr. with a very common description of slack. AJy required for Combustion. Atmospheric air is composed of 1 Ib. of oxygen and 3! Ibs. of nitrogen by weight, or i cubic foot of oxygen and 4 cubic feet of nitrogen by volume. Nitrogen being a neutral gas is present as a dilutent simply, and passes through the fire without chemical alteration. For every cubic foot of oxygen required in combustion, 5 cubic feet of air must be supplied. For the complete combustion of t Ib. of hydrogen, 500 cubic feet of air are required, and for the complete combustion of i Ib. of carbon 160 cubic feet of air are required. For the combustion of i Ib. of sulphur 60 cubic feet are required. The quantity of Air chemically consumed is 1 50 cubic feet per Ib. of coal consumed, but in order to ensure complete combustion of coal, and prevent the formation of carbonic-oxide instead of carbonic acid, or the formation and discharge of smoke, it is necessary to admit a much larger quantity of air to the furnace than is theoretically required, so that each particle of gaseous combustible matter may be supplied with its due equivalent of oxygen. The supply of air to a furnace should equal double the quantity chemically consumed, or 300 cubic feet of air at 62 Fahr. per Ib. of coal. The weight of Air per Ib. of Coal required in practice to secure sufficient dilution of the gases to ensure their combustion, and absence of smoke, is 24 Ibs. with natural or chimney draught, and 18 Ibs. with forced or artificial draught. The Products of Perfect Combustion are steam and carbonic acid, each being invisible and incombustible, steam is formed from the hydrogen gas given out by the coals combining with its equivalent of oxygen from the air, in the proportion of 2 volumes of hydrogen to i of oxygen, or by weight as i to 8. Carbonic acid is formed from the carbon of the coal combining with its equivalent of oxygen from the air, in the proportion of 2 volumes of oxygen to i of carbon, or by weight as 1 6 to 6. The Products of Imperfect Combustion are, carbonic-oxide, in- visible but combustible, and smoke, partly invisible and incombustible. Carbonic- oxide is formed from the carbonic-acid first produced, receiving another volume of carbon in passing through the fire, which last volume of carbon is unconsumed, and forms the combustible carbonic-oxide, whilst carbonic acid, having its carbon consumed, is incombustible. Carbonic- PRODUCTS OF COMBUSTION. 83 oxide burns with a pale blue flame, and its presence in a furnace denotes imperfect combustion, from a deficient supply of air, as it indicates that only 8 parts of oxygen instead of 16 parts have united with 6 parts of carbon. The Vitiation of the Air by the products of Combustion is chiefly caused by the carbonic acid and steam produced by combustion. Petroleum and solar oil produce least of both substances, and tallow, coal, and coal-gas most. Coal-gas also contains sulphur, which forms sul- phurous and sulphuric acid to the injury of plants and polished metallic surfaces. The quantities of carbonic acid and steam produced by various kinds of combustibles, or the effects of artificial light on air in closed rooms, may be ascertained from the following Table. Table 27. COMPOSITION OF VARIOUS COMBUSTIBLES. THE TOTAL HEAT EVOLVED BY THEIR COMBUSTION ; THE WEIGHT OF OXYGEN J THE QUANTITY OF AIR CONSUMED, AND THE PRODUCTS OF THEIR COM- BUSTION. Quantity PRODUCTS OF Units of COMPOSITION, PER CENT. Weight of Oxygen of Air chemi- COMBUSTION FROM I LB. OF Heat evolved by Description of consumed cally con- COMBUSTIBLE. the Com- Combustible. per Ib. of sumed per bustion of Com- Ib. of T Ib. i,f the Carbon.! "- Oxygen. bustible. Com- bustible. Carbonic Acid. Water. Cora- bustible. Ib. Ib. Ib. Ib. Uni<;.. Coal, average 80'4 5-2 8-0 2-46 I 2 'DO 2'95 '47 14300 Coal-gas . 70-5 3-2 3'25 14-16 2-60 2-05 21000 Tallow . . 7 8-8 n-8 9*4 2'95 12-85 3'<9 '35 l8l2O Stearine . . 76-3 12-4 11-3 3'45 15-00 3' J 7 3 2 17950 Wax . . . 81-5 13-6 4*9 3' 2 4 14-14 3-o8 17 19950 Sperm . . 80-5 13-5 6-0 3-18 13-84 3'5 18 19680 Paraffin . . 85-5 H'5 3-48 I5'H 2-90 08 21460 Colza-oil . . 77'3 3'3 9'4 3-08 13-40 2-86 25 18840 Solar-oil . . 77-5 i3'5 9-0 2-97 12-79 2-84 16 18990 Petroleum 85-3 i47 3-20 13-92 2-72 *3 21560 Smoke is formed during combustion, from the hydrogen and carbon which have not received their respective equivalents of oxygen from the air, and thus pass off unconsumed. Prevention of Smoke. Coals can be burnt without smoke by pro- viding a proper supply of air to the furnace, to secure sufficient dilution of the gases to ensure their combustion, and to prevent the formation of smoke ; but when smoke has been produced, it can neither be consumed nor converted to heat. The colour of smoke depends upon the carbon passing off in its dark pulverised state, but the quantity of heat carried away is not dependent upon the carbon alone, but also upon the invisible but combustible gases hydrogen and carbonic-oxide, so that whilst the tcolour may indicate the amount of carbon in the smoke, it does not indicate 8 4 THE PRACTICAL ENGINEERS HAND-BOOK. Fig. 50. Furnace-front. the amount of heat lost. The prevention of smoke considerably increases the economic value of the fuel and the evaporative power of the boiler. The Supply of Air to the Boiler Furnace may be regulated by means of a furnace-door, having a sliding grid on the outside, as shown in Fig. 50. A perforated box-baffle-plate is fixed on the inside of the door for admitting air above the fire. The sum of the perforations should not be less than 3 inches per square foot of fire-grate surface. After firing, the ven- tilating-grid in the door is opened for about a minute, and the proper supply of air is admitted to the furnace ; by this means, and with careful hand-firing, the emission of smoke may be effectu- ally prevented. Quantity and Temperature of Air in Steam Boiler Furnaces. The quantity of air required is, as already stated, 300 cubic feet at 62 Fahr. per Ib. of coal consumed. The air enters the fire at 62 Fahr., and leaves it at about 1250 Fahr., and expands to 35 times its initial volume ; the maximum temperature of the furnace is about 2400 Fahr., so that the air departs at about one-half of the maximum temperature of the furnace. After leaving the furnace the air decreases in temperature and volume on its way to the chimney, where its temperature is from 552 to 600 Fahr., and its volume about 600 cubic feet. The Quantity of Eot Gases evolved by Combustion at any special temperature per hour, may be found from the following formula: Let Q = Ibs. of coal consumed per hour. C = volume of cold air reduced to the temperature 32 Fahr. required in cubic feet per Ib. of coal. V = volume of heated gases per hour. T = temperature in the chimney. t = the temperature of the external air. Then V = Q C [i + '00203 (T t)]. Weight of Gases and Vapours. The weights and volumes of gases and vapours at 62 Fahr., under an atmospheric pressure of 30 inches of mercury, are as follows : Ib. per cubic ft. & the ) volume of i Ib. is J 18973 Atmospheric air wei^ Hydrogen eras , Nitrogen gas Oxygen gas Vapour of water Carbonic acid gas Carbonic oxide gas Vapour of alcohol jhs -076098 005264 "073795 084133 047398 116365 073632 120876 cubic ft, 1 1 '90 2I'OO 8'60 13-65 8-30 VOLUME OF THE PRODUCTS OF COMBUSTION. Vapour of oil of tur- 7 u . A (Ib. per cubic ft. & ") . , pentine j weighs ^ 2 IO 3 | the volume of i Ib. is } 2>8 cubic fl ' Vapour of sulphuric ether -197016 , 5-00 529911 . 1-90 206152 , 5-10 404613 , 2-60 073395 > 13*84 '044726 , 23-10 041943 ,, 34-66 033300 . 30-00 V r apour of mercury Vapour of benzine Chloroform defiant gas Ammoniacal gas Light carburettedhydrogen Coal-gas The Weight of a cable foot of Gaseous Steam is -622 or about of that of a cubic foot of air, of the same pressure and temperature. The Volume of the Products of Combustion can be calculated as follows. In the case of a combustible composed only of carbon, i Ib. of carbon unites with 2*66 Ibs. of oxygen to form 3-66 Ibs. of carbonic acid, the volume of i Ib. of carbonic acid it appears from the above Table is 8'6, then 3-66 x 8'6 = 31-476 cubic feet, the volume of gas produced. The volume of the oxygen consumed will equal 2'66 X 11*9, its volume from the above Table, = 31-654, from which it appears that the volume of car- bonic acid gas produced by the combustion of i Ib. of carbon is the same as that of the oxygen consumed. Hence when a fuel is composed only of carbon, the volume of gas in the chimney will be the same as that of the air entering the furnace, except that it will be expanded to the volume equal to its increased temperature. When a combustible contains hydrogen, as previously stated, i Ib. of hydrogen unites with 8 Ibs. of oxygen and forms 9 Ibs. of steam, such as coal containing '052 of hydrogen which unites with -052 x 8 = -416 Ib. of oxygen to form -052 +'416 = -468 Ib. of water, which taking the volume of the vapour of water as given in the above Table at 2 1 cubic feet per Ib. will give '468 x 21 = 9*828 cubic feet of vapour at 62 Fahr. ; and as 300 cubic feet are required for combustion per Ib. of coal, the volume of gases produced at 6 2 Fahr. will be 300 + 9-828 = 309-828 cubic feet per Ib. of fuel. Assuming the temperature of the chimney of a steam-boiler to be 5 5 2 Fahr., at which temperature the volume of air is double that at 62 Fahr., the volume of vapour, air, and gases in the chimney will be 309-828 X 2 = 619-65 cubic feet. In round numbers there will be 620 cubic feet of the gaseous products of combustion at 552 Fahr. per Ib. of coal, in the chimney. The Volume of the Gaseous Products of Combustion in the furnace of a steam-boiler per horse-power, may be calculated from the above data: Assuming lolbs. of coal to be consumed per nominal horse- power per hour, then 620 x 10 = 6200 cubic feet of gases will be dis- charged by the chimney per horse-power per hour. Chimney Draught is due to the motion of the air caused by the difference in weight of the air inside and that outside the chimney. The draught can be checked by closing the damper or opening the furnace- door. The resistances to draught, are the passage of the air through the interstices of the coals on the fire-grate, and the friction of the air and gases against the sides of the furnace and flues. 86 THE PRACTICAL ENGINEER'S HAND-BOOK. The Draught is most efficient when the temperature of the heated gases passing up the chimney is 552 Fahr. The gases only then weigh one- half that of the air outside the chimney at 62 Fahr. This refers to natural draught. The Temperature of the Smoke in the Funnel of well-arranged marine steam-boilers with natural draught is 600 Fahr. When Flame issues from the Top of the Funnel, it is due to the burning of gases which have escaped from the furnace without being consumed, owing to a deficiency in the supply of air to the furnace. It is detrimental because it denotes loss of heat and waste of fuel, besides causing injury to the funnel. The Loss of Fuel due to a High Temperature in the Funnel of a marine steam-boiler may be calculated by this Rule : Multiply the normal consumption of coal in tons per day, by the difference between what the temperature in the funnel should be, and what it actually is, and divide the product by 2200, the quotient will give the increase of consumption per day, due to the high temperature in the funnel. Example : The consumption of coal at the beginning of a voyage of a steamship was 30 tons per day, the temperature of the funnel then being 556 Fahr., but after a few days the temperature of the funnel increased to 706 Fahr., for the same supply of steam under the same conditions, what was the increased consumption of coal due to the increase of temperature in the funnel ? 30 tons per day x (706 5 56) Then *- 2200 ~ ~~ = 2 '45 tons P er 3ay, increase of consumption, thus raising the consumption of fuel from 30 tons per day to 30 + 2-045 = 3 2 '45 tons per day. The Temperature of the Funnel of a marine steam-boiler may be calculated from the increased consumption of fuel due to its excessively high temperature by this Rule : Multiply the difference between what the temperature in the funnel should be, and what it actually is, by 2200, and divide the product by the normal consumption of coal in tons per day, the quotient will give the increase of temperature in the funnel. Example: The temperature of the funnel at the beginning of a voyage of a steamship was 556 Fahr., the consumption of coal then being 30 tons per day, but after a few days it increased to 32-045 tons per day, for the same supply of steam, under the same conditions, what was the increase of temperature in the funnel ? TK^r, 2200 x (32-045 tons 30 tons) o T- u c I hen - _L3 ^J .. orJ .*J = ICQ Fahr. increase of 30 tons normal consumption per day temperature in the funnel, thus raising its temperature from 556 Fahr. to 556 + 150 = 706 Fahr. The Normal Temperature of the Gases escaping from the Funnel of a marine steam-boiler will be increased at the rate of 22 Fahr. for i per cent, increase in the cost of evaporation. Example : Taking the data from the previous example, the increase is 32-045 tons 30 tons = 2-045 tsiis - This increase on 30 tons will equal _? = 14-67 and 2-045 - - = 6-87 per cent., therefore the increase of temperature above the CONSUMPTION OF COAL IN MARINE BOILERS. 8/ normal temperature, will be 6'82 x 22 = 150 Fahr., and this added to the original temperature will give 150 + 556 = 706 Fahr., or the same result as obtained by the previous Rule. The Consumption of Coal in Marine Boilers varies as the distance steamed, multiplied by the square of the speed of the ship. Example : A steamship made a voyage of 900 miles at a spe2d of 10 knots per hour, the total consumption of fuel being 100 tons. Required the consumption of fuel, C., for a voyage of 1 500 miles at a reduced speed of 8 knots per hour. Then C = 900 x io 2 : 1500 x 8 2 : : 100 tons ; 1500 miles x 8 2 knots X 100 tons or 900 miles X io 2 knots = Io6 tons ' Consumption of fuel at the reduced speed. The Consumption of Coal in Marine Boilers per unit of time, varies as the cube of the speed of the ship. Example i : A steamship attained a speed of io knots an hour with a consumption of 7 tons of coal per day. Required the consumption, C, at a reduced speed of 8 knots per hour. Then C = io3 knots : 8* knots : : 7 tons; or 8 * knots X ? to "* _ io 3 knots 3-584 tons. Example 2 : On one voyage a steamship attained a speed of 8 knots an hour with a consumption of io tons of coal per day. After undergoing repairs, this ship attained, on another voyage, a speed of 9 kn3ts an hour. Required the consumption, C., of coal at the increased speed. Then C = 8 3 knots : 9 3 knots : : io tons; or 9 3 knots x io tons = 8 3 knots 14-23 tons. The Speed of a Steamship due to a given consumption of Coal may be found by the converse of the last Rule : Example i : Taking the data from example 2 above. A steamship attained a speed of 8 knots per hour with a consumption of io tons of coal per day. Required the speed attained with a consumption of I4'23 tons of coal per day. Then ^ 2 3 ^J* knots = 729 and jj 729=9 knots per hour, the speed due to the increased consumption of coal. Example 2 : Taking the data from example i above. A steamship attained a speed of io knots per hour with a consumption of 7 tons of coal per day. Required the speed attained with a consumption of 3*584 tons of coal per day. Then *$* tons x io knots = and ^ 7 tons V 8 knots per hour, the speed due to the decreased consumption of coal. The Consumption of Coal in a Voyage of a steamship may be found by this Rule : Multiply the speed in knots per hour by 24, the product will be the number of knots the ship makes per day. Then as the number of knots sailed per day is to the number of knots in the voyage, so is ths consumption of coal per day to the consumption of coal on the voyage. Example : A steamship attained a speed of io knots per hour with a consumption of 20 tons of coal per day. Required the consumption, C, of coal in a voyage of 1000 knots. 88 THE PRACTICAL ENGINEER'S HAND-BOOK. Then the speed per day will be 10 knots x 24 hours = 240 knots, and G = 240 knots : 1000 knots : : 20 tons, or * OOP knots x 20 tons tQns> 240 knots The Quantity of Coal left at the end of a Voyage of a ship steaming at a uniform speed, may be found as follows. As the number of knots made is to the number of knots in the voyage, so is the coal which has been consumed in the knots made. The result will be quantity of coal consumed during the voyage. Example : A steamship is provided with a stock of 350 tons of coal for a voyage of 2400 knots, it was found after steaming 800 knots that 100 tons of coal had been consumed. How much coal will there be left at the end of the voyage, the speed being the same for the whole voyage ? Then 800 knots : 2400 knots : : lootons coal : quantity of coal consumed during voyage, or 24 k . nots X IO tons = 300 tons of coal consumed 800 knots steamed during the voyage, which deducted from the stock at starting on the voyage, or 350300=50 tons, the quantity of coal that will be left at the end of the voyage. The Consumption of Coal per indicated horse-power of the engine may be ascertained by this Rule : Multiply the number of tons of coal consumed per day by 2240, and divide the product by 24, the quotient will be the number of Ibs. of coal consumed per hour, which divided by the indicated horse-power of the engine will give the consumption of coal in Ibs. per indicated horse-power per hour. Example : The consumption of coal during the voyage of " a steamship was 140 tons per day, the average indicated horse-power of the engines was 5400. Required the consumption of coal per indicated horse-power per hour. Then 140 tons x 2240-^-24=13066 Ibs. of coal consumed per hour, and V -- = 2-23 Ibs., the coal consumption per indicated horse- 5400 horse-power power per hour. The number of Baskets of Coal burnt in a watch on a steamship may be ascertained by this Rule : Multiply the consumption of coal in tons per day by 2240, and divide the product by the weight of coal contained in the basket, the quotient will be the number of basketfuls of coal consumed per day, which divided by the number of watches per day will give the number of basketfuls burnt in a watch. Example : The total consumption of coal on a steamship is 140 tons per day, how many basketfuls of coal, each weighing 60 Ibs., will be burnt in a watch of 4 hours ? Then 140 tons x 2240 Ibs.=3i36oo Ibs. of coal consumed per day, and T rr ~-2-r FT i F-r=5 22 6'6 basketfuls per day. As the watch is 60 Ibs. weight of basketful 4 hours there will be 24-^-4=6 watches in the day, then 5226-6 basketfuls per day-^6 = 87i'i basketfuls per watch. The number of Basketfuls of Coal burnt per day during the voyage of a steamship being given, the consumption of coal in tons per day may be ascertained by this Rule : Multiply the weight of coal contained in the basket by the number of basketfuls, and divide the product by 2240, the quotient will be the coal-consumption in tons per day. CONSUMPTION OF COAL IN LOCOMOTIVE-BOILERS. Example : The consumption of coal on a steamship during a voyage was 5226-6 basketfuls per day, each weighing 60 Ibs. Required the coal- consumption in tons per day. r^, 5226-6 basketfuls x 60 Ibs. each , , Then * n =140 tons of coal consumed per day. 2240 Ibs. per ton The Consumption of Coal in tons during the voyage of a steamship may be ascertained by dividing the number of cubic feet of coal used by 45, the number of cubic feet in a ton. Example : A steamship after 7 days' steaming was found to have used coal that occupied a space 18 feet in length of a coal-bunker which is 25 feet long, 14 feet wide, and 15 feet high. Required the daily consump- tion of coal in tons. r- 14 feet width x 15 feet height x 18 feet length of coal burnt _ 45 cubic feet of coal per ton x 7 days 12 tons daily coal-consumption. The Consumption of Coal by Locomotives per indicated horse- power per hour increases with the speed of the engine. If the speed of the engine be doubled and the weight of the train remain the same, the quantity of fuel burned in a given time would also be doubled ; but as only one-half the time would be occupied in travelling a mile, the consumption of fuel per mile would be the same in both cases. Therefore the rate of consumption of fuel per train-mile varies with the weight of the train and is independent of the speed. The consumption of coal per train-mile varies considerably on different railways, as will be seen from the following Table, collated from recent practice: Table 28. AVERAGE CONSUMPTION OF COAL PER TRAIN-MILE BY PASSENGER LOCOMOTIVES ON VARIOUS ENGLISH RAILWAYS. BRIGHTON AND SOUTH COAST. NOKTH-WESTERN. Great Western Express. Great Northern Express. Midland Express. Light Express. Tajik Engine. Heavy Express. Express. Com- pound. Ibs. Ibs. Ibs. Ibs. Ibs. Ibs. Ibs. Ibs. Average con- sumption of coal per mile . . 22 24 30 25 27 28 34 38 The consumption of coal per train-mile by goods engines averages from 45 to 52 Ibs. In an experiment made to ascertain the power required to haul a train, weighing with the engine 335^ tons, from Brighton to London, Mr. Stroudley found that i Ib. of coal would convey i ton weight of the train 13^ miles, at an average speed of 43*38 miles per hour, over the Brighton Railway, the rate of consumption being 2*03 Ibs. of coal per indicated horse-power per hour : the evaporation was 12-95 Ibs. of water per Ib. of coal. 90 THE PRACTICAL ENGINEER'S HAND-BOOK. Consumption of Petroleum-Refuse Fuel.- -A series of careful trials were made by Mr. Thomas Urquhart to ascertain the mean consump- tion of petroleum-refuse fuel in locomotive-engine boilers, during continuous trips in winter and summer.* The mean result for the whole year for six-wheeled coupled goods- engines is a coal consumption of 69*80 Ibs. as compared with 43- 19 Ibs. of petroleum, at a cost of 10*212 pence for coal, and 5*459 pence for petro- leum ; being an advantage of 38 per cent, in weight and 46 per cent, in cost of petroleum-refuse. The mean result per train-mile, with four- wheeled coupled passenger-engines is 39*38 Ib. of coal, against 29*62 Ib. of petroleum, at a cost of 5*672 pence for coal, and 3*808 pence for petroleum ; being an advantage of 25 per cent, in weight, and 33 per cent, in cost of petroleum-refuse. Petroleum is also successfully used in the above-named boilers as an anti-incrustator ; about 4 Ibs. of petroleum are used for every 100 miles run, and the boilers are washed out every 600 miles. Table 29. COMPOSITION, HEATING POWER, AND THEORETICAL EVAPORA- TIVE POWER OF PENNSYLVANIAN AND RUSSIAN CRUDE PETROLEUM OIL. RUSSIAN. Crude Petroleum Oil. vanian. Light. Heavy ; Naphtha- Refuse. Per cent. Per cent. Per cent. Per cent. Carbon ..... 84*9 86*3 86-6 8 7 -I Hydrogen ..... 137 13-6 12*3 117 Oxygen .... I '4 I 1*1 I'2 IOO IOO IOO ICO Specific gravity at 32 Fahr., water =1000 . . . . 886 884 886 928 Units Units. Un-s Units Heating-power in British ther- mal units .... I92IO 22628 I94IO 19260 Ibs. Ibs. Ibs. Theoretical evaporation at 120 Ibs. or 8 atmospheres pres- sure, in Ibs. of water per Ib. of fuel .... 16*2 17*4 16-4 16-2 * See a paper read before the Institution of Mechanical Engineers by Mr. Thomas Urquhart. RATE OF COMBUSTION IN STEAM BOILERS. QI Table 30. COMPARATIVE TRIALS OF A LOCOMOTIVE ENG:NE BURNING PETROLEUM, ANTHRACITE, BITUMINOUS COAL AND WOOD. CONSUMPTION, INCLUDING LIGHTING- CONSUMPTION, INCLUDING UP IN WINTER. LIGHTING-CP IN SUMMER. Description of Fuel used. Total. Per Mile. Cost of Fuel per Train- Mile. Tempera- ture and Weather. Total. Per Train- Mile. Cost of Fuel per Train- Mile. Ibs. Ibs. Pence. Ibs. Ibs. Pence. Anthracite 3 X 779 81-90 11-96 1 6 to j -?*' Bituminous coal 37558 96-53 14-09 / Strong 14084 72-6O 10-60 Petroleum-refuse . 9462 4877 5-49 side j wind. 6176 3I-84 3-58 Anthracite . . 12640 65-15 9-52 12784 65-90 9'62 cubic ft. cubic ft. 12 Wood, in billets . IO72 5-52 8-50 Fahr. - Light Ib. Ib. side- wind Petroleum-refuse . 7223 37-23 4-19 6lO4 3 I- 46 3^4 Prices of Fuel used. Petroleum refuse, 2is. per ton; anthracite and bituminous coal, 275-. 3^. per ton; wood in billets, 42-$-. per cubic sajene = 343 cubic feet, equivalent to 1-47 penny per cubic foot. Dimensions of Locomotive Engines. Cylinders, i8 inches diameter, and 24 inches stroke ; wheels, 4 feet 3 inches diameter. Total heating- surface, 1248 square feet. Total adhesion-weight, 36 tons. Boiler-pressure, 1 20 135 Ibs. The rate of Combustion in Steam Boilers is the weight of fuel in Ibs. per hour burnt on each square foot of fire-grate ; it depends upon the quantity of draught and the combustibility of the fuel, and it varies with different classes of boilers. The Average rate of Combustion in Steam Boilers per square foot of fire-grate per hour is as follows : Egg-ended boilers, externally fired Water-tube boilers Gallo-.vay-boiler Portable-engine boilers Vertical boilers Cornish boilers . Lancashire boilers . The nozzle boiler Marine boilers with Marine boilers with Marine boilers with Locomotives burning coal . Torpedo-boat boilers Locomotives burning coke 6 to 10 Ibs. rs latural draught . 8 . . 9 . 10 . 12 * 14 . ! 28 ;; \i v 30 14 ,,18 26 24 3 ir pressure coal .... coke 34 . . 40 . 60 . . 65 40 " 6 i IIO 92 THE PRACTICAL ENGINEER'S HAND-BOOK. The rate of Combustion of various Coals in Ibs. of coal burnt pe. square foot of fire-grate per hour, with natural draught, is as follows : Welsh steam coal . . 20 to 21 Ibs. per sq.ft. of fire-grate per hour. Newcastle steam coal . 24 ,, 30 ,, ,, Yorkshire steam coal . 25 ,, 30 ,, ,, Lancashire steam coal 26 ,, 28 ,, The Force developed by Combustion, or its dynamical value, may be ascertained by multiplying the number of units of heat developed by the complete combustion of i Ib. of fuel by the mechanical equivalent of each unit of heat, or 772. Hence the force developed by i Ib. of carbon in burn- ing to carbonic acid is equal to 14500 x 772 = 11,194,000 foot pounds. The Force developed by the complete Combustion of one Ib. of good Coal, taking its calorific power at 14000 thermal units per Ib. of coal, is equal to 14000 x 772 = 10,808,000 foot pounds, or equal to 10,808,000 pounds raised one foot high. The Horse-power theoretically developed by the heat yielded by the complete combustion of i Ib. of coal per hour will equal 10808000 foot pounds _ = ho represent- 33000 toot pounds per minute x oo minutes ing a consumption of coal per indicated horse-power of '185 Ib , a result which has not yet been attained in practice, as the best engines only peiform about one-tenth of that duty. The Actual Power developed by the Combustion of -one Ib. of Coal in Practice is on an average equal to one-eleventh part of the powef theoretically developed by the coal in first-class compound condensing engines, or '185 Ib. x n = 2*035 Ibs., or say 2 Ibs. coal-consumption per indicated horse-power per hour ; but in some cases it has been less than this, or about i J Ib. In high-pressure non-condensing engines the actual power developed is on an average only about one-tweniieth part of that theoretically due to the coal, or -185 X 20 = 37 Ibs. coal-consumption per indicated horse-power per hour. The Consumption of Coal per Nominal Horse per Hour averages 10 Ibs in ordinary stationary engines. Small Vertical Engines with vertical boilers, on an average consume 6 Ibs. of coal per indicated horse-power per hour. Stationary Engines, non-condensing, on an average consume from 3 to 4 Ibs. of coal per indicated horse-power per hour. Stationary Engines, condensing, on an average consume from if to 2\ Ibs. of coal per indicated horse-power per hour. Portable-Engines on an average consume 4 Ibs. of coal per indicated horse-power per hour. Stationary and Portable Compound Non-condensing Engines on an average consume from 2\ to 3 Ibs. of coal per indicated horse-power per hour. Locomotive Engines on an average consume from 2 to 2\ Ibs. of coal per indicated horse-power per hour. Double Expansion Compound Marine Engines on an average con- sume from 2j to 2| Ibs. cf coal per indicated horse-power per hour. ACTION OF FLAME IN BOILER-FLUE TUBES. 93 Triple Expansion and Quadruple Expansion Marine Engines on an average consume from ij to i| Ibs. of coal per indicated horse- power per hour. The Difference between the Theoretical and Actual Force developed by steam-boilers is partly due to imperfect combustion and j'artly to the small portion of the total heat developed by combustion which, in practice, can be applied to the heating surfaces of boilers and absorbed by the water, the remainder being wasted, owing in many cases to the heating surfaces of the boiler not being arranged in the best manner for effectually depriving the products of combustion of their heat. In order to obtain high economical results from the combustion of fuel, it is necessary in designing steam-generators to understand the true prin- ciples of boiler-construction, regarding the combustion of fuel and the liberation, absorption, radiation, conduction and convexion of heat. Com- bustion has been previously treated, and the following subjects may now be briefly considered. Action of Flame in Boiler-Flue Tubes. Peclet says, in speaking of the heating of liquids by gas, as for example, in the case of a steam- boiler, and of that portion which does not receive the direct rays of heat radiated from the fuel on the fire-grate, that is to say in the flues, the quantity of heat which traverses the plate is invariably determined by the difference in temperature on its opposite sides ; the absorbing and emissive powers of the two surfaces of the plate, and above all, by the movements of the sheets of gas which are in contact with the metal. It will be found in all cases that the rapid renewal of layers of liquid or gas which touch the surface of the metal plate, has a great influence on the transmission of heat ; but this circumstance is much more important in the case of gases than in the case of liquids. Suppose, for example, that the products of combustion escape at a high temperature into a circular flue surrounded with water which we wish to heat, the sheets of gas which are in contact with the plate are cooled down with great rapidity, but all the little elementary currents having a direction parallel with the axis of the flue, the sheets of gas change places very slowly, because the only cause for change lies in the acquisition of density which results from cooling ; but this change of temperature only takes place in the upper portion of the flue, and it lends to produce displacement with a slow speed. Hence if the section of a flue be considerable, and the speed at which the gases move through it be high, the greater part of the central veins will not come in contact with the surface of the plate, and they will therefore preserve their original temperature. The Flame in passing from the Furnace through the Flue-Tube of a Cornish Boiler acts in a similar manner to the above. The atoms of heated gas come in contact with the top of the flue-tube, impart heat to it, and as they move along the flue they cool and sink away from it and are replaced by others; and it is probable that the central portion of the volume of heated gases sweeps through the flue and reaches the end of the boiler without coming in contact with the surface of the tube and without any sensible diminution in temperature. The gases in turning round the boiler-end come in contact with bends and angles and are thereby broken up and yield heat which would otherwise escape to the chimney unused. 94 THE PRACTICAL ENGINEER'S HAND-BOOK. This shows that the flame operates at a great disadvantage when travelling through a horizontal flue-tube in a direction parallel to its axis, and means should be adopted to diffuse the heat by breaking up and subdividing the stream of heated gases in order to cause fresh portions of the gases to come in contact with the surface of the tube, which is best effected by placing Galloway-tubes in the flue. If these tubes are properly arranged and placed at proper intervals the flame not only impinges against the face or surface of the tubes facing the fire, but where there is a good body of flame it laps well round the tubes, becomes split up, and is brought into contact with the main flue-tube. The Flame in passing through Small Tubes, such as boiler-tubes, assumes a winding manner which considerably adds to their efficiency as heating surface, because the whirling motion brings fresh portions of the products of combustion against the surface of the tubes. The flame will pass right through boiler-tubes of ordinary diameter and length, with a proper supply of air to the furnace and a moderate draught. The Products of Combustion Escape to the Chimney at a High Temperature, that being necessary to obtain a good natural draught, the effect of heat in the chimney being to increase the draught and to accelerate combustion. The heated gases pass up the chimney on an average at a tem- perature of from 400 10425 Fahr. in boilers of portable engines; at from 552 to 600 Fahr. in Cornish and Lancashire boilers and marine boilers, with natural draught, and at from 400 to 450 Fahr., with well-arranged forced draught. The temperature in the smoke-box of the boiler of a locomotive engine generally varies from 450 to 600 Fahr. when the engine is working lightly, and from 800 to 900 Fahr. when the engine is hard worked, according to the load. In the case of boilers with forced draught the products of combustion may be utilised in heating the air supplied to the furnace ; if the air abstract from the escaping gases, in passing through a heating chamber placed in the chimney, say 200 of heat, and 18 Ibs. of air be required per Ib. of coal, then 200 x 18 Ibs. x '238 specific heat of air = 856*8 units of heat per Ib. of coal consumed, will be recovered by the air from the waste gases which would otherwise escape up the chimney and be wasted. The Proportion of the Total Heat Developed on the Fire-grate which is absorbed by the surfaces surrounding the fire, varies considerably in different boilers. Peclet found that one-half the heat of a fire of peat was given out by radiation. The radiant power of coal and other fuels may be taken at the same as that of peat, so that of the total heating power cf coal and other fuels one-half the heat is given out by radiation and the remainder is absorbed by the air in passing through the fire, which in the case of a steam boiler is partly recovered by passing the products of combustion through flues surrounded by absorbing or heating surfaces. The Temperature of the Products of Combustion at Different Stages between the Fire and the Chimney, may be ascertained by A series of calculations which may be illustrated by taking the case of the plain cylindrical egg-ended steam-boiler, shown in Fig. 51, and calculating the temperature of the gaseous products of combustion at various points of the length of the boiler. Then, let the external diameter of the boiler be 4 feet; length of boiler, 37 feet; length of fire-grate, 5 feet; and width TEMPERATURE OF THE PRODUCTS OF COMBUSTION. 95 of fire-grate, 4 feet. Taking the maximum calorific power of coal of average quality at 14300 units per lb., and allowing 10 per cent, for imperfect combustion, it leaves 14300 1430=12870 units, the available quantity of heat. The quantity of air required with natural draught will be 24 Ibs. for each pound of coal, and the temperature of the air on admission to the fire will be, say, 60 Fahr. In externally-fired boilers only one-fourth of the heat developed by the combustion of fuel on the fire-grate is given out by radiation to the boiler over the fire, the remainder, or three-fourths, being carried off by the air which passes through the furnace. There- f )re, 12870 -4- 4 = 3217 units of heat will be absorbed by the surface of the boiler, and the remainder, or 12870 3217 = 9653 units will escape past the bridge of the furnace. The tem- perature of the air and the gaseous pro- ducts of combustion when passing from the fire over the furnace-bridge, will be Boiler Fig . 5I ._Method of setting plain cylindrical or eeg-shaped boilers. 9653 units of heat 6Q o initial 24 Ibs. of air x '238 the specific heat ot air temperature = 1750 Fahr. If the absolute pressure of the steam in the boiler be 70 Ibs. per square inch the temperature of the boiler will be 303 Fahr., and the quantity of heat abstracted from the gases on their way to the chimney at different points in the length of the boiler, will be in proportion to the difference between the temperature of the escaping gases at each point, and the tem- perature of the boiler. As the gases give out the greatest heat after passing the furnace-bridge for a distance equal to about the length of the fire-grate, it may be assumed that one-fourth of this difference of temperature will be given up from point to point for that distance, and one-eighth of this differ- ence from point to point for the remainder of the length of the boiler, and the temperature at the different points may be calculated as follows, supposing no heat is lost in heating the setting : The temperature of the gases at the furnace-bridge = 1750 Fahr. ; tem- perature of boiler = 303 Fahr., Then, 1750 I7 " O ~ 3 3 = 1388 Fahr., the temperature of the first point beyond the bridge. 1388 I3 ~ 3 3 =iii7 Fahr., the temperature of the second point beyond the bridge. 1117 =I0 05 Fahr., the temperature of the third point beyond the bridge. 1005 - = 917 Fahr.i the temperature of ths fourth point beyond the bridge. 9 6 THE PRACTICAL ENGINEER'S HAND-BOOK. And so on for the remaining points in the length of the boiler, the results being as follows : Temperature of the Gaseous Products of Combustion at, and beyond the Bridge of the Furnace of the Boiler shown in Fig. 51 : Degrees Fahr. Temperature at the bridge of the furnace .... 1750 Temperature at a distance of 2 ft. 6 in. beyond the bridge 8 ii H 17 20 2 3 26 29 3 2 1388 1117 1005 917 840 773 7H 663 618 578 at end of boiler or entrance ") to the flue of the chimney ) ^44 The walls shown in Fig. 51 behind the furnace-bridge, form baffling- bridges to insure the contact of the gaseous products of combustion with the heating or absorbing surface of the boiler, and to retard the escape of the gases and promote their admixture with the air. This is the best method of setting plain cylindrical or egg-ended boilers of proper length. It will be seen from the above temperatures at various points in the length of the boiler, that it is necessary to make this class of boiler of sufficient length to prevent the gases escaping to the chimney before they have been thoroughly deprived of their heat. For instance, if the boiler had only extended to a length of 1 1 feet beyond the bridge, the gases would escape to the chimney at 917 Fahr., causing a loss of 917544 = 373 of heat. The quantity of heat lost when the gases enter the chimney at a temperature of 544 Fahr. is = 54460 x (24 Ibs. of air x 230 specific heat of air) = 2765 units, and the quantity of heat lost if the gases entered the chimney at 917 Fahr. would be = 917 60 x (24 x 238) = 4896 units, showing a loss of heat = 48962765 = 2131 units greater with the short than with the long boiler above described, which allows the gases to escape at 32 feet beyond the bridge at a sufficiently high temperature to ensure a proper draught. Absorption is the power of taking in heat. Coated surfaces absorb more readily than uncoated surfaces. Good radiators of heat are good absorbers, and bad radiators are bad absorbers of heat. For instance, lampblack is a good absorber of heat and also a good radiator, hence the same numbers which express the relative radiant powers of any series of substances will also express their relative absorbent powers. Heat is Communicated from one body to another in three ways : i st. By direct contact, called conduction. 2nd. By right lines, called radiation. 3rd. By carrying, called convection. CONDUCTION AND RADIATION OF HEAT. 97 Conduction is the power that substances possess of conducting heat from other bodies in immediate contact with them, the power varying according to the nature of the substance. The conducting power of metals when pure is nearly the same for heat and electricity. Woods conduct better in the direction of the fibre than across the fibre. The conducting power of the bark of a tree is lower than that of the wood. Non-Conductors of Heat, or, more properly, slow or bad conductors or retainers of heat are the following, viz., stones, glass, terra-cotta, brick- work, straw, white paper, wool, hair, felt, &c., each being successively lower in their conducting powers according to careful experiments, the results of which are given in the following Table : Table 31. HEAT CONDUCTING POWER OF VARIOUS SUBSTANCES BY WlEDMANN AND FRANTZ, AND OTHERS. Silver .... IOO Steel n-6 Copper 73-6 Lead .... 8-5 Gold .... 53'2 Platinum . 8-4 Tin . 4'5 Rose's alloy . . . 2-8 Iron . . . . 11-9 Bismuth . r8 Stone . IOO Wood-ashes . . 37 Glass Terra-cotta . 50 3 Mahogany sawdust . 3-6 Hemp . . . 3-3 Brickwork 25 Cork-chips . . . I 3*1 Coal-ashes, fine . . 10-8 White writing paper . 2*5 Chalk, powdered 6-3 Cotton wool or lint . 2-4 Chaff .... 5-6 Sheep's wool 2-3 Bran 4*5 Hair felt . . . 2'I Straw, chopped . . 4-0 Eiderdown 2'O Radiation is the heating effects produced by direct rays from a hot body through space, as light is from that of a luminous body, the heating effect being inversely the square of the distance from the hot body. If at any given distance a certain heating effect is produced, at twice that distance the power or effect will be one-fourth, and at three times the distance one-ninth ; but the radiating powers of substances vary in effect with the nature and colour of their surfaces. Thus, polished iron does not, at the same temperature, give out so much heat by radiation as when its surface is in a corroded state. Hence the cylinder covers of engines should be kept constantly bright to prevent loss of heat by radiation. A white surface will not diffuse heat by radiation equal in quantity to that of a darker colour. Bodies coated with a thin plate of bright metal suffer very little loss from radiation of heat. Leslie found that a tin vessel filled with hot water and covered with lamp- black possessed a radiating power of 100. The following Table contains the comparative radiating power of other materials. 9 3 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 32. RADIATING POWER OF MATERIALS. Surface covered with lampblack IOO white lead 100 writing paper 98 ,, resin 96 ,, ordinary white glass . . . . Qi China ink ..... 88 ,, red lead 80 ,, plumbago 75 ,, isinglass 75 ,, tarnished lead 44 ,, scratched tin 22 ,, mercury ...... 20 polished lead !9 ,, polished iron 15 ,, tin-plate 12 ,, gld, silver, copper, each . 12 Other authorities consider that the radiating power of the metals given above are about 70 per cent, too large. The Loss of Heat by Radiation from Steam-pipes is considerable, even when the pipes are clothed with a non-conducting material, as will be seen from the following Table, which contains the results of careful experi- ments to determine the loss by radiation from steam-pipes protected with various non-conducting materials. The best results were * obtained with hair-felt surrounded with a covering of burlap, and it was found that coverings owe their efficiency chiefly to their interstices being filled with air, but not being open enough to permit a circulation. Table 33. RADIATION FROM STEAM-PIPES COVERED WITH VARIOUS NON- CONDUCTING MATERIALS, THE RESULTS BEING GIVEN IN POUND- FAHRENHEIT HEAT-UNITS RADIATED PER HOUR, FROM A SURFACE OF ONE SQUARE FOOT, THE RESULTS OF EXPERIMENTS BY PROFESSOR ORDWAY. Material. Diameter, Inches. Weight per Foot, Ounces Avoir. Pound- Fahr., Heat Units per Hour. Hair-felt, burlap 5*37 21'4 51-0 Asbestos-paper, hair felt, duck . . . . 4'5 4*5 I 3 -2 I7'3 56-6 597 ,, ,, paper-duck 4*5 19-9 62-<; ,, ,, ,, . . . 5' 18-4 63-8 ,, ,, ,, 4*o 17-2 70-6 4'5 16-1 77'9 Fossil -meal with 12 per cent, cork dust . ,, ,, strawboard *. ' . . 5-12 5'12 247 20-8 64-8 68-4 Paste of fossil-meal and hair .... 475 607 839 ,, ,, ,, .... 4-25 3i-9 91*0 4-12 26-9 93 -I ., asbestos . . . . 4 '5 34 '4 117-5 RADIATION FROM STEAM-PIPES. 99 Table 33 continued. RADIATION FROM STEAM-PIPES, &c. Material. Diameter, Inches. Weight per Foot, Ounces Avoir. Pound-Fahr., Heat Units per Sq. Ft. per Hour. Best slag- wool, strawboard .... 475 13-2 66-6 Poor ,, ,, 4'25 24-1 90'5 Asbestcs-paper, slag-wool, asbestos-paper Air space, tin-plate, hair felt, duck . . . 4-00 475 26-2 20-8 117-0 697 ,, strawboard, cork, strawboard 5-12 12-0 79-0 ,, ,, hair-felt, drilling . . 5-12 79-0 J J 5 J 5 12 79 '5 ,, asbestos-paper, paper-cylinder . . ,, strawboard, hair-felt 475 475 29-3 I2X> 81-1 82-1 ,, ,, sphagnam, cotton-cloth 4-75 10-6 85-8 ,, ,, pine - turnings, straw- board 5-12 14-0 89-6 ,, ,, paper-pulp, strawboard 5-12 137 917 ,, ,, rice-chaff, strawboard . 5-12 17-1 94 -6 ,, ,, cotton-roving stair-pad 475 14-6 96-0 ,, ,, wire-netting, paste of fossil-meal, asbestos 5-00 41-0 3"4 ,, multiplex, with strawboard and cords ..... 4'37 28-1 "5'3 ,. strawboard, cotton-roving . . . 4-25 8-3 124-0 ,, simple 2-94 1 95 '4 Silicated cork-chips, drilling .... 5-25 i4 : 8 71*4 5 >2 5 147 7 2 7 Air space, strawboard, cork-chips, strawboard 5-12 I2X> 79'o Cork in strips ...... 3-62 67 105*3 Silicated pine-charcoal 34'5 ,, hard wood 5-00- 4I-9 97 "8 ,, rice-chaff, cotton-cloth . . . 475 22-7 80-2 5-25 V 7"5 85'4 Rice-chaff, strawboard . . . . 5' 12 / j 167 87-0 Air space, strawboard, rice-chaff, strawboard . 5-12 17-1 94'5 Rice-chaff, strawboard . ... 375 8-4 io9"5 Paper made of wool-pulp and wool-waste 4'37 30-5 78-1 Cotton-batting 4-00 6-0 797 Air spnce, asbestos paper, paper cylinder Straw rope, four thicknesses cotton cloth . . 475 4'5 29-3 20-2 Sri 96-9 Silicated cotton-seed hulls, drilling . 5-12 5I"O 107-6 Blotting-paper 4-00 28-9 127-8 Asbestos-paper 4-00 131-2 . 2-87 223-7 Anthracite coal-ashss (fine), strawboard . 5-00 37 '6 96-8 Bituminous ,. . . 5-00 41-2 98-4 Anthracite ,, (coarse) ,, . 57-3 131-2 Paste of fossil-meal and hair . . . . 475 607 3'O 3> .... 4*^5 3 I- 9 91-0 . 4-12 26-9 93 'i Air space, fossil-meal and hair, asbestos . 500 41-0 Carbon, plaster-of-paris, flour and hair. . 4-50 4-50 35-4 33 ' "7'5 106-8 Clay and vegetable- fibre . . . . . Anthracite-ashes, plaster-of-paris, flour and hair Clay and vegetable-fibre . . .... 475 94-1 79-2 65-2 146-0 I55-4 205-3 Naked pipe . . '. . . . I555-I IOO THE PRACTICAL ENGINEER'S HAND-BOOK. Convection is the power possessed by fluids of conveying heat acquired at one place to another place. Convection is caused by currents both in air and water. Smoke ascends the chimney, and ventilation is caused by the same principle. Gaseous bodies, from the great mobility of their particles, are the most rapid conveyers, although they are the slowest con- ductors of heat. Any body hotter than the air heats it and sets it in motion in an upward current, which may be seen rising from highly heated bodies, and the particles which rise are immediately replaced by the influx of other particles from every side. The slightest difference in temperature is sufficient to produce these effects, hence the rapidity with which air reduces solid bodies to its own temperature. A body colder than the air, such as a lump of ice, produces an opposite action ; it cools the air in contact with it, which, becoming denser, descends in a continual stream, supplied by an influx of air from all sides to the ice, until the whole is melted. Heat in distributed by Convection through the Water in a Boiler, the heat imparted to the outside of the plate from the furnace, is conducted through the plate, and the water in contact with it absorbs heat, expands, and rises from it, and colder water immediately descends, and occupies its place. Water, being a bad conductor of heat, can only be warmed very slowly by conduction. Owing to the low conducting power of water, the application of heat to its upper surface is of no effect in heating the mass of water beneath, and it may be boiled at the surface, while a lump of ice, fixed at the bottom, remains unmelted, as shown at Fig. 52. Effect of Heat on Water. There is no change of temperature in liquids under ordinary conditions without causing a displacement of particles. If heat be applied under a vessel of water, the particles near the bottom of the vessel being heated first and expanding, become specifically lighter and ascend; colder particles occupy their place, become heated and ascend in their turn, and thus a current is established, the heated particles rising up through the centre and colder particles descending at the sides. Hence ample area should be provided in Fi 2 A iication ^ wat er-spaces of boilers for both ascending and de- 'fr he'at to the* surface scending currents. The heat is not conducted from par- O f water. t j c j e to p ar ti c i e without displacement, as in the case of solids; but each particle, as fast as it receives a fresh accession of heat, conveys it to a distance, displacing other and colder particles in its progress. When Heat is applied to the Surface of Water it is not diffused by convection, but creeps very slowly downwards by conduction. Hence water placed underneath a hot tube on being heated and becoming lighter clings to the surface above it and diffuses no heat downwards : for instance, in Cornish boilers, without Galloway tubes for promoting the circulation, the water under the flue-tube is frequently comparatively cold some time after the steam has been raised. It will be seen from this that the under portions of the internal flue-tubes of boilers are almost of no value for raising steam. Circulation is caused by the difference of density of water in a boiler, due partly to difference of temperature, but principally to the action of steam- bubbles, which lighten the water, hence there is a difference of density of those portions which produce the most and the least steam. SECTION II. EVAPORATION ; BOILER - SHELLS, BOILER- FURNACE-TUBES ; BOARD OF TRADE, LLOYD'S, AND NUMEROUS OTHER RULES AND DATA FOR STEAM-BOILERS; BOILER- CONSTRUCTION ; BOILER - EXPLOSIONS, ETC. SECTION II. EVAPORATION ; BOILER - SHELLS, BOILER- FURNACE-TUBES ; BOARD OF TRADE, LLOYD'S, AND NUMEROUS OTHER RULES AND DATA FOR STEAM-BOILERS ; BOILER- CONSTRUCTION ; BOILER - EXPLOSIONS, ETC. EVAPORATION OF WATER TO STEAM IN STEAM-BOILERS. The Evaporative Efficiency, E, of a perfect steam generator, having perfect combustion with the proper quantity of air, would be expressed by the following formula, in which T 1 and T 2 denote the temperatures of the r Y T furnace and the chimney in degrees Fahr. E= -? * Tj + 461- For instance, if the temperature of the boiler- furnace be 2400 Fahr., and that of the chimney =550 Fahr., then the efficiency is : -p_ Heat utilised _24oo 55O*_. fi _ ~~ HeaTsupplied ~~ 2 400 + 4 67 ~~ that is, the heat utilised is 65 per cent, of the heat supplied, the maximum efficiency theoretically possible with this range of temperature. The Actual Evaporative Efficiency of a Steam-Boiler is measured by the amount of the total heat of combustion absorbed into the boiler and applied to the evaporation of water to steam. ~, t 1 ffi ' Dumber f thermal units transmitted to the water, Calorific power of the fuel. The Evaporative Power of a Steam-Boiler is expressed by the quantity of water evaporated to steam per hour. The Total Heat of Saturated Steam or the total heat of evaporation is the sum of the latent and sensible heats of evaporation, or the quantity of heat necessary to raise lib. of water from 32 Fahr., the freezing-point, to a particular temperature and to evaporate it at that temperature. The Sensible Heat is that required to raise the temperature of water from the freezing-point to the temperature of ebullition : and the latent heat is that required to evaporate the water at the given temperature, or the heat which disappears in effecting the conversion of water into vapour. Liquids on the application of heat absorb a quantity of heat in passing from water to steam, which remains latent in the steam. This heat can be restored to sensibility and communicated to other bodies, when the vapour is condensed into liquid. 104 THE PRACTICAL ENGINEER'S HAND-BOOK. The Latent Heat, L, of Saturated Steam, at any given tem- perature, T, in degrees Fahr., may be found by this Rule: =966 -7 (T-2I2). Example : Required the latent heat of steam of 43 Ibs. absolute pressure, the temperature of which is 272 Fahr. Then 272 212x7=42, and 966 42= 924 units of latent heat per Ib. of steam. Total Heat of Steam. The sensible heat required to raise the tem- perature of water from the freezing to the boiling point is 212 Fahr. 32 Fahr.= i8o thermal units, the latent heat of evaporation of i Ib. of steam at atmospheric pressure is 966, hence the total heat in i Ib. of steam at atmospheric pressure is 966 + 180=1146 thermal units, being the amount of heat expended in the generation of i Ib. of saturated steam at 212 Fahr. from water at 32 Fahr. The Total Heat, H, incorporated in i Ib of saturated steam at the temperature, T, is equal to the latent heat of evaporation of steam at nearly 32 Fahr., increased by the product '305 T. It is expressed by the formula: H= 1082 + '305 T. Example: Required the total heat of steam at a temperature of 310 Fahr. Then 310 x '305 = 94*55 and 1082 + 94-55 = 1176-55, or in round numbers there are 1177 total number of units of heat in i Ib of steam at 310 Fahr., or 77 Ibs. absolute pressure. The Volume of Steam, or number of cubic feet of steam, evaporated from i cubic foot of water, compared with that of water at 39 Fahr., may be calculated by the following formula of Fairbairn and Tate : Let V=the volume of saturated steam at the pressure, P, measured by the height of a column of mercury in inches. Then = 25-62 +- F + '7 2 Example: Required the relative volume of steam of 31 Ibs. absolute pressure, or 63-15 inches pressure in inches of mercury. Then 63'i5 + 72 = 63-87 and 49513-^-63-87=775-23 and 775-23 + 25-62 = 800-85 relative volume. The Pressure of Steam measured in Inches of Mercury may be found by the converse of the last formula as follows : P= 49513^ 72 . -25-62 Example : Required the pressure in inches of mercury of steam of 80-085 relative volume as given in the last example. Then 800-85 -25-62 = 775-23, and 495 i3H-775'33 = 63-87,and 63-87-72 = 63-15 inches of mercury, the pressure of the steam. The Efficiency of a Steam-boiler is usually expressed by the weight of water evaporated to steam per Ib. of fuel, from and at 212 Fahr. The Equivalent Weight of Water Evaporated to Steam from and at 212 Fahr., the weight of water being supplied at a given temperature and evaporated at a given pressure, may be calculated as follows : Let H = the total heat of the steam at the given absolute pressure, which may be found in Table 79 : t = the temperature of the feed-water; F = EVAPORATIVE POWER OF FUEL. IO5 the factor ot evaporation ; W = the actual evaporation per Ib. of fuel ; Wj = the equivalent weight of water evaporated as from and at 212 Fahr. C = a constant divisor = 966 for feed-water supplied at 212 Fahr., this being the standard usually adopted in Boiler-Tests. When the equivalent weight of water is to be evaporated as from a less temperature than 212 Fahr., then C = a constant divisor = 1078 for feed-water supplied at 100 Fahr. C = do. 1116 do. do. 62 do. The water in each case to be taken as evaporated at 212 Fahr. Then F = H + 3*-t. and W, = W x U + * 2 ~*. O \_/ Example : Steam is generated at 65 Ibs. per square inch absolute pres- sure, the temperature of the feed-water is 100 Fahr., and 81bs. of water are evaporated per Ib. of coal. Required the equivalent weight of water evapo- rated as from and at 212 Fahr. H=ii73 units of heat per Ib. in steam of 65 Ibs. absolute pressure. Then 1173 + 32 = 1205 1 00= 1105 -7-966= 1*143, tne factor of evapora- tion, and 8 Ibs. x i * 143 = 9' 144 Ibs., the equivalent weight of water evaporated per Ib. of fuel. The "Weight of a Cubic Foot of Steam at various temperatures is obtained by dividing 62*5 the weight of a cubic foot of water by the relative volume of steam. Example : Required the weight in Ib. per cubic foot of steam of 30 Ibs. absolute pressure, the volume of which compared with one cubic foot of water at 39 Fahr. is 827 cubic feet. Then 62'5-'-827= > O755 Ib. weight of one cubic foot. Evaporative Power of Fuel. The evaporation of i Ib. of water at a temperature when evaporisation commences, or 212 Fahr. to steam of the same temperature, requires the addition of 966 units of heat. Therefore if the maximum calorific power of the fuel, or the number of thermal units it will develop per Ib. in burning, be divided by 966, it will give the number of Ibs. of water that each Ib. of fuel is theoretically capable of evaporating to steam from and at 212 Fahr. If the temperature of the water be less than 212 Fahr., say 100, a further quantity of heat will be required amounting to 212 100=112 thermal units, and this quantity must be added to the divisor, increasing it to 966+112 = 1078. Example : Required the quantity of water in Ibs. which coal, having a total heat of combustion of 14297 thermal units, is capable of evaporating for each Ib. of coal burnt. Then i4297-"-q66=i4-8 Ibs of water. The heat developed by hydrogen is 4^31 times as great as that of carbon, hence the evaporative power of any fuel may be found by the following formula, where C,H,O represent the constituents, carbon, hydrogen, and oxygen, U = the thermal units developed by the fuel, and E represents its evaporative power. Then E = Iig?x c + 4 '3i(H-o) ] =15 { C + 4 . 3 i ( H ~o The quantity -g- represents the deduction to be made from the constituent io6 THE PRACTICAL ENGINEER'S HAND-BOOK. hydrogen, or that portion which forms steam with the constituent oxygen. The number 14500 is the thermal units developed by one Ib. of carbon in burning to carbonic acid. Example : Required the evaporative power of coal composed of '86 carbon ; -05 hydrogen ; -03 oxygen. Then 15 86 carbon + 4*31 f '05 hydrogen '03 oxygen J = '03 -=- 8= '0072 '05 = '0428 x 4-31 = -184 + '86 = i '044 x 15 = 15-66 Ibs. of water per Ib. of fuel, the maximum theoretical evaporative power of that coal, which is much greater than that realised in practice. The Theoretical Evaporative Power of Coal and other fuels in Ibs. of water evaporated per Ib. of fuel from and at 212 Fahr. is given in the following Table. Table 34. THEORETICAL EVAPORATIVE POWER OF FUEL IN LBS. OF WATER EVAPORATED PER LB. OF FUEL. Description of Fuel. Lbs. of Water evaporated to Steam from and at 212 Fahr. Description of Fuel. Lbs. of Water evaporated to Steam from and at 212 Fahr. Ibs. Ibs. Petroleum . 22 Newcastle coal, good, Creosote-oil or tar-refuse 18 average . . . I4-80 Asphalte . . . . I7-l8 Lancashire coal . I4-6O Welsh coal, Ebbw Vale . I6-82 Derbyshire coal I4-50 Welsh coal, Powell's Yorkshire coal I4-38 Duffryn . 16-34 Scotch coal, best . . I4-I5 Welsh coal, best Aber- English coal, average of dare . . . . *5'93 a number of samples Welsh coal,Llangennech 15-25 of good steam-coal . 14-00 Welsh coal, Anthracite Coke .... 13-00 (Jones & Aubrey) U'59 Mixture of i part each Welsh coal, average of a of broken coke and number of samples of good slack . . ID-CO good steam-coal . . i5'5 Peat, dry . . . . lo-oo Patent fuels . 15-48 Breeze and slack, equal Bituminous lignite . . 14-90 parts . . . . 8-00 Perfect lignite 12-00 Wood, dry . 7'5Q Imperfect lignite . . IO'I2 Tan-refuse Oak bark . 6*50 Best Newcastle steam- Straw . . . ; 4-00 coal .... 15-30 The Actual Evaporative Power of various Steam-Coals of good quality, and other fuels, the average results of a number of boiler-tests with natural draught, in Ibs. of water evaporated from and at 212 Fahr., per Ib. of fuel, is given in the following Table : EVAPORATIVE POWER OF FUEL. ID/ Table 35. ACTUAL EVAPORATIVE POWER OF VARIOUS STEAM-COALS AND OTHER FUELS, WITH NATURAL DRAUGHT. Description of Fuel. Welsh steam-coal Crude petroleum-oil ..,,.... Best Newcastle steam-coal Best Lancashire steam-coal Creosote-oil, or residue from the distillation of tar Newcastle steam-coal, good average . . Lancashire steam-coal, good average ... Yorkshire steam-coal Coal, good, average of a number of samples from various districts Coal, medium quality, average of a number of samples from various districts Best slack, average of a number of samples from various districts Common slack, average of a number of samples from various districts Breeze and common slack, mixed half and half by weight . Tan-refuse Oak bark ....... Coal-dust and sawdust, mixed half and half by weight . . Lbs. of Water evaporated pet Ib. of Fuel. Ibs. I2'5O 12-25 I2'OO II-90 II'IO II'OO 10-85 10 7* 6 5* 5 The Actual Evaporative Power of Fuel in Practice is much less than the theoretical power. The total heat which may be developed by the combustion of i Ib. of good coal will theoretically evaporate 14 Ibs. of water from 100 Fahr. to 212 Fahr. With a clean boiler, good coal and skilful firing, from 10 to 12 Ibs. of water at 212 Fahr., have been evaporated per Ib. of coal with natural draught, and a well-arranged boiler should evaporate 10 Ibs. of water per Ib. of coal. Few boilers evaporate more than from 8 to 9 Ibs. of water per Ib. of coal burnt, and a great many only evaporate 7 Ibs. of water per Ib. of coal, or one-half the theoretical quantity. The difference between the theoretical and actual evaporation is chiefly due to radiation, imperfect combustion, and to the quantity of heat necessarily expended in producing chimney-draught when natural draught is used for combustion. Therefore it is not possible in practice to use all the available heat. In a careful test of a Cornish boiler with natural draught, 812 Ibs. of good small coal evaporated 6691 Ibs. of water at 55 Fahr. to steam at 212 Fahr. = (H78 -55) x 6691 Ibs. of water = f heat 812 Ibs. of coal burnt per Ib. of coal, and equal to 6691 -5- 812 = 8*24 Ibs. of water evaporated per Ib. of coal. The Loss of Heat in a Boiler-Furnace is caused chiefly by fuel falling unburnt through the bars, and by gases escaping at a high temperature 1 08 THE PRACTICAL ENGINEER'S HAND-BOOK. to the chimney. The available heat left for the generation of steam, being only about 60 per cent, of the heat theoretically developed by the fuel, in internally-fired boilers ; the loss being 10 per cent, greater in externally- fired boilers. The evaporative efficiency varies considerably in different classes of boilers. Effect of Blast-Pressure in a Chimney. Experiments have been made with steam-boilers to ascertain the effect of a steam-blast in the chimney, which resulted in showing that it increased the consumption of coal on the fire grate from 40 to 50 per cent, over natural draught, with an increase of efficient power not exceeding 15 per cent., and that a steam jet was very wasteful. Mr. Longridge, in some experiments, also found the blast-pipe in a chimney to be wasteful, and that only about one-eleventh of the power escaping is utilised in drawing air through the tubes. A strong air-blast has also been tried in a chimney which scarcely gave one-half as good a result as was obtained from forced draught with an air pressure of two inches of water in the stokehold. The Evaporative Performance of Steam-Boiler a in Practice is given in the following Table, which contains the average results of a number of tests of well-arranged steam-boilers with natural draught. Table 36. EVAPORATIVE PERFORMANCE OF STEAM-BOILERS IN LBS. OF WATER EVAPORATED PER LB. OF COAL FROM AND AT 212 FAHR. Lbs. of ! Lbs. of VNater - , ; Water Description of Steam- Boiler. ; evaporated 1 Description of Steam- Boiler. " evaporated perlb.of per Ib. of Coal. Coal. Ibs. Ibs. Galloway boiler 1 1 "j2 The Field boiler lO'OO Water-tube boiler II'OO Marine boiler 875 Lancashire boiler, with Cornish boiler . . . 8-00 Galloway tubes . 1075 Torpedo - boat boiler, Portable-engine boiler . 10-50 . locomotive type . 1 7 '50 Locomotive, compound, Vertical tubular boilers . 7*00 with coke . ICTOO Vertical cross-tube i Locomotive , ordinary, boilers . . . 6^25 with coke . . . IO - OO Egg-ended boiler, ex- > The nozzle boiler . lO'OO ternally fired . . 6' 20 An evaporative efficiency of about 90 per cent, has been obtained as the result of tests of boilers of the locomotive type. The Efficiency of the Boilers in the above Table may be ascertained by dividing the actual evaporative power by the theoretical evaporative power. Taking the theoretical evaporative power of i Ib. of average good coal at 14 Ibs. of water per Ib. of coal, the evaporative per- formance of the Galloway boiler shows an actual efficiency of ll 7 2 __ .g^. The efficiency of the Lancashire boiler, I0 75 _. = '76 ; the portable-engine EVAPORATIVE PERFORMANCES OF LOCOMOTIVES. ICQ boiler, J = 75 : the marine boiler ^ = 62 : the Cornish boiler, = 14 ' 14 H 57, and the vertical boiler with cross tubes, -? ='44, or less than one- half the theoretical evaporative power. The theoretical evaporative power of coke is 13 Ibs. of water per Ib. of coke, and the efficiency of ordinary locomotives is = 76. J 3 Evaporative Efficiency of Locomotive-Engine Boilers. The evaporative performance of a well proportioned locomotive boiler is given in Table 37, which contains the results obtained by Mr. Stroudley in a careful trial with one of his engines, the feed-water being heated to 1 88 Fahr., from which it will be seen that io| Ibs. of water were evaporated per Ib. of Welsh coal. Table 37. EVAPORATIVE PERFORMANCE OF A LOCOMOTIVE-ENGINE BOILER. Trip First, London Bridge to Brighton, 6*5 p.m. Average Coaches. Fuel, Ibs. per Mile. Lbs. of Water evaporated per Foot of Grate Surface. Lbs. of Water evaporated per Foot of Heating Surface. Lbs. of Water per Ib. of Coal. I 5 -6 2 3 -2 12-30 -I 93 10-08 Trip Second, London Bridge to Brighton, 5 p.m. 10*05 19-96 1 1 '09 173 IO-5O Fire-grate Area. Square Feet. Heating Surface of Tubes. Square Feet. Heating Surface of Fire-box. Square Feet. Tubes. Diameter, i j in. Total Heating Surface. '9 IIOO 110 206 I2IO Description of fuel used on each trip Welsh coal. The Evaporative Performance of a Locomotive-Engine Boiler under different arrangements in the supply of feed-water, are given in Table 38, which contains the results of an experiment by Mr. Drummond to determine the relative economic efficiency of a locomotive boiler when fed with feed-water by a feed-pump with water-heater, and when fed by an injector : from which it will be seen that there is very little difference in the weight of water evaporated per Ib. of coal, whether the bailer is fed by a pump or by an injector. I 10 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 38. RESULTS OF TRIALS ON THE NORTH BRITISH RAILWAY, SHOWING THE EVAPORATIVE EFFICIENCY OF A LOCOMOTIVE-ENGINE BOILER WHEN FED WITH A PUMP WITH FEED-WATER HEATER AND WHEN FED WITH AN INJECTOR. ENGINE. TRAIN. AVERAGE PER TRIP, GLASGOW TO CARL SLE. .5 i-d i .-2 18 in. by 26 in. Cylinders. 5 ft. Wheel. 150 Ib. Boiler press. Adhesive weight, 39^ tons. I 1 Description. 1 of Stoppages. Shunting. > Standing. age weight tra , wagons, and V 5 g i u-iNO OQNCNONONCNONONC u~i LTINC CO U->NO m\O mvO NO NO mvo NO B i" i Ji j & NO NO O O CO CO ON C3 O O *NI c* O O NO NO <+ ^"NO CO O O O ^t* CO ^ O CO ^ El fS gfO NO 10 IT. ~ _.eNMM^e M e.-..-. MMM N X .= : -t. r | **" \o NO 1-1 i 1 ON i-i CO CONO" COCONOOO rt-COC^NONONO 't-OO CO-^-^mo ^?CONOOcTNO i H 2 j t 1 4 i ! l| .OOOO^l-NCOON ONNO "J-coONOOOOOOu^wO * ONNO ^i- O NO i | H I j i ^^-c^>oo>o^^oooo^c- > a,^oo~oo m o' H ^-S; 5 PARTICULA ' i ^lllllllllllllllllllllllllll "s \ d ^H ^ co ^j~ to^o t^co <^ o | ~ 4 ^ ^o ^~ u~i'O t^co 0^ o | ~ < ^ ^o ^ u^\o rxoo ^ 1 (0 S 1 _,NONO ONO O NO NO O O NO O NO O O O ONNO NO CO NO NO ON O O ON O ^ I h Q 1 iameter. ^. <^ <^ O O *O V O ^t* l^ ON ON U">vO t^. O^OO ^O t" 1 ^ U"> ^^ I ^' V O ^^O i/^ O** ON^O > (-1 S. fj :| ^t 8 s $? il ^|R^ la K^K| ,? | ;='- W MMMM NC CO^-C.NCJC.^COC.COMC.C.CO ^CONOt^CO 5 | J-- c* c^ NO NO o meters. O O ON ON^O t^. l/"> l/% t>OO VO IOOO I> t>* I>* 1 O t^* lOO ^O t^x io\O l/^OO OO t>* 2 HM Hei eel-*. e 5 &S$$;?1?s3ir;v^^^ ^ J t g 1-1 c CO ^ U-^NO t>~CO O\ O i 1-73 1-28 27-00 36-42 '35 DHP 24 65 520 1.800 2- 4 I I-94 21-42 26-62 242 DHP 25 69-5 552 1,360 2- 5 6 I- 9 I 21-59 28-90 338 DHP 26 59 590 2,600 2-435 I- 7 8 16-88 23-05 3 6 5 D HP 27 66 660 3,400 2-52 2-04 16-18 19-97 234 DHP 28 73 5" 2,058 3-215 2-0 5 17-10 10-92 565 Average of all twenty-eight 3-274 2-14 II'22 17-08 522 of natural draught 3*560 2-25 8-91 13-92 "573 ,, of forced draught 2-412 I-72 20-98 28-15 336 D = forced draught. H = feed-heater. P = Pass-over slide valve. SURFACES. RATIOS. I. H. P. PER SQ. FOOT. Name of Vessel. I. H. P. Grate. Heating. Condensing. G. toH. Grat*" Heat- Grate. inj ,. Con- densing Parisian 6O2O 544 13176 9624 127-9 ... 11-06 -396 -625 Gallia 5300 538 13000 8300 :24'9 147 9-85 -468 638 Devastation 6637 742 17806 67IO 8- 9 4 -378 989 Mexican . 3400 33 10000 5500 :3o*3 '4-85 IO-3 ... Inchonal . 1559 107 3800 1900 : 35' : 4 -6 12-4 '349 698 Aberdeen . 2631 252 7128 5270 '33" 4' 2 9 12-53 -370 500 Servia . . 10350 1014 27483 15000 :27'i 15-5 9-86 -383 '690 Arizona . 6357 780 19500 12540 125- 8-08 -324 503 Monarch . 2283 247 7803 5050 9-22 -293 456 * The author is indebted for the particulars of the first 28 steamers in this Table to a. Paper read before the Institution of Mechanical Engineers by Mr. Alfred Blechynden. HEATING-SURFACE OF LOCOMOTIVES. 117 Relative Value of the Heating Surface of the Tubes and Fire-Box of the boiler of a locomotive engine. It was found, as the result of a number of experiments with locomotives, that, under ordinary work, the fire-box of a locomotive boiler evaporated one-fifth and the tubes four-fifths of the water. The Proportion of the Heating Surface of the Tubes to that of the Fire-Box of a locomotive engine boiler is generally from 10 to 12 to i. The heating surface of the fire-box of an ordinary-sized locomotive boiler is frequently about no square feet and the heating surface of the tubes about i ico square feet. The Total Heating Surface of a Locomotive Engine Boiler, to obtain an ample supply of steam, should = (diameter of one cylinder) 2 x 4, This Rule gives the following results : Diameter of locomotive cylinder 16 in.=i6 x 16 X 4= 1024 square feet. M 17 in -= i? x 17x4=1156 square feet. 18 in.= 18x18x4= 1296 square feet. ., 19 in.= 19 x 19x4=1444 square feet. Table 43. STANDARD PROPORTIONS OF HEATING SURFACE OF FiRE-Box AND TUBES OF BOILERS OF LOCOMOTIVE ENGINES ON VARIOUS ENGLISH RAILWAYS. Railway. Diameter of Cylinder. Fire- Grate Area. HEATING SURFACE. Fire-Box. Tubes. Total. Inches. sq. ft. sq.ft. sq.ft. sq.ft. Great Northern Railway . . 18 17-6 122 1043 1165 Brighton Railway 17 17-8 IO2 1080 Il82 Brighton Railway . . . . 18* 20-65 112 1373 1485 Brighton Railway, tank engine . 17 16 9 8 5 8 948 Midland Railway . . . . 18 17*5 no 1096 I2O6 Great Western Railway, B. G. . 18 21 153 1800 J953 Great Western Railway, N. G. . i7 16-25 97 1216 J 3 J 3 Great Western Railway, N. G. . i 18 17 J 33 1145 1278 London and North- Western Rail- way 16 15 85 IOI3 1098 London and North-Western Rail- way , . . . . . 17 15 89 IOI3 IIO2 London, Chatham, and Dover Railway irt 16-3 107 962 1069 South- Western Railway . . . i8| 17-5 104 III2 1216 Great Eastern Railway 18 i7'3 117 1083 I2OO Manchester S. & L. Railway . 7| 17 87 1057 "44 The power developed by the Heating surface of Locomotive- Engine Boilers may be estimated approximately by this Rule. Total Heating-surface in square feet x -5= the average indicated horse-power Il8 THE PRACTICAL ENGINEER'S HAND-BOOK. in ordinary service; and total heating-surface in square feetx'7=the maximum indicated horse-power. For instance, a locomotive-engine with a total heating surface of 1429 square feet, averages in ordinary service= 1429 x -5= 714 indicated horse-power, and its maximum power is=i429X 7=1000 indicated horse-power. The Bate of Transmission of Heat through Plates depends upon the condition and thickness of the plate. The rate of conduction in thermal units through boiler-plates and tubes per square foot of surface per hour may be calculated by Rankine's formula, as follows : Let T = the temperature of the gaseous products of combustion in the furnace / = the temperature of the water A = a constant varying between 160 and 200 U = thermal units transmitted per square foot of heating surface per hour Then U Example: The temperature of the gases in a boiler furnace is 2580 Fahr., and the temperature of the water in the boiler is 280 Fahr., required the number of thermal units transmitted per square foot of the heating surface per hour. ; Then ^^ __ = 2 - 6 thermal units hour< After 200 200 leaving the furnace the gases decrease in temperature on their way to the chimney, where their temperature would be about 600, so that the tempera- ture of the gases at the point where they quit the boiler would be, say, 650, and the rate of transmission at that point would only be ??-*~ 2 Q ' = 200 [37- =684-5 thermal units per hour. J200 Grate Surface and Heating Surface. The relation of grate-area heating surface, and consumption of fuel and water in steam-boilers has been fully investigated by Mr. D. K. Clark, with the following results: 1 i st. For a given extent of heating surface, the economical hourly con- sumption of fuel or water decreases directly as the grate-area is increased, land consequently in order to maintain the same efficiency or economical effect, the total hourly consumption should be reduced at the same rate as the grate-area is increased. 2nd. For a given area of fire-grate the total hourly consumption should vary as the square of the heating surface. That is, if we double the area of heating surfaces, we can burn four times the quantity of fuel with the same grate-area, and maintain the same evaporative efficiency or economy. 3rd. For a given hourly consumption, the area of the fire-grate should vary as the square of the heating-surface, in maintaining the same efficiency. That is, if the heating-surface be doubled, the fire-grate area may be in- creased four times, and the same economical consumption maintained. The first conclusion applies to all boilers, but the two last conclusions apply more especially to boilers of the locomotive type. EFFICIENCY OF HEATING-SURFACES. 119 The Efficiency of the Heating-Surface of a Boiler may be deter- mined by Mr. D. K. Clark's formula : Where W = Ibs. of water evaporated per square foot of fire-grate per hour c = Ibs of fuel consumed per square foot of fire-grate per hour r = ratio of heating surface to fire-grate-area = Heating-surface Grate-surface a = a constant, specific for each kind of boiler = -016 for marine boilers, and '0222 for stationary boilers. B == a constant, specific for each kind of boiler = 10-25 f r marine boilers, and 9.56 for stationary boilers. Thus the Ibs. of water evaporated from and at 212 Fahr. per Ib. of fuel W and the efficiency = w X IO Example : Required the efficiency of the heating-surface of a marine boiler which consumes 1 6 Ibs. of coal per square foot of fire-grate surface per hour ; the heating surface is 35 times that of the fire-grate surface, or a ratio of 35 to i. Then the Ibs. of water evaporated from and at 212 Fahr. per Ib. of fuel, w = 35 x 35 j^g. 1 ^ = 1-225 + io' 2 5 = n'475 Ibs., and the efficiency 1 6 Ibs. of coal of the heating surface is = V^ 75 ^ IO , =7172 per cent. 1 6 Ibs. of coal The Efficiency of the Heating-Surfaces of Boilers is frequently calculated by the following formula by Rankine, which is based on the two fundamental principles that : i st. The smaller the quantity of air used per pound of fuel the higher the temperature of the fire ; and that 2nd. The greater the difference between the temperature of the fire and that of the water the greater the efficiency of the heating surface. Where E' = the available evaporative power, and E = the evaporating power of i Ib. of a given kind of fuel in an ordinary boiler, in which S = the total area of heating surface, including feed-water heater if any ; F = the number of pounds of fuel burnt per square foot of fire-grate per hour. A and B are constants found by experience ; A is probably approximately proportionate to the square of the quantity of air supplied per Ib. of fuel ; B is a fractional multiplier to allow for miscellaneous losses of heat. For boilers with chimney draught, B = A='5. For boilers with forced draught, B= - A='3. I2O THE PRACTICAL ENGINEER'S HAND-BOOK. Example : The consumption of coal in a boiler with natural draught is 12 Ibs. per square foot of fire-grate surface. The heating-surface is 30 times that of the fire-grate surface, or a ratio of 30 to i. Required the efficiency of the heating-surface of the boiler. Then 3 x T-^ _ .75^ or ^6-4 p er cen t. In some cases B is taken at 20 per cent, for boilers with natural draught, then For boilers with chimney draught, B = -. Example-: In a Lancashire boiler, the coal consumption is 14 Ibs. per square foot of fire-grate surface per hour, the heating surface is 25 times that of the fire-grate surface, or 25 to i. Required the efficiency of its heating surface. Then ^ X2 5 = = -625, the efficiency of the heating surface of the 25 + i4X'5 32 boiler. In Lancashire and Cornish boilers a great portion of the heating surface is frequently rendered useless, in consequence of the flues not being kept clean. Forced Draught effects great economy in the production of steam. The sharper the draught the less is the quantity of air required for dilution, the higher the temperature of the products of combustion, and the less are their volume and velocity. The economy is due to the high temperature of the furnace which ensures such rapid and efficient diffusion and combina- tion of the gases, that they cannot escape from the furnace unburnt, and the formation of carbonic oxide and discharge of smoke is prevented. It also permits the products of combustion to be effectually deprived of their heat and discharged into the chimney at the lowest temperature. Such a con- dition cannot be effected with natural draught, as a high temperature in the chimney is necessary to create a draught. By forcing the draught, the maximum rate of combustion is obtained with the minimum quantity of fuel and air, from the minimum grate and heating surface. The following are a few of the advantages of combustion with forced draught. It enables an inferior and cheaper class of coal to be used, with ths same or better results than are obtained from best coal with natural draught. It increases the temperature of the furnace, the rate of combus- tion, and the efficiency of the heating surface. It enables the area of the fire-grate surface and tube-surface to be reduced, and a much smaller boiler can be used, to develop the same power, than is required with a natural draught. The air required for combustion can be efficiently warmed by the waste products of combustion, which is conducive to economy in th? generation of steam, as about 13 per cent, of coal is wasted by supplying cold air to the furnace. The indicated horse-power obtainable with forced draught, per square foot of fire-grate and per ton of boiler, is double that which can be obtained from the same boiler with natural draught. NATURAL DRAUGHT EXPERIMENTS. 121 Table 44.* NATURAL DRAUGHT EXPERIMENTS ON A HORIZONTAL RETURN- TUBE BOILER AT PHILADELPHIA. Refererce Number, r Heating Surface in Square Feet. Grate in Square Feet. Heating Surface. Grate | Area. I Total Combustible = Fuel, 1 less Refuse, in Pounds. Refuse per Cent, of Fuel. I Pounds of Combustible per Foot of Grate. I Square Ftet of Heating 1 Surface. Pounds of i Combustible. 1 Pounds of Wa'er i er Pound of Combustible Funnel Temperature. Pounds Of Air per Pound of Combustible. Efficiency, taking Calorific Value of Combustible at 16. Per Cent, of Error. Rankine. Per Cent, of Error D. K. Clarke. 59 .6381 36 17-7 4i7 21 ""57 i 33 12-77 Lead melts . 16 798 -13-5 -16-3 47 950 36 536 21 '5 14-88 i"77 12-75 ,, 16 '797 -10-4 1 3'7 63 30 9'- 08 21'3 2-43 3'7 13-6 383 18 85 5'i -20-6 61 482 36 i3'4 310 2I'4 8-62 i'5S 12*28 Lead melts 19 767 - 9-6 -13-8 48 95'J 36 26-4 549 203 15-24 i- 73 12-17 i . . 20 760 - 6-6 - 9-8 16 I 950 36 26-4 256 I 9 -6 7-12 3'7 12 71 510 20ry '795 + i'S 64 j 95o 19 i 950 36 ,26-4 507 36 26*4 601 $6 14-09 16*69 1-87 I'Stf 1I-72 9*96 Lead and zinc melt melts . 2 2 4 '733 748 7-0 - s;8 500 36 15-5 43 18-7 11-28 1*40 Il'Sl >. 223 738 - 8-8 -10*3 7 66 95C 36 36 26-4 26-4 282 23-7 519 18 7-84 14-42 1-83 I2-45 "'75 512 Lead melts 22* 2 3 778 "734 + 2*4 2'0 - 6-2 6-21 050 3 26-4 628 22*2 I 7'44 I"5I 11*2(5 Zinc a y 704 -3*4 5 716 36 19-9 482 18-9 I3-4 1*48 1167 Lead 23i 729 - 6-0 -li 2 4 950 21-6 44 400 22*5 18-51 2"375 11-62 . 23* 726 4 4-1 4 2-6 57 004 36 22-3 505 20-2 14-03 J 59 11-58 >, 24 724 - 3-8 - 6*6 6.5 95 36 26-4 546 18-9 15-18 i '74 "'55 24 1 722 i'5 4'93 10 2 3 950! 24 95| 28-8 39'5 33 424 22 17 68 438 20-9 15-2 "16 11-52 11-52 ',', " ' 24! 720 72 "I" 4 + 3'3 4 1-2 x'l 9 950| 30 3'"7 260 18*9 I 8*65 3'65 I2'2 510 25 762 + 5'9 0-7 18 32 950 95o 36 36 26-4 26-4 S3 *3'3 16*2 .13 7-03 1-42 13-08 1 371 10*78 Zinc melts 25 26 818 673 to-i 4 0-6 8 26 950 950 95o 950 18 36 52-8 % 663 565 22-8 19-4 i 9 *i 18*43 1 15-68 '"77 i'43 1*68 11-52 10-79 10-44 10*6 570 Lead melts . ,, and zinc melt melts . . -7 29 720 675 + 7-6 + 62_ 4 6'6 4 9-2 4 3'4 73 95 950 1 26-4 26*4 52*8 37 635 152 13*6 . 10*26 .' 2*56 11*81 17-6 17*64 i 1*5 10-45 20*3 8*43 . 6*25 12*29 Lead melts 399 ;-'i 738 '52 -- 3-8 - 5 10*4 -4-6 426-4 T- 950 95" 36 5 70*4 26-4 109 ; 23-3 S'o8 | 8-7 12-53 244 1 13-6 6-79 3-9 ii 96 360 427 i "783 "747 10*6 8*5 46o'i 0-59 28 *7 95 95" 9 26-4 26-4 668 645 i5'7 '8-56 1-42 9-47 j Zinc melts i6'i 17-92 i 47 9-99 | Lead 34 592 624 - 1*4 - - 9*8 t'i-1 14 950 13-5 70*4 25? 20-4 19-02 3-69 11*26 478 io 704 428 95 24 39 '5 209 16*4 8- 7 i 4-78 11-65 36 728 I V? 412-6 20 950] 36 26*4 437 16*7 12*15 | 2*17 11*05 i 478 38 790 -- 7-8 4 i -i 27 950] 36 26*4 733 18*1 20*35 j 1-295 7-51 Zinc melts 46 -40-4 444-6 29 95| 3 6 26*4 772 18-2 21-43 1 i'23 7-4i j <8 '463 40-6 +47 '9 7 1 950 36 26*4 123 15 3*42 | 7*71 1125 337 54 703 22-3 420*09 Ref. No. :L ,j Remarks. i j^J'l Remarks. kef No Remarks. 59 Four upper rows of tubes I 58 Three upper rows of tubes 12 Grate reduced. p ugged. plugged. o i > 63 Eight upper rows of tubes 24 plugged. i 57 Grate reduced. Two upper rows of tubes 73 Ferrules in" tubes. fy Six upper rows of tubes plugged. 13 Gi ate reduced. plugged. ! 65 Ferrules in tubes 15 6 4 Ferrules in tubes. | 10 Grate reduced. 72 Ferrules in tubes. 60 Five upper rows of tubes 23 .4 Grate reduced. plugged. j 32 Ferrules in four upper rows 11 66 Ferrules in tubes. of tubes. 7- Ferrules in tubes. * The Author is indebted for Tables 4446 to a Taper read before the North-East Coast Institution of Engineers and Shipbuilders by Messrs. J. Patterson and M. Sanderson. 122 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 45. NATURAL DRAUGHT TRIALS ON BOILERS AT KIMBERLEY WATERWORKS. i b. of Coal foot of Gra 8 6-70 7-84 4'44 7-62 3-56 5'3 1 1 '43 4 5' 3 6 4'3 3-6 4 6 '44 8-05 6-44 8-05 S 10-73 "3 iji Ii '758 '754 '734 '755 7 28 776 7 6o 778 707 '550 562 10-5 + 2'6 + 18-4 + 9'5 JJ + 18-5 + 17-1 +29-4 + 61-4 + 57 '4 ,3-8 37 47 These experiments show that an excessive supply of air to a furnace rapidly di finishes the efficiency of the heating-surface of a boiler. The supply of air can be reduced to a minimum, and the efficiency of the heat- ing surface is increased, by forcing the draught. In combustion with natural draught, about one-fourth of the heat developed in a furnace is expended in creating a draught. Table 46. FORCED DRAUGHT EXPERIMENTS ON A HORIZONTAL RETURN- TUBE BOILER AT PHILADELPHIA. j g 18-3 21-62 22-37 21-67 21-76 te i ill s? I0'0 9-88 9'25 Funne Temperat 1 o o s iaJ 710 6 99 6x 578 Fan. Fan. Fan. Jet. Fun. Fan. The Performance of Steam Ships with Natural Draught and with Forced. Draught in the Boilers are given in Tables 47 and 48. It will be seen from column 7 of Table 47, that in the ship with natural draught only io|- indicated horse-power was developed, per square foot of fire- grate ; but that with forced draught from 1 6 to 17 horse-power were developed per square foot of fire-grate, the boilers being practically the snme in the two cases. BOILERS WITH NATURAL AND WITH FORCED DRAUGHT. Table 47. PERFORMANCE OF STEAM SHIPS, EACH FITTED WITH THE SAME SIZE OF BOILERS, WITH ORDINARY OPEN STOKEHOLDS AND NATURAL DRAUGHT, AND WITH CLOSED STOKEHOLDS AND FORCED DRAUGHT. INDICATED Ship. Load on Safety Valves. Indicated Horse- Power. Weight Boilers. Area of Firegrate. HORSE-POWEK PER Square Ton of Foot of Firegrate. Boiler. Ib. tons. OPEN STOKEHOLDS. Natural Draught. Inflexible . ... 60 8484 756 829 IO'2I II'22 Colossus 64 7492 594 645 II-62 I2'6l Phaeton . . . . 9 5588 462 546 IO-23 I2'I CLOSED STOKEHOLDS. Forced Draught. Howe .... 9 II725 632 756 i5'54 18-5 Rodney (9 boilers) 9 9544 474 567 16-83 2O'I Mersey no 6628 306 399 16-61 21-7 Scout . . . . I2O 3370 174 207 16-28 '9'3 Trafalgar (estimated) . 135 I2OOO 5M 609 20'00 23'3 NOTE. The weight of boiler given includes weight of water, funnel, uptakes, fittings, spare gear, &c. Table 48. RESULTS OF TRIALS OF SIMILAR STEAMSHIPS WITH OPEN STOKEHOLDS AND NATURAL DRAUGHT, AND WITH CLOSED STOKE- HOLDS AND FORCED DRAUGHT. Particulars. OPEN STOKEHOLDS (NATURAL DRAUGHT). "Inflexible." " Colossus." "Phaeton." Duration of trial in hours . 6 5 5 Number of boilers used . . . 12 10 8 Mean steam pressure in boilers . Ib. 6ro6 61-52 85'35 Mean pressure in cylin- ( High pressure 2 9'55 40*66 43'56 ders in Ibs. per sq. in. ( Low 9' 8 33 12-09 n'43 Mean revolutions per minute 73-26 89-96 I00'26 Mean speed of piston, in ft., per minute 586 585 802 Indicated horse-power . . . . 8483 7492 5588 Area of firegrate used in square feet . 829 645 546 I.H.P. per square foot of firegrate . . IO'2I 11-62 10-23 Heating surface per I.H P. C Tubes . 2'2O 1-97 223 in square feet . . ( Total 2-6 3 2> 33 2'6l Coal used per I.H.P. per hour, in Ibs. 2 '06 2-55 2-39 ,, hour, in tons . . 7'80 8'53 5-96 f Blast used Blast used Natural Remarks . . . . \ last half throughout draught C hour only. the trial. only. 124 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 48 continued* RESULTS OF TRIALS OF SIMILAR STEAMSHIPS, &c. FORCED DRAUGHT. Particulars. * .. , OJ 8 i l 1 Rodney." 1 ? K Duration of trial in hours . 3 4 4 3 4 6 Number of boilers used . 6 4 12 9 12 2 Mean steam pressure in boilers . . Ib. 107-8 11309 93-06 92-74 89-21 84-52 Mean air pressure in boiler rooms, in inches of water 2'O2 1-52 1*4 1-89 2-05 1 5 Mean pressure^ High | in cylinders f pressure ) in Ibs per C Low ) square inch ) pressure j 5 6> 53 22-82 61-42 24-31 59-92 12-8 4973 43'9 12-79 Mean revolutions per min. 122 34 153-33 103-42 100-13 106-63 778 Mean speed of piston, in feet, per minute . 795 762 776 75i 800 389 Indicated horse-power . . 6628 3370 11158 9544 II725 983 Area of firegrate used in square feet 399 207 756 567 -756 545 I H. P. per sq.ft. of firegrate 16-61 16-28 1475 16-83 I 5'5 I l8'O2 Heating surf ace per ") Tubes 1-56 1-63 i'35 1-46 1-24 I.H.P. in sq. ft. ) Total 1-77 I-83 1-82 r6 173 1-43 Coal used per I.H.P. per hour, in Ibs. . . . 2-48 2-6 2'2 2-16 2-54 Coal used per hour, in tons 7'33 3-92 II ... 11-30 in NOTE. The indicated horse- power recorded, is that developed by the main engines only, and does not include the indicated horse- power expended in working the feed and circulating pumps, blowing fans, and other auxiliary machinery. The maximum air pressure = 2-02 inches of water in the above trials, is equal to a pressure of about -^ Ib. per square inch. The cubic capacity of one boiler of the Howe is 1344 cubic feet. The indicated horse-power given by the boiler was 644 with natural draught, and 977 with forced draught, the indicated horse-power per cubic foot of boiler was '479 with natural draught, and -727 with forced draught. The performance of steamships of various nations with natural draught and with forced draught is shown in a compact form in the following Table, which gives the method of forcing the draught, the consumption of coal per indicated horse-power, and the percentage of gain. * -The Author is indebted for Tables 47 and 48 to the " Reports of the Proceedings of the Institution of Naval Architects. " BOILERS WITH NATURAL AND WITH FORCED DRAUGHT. 12$ ' I 3 [ 5 1 1 j 6 S 1 : ^ ^,4 .,. | s | e ... J \ 5 in c o 1 ! T3 -^ TJ J 1 - w > S i A ^ G * o si 3 ;|l SSl^a j ls^ !^^ s?- ts*; | Pi'o'- B p. 11 - jo^g^ . :::*:::.-<:::_:: : : : V < K c*.$ N H "- M ^ 4 MCSCO^C* O'*' I-H\O- * M M 1 M rOOO OOOOM ..\O.O\ t^MOOH . * fv N . . p ..i-c 6- oodor^t^r^ON -QN^t^ r^oOO O O -^b \O _, N, .0 ii MOVOO^OO ro ITM^OM^ ' '^t- -% 8 2 h < ^3 n | O = 14 MO^O^C ::0: ^o o o ::g-^::^|g:o .2 fc| t^t^^-fOMt^ un ir^ ir> MM Mj M ^3 "BJS OOQ^^^O oosOOOfO OOMITM^ rot^OOOOOO vO-fO ^ g OOOMf-^u-l U-IK- u-vOO O VO tx ^- fl O -"> M M OO OO CO M M a o OOOO^rOMt^ O^^COON-* * cnrorOCO MM 1-^vO M H JJ II ^JCSvS'&S vS^SSS^ ^M^ D;?88^1C^ ^ P,^ * ,s OQM\OMO COH^O i-OSO f^-ii-(i-i t-ii-i-^-i-'OOOOr^ CT^ MO vOvOfOMMu^oOOOWl^'^- rf MM MM vOw 1 . ^ .3 T3 ,~VO " . ' .**' ' 'i *l-|l i *j j x-s j, | ' -^ ' -I '5 ? S "o. 1 1 ?='-'JliliJ'^i'-|f|lr |i! ; ll W W O M > 126 THE PRACTICAL ENGINEER'S HAND-BOOK. Forced Draught with Warm Air. In Howden's system of forced combustion in steam-boilers, the air supplied to the furnaces is warmed by passing it through a series of tubes, placed in the path of the escaping gases Fig. 54- Figs. 53-55. Howden's system of forced draught. or products of combustion. The arrangement of the furnace is shown in Fi s - 53 55- Th e ashpit is closed, as shown in Fig. 55, and the hot air is supplied to the fire both above and below. the. .bars. ... Quick gasifying of the FORCED DRAUGHT WITH WARM AIR. I2 7 fuel and complete combustion is obtained by the following means : The air in the ashpit, with a given area of air-space through the fire-bars, and a given average depth of fuel, is maintained at a pressure designed to pass a quantity of air through the fuel sufficient to gasify it, and bring it to the surface largely in the form of carbonic oxide. The air in the casing between the two furnace doors is maintained at a considerably h-gher pressure than in the ashpit, and is thus received by the distributing boxes inside the furnace-plate and inner furnace door. The air then, at a considerable temperature, and at a high velocity, issues in minute streams from small holes in the interior side of the air-boxes, their aggregate area being pro- portioned to the normal work of the furnace, and their position arranged to cause the air to strike the fuel with force equally over the surface within the limits of the fire-bars. By means of these differential pressures, the weight of air required f 3r the complete combustion of a given weight of fuel can be made much less than is necessary in an ordinary furnace, while, with the complete stage of combustion being chiefly on or above the surface of the fuel, a clear white flame and intense heat is generated where most effective for radiation, and most innocuous in its effect on the furnace-bars. Two voyages were made by a steamship under similar conditions, one being made with boiler-furnaces worked with natural draught, and the other with boiler-furnaces worked with Howden's system of forced draught. The results of this trial are given in the following Table : Table 50. EVAPORATIVE PERFORMANCE OF A MARINE BOILER FITTED WITH HOWDEN'S ARRANGEMENT OF FORCED DRAUGHT COMPARED WITH A LARGER MARINE BOILER WITH NATURAL DRAUGHT. Boiler -with Natural Draught. Voyage. DRAUGHT. Average Revolu- Average Indicated Coal. Consump- tion per Twenty- Weather. Aft. Forward. tions. Power. Four Hours. ft. in. ft. in. tons. i. Homewards 20 3 19 3 S6 56 4 Welsh. *si Fair. 2. Outwards . 20 4 18 10 59 Not Ryhope. 15 ,, taken. Boiler with Forced Combustion, or Forced Draught. \ DRAUGHT. Consump- Voyage. Average Revolu- Indicated Horse- Coal. tion per Twenty- Weather. Aft. Forward. tions. Power. Four Hours. ft. in. ft. in. tons. i. Outwards . 20 4 18 10 57 Not Scotch. I I Fair. taken. 2. Homewards 20 3 19 6 60 623 Welsh. Q^ Fair, and head wind 123 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 50 continued. EVAPORATIVE PERFORMANCE OF A MARINE BOILER, &c. Dimensions of Boilers. Dimensions. Boiler with Natural Draught. Boiler with Forced Draught. Length without uptake . 1 7 ft. II ft. Diameter 12 ft. 6 in. . 14 ft. Steam domes Two None. Number and diameter of furnaces . Four, 3 ft. 5 in. Three, 3 ft. 4 in. Number, length, and diameter of ( 372, 6 ft. 4^ in. 2 10, 8 ft. by tubes ( by 3! in. 3in. Tube surface 2173 sq.ft. 1319 sq. ft. Length of firebars, over all 5 ft. 6 in. 4 ft. \\ in. Aggregate firegrate . . . . 75 sq. ft. 36 sq. ft. The air-heating tubes for the forced draught were 40 in number 2 ft. 3 inches long, and 3^ inches external diameter. Forced Combustion in Steam-Boilers on Howden's system will, it is estimated, give an evaporative power per square foot of fire-grate of about 25-indicated horse-power with compound engines, at 80 Ibs. per square inch pressure of steam, and 3o-indicated horse-power with triple expansion engines at about 140 Ibs. per square inch pressure of steam, at rates of consumption not exceeding 1-35 Ibs. and n Ibs. respectively per indicated horse-power per hour. Forced Combustion by Induced Draught. In Martin's system of induced draught, fans are placed in the base of the funnel, by means of which the air is exhausted through the furnace and flue-tubes of the boiler : the draught is thus rendered independent of the height of the funnel. Trials were made of this system of forcing combustion, with a steel marine- boiler 5 feet 6 inches diameter and 6 feet long, having a single furnace-tube 2 feet 3 inches diameter, with 44 tubes 3 inches diameter and 4 feet 6 inches long. Heating surface. Tubes, 97 square feet; furnace, 17 square feet; com- bustion chamber, 38 square feet. The draught was induced by a pair of fans 24 inches diameter, driven by friction-gear ; the inlets of the fans were 1 2 inches diameter, a larger inlet being required than is necessary for cold air, on account of the expan- sion of the gases. The centre portion of the shaft of the fan, which passes through the uptake, was protected from heat by a sleeve and hollow couplings, so that the bearings of the shaft are not affected by heat. The fans made 1400 revolutions per minute. The results of the trials are given in the following Table : BOTLER-PLATES AND RIVETED-JOINTS. I2 9 Table 5 1 . RESULTS OF TRIALS OF A BOILER WITH MARTIN'S SYSTEM OF INDUCED DRAUGHT, AND WITH NATURAL DRAUGHT. Particulars. i 2 Duration of trial 4 hours. 4 hours. Description of coal used . . . (Nixon's (Nixon's Total coal consumed . . . . Ibs. Navigation) 500 Navigation , 35 Heating surface in square feet . . 152 Grate surface in square feet . . .6-75 Lb. of coal per foot of grate . . . 1 8*5 12-96 Temperature of feed water .... 72 72 Total water evaporated at actual temperature of feed Ibs. 5678 2788 Water evaporated per Ib. of coal at actual temperature of feed . . . . Ib. Water evaporated per Ib. of coal at 212 *35 13 7-96 9 12 Water evaporated per square foot of grate 210 103-2 Steam pressure per square inch 70 Ibs. 60 Ibs. Revolutions of fan per minute 1400 The temperature was found to be on one occasion = 1950 Fahr. in the furnace ; 736 Fahr. in the tubes, 24 inches from the smoke box end ; 612 Fahr. in the smoke-box ; and 442 Fahr. in the funnel. The induced draught produced a clear brisk fire and complete com- bustion of the fuel ; and the tubes remained free from cinders. BOILER-PLATES AND RIVETED-JOINTS; BOILER-SHELLS AND FURNACE-TUBES. Arrangement of Boiler-Plates. Externally-fired boilers have the plates arranged so that the laps of the ring-seams do not face the fire. Internally-fired boilers have parallel belts of plates arranged with alternately outer and inner belts. In locomotive boilers there are three belts of plates of diminishing diameter arranged telescopically: the first belt is the largest, and it is lapped inside the fire-box shell ; the second belt is lapped inside the first, and the third inside the second. Strength of Boiler-Plates. The tensile strength of ordinary good wrought-iron boiler-plates is 21 tons per square inch along the grain, and 1 8 tons per square inch across the grain. With an elongation of about 7 per cent., they should admit of being bent hot, without fracture, along the grain to an angle of 130, and across the grain to an angle of 100; and they should bend cold without fracture to the following angles : Plates J^-inch thick to 55 lengthways of the grain, and 25 across the grain ; f inch to 70 lengthways, and 3 5 across ; f\-inch to 80 lengthways, and 45 across ; g--inch 90 lengthways, and 55 across the grain. The tenacity of best Yorkshire or Lowmoor iron is 24 tons along the grain and 22 tons across 130 THE PRACTICAL ENGINEER'S HAND-BOOK. the grain ; with an elongation of about 1 2 per cent., these plates should admit of being bent double, either along or across the grain when red hot. Soundness of Plates. In order to ascertain whether plates are internally sound and free from blisters and laminations, they are tested in three ways. First, the plate is placed on edge and tapped all over with a light hammer, when a sharp ringing sound indicates a sound plate, and a dull heavy sound indicates the presence of defects or laminations. Second, the plate is supported horizontally at its four corners, and the upper surface is covered with fine sand: on tapping the plate lightly with a hammer, if the plate be sound the sand will be thrown off by the vibration, but if laminated the sand will remain stationary on the defective portions. Third, the plate is heated to redness and placed aside to cool, when the laminated or blistered portions will turn black while the sound portions retain their redness. Steel Boiler Plates should be of the mildest quality of steel, contain- ing such a low percentage of carbon as to be incapable of acquiring any degree of temper when heated and suddenly cooled. Steel-plates should be worked at a cherry-red heat : at a higher temperature the plates are liable to burn and become brittle. It is essential in working steel-plates hot, to obtain a uniform cherry-red heat, as the ductility is considerably lessened if they are worked at a blue heat ; hence if steel-plates are improperly worked they are much less reliable than wrought-lron plates. The Tensile Strength of Steel Boiler-Plates ranges from 26 tons to 32 tons per square inch, with an elongation of from 22 to 30 per cent. As thick plates require more carbon than thin ones, to enable them to stand the same mechanical tests, the thicker the plate the milder the steel, and the less the tenacity should be. For plates over f-inch thick, the tenacity should not exceed 28 tons per square inch, otherwise the amount of carbon in the steel may admit of the plates acquiring some degree of temper when heated and cooled, and cause them to become brittle. The Rivet-Holes of Steel-Plates should be drilled : and when the plates contain a high proportion of carbon, they should be annealed before being bent, in a plate-bending machine, by heating them to an uniform red heat in a furnace, after which the fire should be allowed to die out, and the plates should remain in the furnace until quite cold. Hydraulic-Riveted Joints are much stiffer and tighter under pressure than hand-riveted joints, and no caulking is necessary if the faces of the plates are clean and form a metal-to-metal joint. Visible slip does not commence in hydraulic-riveted joints until double the pressure has been applied at which slip commences in a hand-riveted joint. Riveted Joints. Mr. Fairbairn found the strength of riveted joints compared with that of the entire plate to be as follows : Strength of entire plate . = 100 Strength of double-riveted joint = 70 Strength of single-riveted joint = 56 Taking the strength of the entire wrought-iron boiler-plate at 21 tons per square inch along the fibre, the breaking strength of double-riveted iron boilers, with seams properly breaking joints, = 21 x '70= 14-7, or about 14! tons per square inch, and of single-riveted boilers = 21 x '56 = ii~j6, or i if tons per square inch. The strength of the plates across the fibre is about 1 5 per cent, less than the above. To obtain the most perfect riveted PROPORTIONS OF RIVETED-JOINTS. joint, it would be necessary to make the strength of the net-section of the plates, after the rivet-holes are made, equal to the shearing strength of the rivets. Proportions of Riveted Joints. The following Table of steam-tight riveted joints gives good proportions for iron plates, iron rivets, and lap joints, for pressure up to 100 Ibs. per square inch, and 200 Ibs. cold- water test, all the rivet-holes, above | inch, being ^ inch larger than the rivets. Table 52. PROPORTIONS OF RIVETED LAP-JOINTS FOR WROUGHT-!RON PLATES AND IRON RIVETS. Thickness of Plate. Diameter of Rivet. PITCH OF RIVETS. BREADTH OF LAP. Single-Riveted Joints. Double-Riveted Joints. Single-Riveted Joints. Double-Riveted Joints. Inches. Inches. Inches. Inches. Inches. Inches f { I I* If if 3 2 4 | If 2 i 2 3 F f f it If 2 2\ 4 2 f 2 8 2 i 2 t 3 3f 4? 4^ t i 2 f 2| 3f 3* 3| 3l 4f 5 tt i 2| 3f 3| 5? 1 irV 2 8 31 3f 5f it 4 3 3f 3| 5f i i If lyV 3| 3f 31 3f 4 4* 4? 4| 4| 6 6i 61 iyV If 3f 4 44 6f i 1 ? lyV 4 4| si 7 The Percentage of Strength of the Riveted Joint in terms of that of the solid plate may be found by the following Rule : Subtract the diameter of the rivet-hole from the pitch of the rivets, and divide the remainder by the pitch of the rivets. The Percentage of Strength of the Rivets to that of the solid plate may be found by the following Rule : Multiply the square of the diameter of the rivet-hole by '7854 and by the number of rows of rivets, and divide by the product of the pitch of the rivets by the thickness of the plate. The Percentage of Strength of the Longitudinal Seams of a boiler, when the diameter of rivet is not known, may be estimated approxi- mately by the following formula, the rivets being in single-shear. Let / = the thickness of plate in inches. p = the pitch of the rivets in inches. n =. the number of rows of rivets. S = percentage of strength of the longitudinal seams. Then S=88 - 22 X / 132 THE PRACTICAL ENGINEERS HAND-BOOK. Example : The thickness of plate of a boiler is f inch, the pitch of the rivets is 3 inches, there are two rows of rivets in single-shear : what is the percentage of strength of the longitudinal seams, the diameter of the rivets not being known ? rp, on 220 x '375 inch thickness of plate 2 rows X 3 inches pitch + (3 X '375) en tmcKness or piate / , ~j . ; -T-- r = 76. the per- ,^.V^o r-\it^l- 1 f *\ sx '\i-rr-\ ' * centage of strength of the seam as compared with the solid plate. Rivet-Holes. The effect of punching the rivet-holes for riveted-joints is to weaken the metal round the holes, and to diminish the tensile strength of the plates to the extent of from 5 to 10 per cent, in soft wrought-iron plates, and from 20 to 25 percent, in hard wrought-iron plates. The tensile strength of steel plates is diminished to the extent of from 20 to 28 percent, by punching the rivet-holes for the joints of the plates. Thick plates are more injured by punching than thin ones. Lloyd's Proportions for Single, Double, and Treble-Riveted Joints are given in Tables Nos. 53 56, for iron-plates, iron-rivets, lap-joints, and drilled-holes ; only 90 per cent, of the rivet-section is considered to be effective in drilled-holes. For Lloyd's Rules for Riveted Joints seepage 162. Table 53. LLOYD'S PROPORTIONS FOR SINGLE-RIVETED JOINTS. PERCENTAGE. Thickness of Iron Plate. Diameter of Iron Rivet. Pitch. Lap. Rivet. Plate. Inch. Inch-s. Inches. Inches. fV yi If 2 rV 67-9 607 1 1 3 Tff 2 Te~ 67-0 6o'o f if i 2i 4r 3 10 64-9 6o'i 58-9 9 T if 2 8 & ?V 3t 6 5 -I 58-6 ifV 2f &3V 3A 637 57'3 Table 54. LLOYD'S PROPORTIONS FOR DOUBLE-RIVETED JOINTS. Thickness of Iron Plate. Diameter of Iron Rivet. Pitch. Lap. PERCENTAGE. Rivet. Plate. Inch. Inches. Inches. Inches 1 F E 4 A* 4A* 2|&lV 4rV 80'2 777 77-2 72-1 7I-I 69-4 T 9 e T!" 3^ 4yi 78'5 70*0 1 i 3? 5 77'3 69-2 F j i i 3 ^i 5 F 5s 76-4 75-0 68-5 68 i LLOYD'S PROPORTIONS OF RIVETED-JOINTS. 133 Table 55. LLOYD'S PROPORTIONS FOR TREBLE-RIVETED JOINTS. Thickness of Iron Plate. Diameter of Iron Rivet. Pitch. Lap. PERCENTAGE. Rivet. Plate. Inch. Inches. Inches. Inches. J, 1 I 3! & ^ 83-9 762 -f it 3 & "sV 4l 84-3 f 4rV 4? i 1 6| 83-9 04-4 83H 75'4 75'4 75-0 T^ l| 4 ^ "sV 6f 83-3 74 5 s" H $ 4i&iV 4f & aV 7l 82-5 82-1 73-8 i '" 4H 7i 82-2 73-4 Table 56. LLOYD'S PROPORTIONS FOR DOUBLE BUTT-STRAPS, DOUBLE-RIVETED DRILLED HOLES. Thickness of Iron Plate. Diameter of Iron Rivet. Pitch. Breadth of Strap. PERCENTAGE. Rivet. Plate. Inch. Inches. Inches. Inches. i 1 4&T-V 6| 8 3 -8 75 '6 Te" ri 2|&3V 6| 82'9 75-2 i 8 3. 4 3 7i 82-4 75-0 F if 3l&^r 3f & TV 8 i 9l 82-1 84-1 74T 75'4 r I iyV ,? 10 i of 840 833 75-2 75-0 a if 4f&^ I! i 83-1 74-8 i irV 4f nf 82-6 74-6 The Board of Trade Proportions for Single, Double, and Treble- Riveted Joints for Steel Plates, steel rivets, lap-joints, and drilled- holes are given in the following Tables, Nos. 57 60. Table 57. BOARD OF TRADE PROPORTIONS FOR SINGLE-RIVETED JOINTS. L Thickness of Steel Plate. Diameter of Steel Rivet. Pitch. Lap. PERCENTAGE. Rivet. Plate. Inch. Inches. Inches. Inches. TT H U&aV 2yV 7 I-8 58-4 1 ff if&TV 2yV 71*4 5 8-I 7 To -H t* 2rl 70-1 58-3 L 2 It 4** H&A f 703 68-1 58-0 56-6 1 ifV 2|&sV 3rV 667 55'2 134 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 58. BOARD OF TRADE PROPORTIONS FOR DOUBLE-RIVETED JOINTS. PERCENTAGE. Thickness of Steel Plate. Diameter of Steel Rivet. Pitch. Lap. Rivet. Plate. Inch. Inches. Inches. Inches. f f 2| & JL. 3l 877 72-1 TV it 2 f 86-2 70-4 i 7. 8 2 I 4| 84-1 69-5 fs I 3tV 5 84-3 69-8 f I xV 5rV 83-2 687 ii ji 3 5| 82-6 67-8 a. 4 if 3t*A 83-1 68-2 Table 59. BOARD OF TRADE PROPORTIONS FOR TREBLE-RIVETED JOINTS. PERCENTAGE. Thickness of Steel Plate. Diameter of Steel Rivet. Pitch. Lap. Rivet. Plate. Inch, Inches. Inches. Inches. -| if 3l 4s 92'2 75'9 ~T5 j 8 5* 9i'6 5. it 3f 5| 9ro 74'I i* :r 1 5! 91-0 9O' 2 75'0 74'4 it if 4?^X 7! 89-6 74'3 73-6 it 1 i 4! 7" 87*2 72'2 i 1 T5 4f & T V 7i 86'5 71-9 i Table 60. BOARD OF TRADE PROPORTIONS FOR DOUBLE BUTT-STRAPS, DOUBLE-RIVETED. PERCENTAGE. Thickness of Steel Plate. Diameter of Steel Rivet. Pitch. Lap. Rivet. Plate. Inch. Inches. Inches. Inches. 1 A F 2f & TV 3 s 92-4 91-5 75'5 75-1 1 5| 8^ 9 0-2 75'0 ft 7. 8 3f 81 9O - 6 74'0 3. 4 it 3I&A 9f 89-6 73-6 it I 3f 10 90' 1 2 73'3 | I* 4 I: i 90-8 74-2 it IP 4| & A n| 9O'6 73'9 I l| 4i & TV \2\ 9cro 74-0 * For the Board of Trade rules for riveted-joints, see page 150. RIVETED-JOINTS IN SOFT STEEL-PLATES. 135 Rive ted- Joints in Soft Steel-Plates. Professor Kennedy in a paper read before the Institution of Mechanical Engineers,* gave the results of 14 series of experiments made by the Research Committee of that Institution, on the strength of riveted joints, of which the following is an abstract. The conclusions given below all refer to joints made in soft steel-plate with steel-rivets, the plates being in their natural state, that is, unannealed. Further, it should be said that all dimensions, thicknesses of plate, &c., were measured by the most accurate means available ; and that in every case the rivet or shearing area has been assumed to be that of the holes, not the nominal (or real) area of the rivets themselves. Also in every case the strength of the metal in the joint has been compared with that of strips cut from the same plates, and not merely with nominally similar material. It is thought that if these points had always been attended to, many of the discrepancies in published riveted-joint experiments would never have appeared. 1. The metal between the rivet-holes has a considerably greater tensile resistance per square inch than the unperforated ' metal. This excess tenacity amounted to more than 20 per cent, (both f-inch and f-inch plates) when the pitch of the rivet was about 1*9 diameters. In other cases f-inch plate gave an excess of 15 per cent, at fracture with a pitch of 2 diameters, of 10 per cent, with a pitch of 3'6 diameters, and of 6*6 per cent, with a pitch of 3^9 diameters ; and f inch plate gave 7'8 per cent, excess with a pitch of 2'8 diameters. 2. The shearing resistance of the rivet-steel is a matter upon which, as has been pointed out, further experiment is required. It may be taken as established that the resistance per square inch in double shear, is as great as that in single shear, so that allowance need not be made for the i\\o shearing planes not being equally stressed. In single-riveted joints, how- ever, the bending of the plates will put considerable tensile stress in the rivets; and this may diminish their apparent shearing resistance. In single- riveted joints it may be taken that about 22 tons per square inch is ihe shearing resistance of rivet-steel,f when the pressure on the rivets does not exceed about 40 tons per square inch. In double-riveted joints, with rivets of about f-inch diameter, most of the experiments gave about 24 tons per square inch as the shearing resistance, but the joints in Series XIII. went at 22 tons. In Series XIII. the larger rivets also went at a low load ; but in the other double-riveted joints with large rivets these latter remained unbroken at a stress of 22 tons per square inch. 3. The size of the rivet-heads and ends plays a most important part in the strength of the joints, at any rate, in the case of single-riveted joints. An increase of about one-third in the weight of the rivets (all this increase, oi course, going to the heads and ends) was found to add about 8| per cent, to the resistance of the joint, the rivets remaining unbroken at 22 tons per square inch, instead of shearing at a little over 20 tons. The additional * Abstract of results of experiments on Riveted Joints, with their applications to practical work. By Professor Alexander B. W. Kennedy, honorary life-member of tha Institution of Mechanical Engineers. t In one pair of single-riveted joints only (Nos. 383 and 384 in Series VI.) a shearing resistance of over 24 tons per square inch was reached ; in none of the others did it exceed 22*5 tons. 136 THE PRACTICAL ENGINEER'S HAND-BOOK. strength is no doubt due to the prevention of so great tensile stress in the rivets through distortion of the plates. 4. The strength of a joint made across a plate is equal to that of one made in the usual direction. (Both this conclusion and the last preceding are stated as the result of a very limited number of experiments ; but there seems no reason to doubt their general truth.) 5. The intensity of bearing pressure on the rivets exercises, with joints proportioned in the ordinary way, a very important influence on their strength. So long as it does not much exceed 40 tons per square inch (measured on the projected area of the rivets) it does not seem to affect their strength; but pressures of 50 to 55 tons per square inch seem to cause the rivets to shear in most cases at stresses varying from 16 to 18 tons per square inch. This conclusion is based on the experiments of Series X., in which the margin was made equal to the diameter of the drilled-hole. For ordinary joints, which are to be made equally strong in plate and in rivets, the bear- ing pressure should, therefore, probably not exceed 42 or 43 tons per square inch. For double-riveted butt-joints, perhaps, as will be note.1 later, a larger pressure may be allowed, as the shearing stress may probably not exceed 16 to 18 tons per square inch when the plate tears. But in this case it would probably be wise to increase the margin. 6. A margin (or net distance from outside of holes to edge of plate) equal to the diameter of the drilled hole has been found sufficient in all cases hitherto tried. 7. To attain the maximum strength of a joint the breadth of lap must be such as to prevent it from breaking zigzag. Such a method of fracture must inevitably be accompanied by unequal stresses in the plate straight between the rivet-holes, and by consequent diminution of strength. It has been found that the net metal measured zigzag should be from 30 to 35 per cent, in excess of that measured straight across, in order to ensure a 2 d straight fracture. This corresponds to a diagonal pitch of -p -\ , if p be the straight pitch, and d the diameter of the rivet-hole. To find the proper breadth of lap for a double-riveted joint, it is probably best to proceed by first setting this pitch off, and then finding from it the longitudinal pitch, or distance between the centres of the lines of rivets. Table 61. SLIP OF RIVETED JOINTS. Rivet Diameter. Type of Joint. Riveting. Slipping Load per Rivet. |-inch Single-riveted Double-riveted Hand 2-5 tons 3-0 to 3-5 tons Machine 7 tons i-inch Single-riveted Double-riveted Hand 3-2 tons 4-3 tons " " Machine 8 to 10 tons 8. Visible slip or " give " occurs always in a riveted joint at a point very much below its breaking load, and by no means proportional to that load. RIVETED-JOINTS IN SOFT STEEL-PLATES. 137 A careful collation of all the results obtained in measuring the slip indicates pretty clearly that it depends upon the number and size of the rivets in the joint, rather than anything else ; and that it is tolerably constant for a given size of rivet in a given type of joint. The loads per rivet at which a joint will commence to slip visibly are approximately as given in Table 61. To find the probable load at which a joint of any breadth will commence to slip, it is only necessary to multiply the number of rivets in the given breadth by the proper figure taken from the last column of the Table above. It will be understood that the above figures are not given as exact ; but they represent very well the results of the experiments in all series from VIII. to XIII. : except Series X., in which the average (for i-inch rivets) was much lower than that given above. In this series, however, the proportions of the joints were intentionally somewhat abnormal ; and it is perhaps not to be expected that in this respect the results should agree with those of the other experiments. This result as to the slipping of a joint, although perhaps unexpected, is not contrary to what ought to have been expected. For experiments show that, long before stresses are reached which could visibly stretch the plates of a joint, there will be quite measurable shear of the rivet. The visible slip therefore will consist almost wholly of this shear, the magnitude of which will depend primarily on the number and size of the rivets in the Table 62. SHEAR OF RIVET-STEEL PINS, i INCH DIAMETER. Test Nos. : - Shearing Stress in Lbs. per Square 343 344 345 346 347 348 i Amount of Shear in Inches. O*O O'O O'O o-o O'O O'O 6365 oio 013 016 022 055 02 1 12730 022 028 030 034 066 032 IQlOO 034 040 042 048 .078 043 25460 -055 060 060 071 091 062 28320 066 3 l8 3 080 '086 082 9 I 113 ''183 35010 093 38190 II 3 113 ''108 114 140 108 41380 141 44550 168 152 142 170 171 155 47740 200 50910 242 '200 196 ''248 238 222 54110 ... B SS B ) Lb -- 54IIO 54930 55240 52830 56670 5353 per sq. in. ) To " s - 24-15 24-52 24-66 23'59 25-29 23-90 138 THE PRACTICAL ENGINEER'S HAND-BOOK. joint. Anything that will hold the plates up better together, such as hydraulic pressure on the rivets, might be expected to diminish this shear or delay its commencement, exactly as seems to have happened. The Table 62 gives the result of experiments on this matter which were made along with those given in the Committee's first report, but which have not previously been published in the Proceedings of the Institution. The experiments are on i-inch turned pins of rivet steel, tested in the single- shear apparatus already described. Of course the shear would commence later, and be at first smaller in extent, when the pin was replaced by an actual rivet, and when the plates were thus forcibly held together, instead of being quite free, except so far as held from motion by the resistance to shear. 9. The value of machine-riveting as compared with hand-riveting, in cases when sound hand-riveting is possible, lies mainly, if not entirely, in the fact that it doubles the load at which the slip of a joint commences. This conclusion is subject to modification by future experiments with the use of higher pressure in closing the rivet, which may probably still further raise the slipping load, so that the advantage of machine-riveting may quite possibly be even greater than it is here assumed to be ; but there is no indication that it is likely to affect the ultimate strength of the joint. The question Qi friction in joint, which has not been specially experimented on by the Committee, no doubt comes in the same way. The friction induced by the rivet will affect the point at which slip commences ; but can hardly have much, if any, relation to the breaking load. It is thought that the load at which visible slip commences is probably proportional to the load at which leakage would begin in a boiler. Looked at this way, it will be seen that the great value of hydraulic riveting appears to lie rather in the increased security and stiffness it gives at ordinary working loads than in any actual raising of the breaking load. From a practical point of view the former is probably the more, and not the less, important function. Table 63. RATIO OF THE DIAMETER OF THE RIVET HOLE TO THE THICKNESS OF PLATE AND OF PITCH TO DIAMETER OF HOLE IN f-iNCH PLATE. Original Tenacity of Shearing Resistance of Ratio Ratio Ratio Plate. Rivets. d P Plate Area Tons per Square Inch. Tons per Square Inch. t d Rivet Area 3 22 2' 4 8 2-30 0'667 28 22 2- 4 8 2-40 0785 30 24 2-28 2-27 0-713 28 24 2-28 2- 3 6 0*690 10. The experiments point to very simple rules for the proportioning of joints of maximum strength, which will be mentioned before any other joints are discussed. Assuming that a bearing pressure of 43 tons per square inch may be allowed on the rivet, and that the excess tenacity RIVETED-JOINTS IN SOFT STEEL-PLATES. 139 of the plate is 10 per cent, of its original strength,* Table 63 gives the values of the ratios of diameter d of the hole to thickness / of plate (-J, and of pitch p to diameter of hole \-\ in joints of maximum strength in f-in. plate. Summed up and rounded off, this means that the diameter of the hole (not the diameter of the rivet cold) should be 2f times the thickness of the plate, and ttie pitch of the rivets 2 times the diameter of the holes.f In mean also it makes the plate-area 71 per cent, of the rivet-area. If a smaller rivet be used than that here specified, the joint will not be of uniform and therefore not of maximum strength ; but with any other size of rivet the best result will be got by use of the pitch obtained from the formula formerly cited, where, as before, d is the diameter of the hole. The value of the constant a in this equation is as follows : For 3O-ton plate and 22-ton rivets, a = 0*524 28 22 ,, o - 558 3 2 4 ,. ., 0-570 28 24 ,, 0-606 or in the mean, the pitch p = 0-56 + d, It should be noticed that with too small rivets this gives pitches often considerably smaller in proportion than 2 times the diameter. For double-riveted lap-joints, a similar calculation to that given above, but with a somewhat smaller allowance for excess tenacity on account of the large distance between the rivet-holes, shows that for joints of maximum strength the ratio of diameter to thickness should remain precisely as in single-riveted joints ; while the ratio of pitch to diameter of hole should be 3^64 for 3o-ton plates and 22 or 24-ton rivets, and 3-82 for 28-ton plates with the same rivets. Here, still more than in the former case, it is likely that the prescribed size of rivet may often be inconveniently large. In this case the diameter of rivet should be taken as large as possible ; and the strongest joint for a given thickness of plates and diameter of hole can then be obtained by using the pitch given by the equation where the values of the constant a for different streng.ns of plate and rivet may be taken as follows : * The excess strength is taken lower than the average result of the experiment, because it is probable enough that the steel used had more than the average softness. f The small difference here from the constants formerly given is due to the assumption, now quite justified, of a somewhat greater bearing pressure than was then allowed. 140 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 64. PROPORTION OF DOUBLE-RIVETED LAP-JOINTS, IN WHICH p a + Thickness of Plate. Original Tenacity of Plate. Tons per Square Inch. Shearing Resistance of Rivets. Tons per Square Inch. Value of Constant. f-inch. 3 24 >Z 5 28 24 22 ,, 30 22 05 28 22 '12 f-inch. 3 24 'I? ,, 28 2 4 25 M 30 22 07 " 28 22 14 Practically we may say that, having assumed the rivet diameter as large as possible, we can fix the pitch as follows, for any thickness of plate from | to | inch : For 3O-ton plate and 24-ton rivets ") . s d 2 , 30 28 />=ro6 \-d In double-riveted butt-joints it is impossible to develop the full shearing resistance of the joint without getting excessive bearing pressure, because the shearing area is doubled without increasing the area on which the pressure acts. In a previous report it was shown that, considering only the plate resistance and the bearing pressure, and taking this latter as 45 tons per square inch, the best pitch would be about four times the diameter of the hole. It is probable that a pressure of from 45 to 50 tons per square inch on the rivets will cause shearing to take place at from 16 to 18 tons per square inch. Working out the equations as before, but allowing excess strength of only 5 per cent, on account of the large pitch, we find that the proportions of double-riveted butt-joints of maximum strength under given conditions are those of the following Table : Table 65. PROPORTIONS OF DOUBLE-RIVETED BUTT-JOINTS. Original Tenacity of Shearing Resistance of Bearing Pressure. Ratio Ratio Plate. Rivet. Tons per Square d p Tons per Square Inch. Tons per Square Inch. Inch. t d 3 16 45 I -80 3-85 28 16 45 I '80 4'o6 3 18 4 8 170 4*03 28 18 48 170 4-27 30 16 50 2'OO 4'20 28 16 50 2'OO 4-42 RIVETED-JOINTS IN SOFT STEEL-PLATES. 141 Practically, therefore, it may be said that we get a double-riveted butt- joint of maximum strength by making the diameter of hole about i'S times the thickness of the plate, and making the pitch 4'! times the diameter of the hole. These are very nearly the proportions which were used for the f-inch joints in Series XL to XIII. ; for the f-inch joints the diameter of the rivet was (as with the lap joint) less than indicated by theory. In thick plates, where it is thought impossible or inconvenient to make the rivet-holes so large as r8 times the thickness, the best pitch for any assumed diameter of rivet cannot be found by the method formerly used ; for here we have not a given maximum shearing stress to work to, but rather the shearing stress which in a given joint causes a given maximum pressure on the rivets. The best ratio of pitch to diameter of hole in double-riveted butt-joints of maximum strength for any assumed diameter of hole d is therefore the same as that given in the last Table, or in mean, 4'!. n. All the experiments hitherto made have necessarily connected them- selves with the question of strength, and the proportions just given belong to joints of maximum strength. But in a boiler the one part of the joint, the plate, is much more affected by time than the other part, the rivets. It is therefore not unreasonable to estimate the percentage by which the plates might be weakened by corrosion, &c., before the boiler would become unfit for use at its proper steam-pressure, and to add correspondingly to the plate-area. Probably the best thing to do in this case is to proportion the joint not for the actual thickness of plate, but for a nominal thickness less than the actual by the assumed percentage. In this case the joint will be approximately one of uniform strength by the time it has reached its final workable condition ; up to which time the joint as a whole will not really have been weakened, the corrosion only gradually bringing the strength of the plates down to that of the rivets. Thus, suppose a single- riveted lap-joint in f-inch plate is in question, and it is considered that corrosion will make this equal to only a |-inch plate before the boiler- pressure has to be lowered. The rivet should then be proportioned as if the plate had a thickness of 0*5 inch, which would give, for 3 F -2- = 49-89 lbs. per square 33 inches radius x o factor of safety inch ; and this shell would burst with a pressure of 49*89 X 6, the factor of safety, = 299-34 lbs. per square inch. The Internal Diameter of Boiler-Shell for a given Thickness of Plate and Pressure may be found by this Rule: Multiply the ultimate tensile strength of the plate in lbs. per square inch by the thickness of the plate in inches, and by the percentage of strength of the riveted joint to that of the solid plate, and divide the product by the product of the working pressure in lbs. per square inch by the factor of safety. Example : Required the internal diameter of boiler-shell suitable for thi particulars of the last example. Then 21 tons x 2240 lbs x -375 plate x -56 = inches radi and 49-89 lbs. x 6, factor of safety 33 inches radius x 2 = 5 feet 6 inches internal diameter. BURSTING-PRESSURE OF CYLINDRICAL BOILERS. 143 The Thickness of Plate for a Boiler-Shell for a given Diameter and Working Pressure may be found by this Rule : Multiply the working pressure in Ibs. per square inch by the factor of safety, and by the internal radius in inches of the boiler-shell, and divide the product by the product of the ultimate tensile strength of the plate by the percentage of strength of the riveted joint to that of the solid plate. Example : Required the thickness of plate suitable for the boiler-shell given in the last example. rp, 49-89 Ibs. pressure x 6, factor of safety x 33 inches radius of shell 21 tons x 2240 Ibs. x '56, percentage of strength of joint = -375 inch. The Total Pressure of Steam on the Internal Surface of a Boiler may be found by multiplying the internal surface of the boiler by the pressure of the steam per unit of surface. Example: A Lancashire boiler, 6 feet diameter, 24 feet long, with two flues each 2 feet 3 inches diameter, is worked at a pressure by the steam gauge of 60 Ibs. per square inch : required the total pressure of the steam on the internal surface of the boiler. Then, The surface of the boiler-shell is 6 feet x 3' 141 6 x 24 feet = 352-39 square feet. The surface of the two flues is 2*25 feet x 3-1416 x 24 x 2 = 339 >2 9 The surface of the two flat ends of the boiler is (6 x 6feet) (2-25 x 2-25feet x 2)x 7854 x 2= 40-64 Total internal surface in square feet . . . 732-32 and, 7 -3i:31^ uare feet x '" x 60 Ibs. pressure = ^ ^ ^ 2240 Ibs. total pressure of the steam on the internal surface of the boiler. Bursting-Pressure of Cylindrical Boilers. The strength of cylin- drical shells to resist internal bursting pressure in a direction parallel to their axis may be calculated by this Rule T x C P = D Where P = The bursting pressure in Ibs. per square inch. T = The thickness of the shell in sixteenths of an inch. D = Diameter of shell in quarter feet. C = A constant, being as follows : 1097 for single-riveted wrought-iron plates. 1372 for double-riveted wrought-iron plates. 1723 for single-riveted steel-plates. 2156 for double-riveted steel-plates. The plates to be sound, and ot good material. *44 THE PRACTICAL ENGINEERS HAND-BOOK. Collapsing Pressure of Wrought-Iron Cylindrical Plue Tubes. The rule usually employed for the strength of cylindrical tubes subject to external pressure, is that deduced by Fairbairn from the results of a series of experiments. It is as follows : 806300 x / 2 ' 19 LxD P = where P = The collapsing pressure in Ibs. per square inch. ,, / = The thickness of tube in inches. ,, L = The length of tube in feet. ,, D = The diameter of tube in inches. The following values of / 2 ' 19 , usually required, may be useful : ~ ) = -09646. = -11671. J =-'3908. i- \2'i9 = -16358- fj = -04803. i^j - -19027. Q Y 19 ( i Y 19 L_J = -06216. f J = '21915. 4?-)* = -25027. = -28364. ( s Y 19 (i) = -35-'5- Instead of the 2*19 power, the square of the thickness is usually taken as sufficiently correct in practice, in which case the formula becomes P = Another rule sometimes used to find the collapsing pressure of wrought- iron furnace-tubes in Ibs. per square inch, is LxD the notation being the same as in the previous example. Working Pressure of Wrought-Iron Cylindrical Flue-Tubes. The formula generally used for ascertaining the working pressure to be allowed for the furnaces of wrought-iron boilers is as follows : Working pressure in Ibs. per square inch = 9 ^ , where /, L, and D, stand for thickness of plate in inches, length of flue in feet, and diameter of tube in inches. BOARD OF TRADE RULES FOR STEAM BOILERS. 145 The above rule would appear to be intended to allow one-ninth of the collapsing-pressure obtained by Fairbairn's formula, given above. Collapsing Pressure of Lap-Jointed Tubes. Mr. Richards, of the Marine Department of the Board of Trade, considers Fairbairn's formula to be unsuitable for obtaining the collapsing pressure of wrought-iron furnace- tubes constructed with lap-joints, and gives the following as the proper formula for such tubes, based on Fairbairn s deductions : Collapsing pressure of lap-jointed furnace-tubes in Ibs. per square Inch = 322462 x/ 2 LxD ' where the notation is the same as in the previous rule. The Collapsing Pressure of Wrought-iron Tubes is frequently cal- culated by the following formula, which provides for the tubes being slightly out of the circular form, as long tubes generally are p_ 375023 X/ ? LxD" where D == the diameter in inches, L = the length in feet, J , the thick- ness in inches, P = the collapsing pressure in Ibs. per square inch. BOARD OF TRADE RULES FOR STEAM BOILERS. IRON STEAM-BOILERS AND SUPERHEATERS. The Surveyor to fix Pressures on Safety Valves. The Surveyor is required by the Act to fix the limits of weight to be placed on the safety valves of passenger steam-ships. In performing this very responsible and onerous duty he must be very careful, as, in the event of accident, it will be necessary for him to satisfy the Board of Trade that he used due caution. On the one hand he must be careful as regards safety, and on the other hand he must not unduly reduce the pressure on a boiler. The Surveyor himself having fixed ihe limits of the weight, is then required to declare that in his judgment the boiler and machinery are sufficient for the service intended, and in good condition, and that they will be sufficient for twelve months, or such other period as he may, in his judgment, determine. For his guidance the following directions are given, and he should not depart from them in any case, without first reporting particulars to the Board of Trade, and asking for instructions. Working Pressure to be fixed by Calculation. The Surveyor should fix the working pressure for boilers by a series of calculations of the strength of the various parts, and according to the workmanship and material. The Board of Trade, upon the request of certain ship-builders and ship-owners, have arranged to receive for examination by their surveyors, plans and particulars of boilers before the commencement of manufacture, by these means hoping to prevent questions arising after the boilers are finished and 146 THE PRACTICAL ENGINEER'S HAND-BOOK. on board. This practice has been found to work well in saving time to the Surveyors, and in preventing expense, inconvenience, and delay to owners. The senior Engineer-Surveyors should therefore receive and report on any plans of boilers intended for passenger vessels, that may be submitted in due course with the form surveys. They are not to report on any tracing or plan that is not accompanied by that form. When the Surveyor has received plans and tracings of new boilers, or of alteration of boilers, and has ap- proved of them, he will of course be careful in making his examination from time to time, to see that they are followed in construction. When he has not had the plans submitted, but is called in to survey a boiler, he will of course measure the parts, note the details of construction, and, if neces- sary, bore the plates to ascertain their thickness, &c., before he gives his declaration; and in the event of any novelty in construction, or of any departure from the practice of staying and strengthening noted in these instructions, he should report full particulars to the Board of Trade before fixing the working pressure. The Surveyor cannot declare a boiler to be safe unless he is fully informed as to its construction, material, and work- manship ; he should, therefore, be very careful how he ventures to give a declaration for a boiler that he is not called in to survey until after it is com- pleted, and fixed in the ship. Stays. In the case of new boilers, the Surveyors may allow a stress not exceeding 7000 Ibs. per square inch of net section on solid iron screwed- stays supporting flat surfaces, but the stress should not exceed 5000 Ibs. when the stays have been welded or worked in the fire. The Areas of Diagonal Stays are found in the following way : Find the area of a direct stay needed to support the surface, multiply this area by the length of the diagonal stay, and divide the product by the length of a line drawn at right angles to the surface supported to the end of the dia- gonal stay : the quotient will be the area of the diagonal stay required. Gusset Stays. When gusset-stays are used, their area should be in excess of that found in the above way. Girders for Plat Surfaces. When the tops of combustion-boxes, or other parts of a boiler, are supported by solid rectangular girders, the fol- lowing formula should be used for finding the working pressure to be allowed on the girders, assuming that they are not subjected to a greater tem- perature than {he ordinary heat of steam, and that, in the case of combustion- thambers, the ends are fitted to the edges of the tube-plate, and the back plate of the combustion-box : =working pressure. W= width of combustion-box in inches. P = pitch of supporting bolts in inches. D = distance between the girders from centre to centre in inches. L = length of girder in feet. d = depth of girder in inches T = thickness. of girder in inches. N = number of supporting bolts. C = N * T00 when the number of bolts is odd. N + i C = ( N + J ) I00 when the number of bolts is even. BOARD OF TRADE RULES FOR STEAM BOILERS. 147 The working pressure for the supporting bolts and for the plate between them should be determined by the rule for ordinary stays. Plat Surfaces of Boilers. The pressure on plates forming fiat surfaces is found by the following formula : Cx ( T +0 2 = working pressure. T = thickness of the plate in sixteenths of an inch. S = surface supported in square inches. C = constant according to the following circumstances. C = 100 when the plates are not exposed to the impact of heat or flame, and the stays are fitted with nuts and washers, the latter being at least three times the diameter of the stay and two-thirds the thick- ness of the plates they cover. If the diameter of riveted washers be at least two-thirds the pitch of the stays, and the thickness not less than the plates they cover, the constant maybe increased to 150. When doubling-plates are fitted of the same thickness as the plates they cover, and not less in width than two-thirds of the pitch of the stays, the constant may be increased to 160. When doubling-plates cover the whole of the flat surface the case should be submitted for the consideration of the Board. C = 90 when the plates are not exposed to the impact of heat or flame, and the stays are fitted with nuts only. C = 60 when the plates are exposed to the impact of heat or flame, and steam in contact with the plates, and the stays fitted with nuts and washers, the latter being at least three times the diameter of the stay and two-thirds the thickness of the plate they cover. C = 54 when the plates are exposed to the impact of heat or flame, and steam in contact with the plate, and the stays fitted with nuts only. C = 80 when the plates are exposed to the impact of heat or flame, with water in contact with the plates, and the stays screwed into the plate and fitted with nuts. C = 60 when the plates are exposed to the impact of heat or flame, with water in contact with the plate, and the stays screwed into the plate, having the ends riveted over to form a substantial head. C = 36 when the plates are expcsed to the impact of heat or flame, and steam in contact with the plates, with the stays screwed into the plate, and having the ends riveted over to form a substantial head. In cases where plates are stiffened by ~J~ or |_ irons, and a greater pres- sure is required for the plate than is allowed by the use of the above con- stants, the case should be submitted for the consideration of the Board of Trade. When the riveted ends of screwed stays are much worn, or when the nuts are burned, the constants should be reduced, but the Surveyor must act according to the circumstances that present themselves at the time of survey, and it is expected that in cases where the riveted ends of screwed stays in the combustion-boxes and furnaces are found in this state it will be often necessary to reduce the constant 60 to about 36. Compressive Stress on Tube-Plates. The Surveyors should not in L 2 148 THE PRACTICAL ENGINEER'S HAND-BOOK. any case allow a greater compressive stress on the tube-plates than 8000 Ibs., f which is that used in the following formula : , (D C 5 inch thickness ,, . , Then, z- =112 Ibs. per square inch working 40 inches mean diameter pressure. Corrugated-Furnaces of Steel-plates. Example of the Rule on page 154. Required the working pressure of a Fox's corrugated furnace- tube, 38 inches diameter and machine made, of steel plates \ inch thick. Then, 14000 x^mchjhickne S1= jg ^ .^ ^ 38 inches outside diameter pressure. Compressive-Stress on Steel Tube-plates. Example of the Rule on page 155. In a steel marine-boiler, the least horizontal distance between the centres of the tubes is 5 inches, the inside diameter of the tubes is 3^ inches, the thickness of the tube-plate is '85 inch, the extreme width of the combustion-box from the front of the tube-plate to the back of the fire-box is 38 inches. What compressive stress may be allowed on the tube-plates, as working pressure ? Then, 5 inche . S ~ 3'5 inches_x -85 x 20000 = ^ 38 mches wide x 5 inches the working pressure which may be allowed on these tube-plates. LLOYD'S RULES FOR STEAM BOILERS. l6l LLOYD'S RULES FOR STEAM BOILERS. Cylindrical Shells of Steel Boilers. The strength of cylindrical shells of steel boilers is to be calculated from the following formula : : . = working-pressure in Ibs. per square inch, where D = mean diameter of shell in inches, T = thickness of plate in sixteenths of an inch, C = 20 when the longitudinal seams are fitted with double butt straps of equal width, C = 19*25 when they are fitted with double butt straps of unequal width, only covering on one side the reduced section of plate at the outer lines of rivets, C = 1 8' 5 when the longitudinal seams are lap joints, B = the least percentage of strength of longitudinal joint found as follows : For plate at joint B = P ~ d x 100. For rivets at joint B = x 85 wnere steel rivets are used. B = n X a x 70 where iron rivets are used. p x / where p = pitch of rivets in inches, / = thickness of plate in inches, d = diameter of rivet holes in inches, n = number of rivets used per pitch in the longitudinal joint, a = sectional area of rivet in square inches. In case of rivets in double shear 1*750 ' ls to be used instead of a. Proper deductions are to be made for openings in shell. All manholes in circular shells to be stiffened with compensating rings. The shell plates under domes in boilers so fitted, to be stayed from the top of the dome or otherwise stiffened. Note. The inside butt strap to be at least f the thickness of the plate. Note. For the shell plates of superheaters or steam-chests enclosed in the uptakes or exposed to the direct action of the flame, the co-efficients should be of those given in the above tables. Stays. The strength of stays supporting flat surfaces is to be calculated from the smallest part of the stay or fastening, and the strain upon them is not to exceed the following limits, namely : Iron Stays, For stays not exceeding \\ inches smallest diameter, and for all stays which are welded, 6,000 Ibs. per square inch ; for unwelded stays above i^ inches smallest diameter, 7,500 Ibs. per square inch. 1 62 THE PRACTICAL ENGINEER'S HAND-BOOK. Steel Stays. For stays not exceeding i inches smallest diameter, 8,000 Ibs. per square inch; for stays above if inches smallest diameter, 9,000 Ibs. per square inch. No steel stays are to be welded. Stay Tubes. The stress is not to exceed 7,500 Ibs. per square inch. Flat Plates. The strength of flat plates supported by stays to be taken from the following formula : x T 2 = working pressure in Ibs. per square inch. where T = thickness of plate in sixteenths of an inch, P = greatest pitch in inches, C = 90 for iron or steel plates T 7 thick and under, fitted with screw stays with riveted heads, C = 100 for iron or steel plates above T 7 thick, fitted with screw stays with riveted heads, C = 110 for iron or steel plates ^ thick and under, fitted with stays and nuts, C = 1 20 for iron plates above ^ thick, and for steel plates above T 7 F and under T 9 ^ thick, fitted with screw stays and nuts, C = 135 for steel plates T 9 thick and above, fitted with screw stays and nuts, C = 140 for iron plates fitted with stays with double nuts, C = 150 for iron plates fitted with stays with double nuts and washers outside the plates, of at least of the pitch in dia- meter and | the thickness of the plates, C = 1 60 for iron plates fitted with stays wit'i double nuts and washers riveted to the outside of the plates, of at least of the pitch in .diameter and | the thickness of the plates, C = 175 for iron plates fitted with stays with double nuts and washers riveted to the outside of the plates, when the washers are at least f of the pitch in diameter and of the same thick- ness as the plates. P"or iron plates fitted with stays with double nuts and doubling strips riveted to the outside of the plates, of the same thickness as the plates, and of a width equal to f the distance between the rows of stays, C may be taken as 175, if P is taken to be the distance between the rows, and 190 when P is taken to be the pitch between the stays in the rows. For steel plates, other than those for combustion-chambers, the values of C may be increased as follows : C = 140 increased to 175, 150 185, 1 60 ,, 200, 175 220, I9O ,, 24O. If flat plates are strengthened with doubling plates securely riveted to LLOYD'S RULES FOR STEAM BOILERS. 163 them, having a thickness of not less than of that of the plates, the strength to be taken from _ ., ^ = working-pressure in Ibs. per square inch ; where / = thickness of doubling plates in sixteenths, and C, T and P are as above. Note. In the case of front plates of boilers in the steam-space, these numbers should be reduced 20 per cent., unless the plates are guarded from the direct action of the heat. For steel tube-plates in the nest of tubes the strength to be taken from 140 * " = working pressure in Ibs. per square inch; where T = the thickness of the plates in sixteenths of an inch, P = the mean pitch of stay-tubes from centre to centre. For the wide water-spaces between the nests of tubes the strength to be taken from C x T" _ . = working-pressure in Ibs. per square inch ; where P = the horizontal distance from centre to centre of the bounding rows of tubes, and C = 120 where the stay-tubes are pitched with two plain tubes between them and are not fitted with nuts outside the plates, C = 130 if they are fitted with nuts outside the plates, C = 1 40 if each alternate tube is a stay-tube not fitted with nuts, C = 1 50 if they are fitted with nuts outside the plates, C = 1 60 if every tube in these rows is a stay-tube and not fitted with nuts, C = 170 if every tube in these rows is a stay-tube and each alternate stay-tube is fitted with nuts outside the plates. The thickness of tube plates of combustion-chambers in cases where the pressure on the top of the chambers is borne by these plates is not to be less than that given by the following rule : T _ P x W x D 1600 x (D d) where P = working pressure in Ibs. per square inch, W = width of combustion- chamber over plates in inches, D = horizontal pitch of tubes in inches, d = inside diameter of plain tubes in inches, T = thickness of tube-plates in sixteenths of an inch. M 2 164 THE PRACTICAL ENGINEER'S HAND-BOOK. Girders. The strength of girders supporting the tops of combustion chambers and other flat surfaces to be taken from the following formula : = working-pressure in Ibs. per square inch ; (L P) x D x L where L = width between tube-plates, or tube-plate and back plate of chamber, P = pitch of stays in girders, D = distance from centre to centre of girders, d = depth of girder at centre, T = thickness of girder at centre. All these dimensions to be taken in inches. Constants for Wrought Iron. 6,000, if there is one stay to each girder. 9,000, if there are two or three stays to each girder. 10,000, if there are four or five stays to each girder. 10,500, if there are six or seven stays to each girder. 10,800, if there are eight stays or above to each girder. Constants for Wrought Steel. 6,600, if there is one stay to each girder. 9,900, if there are two or three stays to each girder. C = (| 1 1,000, if there are four or five stays to each girder. 11,550, if there are six or seven stays to each girder. 1 1, 880, if there are eight stays or above to each -girder. Circular Furnaces. The strength of plain furnaces to resist collapsing to be calculated from the following formula : 80 600 x T 2 i . -11 J*l _ - . = working pressure in Ibs. per square inch ; L x D where T = thickness of plates in inches, D = outside diameter of furnace in inches, L = length of furnace in feet. If strengthening rings are fitted, the length between the rings is to be taken. If the plates do not exceed -^ in. in thickness, the pressure, however, is not to exceed T If the plates are of steel and exceed -^ in. in thickness, the pressure is not to exceed 8_,8oo_x_T = lb If the furnaces are fitted with a single Adamson-ring at about the middle of their length, the pressure may be calculated from 10,400 x _ wor kj n g_p ressure j n I DS- per square inch. LLOYD'S RULES FOR STEAM BOILERS. 165 If the furnaces are fitted with two Adamson-rings, then the pressure may be calculated from 00 = working-pressure in Ibs. per square inch. If the furnaces are fitted with a series of Adamson-rings at intervals not exceeding 23 inches, the pressure may be calculated from i^2! x * D = working-pressure in Ibs. per square inch ; where T = thickness in sixteenths of an inch, D = outside diameter of furnaces. The strength of corrugated furnaces made of steel, having a less tensile strength than 26 tons per square inch, the corrugations being 6 inches apart and 1 1 inches deep, to be calculated from 1,000 x ( - 2) __ working-pressure i n ib s> p er S q Uare inch. The strength of furnaces made of steel, having a tensile strength between 26 and 30 tons per square inch, and corrugated on Fox's or Morison's plans, to be calculated from *' 2 59 x ( nJy working-pressure in Ibs. per square inch. The strength of ribbed furnaces (with ribs 9 inches apart) to be calcu- lated from the following formula : I ^ [ ' X * 21 = working-pressure in Ibs. per square inch.' The strength of spirally corrugated furnaces to be calculated from the following formula : 2 1 = working-pressure in Ibs. per square inch ; where T = thickness of plate in sixteenths of an inch, and D = outside diameter of corrugated furnaces, or outside diameter of the plain parts of ribbed furnaces, in inches. The strength of Holmes' Patent Furnaces, in which the corrugations are not more than 16 inches apart from 'centre to centre, and not less than 2 inches high, to be calculated from the following formula : Working-pressure in Ibs. per square inch = 945 _^_ I _J where T = thickness of plain portions of furnace in sixteenths of an inch, D = outside diameter of plain parts of the .furnace in inches. 1 66 THE PRACTICAL ENGINEER'S HAND-BOOK. ILLUSTRATIONS OF LLOYD'S RULES FOR BOILERS The Method of Determining the Working-Pressure on each part of a Steam-Boiler, according to Lloyd's Rules, may be illustrated by applying them to the marine-boiler shown in Figs. 61 and 62, and calculating the working pressures of the various parts. Figs. 61 and 62 Fig. 61. 62. Figs. 61 and 62. Return tube marine boiler. represent a steel-boiler 12 feet 3! inches diameter to work at a pressure of 90 Ibs. per square inch. Diameter of rivets ff inch = -9375 inch. Area of one rivet ='6903 square inch. Mean diameter of boiler-shell = 147- 5 inch. Thickness of steel-shell plates = 75 inch. End-plates are fitted with stays with double nuts, therefore the constant is 140. Pitch of stays for end-plates in inches, 14*5 inches, and I4'5 2 = 210*25. Area of stay, 2-95 square inches. Pitch of stays in combustion-chamber sides = 9 inches, and 9 3 = 81. Pitch of stays in combustion-chamber backs = yf inches, and yf 2 = 5 8' 14. Thickness of furnace-plates = '53125 inch. Length of furnace = 7*25 feet. Outside diameter of furnace =37 inches. LLOYD S RULES FOR STEAM-BOILERS. I6 7 THICKNESS OF PLATING. Circumferential shell . Front and back upper plates Back mid . . . . Back lower Front tube-plates . Front lower Furnace crowns . Furnace bottoms Inner tube-plates Combustion-chamber, sides Combustion-chamber, backs Steam-chest shell . Steam-chest ends Steam-chest connection . steel | inch thick. ,' A . -H ' ? :f ;t iron f The Working-Pressure of each part of the Boiler may be calcu- lated with the above data as follows : Plate-section Rivet-section . Circumferential shell . End-plates in steam-space Stays in steam-space . Outer tube-plates . Stay-tubes .... Furnaces Combustion-chamber, sides Combustion-chamber, backs WORKING PRESSURE BY LLOYD'S RULES. 3-625 - -9375 3-625 2 X '6903 X 85 x ioo = 74- 1 3% x 175= 75-4% 20 X (12 -2) X 74" 13 = I00 . 5lbSi '4 x (") = 95 -8 Ibi = 105 lbs. 2IO'25 140 X < 12 ) 2 = 99-3 lbs, 203 (8-8^6:5) x 7500 = 6 ^ (I 4 '5 X 12) - 48 89600 x "28226 7-25 x 37 I2O X 64 no x 4-9 58-14 = 94-2 lbs. = 94-8 lbs. = 92-7 lbs. 1 68 THE PRACTICAL ENGINEER'S HAND-BOOK. WORKING PRESSURE BY LLOYD'S RULES continued. I'22 X 60OO Combustion-chamber, side-stays . 7875 . , , , 90 x 6000 Combustion-chamber, back-stays. Z _ Steam-chest, plate-section . Steam-chest, rivet-section . Steam-chest, shell 275 - -8125 275 275 x '4375 = 92-9 Ibs. = 1 02 Ibs. = 70% = 73% . "5 X '*375 x 70 = I40 lbs> FURNACE-TUBES, PLATES AND TUBES OF BOILERS. Corrugated Furnace-tubes, shown in Fig. 63, are much stronger to resist collapsing pressure than plain furnace-tubes, but inferior to them as regards staying the boiler-ends, and it is necessary to place longitudinal stays close to corrugated furnace-tubes. Lloyd's Rule for these tubes, given at page 167, may be illustrated by the following example. Required the work- ing pressure of a corrugated furnace-tube with corrugations i inches deep, the thickness of the plates being ^ inch and the greatest diameter of the furnace-tube being 36 inches. Then looo x (8-2) = 36 inches diameter 167 Ibs. per square inch, the working pressure of this fur- nace-tube. Strength of Corrugated Furnace-tubes. A test was made of a corrugated furnace-tube, of mild-steel, 6 feet 9 inches long, 3 feet if inches outside diameter, had 13 corrugations i| inches deep, and pitched 6 inches apart from centre to centre of each corrugation. The Fig. 63. Return-tube marine boiler, with corrugated furnace -tubes. STRENGTH OF RIBBED FURNACE-TUBES. I6 9 tenacity of the steel was 27-2 tons per square inch, with an elongation of 35 per cent, in 10 inches. The results were as follows : Table 69. PARTICULARS OF TEST OF A CORRUGATED FURNACE-TUBE. Pressure in Pounds per Square inch. ALTERATION OF FORM TRANSVERSELY. Permanent Set. Elongation in a Length of 1 5 ft. 9 in- 07 07 07 9 II Horizontally. Vertically. 400 500 6OO 700 800 850 9 00 03 03 04 10 Tota 015 015 03 05 collaj; 03 03 05 08 >se ens 03 nil 04 ued. 025 025 025 025 03 03 03 03 035 04 035 Ribbed Furnace-Tutes shown in Fig. 64 combine the longitudinal strength of plain furnace-tubes, and the diametrical resistance to collapse of corrugated furnace-tubes. The ribs or strengthening rings are rolled on the plate, and there is no necessity, as in the case of corrugated furnace- tubes, to weld the joint for the subsequent process of corrugating. An experiment consisting of testing, with hydraulic pressure, of a furnace-tube % Inch thick Fig. 64. Ribbed furnace-tube. to destruction was made with a ribbed-tube of the dimensions given in the following Table : Table 70. DIMENSIONS OF A RIBBED FURNACE-TUBE TESTED TO DESTRUC- TION AT THE WORKS OF MESSRS. JOHN BROWN AND Co., LIMITED, SHEFFIELD. Length INTERNAL DIAMETER. rVi* v between Furnace Tube. Furnace Tube over all. Centres of Inner Rows of Rivets in End FRONT END. MIDDLE. BACK END. Angles. Vertical. Horizontal. Vertical. Horizontal. Vertical. Horizontal. Inch. ft. in. ft. in. Inches. Inches. Inches. Inches. Inches. Inches. \ 7 o 6 6| 37M 37M 37H 37# 37H 37tf I/O THE PRACTICAL ENGINEER'S HAND-BOOK. Result of the Test. The ribbed-tube collapsed opposite to the butt- strap, at a pressure of 780 Ibs. per square inch. There was no appreciable deformation diametrically at 700 Ibs. per square inch, the highest pressure at which the tube was gauged. It is claimed for this form of furnace- tube that besides being practically of the same strength as a corrugated furnace-tube to resist collapse, it possesses very much greater longitudinal strength, and that therefore it will not require longitudinal stays close I Stays t dia\ if^reads per inch. \ %$& rrt^^tti;ilfr alongside it. It also will not be liable to an accumulation of scale upon its crown to a greater extent than plain furnaces a point of very considerable importance in the cases of vessels making very long ocean voyages. The longitudinal joint of these furnaces are best made with a butt-strap, which is, of course, placed below the fire-bar level, a truly circular form being thus obtained with a thoroughly trustworthy joint, which is not likely to give trouble by leakage as soon as a slight corrosion has occurred upon some part of the joint, as has often happened with welded joints. Further, it is considered that a welded joint is more likely to suffer from corrosion than a riveted one, on account of the material not being so homogeneous at the weld as at the other portions. The Strength of Ribbed Furnace-Tubes is the same as corrugated furnace-tubes, and this form of furnace has been approved by Lloyd's for a working pressure as found by their formula for determining the working pressure to be allowed upon corrugated furnace-tubes. FIRE-BOX ROOF-STAYS. I/I Stay-Bolts for Fire-Box Roofs of Locomotive Engines. The strongest and most efficient arrangement of stays for staying the roof of a locomotive fire-box is that shown in Fig. 65. The stays do not impede the circulation of the water, which can freely circulate over the hottest parts. For very high temperatures, the stay-bolt should be screwed into both plates, and have their ends riveted over to form good heads. IBiOof-Stays of the Fire-Box of Locomotive Engines are frequently o o o o o o..-Q-o_~"6",p--e-t"q / vs Fig. 66. Fire-box of a locomotive-boiler. made in the form of the girder-stay, shown in Fig. 66, in which there are 8 wrought-iron girder-stays, 2 inches thick, mean depth 6| inches, length of girder 53 inches between the points of support. Each girder is attached to the fire-box by best Yorkshire iron-bolts i inch diameter, pitched at 4! inches. Four of the bars are connected by means of sling-stays to angle- irons riveted to the crown of the fire-box shell. The stays are pitched 4| inches transversely, leaving a space of zf inches between the stays. The ultimate breaking- weight of each girder-stay may be found by 1/2 THE PRACTICAL ENGINEER'S HAND-BOOK. Mr. D. K. Clark's formula for the transverse strength of rectangular bars of wrought-iron loaded at the middle, which is : Breaking weight in tons = * 6 x bre f dth i " ches X de P* h in inches2 Length ot span in inches. , ru 26 x 2 inches broad x 6^ x 6 inches depth Then r ^ = 41*45 tons, 53 inches, length of span of girder the ultimate breaking-weight required to break each of these girder-stays when loaded at the middle ; but as the weight is uniformly distributed, the ultimate breaking-weight is 41*45 x 2 = 82-90 tons. The area of fire-box roof supported by each roof-stay is 4*875 inches pitch of girders X 53 inches span = 258*375 square inches, and when tested by hydraulic pressure to the usual pressure of 200 Ibs. per square inch, each girder-stay would be loaded to 2 5 8 '375 x 200 Ibs. _ tong> 2240 Ibs. Cast-Steel Girder-Stays for Fire-Box Roofs, as shown in Figs. 67 and 68, are more efficient than wrought-iron girder-stays, as they can be made of the maximum strength and rigidity with the minimum bulk and weight. The Thickness of Wro tight-Iron Girder-Stays or Fire-Box Bocf- Stays for supporting the tops of combustion-chambers and other flat-surfaces may be found by the following formula : Working pressure in Ibs. per square inch x (W P) D x L_ Constant x d* Thickness of the girder-stay in inches by Board of Trade Rule. Working pressure in Ibs. per square inch x (LP) x D X L_ Constant x d* Thickness of the girder-stay in inches at the centre by Lloyd's Rule. The constants to be taken from pages 146 and 164. A wrought-iron roof-stay for the combustion-chamber of a marine-boiler is shown in Figs. 69, 70, 71. The Strength of a Combustion-Chamber with a Curved Be of, as shown in Fig. 72, may be calculated, when the radius of the curvature is known, by the rules for determining the collapsing strength of furnace- tubes, the radius of the largest curvature of the roof to be taken. The Thickness of Plate required for a Cylindrical Boiler-Shell for a given working pressure, may be found by the following Rules, the notation being the same as given previously for the Board of Trade and Lloyd's Rules, by which the percentage of strength of the joint is to be calculated : Thickness of plate in"} Working pressure in Ibs. xthe inside diameter of inches by Board of > = the shell in inches X factor of safety Trade Rule. ) 47000 x percentage of strength of joint x 2 Thickness of plate in inches ") _Workingpressure in Ibs. per square inch x D by Lloyd's Rule. ) ~~ C~x~B _ Working pressure in Ibs. per sq. inch x mean diameter of shell in inches Co-efficient from table x percentage of strength of joint. THICKNESS OF TUBE-PLATES AND FURNACE-TUBES. 173 The Thickness of Plate required for Plat-surfaces cf Boilerc may be found by the following formulae : Working pressure inlbs. per square inch x S 6 Constant ~=( T + ')' and STT* I) =thickness of plate by Board of Trade Rule. Working pressure in Ibs. per square inch x P 2 Constant ~ ness of plate by Lloyd's Rule. The constants to be taken from pages 147 and 163. */ = T and V r " = thick ' Figs. 67 and 68. Cast-steel fire-box roof-stays. Fig. 69. Fig. 70. Fig. 71. Figs. 69 71. Wrought-iron roof-stay. Fig. 72. Combustion- chamber with curved roof. The Thickness of Tube-plate may be found by the following formula : Wm-kin g _ P ressure in Ibs. per square inch X Wx D = ^ t i5ooox(D a U H KB s ^ o ^ 1 1 2^ sg NO ON O "-I NO in ft CO CM -H O ONOO l~~>vO in -*t co N M i-c vo in * co N CM i-c o ONOO r^NO in ft co co OO ON O i-c -> i- 1 ON 1 R vo in ft co * mvo I^OO NO in in rt* co CM i c O ONOO co t^NO m ^t- co *M -i O ON ON O O O O O O O ONONONONONONONONONON ONCO CO JNDS PEG NO O O i" OO ON ON O -> co O in TJ- co -i O O ONOO IT^NO in^tcoo) w >-< O ONON O O O O O O O OvONONONONONONONONON ONOO CO CO O CO ^t- in\O t^CO ON ON O ^^ c^ co ^t mxO t CO ON t^ in 't CO CM i-c O ONOO t^ t^NO m * CO CM i-c -i O ONOO OO 1-^vO in ft co CM H-I O O ONCO t^ t^ O O O O ONONONONONONONONONONON ONCO OO OO CO ----'-' Temperature of the Feed Water in Degrees Fahr. tNOOOOOOOOOOOOOOOOOOo co TJ- ino t^OO ON O i-c -> N 2 I SO THE PRACTICAL ENGINEER'S HAND-BOOK. calculated by means of Table 72, which gives the equivalent evaporation from feed-water of 100 Fahr. to steam of 70 Ibs. pressure, for various pressures of steam. Example of the use of the above Table : A boiler evaporates 24000 Ibs. of water in one hour from feed-water at 70 Fahr. to steam of 80 Ibs. pressure, per square inch, What is the equivalent evaporation from feed-water at 100 Fahr. to steam of 70 Ibs. pressure per square inch ? Then on a line with temperature 70 in the first column, is, under the column headed 80 Ibs. pressure, the figures 1*029, which multiplied by 24000=2469-6 the equiva- lent evaporation from water at 100 to steam of 70 Ibs. pressure per square inch, and 2469-6 -4- 30 Ibs. evaporation = 82-3 horse-power. The Nominal Horse-power of Boilers is frequently measured by the evaporation of one cubic foot of water, or 62-4 Ibs. to steam per hour. SAFETY-VALVES FOR STEAM-BOILERS. A Safety-valve should discharge steam so rapidly, that when the blowing-off pressure, for which the valve is set, is reached, no considerable increase in the pressure of steam can take place, however rapidly the steam is generated. When the steam is shut off from the engine, with a good fire in the furnace, or should the fires be forced, the safety-valve should prevent the pressure of the steam rising above a fixed point, and it should carry off all the steam generated, without the initial blowing-off pressure being exceeded by more than 10 per cent. The top of a safety-valve is, where convenient, preferably made open to the atmosphere, as it can then easily be seen when the steam has risen too high in the boiler, or when the valves are leaky and are wasting steam. When the valves are bonneted, or provided with a casing over the valve, to which a waste-steam pipe is attached, a drain-pipe should be inserted at the lowest point of the pipes, to carry off the water formed from the condensed steam, otherwise water will accumulate, which, besides causing additional load on the valve, is liable to freeze in frosty weather and render the valve inoperative. Two small safety-valves are more efficient than one large one. Flow of Steam through Safety-valves. The velocity with which steam will flow through an orifice from a boiler, such as a safety-valve, is the same as that of a body falling by gravity from the height of a column of steam of uniform density. The formula for gravity is : V= v/2 g h, or V=8 ^/~1T Where V = the velocity in feet per second. g = the velocity acquired by a body in falling freely from a state of rest, at the end of one second, being 32-2 feet per second. h = the height in feet through which the body falls. Example : Required the velocity with which steam of 75 Ibs. per square inch, absolute pressure, will issue through an orifice, or a safety-valve. Then, as a column of water, 2^309 feet high, will equal a pressure of i Ib. SAFETY-VALVES FOR STEAM-BOILERS. l8l per square inch, the pressure will equal 60 x 2-309 = 138*54 feet of water. It will be seen from Table 78, that the volume of steam of 75 Ibs., absolute pressure, is 349 times greater than water, and the height of the column of steam will be 138-54 feet x 349 = 48351 feet; the velocity due to that height will, by the above formula, be ^48351 x 8 = 1760 feet per second. The Plow of Steam through an Orifice or a Safety-valve, if there were no diminution in the area of the jet of issuing steam, would be, in cubic feet per second, through an orifice i square inch in area, equal to the velocity in feet per second, found by the previous rule, divided by 144. Thus, for the pressure of steam given in the last example, the velocity was found to be 1760 feet per second; therefore, the quantity of steam dis- charged through an orifice i square inch in area, would =lZ-5= 12' 2 2 cubic 144 feet per second of steam of 75 Ibs. absolute pressure. But the area of the issuing jet of steam in passing through the narrow opening of the valve is reduced to '64 of the actual area, and the actual quantity discharged will be 1760 feet x -64_ 7 70 x 100 Flow of Steam through a Pipe. In an experiment on a loco- 182 THE PRACTICAL ENGINEER'S HAND-BOOK. Fig. 74. Locomotive safety- vaK motive-boiler, fired hard, Mr. Webb found that all the steam generated was discharged through an open pipe f inch diameter, without raising the pressure more than 10 Ibs., and a pipe ij inch diameter, was sufficient to discharge it as fast as generated without raising the pressure, which was however very high at the beginning. Safety-valves are loaded directly by springs or weights, or indirectly by levers and weights. When the fulcrum is secured by a pin, the hole in the lever should be bushed with brass to prevent cor- rosion. In some cases the lever-end is ar- ranged to turn on a case-hardened knife- edge as shown in Fig. 74, by which arrange- ment the friction is reduced to a minimum. Safety-valves loaded with. Lever and Weight. In order to find the weight to be placed on the end of a safety-valve lever, to balance a given pressure of steam on the valve, it is necessary to ascertain the load on the valve due to the weight of the lever. The leverage with which the weight of the lever acts is measured by the distance of its centre of gravity from the fulcrum ; the centre of gravity may be found by balancing the lever on a knife-edge, and the weight of the lever and valve may be obtained by weighing them. In Fig. 75, w is the weight at the end of the lever"; L is the distance between the weight and the fulcrum; G is the distance of the centre of gravity of the lever from the fulcrum ; z is the distance between the centre of the valve and the fulcrum. The Weight to be placed at the end of the Lever of a Safety- valve, the pressure on the valve, and the length of lever required for a safety-valve, may be found by the following formulae : Let W = the weight in Ibs. at the end of the lever. L = the distance in inches between the weight and the fulcrum. w = the weight of the lever in Ibs. G = the distance in inches of the centre of gravity of the lever from the fulcrum. P = the pressure of the steam in Ibs. per square inch above the atmosphere. V = the weight of the valve in Ibs. A = the area of the valve in square inches. Z = the distance in inches between the fulcrum and the centre of the valve. The weight in Ibs, to be placed at the end of the lever = Fig. 75. Safe.y-valve with lever and weight SAFETY-VALVES FOR STEAM-BOILERS. 1 8* The pressure in Ibs. per square inch on the valve=. p |(pxG) "I 7% 8 lbs. weight of lever x 10 inches distance of the centre of 3-5 inches distance between the centre of the valve and gravity from the fulcrum = ^ = = the fulcrum product F. ( 3 rd). 577-26-26-85 x 3-5 . the d . stance be 70-052 lbs. weight on the lever tween the weight and the fulcrum, or the length of lever. SAFETY-VALVES FOR STEAM-BOILERS. I8 5 The Diameter of a solid Cast-iron Ball may be found by this Rule : Diameter in Inches: V weight of the ball in Ibs. v 'S236 x '26 cubic inch per Ib. Then the diameter of a cast-iron ball for the safety-valve lever described , . 3 /7O'O52 Ibs. weight of ball . . , in the previous examples is= \f - ^ ^-g = 6V inches diameter. Counter-balanced Safety- Valve Levers. If the lever be prolonged beyond the fulcrum, and provided with a weight sufficient to balance the weight of the lever, valve, and connections, as shown in Fig. 7 5 A, then the rules become simplified, and are as follows : To find the weight to be placed on the lever. RULE : Multiply the pressure in Ibs. per square inch above the atmosphere by the area of the valve, and by the distance between the centre of the valve and the fulcrum, and divide by the distance between the weight and the fulcrum. To find the length of lever or "distance between the weight and the fulcrum. RULE : Multiply the pressure in Ibs. per square inch above the atmosphere by the area of the valve, and by the distance between the centre of the valve and the fulcrum, and divide by the weight at the end of the lever. To find the pressure on the valve in Ibs. per square inch above the atmosphere. RULE: Multiply the weight at the end of the lever by the distance between the weight and the fulcrum, and divide by the product of the area of the valve by the distance between the centre of the valve and the fulcrum. Safety-valve lever with Spring Balance. When the lever is pressed down by a spring-balance, as shown in Fig. 76, the lever is generally pro- Fig. 75A. Safety-valve with balanced lever. Fig. 76. Locomotive safety-valve. Fig. 77. Spring-balance with a ferrule on the screw. portioned, so that i Ib. at its extremity balances i Ib. per square inch on the valve. A ferrule should be placed on the screw of the spring-balance, between the nut and the casing, as shown in Fig. 77, to prevent the valve 1 86 THE PRACTICAL ENGINEER'S HAND-BOOK. being tampered with, or overloaded by screwing down the spring beyond the blowing-off pressure for which the valve is set. Safety-valves loaded with Direct-acting Springs. Mr. Thomas Adams gave the fol- lowing graphical method of determining the dimensions of helical springs. In fig. 78 draw A D equal to the length of the spring, and describe an isos- Fig. 78. Diagram of a helical spring. celes triangle, having the angle BAG equal to 1 5 degrees ; take two- thirds of B D as radius D E, describe the semi-circle and set off the angle E D F equal to 60 degrees ; draw F G, which gives the pitch of the coils, and H G is the side of the square of the steel of which the springs should be made. BOARD OF TRADE RULES FOR SAFETY-VALVES. Safety-valves. The provisions relating to safety-valves are in substance as follows : Every steam-ship of which a survey is required shall be provided with a safety-valve upon each boiler, so constructed as to be out of the control of the engineer when the steam is up, and if such valve is in addition to the ordinary valve, it shall be so constructed as to have an area not less, and a pressure not greater, than the area of and pressure on that valve. Cases have come under the notice of the Board of Trade in which steam- ships have been surveyed, and passed by the Surveyors with pipes between the boilers and the safety-valve chests. Such arrangement is not in accord- ance with the Act, which distinctly provides that the safety-valves shall be upon the boilers. In all new boilers, and whenever alterations can be easily made, the valve-chest should be placed directly on the boiler; and the neck or part between the chest and the flange which is bolted on the boiler, should be as short as possible and be cast in one with the chest. Area of Safety-valves. The area per square foot of fire-grate surface of Government safety-valves, or (when there is more than one Government safety-valve on the boiler) the combined area of the Government safety- valves locked up, should be not less than that given in the following Table opposite the boiler pressure intended, provided the valves are not less than 3 inches in diameter. When, however, the valves are of the common description and are made in accordance with the Table, it will be neces- sary to fit them with springs having great elasticity, or to provide other means to keep the accumulation within moderate limits ; and as boilers with forced draught require valves considerably larger than those found by the Table, the design of the valves proposed for such boilers should be submitted to the Board for consideration. BOARD OF TRADE RULES FOR SAFETY-VALVES. is; Table 73. SAFETY-VALVE AREAS FOR VARIOUS PRESSURES OF STEAM. Boiler Pressure. Area of Safety-valve per Square Foot of Fire-grate. Boiler Pressure. Area of Safety-valve per Square Foot of Fire-grate. Boiler Pressure. Area of Safety-valve per Square Foot of Fire-grate. Boiler Pressure. Area of Safety-valve per Square Foot of Fire-grate. Ibs. sq. in. Ibs. sq. in. Ibs. sq. in. Ibs. sq. in. 15 250 62 487 109 302' 155 '22O 16 209 63 480 110 3 00 156 219 17 171 64 '474 III 297 157 218 18 136 65 468 112 295 158 216 19 'IO2 66 462 113 292 159 215 20 071 67 '457 114 290 160 214 21 I '04! 68 H5 288 161 213 2i I-OI3 69 446 116 286 162 211 2J 9 86 70 441 117 28 4 163 210 24 9 6l 436 118 28l 164 209 25 937 72 431 119 279 165 208 26 914 73 426 1 20 277 166 207 27 892 74 421 121 275 167 206 28 872 75 416 122 '273 168 204 29 852 76 412 I2 3 2 7 I 169 203 30 833 77 407 I2 4 269 | 170 '2O2 31 815 78 403 125 267 171 201 32 797 79 398 126 265 i 172 200 33 781 80 '394 127 26 4 173 199 34 765 Si 390 128 262 174 I 9 8 35 750 82 386 129 260 1 75 197 735 83 382 I 3 258 176 1 9 6 37 721 84 378 256 ! 177 195 38 707 85 '375 132 255 I 7 8 194 39 694 86 371 133 253 179 193 40 68 1 87 367 134 251 1 80 192 4 1 669 88 364 250 181 191 42 657 89 360 136 2 4 8 182 43 646 90 357 137 2 4 6 183 44 635 '353 138 245 184 45 '625 92 350 139 243 185 I8 7 46 614 93 '347 I 4 241 1 86 186 47 604 94 '344 I 4 I 240 187' 185 48 49 50 576 3 97 340 337 '334 I 4 2 143 144 2 3 8 237 235 188 189 190 184 183 182 568 98 234 191 181 52 ;559 99 328 146 232 192 181 53 100 326 147 231 193 180 54 '543 101 323 148 230 194 179 55 '535 102 320 149 228 195 178 56 528 I0 3 317 150 227 196 177 57 520 104 315 225 197 176 58 513 105 312 152 224 198 176 59 506 106 309 153 223 199 175 60 500 107 307 154 221 200 174 61 493 1 08 304 The Safety-valves should be fitted with lifting-gear, so arranged that the two or more valves on any one boiler can at all times be eased together, without interfering with the valves on any other boiler. The lift- 188 THE PRACTICAL ENGINEER'S HAND-BOOK. ing gear should in all cases be arranged so that it can be worked by hand either from the engine-room or stoke-hold. Care should be taken that the safety-valves have a lift equal to at least one-fourth their diameter ; that the openings for the passage of steam to and from the valves, including the waste steam-pipe, should each have an area not less than the area of the valve, and that each valve-box has a drain-pipe fitted at its lower part. In the case of lever-valves, if the lever is not bushed with brass, the pins must be of brass ; iron and iron-working together must not be passed. Too much care cannot be devoted to seeing that there is proper lift, and free means of escape of waste steam, as it is obvious that unless the lift and means for escape of waste steam are ample, the effect is the same as reducing the area of the valve or putting on an extra load. The valve-seats should be secured by studs and nuts. Spring Safety-valves. When spring-loaded valves are used in place of dead-weighted valves, two separate valves are to be fitted to each boiler, except in the case of small boilers, in which the grate-surface does not exceed 14 square feet, in which case a single safety-valve may be passed, provided it is not less than 3 inches diameter. The springs and valves are to be cased in, so that they cannot be tampered with ; provision must be made to prevent the valves flying off, in case of the springs breaking ; and screw lifting-gear must be provided to ease all the valves. The Size of Steel for Safety-valve Springs is to be that found by the following formula : Where s = the load on the spring in Ibs. D = the diameter of the spring in inches, from centre to centre of wire. d = the diameter, or side of square, of the wire in inches. C = 8000 for round steel. C = nooo for square steel. The springs are to be protected from steam issuing from the valves when valves are loaded by direct springs ; the compressing screws should abut against metal-stops or washers, when the loads sanctioned by the Surveyors are on the valves. SPRING-LOADED AND OTHER SAFETY-VALVES. The Board of Trade Rules for Safety-valve Springs may be illus- trated by the two following examples : Size of steel for the spiral spring : Example : A safety-valve 4f inches diameter is loaded with a spiral spring of round steel 5 inches diameter from centre to centre of wire coils. The boiler pressure of steam shown by the steam-gauge is 90 Ibs. per square inch. Required, the diameter of the spring-steel. SAFETY-VALVE SPRINGS. 189 The load on the spring=area of the valve in square inches x pressure of steam in Ibs., and 3 / 7854 x 475 x 475 inches x 90 Ibs. x 5 inches centres of the spring v 8000 constant for round steel = i inch, the diameter of the steel required for that spring. Pressure of a spring on a safety-valve : Pressure in Ibs. per square inch \ _8ooo x (diameter of steel) 3 due to springs of round steel ) "centres of spring in inches Pressure in Ibs. per square inch | _nooox (side of square of steel) 3 due to springs of square steel ) centres of spring in inches Example : A safety-valve 4jr inches diameter has a spring of f-inch round steel, 3! inches diameter from centre to centre of the wire coils. Required, the pressure on the valve, or load due to the spring, and also the pressure if a spring of f-inch square steel were employed in place of one of round steel. r PU 8000 x 75 x 75 x 75 inch diameter of steel ,, ., , , Then /:) - '? L2 _ = ooo Ibs., the load on 375 inches centres of the coil the valve, and 9 po Ibs. load on the valve = fi lbs _ 4-5 x 4-5 inches diameter of valve x 7854 square inch, the pressure or load on the valve due to a spring of f-inch round steel. Again Hgo^75 X75 X75jide_d^ square of steel = lbg the 375 inches centres of the coil , , iU , 1237-5 Ibs. load on the valve load on the valve, and iL_2_ _ r = 77-8 Ibs.,. 4-5 X4'5 inches diameter of valve x 7854 per square inch, the pressure or load on the valve due to a spring of f-inch square steel. The Size of Steel in sixteenths of an inch required for the Spring of a Safety-valve, shown in Fig. 79, may be found by the following formula? : Let W = the load on the spring in Ibs. D = the diameter of the spring from centre to centre of the wire coil. d = the diameter of round steel, or side of square of square steel. Size of steel for the spiral spring : Then d = /\/ W * D for round steel d = y^JIir for square steel. Pressure of a spring on a safety-valve : Pressure in Ibs. per sq. ^ (diameter o f steel in sixteenths of an inch) 3 x 2, i = c^ntr^fthe coil of spring in 5^," 190 THE PRACTICAL ENGINEER'S HAND-BOOK. * in sixteentns of an inch) = _ of square steel . .) centres of the coil of spring m inches Size of steel for spiral spring : Example : A safety-valve 4 inches diameter has a spring of round steel 3^ inches diameter from centre to centre of the wire coil; the pressure of steam by the steam-gauge is 70 Ibs. per square inch. Required the diameter of steel for a spring of round steel, and the side of the square for a spring of square steel. Then the load on the spring=4X4 inches diameter x 7854 x 70 lbs.= 879-2 Ibs. per square inch, and ^/879-albs.x 3 -5jnches^ce: ie ^ rin .?= 11-54 sixteenths of an inch=|i and ^V inoh, the diameter of round steel required for that spring, and ^79^_ ies_ce 1^1^= Io sixteenths of an inch = | inch, the side of the square of square steel required. Pressure of a spring on a safety-valve : Example : A safety-valve 4^ inches diameter has a spring of if inch diameter steel ; the diameter of the centres of the coil is 3^ inches. Required, the pressure on the valve, or load due to the spring, and also the pressure >f a spring of square steel be employed in place of one of round steel. Then -13 x 13 x 13 sixteenths of an inchxj_ = lbs load Qn the 3' 5 inches centres of the coil of spring , , I2=5=5'4 lbs. load on the valve 00 ,, ... valve, and i2- __ _ =88-5 lbs. per square inch, the 4-25x4-25 inches X 7854 pressure on the valve or load due to the spring of round steel. Again _I3.JULL*i3 sixteenths of anjnchxj . =l88 lbsjoad on the 3-5 inches centres of the coil of spring valve, and *ggHJbs_. joadonjie valve = ^ are mch the 4-25x4-25 inches X 7854 pressure on the valve, or load due to the spring of square steel. Lloyd's Regulations for Safety-valves. Two safety-valves to be fitted to each boiler and loaded to the working pressure in the presence of the Surveyor. If common valves are used, their combined areas to be at least half a square inch to each square foot of grate-surface. If improved valves are used, they are to be tested under steam in the presence of the Surveyor; the accumulation in no case to exceed 10 per cent, of the working pressure. Each valve to be arranged so that no extra load can be added when steam is up, and to be fitted with easing-gear which must lift the valve itself. All safety-valve spindles to extend through the covers and to SPRING -LOADED SAFETY-VALVES. 191 be fitted with sockets and cross handles, allowing .them to be lifted and turned round in their seats, and their efficiency tested at any time. Spring-loaded Safety-valves are used for marine and locomotive boilers, because they are not affected by motion or vibration. A spring- loaded safety-valve for a marine-boiler is shown in Fig. 80. The spring Fig. 80. Single safety-valve. Fig. 81. Double safety-valve. and valve is cased in, so that no extra load can be added to the valve when steam is up and it cannot be tampered with. The compression of the spring is frequently made equal to the diameter of the valve, and a maximum lift is provided for equal to one-fourth the diameter of the valve. Easing- gear is fitted to the cap of the spindle, by which the efficiency of the valve may be tested ; the valve being attached to the spindle to enable it to be raised or turned round with the spindle, on which the valve is hung loosely to enable it to vibrate freely. A double safety-valve for a marine boiler is shown in Fig. 81, which clearly shows the arrangement of gear for easing the valve. A Spring-loaded Safety-valve for the Boiler of a Locomotive- engine is shown in Fig. 82. Tt is fitted with a lever and spring on Rams- bottom's principle. The advantage of this form of safety-valve is, that the 192 THE PRACTICAL ENGINEER'S HAND-BOOK. point of attachment of the spring to the lever being below the points of the lever pressing on the valves, when one valve opens it tends to relieve the pressure on the other, whereas if the point of at- tachment were higher, the opening of one valve would put a greater weight on the other valve. When steam is suddenly shut off with a good fire burning in the fire-box, the rise of pressure in the boiler of a locomotive-engine, fitted with a pair of these safety-valves 3 inches diameter, is not more than 5 per cent. Fig. 8 2 .-Locomotive A Spring-loaded Safety-valve with Bams- safety-vaive. bottom's Lever and Spring of the pattern used on locomotives on the London and North-Western Railway, is shown in Figs. 83 94. The valves are 3 inches diameter ; they are loaded by a spring of six coils of 2\ inches internal diameter, made of steel \ inch by f inch. The spring is held between the large circular head of a bolt, and a circular plate at the end of a stirrup-link hung on the lever as shown. The plan of the circular head of this bolt is shown in Fig. 87. Fig. 88 is a plan of the disc against which the spring abuts at its lower end. Fig. 89 is a plan of the stirrup-link, and Fig. 90 is a plan of one of the valves. The spring is placed in a recess in the casting, which has side openings fitted with the perforated plates shown in Fig. 91, and the top of the recess has a perforated cover attached to the lever, shown in plan in Fig. 92, their object being to prevent the spring being tampered with. The lever is shown in Figs. 93 and 94. The Lift of a Safety-valve, with a flat face, necessary "to give a free escape of the steam equal to the area of the valve, is , area of valve diameter z x '7854 _ diameter circumference diameter X 3-1416 4 that is, the lift must be equal to one-fourth the diameter of the Valve for the area of opening for the escape of the steam to be equal to the area of the valve. Thus a safety-valve 4^ inches diameter must lift 4*5-7-4=1! inches to obtain an escape equal to the area of the valve. The Pressure or Load required to Lift a Safety-valve, having a flat face, a given height when loaded for a given pressure of steam, may be found as shown by the following example : Example : A safety-valve, 4 inches diameter, with a flat face, is loaded with a spiral-spring having a compression of 4 inches ; the working pres- sure of steam for which the valve is loaded is 80 Ibs. per square inch. Required the lift of the valve to give an area of escape equal to one-sixth the area of the valve, and what will be the extra load on the valve due to that lift ? Then 4 inches diameter of valve -4-4=1 inch lift to give an escape equal to the area of the valve, and one-sixth of i inch = * 1 66 inch, the lift required to give an escape equal to one-sixth the area of the valve,, or 4 inches diameter x i = fi fa 4x6 SAFETY-VALVE FOR A LOCOMOTIVE- BOILER. 193 Fig. 83. Figs. 83 94. Details of safety-valve with Ramsbottom's lever and spring. 194 THE PRACTICAL ENGINEER'S HAND-BOOK. The compression of the spring will be increased to 4-H'i66 inch=4*i6() inches, and the pressure will be increased in the same proportion. Then 4 : '166 : : 80 : 3-32 Ibs., the extra load on the valve, due to the compression of the spring to the extent of the lift. And 80 Ibs. working load + 332 Ibs. extra load = 83-32 Ibs. the lifting load of the valve. The Weight of Steam that will escape through an Orifice i inch square in area in 70 seconds is equal to the number of pounds in the gross pressure of steam per square inch, for steam above 12 Ibs. pressure above the atmosphere, whence the width of opening of a safety-valve may be ascertained. Example : Required the width of Opening or height to which a safety- valve, 4 inches diameter, must rise to, allow 7300 Ibs. of steam to escape per hour, the boiler-pressure of the steam shown by the steam-gauge being 65 Ibs. per square inch. Then the absolute pressure of the steam is 65 Ibs. + 15 lbs. = 80 Ibs. per square inch, and there are 60 x 60 = 3600 seconds in an hour .*. 70 seconds : 3600 seconds : : 80 Ibs. : 41 14-28 Ibs. weight of steam escaping in one hour through an orifice of one square inch area /. 4114-28 Ibs. : 7300 Ibs. : : i square inch : 1*767 square inch, the area required for the escape of 7300 Ibs. of steam in one hour and 1767 squareinch inch Qr , inch ^ nft Q 4-5 inch diameter of valve x 3*1416 safety-valve required to allow the escape of that quantity of steam per hour. The Increase of Pressure on a Spring-loaded Safety-valve due to the Increased Compression of the Spring in Blowing off Steam when the fires are bright and the engines stopped, is approximately equal to the quotient of the diameter of the valve divided by the original com- pression of the spring, when the area of the valve equals f inch per square foot of fire-grate according to the Board of Trade Rule. Example : The spring of a safety-valve has a compression of 4| inches, there are 39*28 square feet of fire-grate to the valve, the loaded pressure is 60 Ibs. per square inch, the increase, irrespective of the spring, would be, say, 10 per cent. : to what pressure would the steam rise, including the effect of the spring ? Then the diameter of the valve according to the Board of Trade Rule would be 39^8 square feet area of firegrate = ^ square inches ^ and ^19.1=5 inches diameter. A A 5 inches diameter of safety-valve 1U , And 3. . L. =1-052 Ib. extra pressure due to 4-75 compression of the spring increased compression of the spring, and 60 Ibs. original pressure, +6 Ibs., or 10 per cent, increase, "irrespective of the spring = 67-052 Ibs. per square inch, the pressure to which the steam would rise on blowing-off. The Extra Pressure on a Direct Spring-loaded Safety-valve due to the Waste-pipe becoming filled with Water, may be found by the following formula : SAFETY-VALVE OPENINGS. 195 Let P = the pressure in Ibs. per square inch due to the weight of the water, then as a pressure of i Ib. per square inch is exerted by a column of water 2 '309 feet high or 277 inches high at a temperature of 62 P A ahr. p _ Height of the column of water in feet 2> 39 p _ Height of the column of water in inches 277 Example : The waste-steam-pipe of a spring-loaded safety-valve was found at one time to be filled with water to a height of 8 feet, and at another time to a height of 41 inches. Required the extra pressure caused in each case by the weight of the water on the safety-valve. Then = 3-46 Ibs. per square inch, the pressure due to the weight of the water on the valve in one case: and - 1 mc es _ r .$ j| DSi per 277 square inch, the pressure due to the weight of the water on the valve in the other case. Safety-valve Openings. The consumption of coal in marine-boilers with natural draught, is not often more than 20 Ibs. of coal per square foot of fire-grate surface per hour, and the water evaporated seldom exceeds 9 Ibs. per Ib. of coal, which corresponds to 1 80 Ibs. per hour, or an evapora- tion of 3 Ibs. per minute per square foot of fire-grate : under these conditions the area of opening requisite to discharge all the steam a boiler can generate, corresponds to four times the square feet of fire-grate divided by the absolute pressure, or pressure shown by the steam-gauge plus 15 Ibs. The consumption of coal in stationary boilers may be taken at 15 Ibs. per square foot of fire-grate surface, and the area of safety-valve orifice may be found by the following formula for each class of boiler. Area of orifice for a safety-valve for a ") _ 4 x square feet of fire-grate marine-boiler . . . . j "absolute pressure of steam Area of orifice for a safety-valve for a ) _ 3 x square feet of fire-grate stationary boiler . . . . ) absolute pressure of steam The Board of Trade allowance is one-half square inch area of safety-valve for each square foot of fire-grate, hence, the lift of the valve is proportional to the diameter and inversely as the pressure. For a discharge of 3 Ibs. per minute per square foot of fire-grate, the requisite lift is obtained by the following formulae* for pressures of steam above 25 Ibs. per square inch. Let L = tb lift of val e in inches necessary for a discharge of 3 Ibs. per minute per square foot of fire-grate. Then 2 x diameter of the valve in inches , L= "absolute pressure of the steam ' for flat ' faced valves - 2-8_xdjarneterofthevaIveininche_s forvalveswith leof seatof 0< absolute pressure of steam * See a " Report on Safety Valves, presented to the Engineers and Shipbuilders ot Scotland," to which the Author is indebted for some of the above and following rules and data. 196 THE PRACTICAL ENGINEER'S HAND-BOOK. Take for example a safety-valve 5 inches diameter = 19-0 square inches area, which corresponds to 2 x ig-6=^g~2 square feet of fire-grate surface, which would evaporate 39^2 square feet x 3 lbs.= 117*6 Ibs. of water per minute. Then, since the area, A, in square inches requisite to discharge any weight, w, in Ibs. of steam per minute at the pressure, p, is ZP It would give, by taking the pressure, p, at 60 Ibs., and the weight, w = 1 17'6 Ibs., the area A= - - "' = 2'6i square inches, which correspond'. 3 x 60 to the opening of a flat-faced valve 5 inches diameter, when the lift equals 2 x 5. === -1667 inches. The circumference of a valve 5 inches diameter being 60 15-7 inches, and i5'7X -1667 = 2'6i square inches of opening as found above. In the Report on safety-valves above referred to it is recommended that two safety-valves be fitted to each marine-boiler, one of which should be an easing-valve and the dimensions of each of these valves, if of the ordinary construction, should be calculated by the following Rule : Let A = area of valve in square inches. G = grate surface in square feet. HS = heating surface in square feet. P = absolute pressure of steam in Ibs. per square inch; or pressure shown by the steam-gauge plus 15 Ibs. rp, . i8xG . -6 x HS Then A = - - - or A = -- . Only one of the valves may be of the ordinary kind and proportioned by this formula, and it is to be the easing-valve. The other may be so constructed as to lift one-fourth of its diameter without increase of pressure, and one such valve, if calculated by the following formula, would be of itself sufficient to relieve the boiler. Area of safety-valve in square inches. 4 x grate surface in square feeO A = absolute pressureof steam in Ibs. > + area of guides of valve. per square inch . . .} 133 x heating surface in square feet") or A = "absolute pressure of steam in Ibs > +area of guides of valve. per square inch. ) The safety-valve calculated by the above formula, should be loaded i Ib. per square inch less than the load on the easing-valve. If the heating- surface exceed 30 feet per foot of fire-grate surface, the size of safety-valve should be determined by the heating-surface. The valves should be flat- faced, and the breadth of face sHnnid not exceed one-twelfth of an inch. DEAD-WEIGHTED SAFETY-VALVES. 197 Fig. 95. Silent Blow-off. The Silent Blow-off Ejector, shown in Fig. 95, is fixed on the side of a ship, for the purpose of discharging the waste-steam from a safety-valve into the sea, without noise or increase of pressure. Dead-weighted Safety- Valves are directly loaded with a number of cheese-shaped weights, placed upon a etrong spindle bearing on the valve, which is hung loosely on the spindle, as shown in Fig. 96 : the weights are encased to prevent their being tampered with. The top of the spindle is covered by a cap, which fits loosely in a hole in the top of the cover of the chest, in order to allow the valve to be turned round on its seat by means of the cross-handle on the cap. The cap is attached to the valve-spindle by a cotter, the cotter-hole is made deeper than the cotter, to allow the spindle to rise in the cap when the valve is raised from its seat, and a forked-lever is fitted to the bottom of the cap, by which the valve may be tested by raising it when required. The area of the waste- steam pipe is equal to that of the valve. This description of safety-valve is now only used for stationary boilers. It is not suitable for marine boilers, because the effect of the weight on the valve is reduced by the heeling of the ship in rough weather, causing the valve to blow-off and waste steam ; and the oscillation of the weights due to the rolling of the ship causes the valve to get out of order and leak. To find the Pressure on a Dead- Weighted Safety-Valve. Rule: Divide the total weight or load in Ibs. on the valve, including the weight of the valve and spindle, by the area of the safety-valve in square inches. Example : A safety-valve 4^ inches dia- meter is loaded with dead-weights as follows : 8 of 105 Ibs. each, 3 of 80 Ibs. each, and one of 55 Ibs., the valve weighs 15 Ibs., and the spindle, 20 Ibs. Required the pressure in Ibs. per square inch on the valve. Then (105 x 8) +(8o x 3) + 55 + 15 + 20 = 1 1 70 Ibs., total weight, or load on the , j 1 1 70 Ibs. total weight. 1U Valve; and ' & = 73-5 Ibs. Fig . 9 6._Dead-weighted Safety valve. 4 D X 4 5 x 754 per square inch, the pressure on the valve. To find the Weight required for a Dead-Weighted Safety- Valve. Rule : Multiply the area of the safety-valve in square inches by the pressure of the steam in Ibs. per square inch. 198 THE PRACTICAL ENGINEER'S HAND-BOOK. Example : Required the weight, including that of the valve and spindle, for a dead-weighted safety-valve, of 5 inches diameter, the pressure of the steam being 60 Ibs. per square inch. Then 5x5 inches x '7854 x 60 Ibs. = 1178'! Ibs., the total weight required, including that of the valve and spindle. When the plates of a steam-boiler become thinned by corrosion or weakened by age, the blowing-off pressure of the safety-valve should be lowered, by reducing the load or weight on the valve to that required for the reduced working-pressure of the boiler. The Reduction to be made in the Weight or Load, when the blowing-off pressure of a dead-weighted safety-valve is reduced, may be found by the following formula : Let W = the original weight or load on the safety-valve. P = the original blowing-off pressure of the steam. p = the reduced blowing-off pressure of steam required. w = the reduced weight on the safety-valve for the reduced pressure of steam. Then w = F ~ p x W Example : A dead-weighted safety-valve is loaded with a weight of 700 Ibs. for a blowing-off pressure of 60 Ibs. per square inch. Required the reduction to be made in the weight or load, if the blowing-off pressure be reduced to 45 Ibs. per square inch. Then 6 Ib 6 7 bs 45 ^ x 7 lbs> wei & ht = J 75 lbs - to be taken off the weight on the valve. The Weight of the Dead-Weights of a Safety- Valve may be calculated approximately from their cubic contents, allowing one cubic inch of cast-iron to weigh -26 Ib. Example : A safety-valve, 3! inches diameter, is loaded with eight dead- weights of cast-iron, each 14! inches diameter, and 2\ inches thick, the weight of the valve-spindle and valve is 33 lbs. Required the weight or load per square inch on the valve, and also how much additional weight must be placed on the valve to produce an additional load of 7 lbs. per square inch ? Then 14-625 x 14-625 x 7854 x 2\ inches thick x 8 weights x '26 lbs. := 873-6 lbs., the weight of the 8 cast-iron weights ; and 873-6 lbs. 4- 33 lbs. = 906-6 lbs., the total weight of the weights, valve-spindle and valve ; and 25 - = 82' 1 1 lbs. per square inch weight on the valve ; 375 x 375 x 7854 and 3.75 x 375 diameter of valve x 7854 x 7 lbs. == 77*28 lbs., the additional weight required to produce an additional load of 7 lbs. per square inch on the valve, making the total load on the valve = 82-11+7 = 89-11 lbs. per square inch. FEED-PUMPS FOR STEAM-BOILERS. I 99 FEED-PUMPS, FEED-VALVES, AND FEED-INJECTORS, FEED- WATER, AND FEED-WATER HEATERS. Feed-water-Consumption in Steam Boilers. The quantity of water used per hour per indicated hcrse-power of the engines, averages as follows : Non- condensing engines use 40 Ibs. of water per indicated horse- power per hour; condensing engines, 30 Ibs. ; compound condensing engines, 20 Ibs. ; and triple-expansion engines, and quadruple expansion- engines, use from 14 to. 1 8 Ibs. of water. Feed-Pumps for Feeding Boilers are shown in Figs. 97 and 98. In pumping hot water the feed-pump should be placed at the same level as the supply-tank, so that the water may flow into the barrel of the pump by its own gravity. The pump-valves should be large and their lift small. A feed-pump should be capable of supplying considerably more water than is actually required for a boiler. The size of a feed-pump, capable of supply- ing three times the quantity of water required to be evapo- rated to steam for a given size of engine-cylinder, may be found by the following formula : Let A = the area of the pump-ram in square inches. C = the area of the engine-piston in square inches. L = the length of stroke in feet, before the steam is cut off. S = the length of stroke of the pump in feet. V = the volume of the steam from Table 78, corresponding to the absolute pressure of the steam, or pressure including that of the atmosphere. _, . C x L x 6 Then A = Vx s Example : Required the diameter of the ram of a feed pump with a 2-feet stroke, to feed the boiler of an engine having a cylinder 30 inches diameter, the steam being cut off when the piston has travelled 1*2 fett of its stroke, the pressure of steam by the steam gauge is 70 Ibs. per square Fig. 98. Horizontal feed-pump, with hollow rac 200 THE PRACTICAL ENGINEER'S HAND-BOOK = 8' 1 8 square inch. Then the volume of steam of 70+15 = 85 Ibs. absolute pressure is, from Table 78, =311, md 3 x 3 inches x 7854 x rz feet stroke of engine x 6 313 volume of steam x 2 feet stroke of pump 2 / y T Q inches, the area of the ram of the feed pump, and A/ = 3 inches, v -7054. the diameter of the pump-ram. The capacity of a feed-pump is frequently made equal to the supply of five gallons of water per hour per indicated horse-power of the engine. The most efficient speed of a feed-pump is about 50 feet per minute. A Feed Back-pressure Valve, or non-return Valve, through which the feed-water enters the boiler is shown in Fig. 99. The lift of the valve can be regulated by the spindle, with which the valve may be locked when required. The lift of a feed-valve is usually f inch ; it should not exceed inch, otherwise the valve- seating soon becomes impaired by the hammering action of the valve. The average rate of the flow of feed-water through the valves is from 200 feet to 400 feet per minute. For locomotive boilers a clack-box with a ball-valve, shown in Fig. 100, is generally used as a non-return feed-valve. Ball-valves are most suitable for the high speed of a locomotive, as they act more freely and are less liable to stick fast than mitre-valves. Feed-valves should be taken out, examined and adjusted when a boiler is cleaned. The Action of an Injector is due to the momentum imparted to the feed-water by a jet of steam moving at a high velocity. The steam used in working the injector is condensed and sent into the boiler with the feed-water, which by this means becomes considerably raised in temperature. The Rise of Temperature of the Feed-water in passing through an Injector may be ex- plained as follows : If i Ib. of steam in motion were mixed with 2 Ib of water at rest, the result produced would be 3 Ib put in motion at one-third the original velocity of the steam. The velocity of water or steam issuing into the atmosphere from the same boiler, is equal to that acquired by a falling body in falling through the height of a column of the same water or steam giving the same effective pressure. And since the velocity acquired by a falling body is proportional to the square root of the height through which it fell, it follows that the velocity of the water and the steam would be propor- tional to the square roots of their relative volumes. And as the volume of steam with one atmosphere effective pressure, or 30 Ibs. absolute pressure, is from Table 78, =827 times that of water, it would issue with the square root of 827=2876, or say twenty-nine times the velocity of the water from the same boiler. Hence, the steam issuing would just balance twenty-nine times its own weight of water trying to issue from the boiler. The number of units of heat in i Ib. of steam of 30 Ibs. absolute pressure is from Table Fig. 99. Feed back -pressure valve. Fig. loo. Clack-box, with ball-valve. AUTOMATIC RE-STARTING INJECTOR. 2CI 79, = 1159 Fahr., and assuming the original temperature of the feed-water at ico degs., the rise of temperature of the feed-water would be = 59 units steam 100 water _ 29 + = 35'3 Fahr., with steam of one atmosphere effective pressure, or 30 Ibs. per square inch absolute pressure. With steam of 3 atmospheres effective pressure, or 75 + 15 = 90 Ibs. per square inch absolute pressure, its volume is 295 that of water; then 1/295 say 17; hence the issuing steam would balance 17 times its own weight of water trying to issue from the boiler. The number of units of heat in steam of this pressure = 1180 per Ib. of steam, and if the original temperature of the feed-water be = 100 Fahr., the rise of temperature of the feed-water would be = Il8o ~ ICO = 60 Fahr. 17 + 1 The Diameter of the Nozzle of an Injector may be found by Rankine's rules, which are as follows : Sectional area of nozzle in square inches = Cubic feet perjiour of gross feed-water ^ 800 v/ pressure in atmospheres Sectional area of nozzle in circular inches = Cubic feet per hour of gross feed-water 630 v/ pressure in atmospheres Example : If a boiler use 1200 Ibs. of coal per hour, and each Ib of coal evaporates 8 Ibs. of water, what is the proper diameter of the narrowest part of the nozzle of an injector to deliver double the required feed, the pressure of steam by the steam gauge being 75 Ibs. per square inch Then (75 + 15)^15 = 6 atmospheres, er inclt 2-233diamr wide? thread. | I Fig. 127. Longitudinal section of a double-ended marine boiler, by the Barrow Shipbuilding Co. 222 THE PRACTICAL ENGINEER'S HAND-BOOK. boiler is 12 feet mean diameter, and 15 feet 2 inches long, made of steel- plates i ^ inch thick. It has 288 plain tubes 6 feet iinch long, 3^ external diameter, No. 8 BVVG thick, swelled | inch at one end ; 84 stay-tubes, 6 feet i inch long, and 3^ inches external diameter, f inch thick. The length over the tube-plates is 5 feet n| inches. The heating-surface of the tubes is 1 893*4 square feet; of the furnaces, 162*4 square feet; and of the combustion-chambers, 146'^ square feet; total heating-surface, 22027 square feet; fire-grate area = 84 square feet. Fig. 128. Half-end view and cross section of the boiler shown in Fig. 127. Ratio of grate-surface to heating-surface = i : 26*2. Ratio of flue-area through tubes, to fire-grate surface = i : 4*88. The plates are flanged outwards at one end of the combustion-chambers and one end of the boiler-shell, to enable the boiler to be completed by machine riveting. The crown- stays of the combustion-chambers are supported at the middle of their length by sling-stays connected to a pair of angle irons riveted to the shell. The arrangement of the shell-riveting is shown in Fig. 129. The rivets are of mild steel i^ inch diameter, and the rivet-holes are drilled in place. The area of the plate between the rivet-holes, and the shearing area of the rivets are respectively 83 per cent., and 88*56 per cent, of the area of the solid plate. Fire-box-stays are best made with a small hole drilled through them, so that in the event of a stay breaking it may be known by the leakage through the hole in the stay. Fig. 129. Riveted seams of the boiler shown in Figs. 127 and 128. MARINE STEAM-BOILERS. 223 The Marine-Boiler, shown in Figs. 130 and 131, has a shell 9 feet - Outside ~ length- /Sfcet - Fig. 130. Longitudinal section of a marine boiler, by Simons & Co. mean diameter, and 18 feet long, made of steel plates f inch thick. The fur- nace-tubes have plain plates \ inch thick, and 3 feet 2 inches internal diameter. The end plates are f inch thick, flanged inwards at each end to join the shell. A plan of the riveting of the shell is shown in Fig. 132. The working pressure is 90 Ibs. per square inch. rz*J Fig. 131. Transverse section of the boiler shown in Fig. 130. Fig. 132. Plan of the riveting of the shell of the boiler shown in Figs. 130 and 131. A Marine Boiler of a Modified Locomotive Type is shown in Figs. I 33 J 34> it differs from a locomotive boiler in the following respects. The fire-box is formed into a water-bottom from which a steady supply of water 224 THE PRACTICAL ENGINEER'S HAND-BOOK. is afforded to the whole length of the surface forming the sides of the fire-box, where the evaporation is most intense. The combustion- chamber extends beyond the fire-bars, as shown in Fig 133, for the purpose of assisting the combustion of fuel and the utilisation of the products thereof, and of preventing intense heat from the furnace playing directly on Fig. 133- Fig. 134- r atTtftrttt -ST tH;r Ui- -fiassn^ Fig. 135- Figs. 133 135. Marine boiler of modified locomotive type, by Hawthorn, Leslie, & Co., Newcastle-on-Tyne. the tube-plate. Fig. 134 is a half cross section through A B, and through c D in Fig. 133, and Fig. 135 is a half- plan section through E F in Fig. 133. Blow-off Cocks, shown in section in Fig. 136, and in plan in Fig. 137, should be fitted with a guard, as shown, in order that the spanner for turning the cock cannot be withdrawn without closing the blow-off cock. The elbow-pipe for connecting the blow-off cock to the boiler should be wrought-iron. Blow-off cocks should be taken apart, examined, adjusted, and greased when a boiler is cleaned. Fusible-Plugs, shown in Fig. 138, are a safeguard against collapse of a furnace-top from over heating, when they are of reliable construction, and in good order and clean on both the fire side and water side of the plate. They require to be frequently renewed, as the nature of the alloy changes with long service. Fusible-plugs should be examined when a boiler is cleaned, and scraped clean on both the fire-side and water-side of the plate. Brass-cones filled with lead are sometimes used for this purpose, but they are not so reliable as those filled with fusible-metal. The following alloys for fusible plugs melt at the temperature of steam of the absolute pressures given below : 2 Tin : i Lead : melts at 34OF.=temp. of steam of 118 Ibs. per sq. in. ic| 4 35QF.= 135 1 7 4 37oF.= 174 4 5 3QOF.= 220 8 n 4 ooF.= 248 Plugs filled with pure tin fuse at 446 Fahr., and those with lead at 620 Fahr. WATER BLOWN THROUGH A RIVET- HOLE. 225 Fig. 136. Fig. 138. Fusible-plug by the National BoiUr Insurance Co. In getting up Steam the fire should not be lighted until water is visible in the glass of the water-gauge, and the boiler should be gradually warmed. The fire should be fed regularly, and the grate- bars kept evenly covered with a thick fire if there be plenty of steam, and with a thin fire if short of steam. In emptying a boiler, water should not be run off under steam-pressure or when the boiler and seating are hot. In case the boiler should be found to be short of water, if the fire be thin and the furnace - crown is not overheated, the fire should be drawn quickly, beginning at the front, but if the fire be thick or the furnace - crown overheated, the fire should be smothered with either wet slack or wet ashes, and the damper closed. The Time required to lower the Water in a Boiler, a certain distance when either a fusible-plug or a rivet is blown out, and the quantity of water blown out, may be found by the following Rules : The quantity of water in cubic feet to be lowered or blown off = the surface of the water in feet x the depth in feet. The quantity of water blown out in one minute = (diameter of hole in inches) 2 x 2f constant x %/ pressure. The time in minutes re- ) _ Quantity of water lowered quired to lower the water J "Quantity of watefWowii "oufper minute. Example : A rivet inch diameter was blown out of a boiler in which the pressure of steam shown by the steam-gauge was 64 Ibs. per square inch, the depth of water in sight in the water-gauge was 5 inches, the area of the surface of the water was 120 square feet : How long would it take to lower the water 5 inches ? Then the depth of water is 5 inches or ~ feet, I2 x 5 = g O cubic feet of water to be blown out through the rivet-hole, and 75 x -75 inch x 2\ constant x v / 64= 11-25 cubic feet of water blown out in one minute. Then 5 cubic feet the quantity to be lowered or blown out_ m j nutes ii'25 cubic feet the quantity blown out per minute 45 seconds. Q Figs. 136 and 137. Blow-off cock. 226 THE PRACTICAL ENGINEER'S HAND-BOOK. Water-Tube Boilers are those in which water is contained in a number of tubes of moderate size, the steam being generated from it by heat applied to the external surfaces of the tubes. It is essential that the tubes of such boilers be regularly supplied with good water, and there must be a rapid circulation of the water to carry off the heat absorbed by the tubes, the heating surfaces of which must be kept clean and free from deposits of sediment. A Water-Tube Boiler of improved construction, with a plain furnace, Fig. 139. Babcock and Wilcox water-tube boiler. is shown in Fig. 139. This boiler is essentially made of three parts, each connected with the others, viz. : (ist.) A series of inclined solid welded water-tubes over the furnace, in which the water being divided into small volumes is quickly raised to a high temperature, and rises through vertical connecting boxes or "headers" at the front end into (2nd.) A horizontal steam and water drum, where the steam separates from the water the remaining body of water returning through the vertical tubes at the back end into the inclined water-tubes, where it is again heated and again passes into the steam and water-drum ; thus a continuous and rapid circulation is kept up and a uniform temperature maintained through- out the boiler. (3rd ) A mud-collector is attached to the lowest point of the inclined water-tubes, and into this the matter held in suspension in the water is pre- cipated by its greater specific gravity as the water falls through the vertical tubes and tube boxes at the rear. Construction. The inclined water tubes are formed of solid lap-welded wrought-iron, expanded at each end into hollow vertical connecting boxes, each containing one zigzag row of pipes. These end connecting pieces are provided with hand-holes opposite each water tube for cleaning purposes the hand-hole covers being faced metal to metal and secured by wrought- iron clamps, thus dispensing with all bolts and perishable material em- ployed in ordinary joints A large and continuous water-way through all the parts is secured by the end connecting boxes being attached to the horizontal steam and water drum by short tubes expanded into accurately bored holes. RESULTS OF TESTS OF A WATER-TUBE BOILER. 227 The steam and water-drum is made of best flanging quality of iron or mild steel, and is double-riveted. The mud-collector is made of cast-iron this metal being found to resist corrosion best and is provided with ample facilities for cleaning. All the water circulates in one direction, no cross currents obstructing it. Tests were made of one of these water-tube boilers, erected at Grant's Mills, Ramsbottom, the results of which are given in the following Table : Table 77. RESULTS OF TESTS OF A BABCOCK AND WILCOX WATER- TUBE BOILER OF 136 NOMINAL HORSE-POWER. Particulars of Tests. Heating surface sq. ft. Grate surface (6 ft. long x 5 ft. wide) . sq. ft. Ratio of heating to grate-surface .... Duration of test Average observed steam pressure . . Ibs. Average temperature of water fed to the boiler by injector deg. Pounds of coal fired Ibs. Pounds of refuse Ibs. Pounds of combustible .... Ibs. Per cent, of ashes .... per cent. Coal consumed per sq. ft. of grate per hour Ibs. Total water evaporated .... Ibs. Water evaporated per hour .... Ibs. Water evaporated per sq. ft. heating surface per hour Ibs. Water evaporated per Ib. of coal actual condi- tions Ibs. Water evaporated per Ib. of coal, assuming feed- water at 212, and under atmospheric pres- sure Ibs. Water evaporated per Ib. of combustible actual conditions Ibs. Water evaporated per Ib. of combustible, assuming feed-water at 2 1 2, and under atmospheric pres- sure . Ibs. Quality of steam percentage of moisture about . Nominal horse-power (i H.-P. =30 Ibs. of water evaporated from 212, at 70 Ibs. pressure) H.-P. Horse-power developed, assuming feed-water at 212 and steam pressure at 70 Ibs. . H.-P. Per cent, above the nominal capacity . per cent. Temperature of boiler-room . . . deg. Temperature of flue gases . . about deg. Force of draught in inches of water . inches Test with Hain Furnace, i furna Test with Regenerative 30 1-5-52 8 hours 85 210 5264 448 4816 8-4 21-9 48100 6125 3'9 2 9 -I 37 9'397 9-987 10-376 i 136 205-8 5i'3 70 r 1563 30 1-^-52 8 hours 90 208 5712 672 5040 1x7 23-80 60900 7612 4-86 io'66i 11-168 12-083 12-651 136 258 89-7 75 600 \ Q 2 228 THE PRACTICAL ENGINEER'S HAND-BOOK. Nut-coal, costing 8s. per ton, was used in the test with the plain furnace. The cost of evaporating 100 gallons of water to steam of yolbs. per square inch pressure, was 4/63 pence. A mixture of equal parts of dross, costing 4s. gd. per ton, and slack, costing $s. ^d. per ton, was used in the test with the regenerative furnace, the cost of evaporating 100 gallons of water to steam of 70 Ibs. per square inch pressure was 2-56 pence. The saving, with the regenerative-furnace, over the test with the plain furnace, being = 8 1 per cent The regenerative-furnace consists of a number of fire-clay-blocks, fitted between the water-tubes over the furnace, which absorb a considerable quantity of heat from the fire while it is bright, and part with a portion of such heat to effect ignition of the gases evolved immediately after firing. CHIMNEYS FOR STEAM BOILERS. A Chimney requires sufficient area to carry off the noxious gases of combustion, and sufficient height to produce a sufficient flow of air, or draught, to maintain steady and efficient combustion. The velocity of the hot gases of combustion may be calculated by Peclet's. formula, which is v=sf 7 461 523 ; V i +G c/+N l(i+ a?) (H 1 where V = the velocity of the hot air or gases in the chimney in feet per second ; / = the whole length of flues and height of chimney in feet ; / = a coefficient of friction equal '012 for the passage of furnace gases over sooty surfaces ; d = the diameter of round, or side of square flues; G = co-efficient of resistance for the passage of air through the fire- grate and the layer of fuel above it, which may be taken at 40 for ordinary boiler-furnaces ; N = the number of bends at right angles to the direction of the current. The Actual Velocity of the Hot Gases in a Chimney is in practice very much less than the theoretical velocity, owing to the friction of winding flues, and to the cooling of a portion of the stream of gases in passing through the flues and chimney. In careful tests of a large number of chimneys, in various parts of this country, the highest velocity of the hot gases in factory chimneys was. found to be 36 feet per second, the lowest 3 feet per second, and the mean velocity 12 feet per second. Therefore, in designing factory chimneys, the velocity of the current of hot gases in the chimney may be taken at 1 2 feet per second. CHIMNEYS FOR FACTORY-BOILERS. 22Q Size of Chimneys for Factory-Boilers. The draught power of a chimney varies as the square root of the height. The retarding of the ascend- ing gases by friction may be considered as equivalent to a diminution of the area of the chimney, or to a lining of the chimney by a layer of gas which has no velocity. The thickness of this lining may be assumed to be 2 inches for all chimneys, or to the diminution of the area by the product of the perimeter by 2 inches (neglecting the overlapping of the corners of the lining). In the following formulae,* let D = diameter, A = area, E = effective area, then o 2 For square chimneys, E = D -- D = A - -- v/A. 12 3 (o \ D 2 D) = A -592 v/A . For simplifying calculations the coefficient of \/ A may be taken as '6 for both square and round chimneys, and the formula becomes E = A 6 A/ A. The power varies directly as this effective area E. A chimney 80 ft. high, 42 in. diameter, has been found to be sufficient to cause a rate of combustion of 120 Ib. of coal per hour per square foot of area of chimney, or if the grate area is to the chimney area as 8 to i a com- bustion of 15 Ib. of coal per square foot of grate per hour. This is a fair practice for a boiler of modern type, in which the flues or tubes are of moderate diameter, gas passages circuitous, and the heating surface extensive in proportion to rate of combustion, so as to cool the chimney gases from 460 to 560, and produce high economy. A chimney should be proportioned so as to be capable of giving sufficient draught to cause the boiler to develope much more than its nominal power in case of emergencies, or to cause the combustion of 5 Ib. of fuel per nominal horse-power of boiler per hour. The Soft, by 42 in. chimney, having 9-62 square feet area will cause the combustion of 9 62 x 120 = 1 154*4 Ib. of coal per hour, or at 5 Ib. of coal per horse-power per hour, is rightly proportioned for 231 horse-power of boilers. The power of the chimney varying directly as the effective area E, and as the square root of the height h, the formula for the horse-power of a boiler for a given size of chimney will take the form, H.-P. = C E J~h, in which C is a constant. For the 80 feet by 42 inch chimney, E = A '6 v/A = 776 square feet. Jh = 8-944 feet. Substituting these values in the formula it becomes 231 = x 776 x 8-944. Whence, C = 3*33, and the formula for horse-powerjs H.-P. = 3-33 E V h, or H.-P. = 3-33 (A - -6 v/A) Jh. If the horse-power of boiler is given to find the size of chimney, the height being assumed, E = = H.-P. v/ h For round chimneys, diameter of chimney = diameter of E -f 4 inches, for square chimney, size of chimney = v/E + 4 inches. No allowance has been made in these formulae for the differences of friction and of rate of cooling of the gases in chimney. Therefore it will * See a Paper by Mr. W. Kemp, in the " Mechanical Engineer," 23O THE PRACTICAL ENGINEER'S HAND-BOOK. be necessary to deduct 1 5 per cent, from the results obtained by these rules to obtain the correct area and power. The Area at the Top of a Chimney for factory steam-boilers is fre- quently made equal to from T ^th to y^th the area of fire-grate for chimneys not less than 90 feet high. When half a dozen boilers are working together with one high chimney, the area at the top of the chimney is frequently made equal to from T Vth to T \th the total area of the fire-grates. BOILER-EXPLOSIONS. Much interesting information on the explosion of steam-boilers has been collected by the chief engineers of boiler assurance companies, whose reports are very valuable, as they reveal the weak points and defects in the construction of steam boilers, and contain practical data given by men of special training and large experience in unravelling the causes of boiler- explosions. The following information on boiler-explosions comprises extracts from the Reports of Mr. E. B. Marten, chief engineer of the Midland Steam- Boiler Inspection and Assurance Company, and other matter ; the appear- ance presented by the boilers after explosion is accurately shown by woodcuts which make the matter plain and shorten description. It appears from these reports that : Marine Boilers have exploded chiefly from corrosion, de'cay of stays, and accumulations of salt, and scale or incrustation. Locomotive Boilers have exploded chiefly from grooving or furrowing, or from cracks caused by the movement of the shell, either from the motion of the boiler, or from the strains of varying pressure. Lancashire Boilers have exploded chiefly from collapse of furnace- tubes, weakness, corrosion, overheating, and improper setting. Cornish Boilers have exploded chiefly from weakness of the large single furnace-tube, corrosion, and improper setting. Plain Cylindrical Egg-Ended Boilers have exploded chiefly from overwork, causing frequent repairs over the fire to be necessary. The enormous fire-grate of these boilers allows them to be forced to do twice the work they should do. Portable-Engine Boilers have exploded chiefly from over-pressure in the hands of inexperienced attendants, and from corrosion. Vertical Rastrick Furnace-Boilers have exploded chiefly from the injury to the plates by the fierce heat opposite the furnace necks, necessitating frequent repairs and patching : and from corrosion. Water-Tube Boilers have exploded chiefly from overheating, caused by a deposit of sediment in the water-tubes. Vertical Cross-Tube Boilers, and Vertical Tubular Boilers with vertical tubes, used for small engines and steam-cranes, usually burst from weakness, either original or from wasting of the plates by corrosion of the fire-box and of the plates underneath the fire-box. This type of boiler is EXPLOSIONS OF VERTICAL BOILERS, 231 the one which probably explodes the most, and with disastrous results ; they require careful periodical inspection. The following particulars of explosions of this class of steam-boiler represent the usual manner of their failure. In an explosion of one of these boilers, shown in Fig. 140, the Fig. 140. Explosion of a vertical boiler from corrosion of fire-box. Fig. 142. Explosion of a vertical boiler from currosion of fire-box. Fig. 143. Explosion of a vertical boiler from over- fire-box was very much corroded on the fire side and three pieces were blown out of the fire-box. The vertical boiler shown in Fig. 141 exploded from corrosion. The fire-box was much corroded on the fire side and ruptured, a small piece of plate being bent inwards. In the explosion of the vertical boiler shown in Fig. 142 the fire-box was much corroded on the water side and collapsed, a piece being blown out of the fire-box. The explosion of the vertical boiler shown in Fig. 143 was caused by the safety-valves having been made fast, which allowed the pressure to accumulate to more than the boiler could Fig. 144. Fig. 145. Explcsion of a vertical boiler from over- pressure. Fie. 146. Co apse of the fire-box fa ver- tical boile from shortness of water. Fifr. 147. Collapse of the fire-box of a vertical boiler from corrosion. bear, a piece being blown out of the fire-box. In the explosion of the vertical boiler shown in Figs. 144 and 145 the safety-valve was defective from the lever being bent, and the pressure accumulated to more than the boiler could bear, especially as the plates were thinned considerably by corrosion on the fire side. In the explosion of the vertical boiler shown in Fig. 146 the fire-box collapsed from shortness of water, the attendant being deceived by the water-gauge, the connecting pipes of which were choked. The explosion of the vertical boiler shown in Fig. 147 was caused by corrosion, the fire-box was much thinned by corrosion on the fire side and collapsed. Weakness, due to the plates of the fire-box being thinned on the fire side by corrosion, has been a fruitful cause of explosion of this type of boiler. 232 THE PRACTICAL ENGINEERS HAND-BOOK. Boiler Explosions may be said to proceed chiefly from the following causes: Corrosion; grooving or furrowing ; overpressure; overheating; injury to the plates from the heat impinging too much on one place; weakness ; deterioriation ; defects in design by which undue strains are thrown upon the materials ; improper setting ; inefficient repairs ; safety- valves sticking fast and allowing the pressure to accumulate beyond the working pressure ; weakening effects of unequal expansion ; weakness from wear and tear ; defects of workmanship and materials. Corrosion, both external and internal, by which the plates are gradually Fig. 148. Explosion of a Cornish-boiler irom corrosion of the shell. Fig. 140. Explosion of Conn-sh boiler from ex ternal corrosion. Fig. 150. Explosion of a marine-boiler from Cv-r- rosion of the combus- tion-chamber. wasted away or thinned, either uniformly or in large or small patches, is a very prevalent cause of boiler explosions. It can only be detected by careful periodical inspection of boilers both inside and outside, and requires 151. Exolosion of a ish-boiler from cor- rosion of the furnace- tube. Fig. 152. Explosion of a Lancashire-boiler from corrosion caused by contact with damp brickwork. attention even if it be confined to, a small patch, as the weakest part of a structure is the measure of its strength. External Corrosion is frequently caused by leaking seams, as was the case in the boiler shown in Fig. 148, which was much corroded outside irom leaking seams and inside from bad water ; the rent ran along longitudinal seams, and the upper part of the shell opened out like a lid. A bad case of external corrosion is shown in Fig. 149, the strength of the shell at the bottom of the boiler had been so reduced by external corrosion, that it ruptured and the rents spread over the whole shell, which was torn into three main pieces. The explosion of the marine-boiler shown in Fig. 150 BOILER EXPLOSIONS FROM CORROSION. 233 v.-as caused by corrosion. The bottom of the combustion chamber was so much corroded on the fire side, that it ruptured and part was forced upwards. External corrosion weakens the furnace-tubes of boilers. This was the cause of the explosion of the boiler shown in Fig. 151, the lower part of the furnace-tube of which was so much thinned and weakened by external corrosion, that it collapsed upwards. External corrosion may arise from a damp situation. It is frequently caused by contact with damp brickwork. This was the cause of the explosion of the boiler shown in Fig. 152, which gave way at the back end on the right-hand side, where the last plate was very much corroded from damp brickwork, the rent extended across this plate, and then up the seams on each side, for a length of 4 feet 5 inches, so that the plate opened out like a trap-door. The front end-plate and bottom of the front end of the shell is frequently corroded from the injurious practice of slacking ashes on the floor-plates. The bottom of the shell is frequently corroded by leakage from the joint of the blow-off pipe, and the blow-off pipe sometimes fractures from being wasted away by corrosion. Improper Setting frequently promotes external corrosion, as was the case with the exploded boiler shown in Fig. 153, which was externally Fig. 153. Explosion of a Lancashire-boiler from external corrosion, due to improper setting. corroded where it rested on a centre wall or mid-feather. It gave way at the bottom, and the fifth belt of plates was nearly torn out. Boilers should not be set in this way, because water from leaking seams or other sources settles on the mid-feather, and rapidly corrodes the plates. Fractured plates and leaking seams have frequently been produced by strains caused by the weight of the boiler not being evenly distributed along its seating, due to part of the foundation settling, and from want of care in replacing the seating after repairs. Internal Corrosion may be produced by bad feed-water, such as is obtained from wells in the neighbourhood of chemical works, or from mines or deep wells. These and other waters, and those impregnated with sewage, frequently contain free acids which rapidly corrode the boiler-plates. The action of these acids can in many cases be neutralized by the proper addition of soda. The feed-water used in the exploded boiler shown in 234 THE PRACTICAL ENGINEER'S HAND-BOOK. Fig. 154, was very corrosive, and the furnace-tube was rapidly reduced in strength by corrosion and collapsed downwards. In some cases the furnace-tube collapses up- /' -^. wards, as was the case in the boiler explosion shown in Fig. 155, which being much corroded internally, the back-end of the fur- - s , nace-tube was so much Fig. i 54 .-Ex P losion of a Cornish-boiler from collapse of furnace- Weakened that it Collapsed tube, from corrosion due to bad feed-water. Upwards f Or One-half of its length. Zinc is the Best Remedy for Internal Corrosion, a galvanic action being induced by the contact of zinc with the plates of the boiler. Zinc slabs, 12 inches long, 6 inches wide, and \ inch thick, are suspended in convenient parts of the boiler, one slab being used per 20 indicated horse- power, or i square foot- of slab to 2 square feet of fire-grate surface. Philip's method of applying zinc for this purpose, consists of a number of Fig. 155- Explosion of a Cornish-boiler from collapse of the furnace-tube, due to internal corrosion. Fig. 156. Philip's methpd of ap* plying zinc for the prevention of corrosion in steam-boilers. small discs of zinc fixed inside the boiler. Each disc or plate of zinc is attached to a stud about 4 inches long, projecting from the plates of the boiler, as shown in Fig. 156 : zinc-sleeves are also attached to the longitu- dinal stays. The proportions are i square foot of zinc to 50 square feet of boiler-plate-surface below the water-level. Zinc has also been used in steam-boilers as a disincrustant. Scrolls of sheet-zinc are said to be more efficacious than zinc-blocks. The sediment in boilers using zinc contains a considerable quantity of that metal. In one boiler employing this means of preventing incrustation, which was fed with water containing a large quantity of lime, the deposit collected when the boiler was cleaned was found to be of the following composition : Zinc-oxide Peroxide of iron Lime Magnesia . Sulphuric acid . Silica . Carbonic acid . 37-15 '35 2O'66 2-36 3^38 1-65 6-45 EXPLOSIONS OF LOCOMOTIVE-BOILERS. 235 The Electrogen is said to be very effective in preventing internal corro- sion. It consists of a ball of zinc with a copper conductor cast through its centre, the copper being so amalgamated with the zinc at the junction of the two metals as to form brass, so that corrosion cannot form between them to stop the galvanic current. The electrogen is fixed inside the boiler, a wire from each end of the conductor being brazed to the plates of the boiler, a constant galvanic current being kept up, by which the interior of the boiler is protected from corrosion, so long as the zinc lasts. Pitted Plates should be scraped and cleaned with a strong solution of soda to remove grease and acids, and then covered with a thin coat of Portland cement to fill up the pit-holes, by which means further wasting of the plate may generally be prevented. Grooving or Furrowing is caused by the bending backwards and for- wards of the plates of a boiler, either from expansion and contraction, or from alternations of temperature and pressure. It is often induced by caulking, which cuts through the skin of the plate, and promotes corrosion. When the end-plates of a cylindrical boiler are too rigidly stayed, it causes grooving either on the end-plates round the edges of the angle-iron, or flanges by which the furnace-tubes are attached to the end-plates, or at the root of the angle-iron, or corner of the flange if the furnace-tubes are flanged. When Cornish and Lancashire boilers have not been well set, or when the draught passed from the flue-tubes first along the side flues and then under the boiler, instead of passing first under the bottom of the boiler and last along the side-flues, the edges of the ring-seams at the lower part of the shell have been frequently found to be deeply grooved. Internal grooving is fre- quently found along the edge of longitudinal seams in the barrel of a locomo- tive-boiler, as shown in Fig. 157, when formed with an overlap j oint, which is caused by the tendency of the barrel to assume a perfectly circular form under pressure. This defect may be prevented by forming the seams with double butt-joints, as shown in Fig. 158, which permit the barrel to be made perfectly circular., Many locomo- tive-boilers have exploded from corrosive grooving, as was the case with the boiler shown in Fig. 159, which gave way at a longitudinal seam, deeply grooved or furrowed from the strain of being worked habitually at more pressure than it was able to bear safely. The locomotive-boiler shown in Fig. 160, gave way where it was grooved, or channelled by internal corrosion or furrowing, resulting from corrosion in a line of strain from continued bending of the boiler-plate backwards and forwards. Overheating may arise from shortness of water ; defective circulation ; a Fig. 157. Corrosive grooving. 58. Double butt rivetted-joint. 236 THE PRACTICAL ENGINEER'S HAND-BOOK. deposit of salt ; attachment of scale, which is a bad conductor of heat and prevents the water reaching the plates to carry off the heat ; a soapy deposit Fig. 159. Explosion of a locomotive- boiler from corrosive-grooving. Fig. 160. Explosion of a locomotive-boiler from corro- sive-grooving. of soda and grease ; a greasy deposit from a boiler composition. It may be due to the use of excessively thick furnace-plates ; badly arranged strengthening rings ; and to the impingement of flame against a double thickness of plate. Many cases of overheating have been caused by grease in the feed-water mixing with deposit in the boiler, and so thickening the water as to offer great resistance to the transmission of heat and cause the furnace crown-plates to become hot, and bulge down over the fire. In many other cases the furnace crown-plates have become hot, strained and bulged down from an accumulation of muddy or greasy deposit from boiler compositions, the plates having become lined with a glutinous coating, which prevented the water reaching the plates to carry off the heat. The Pouring of Cold Water into a Hot Boiler will not cause an explosion, because a large quantity of steam cannot be generated by throwing water on to a hot plate, owing to the low specific heat of the material, which cannot retain sufficient heat to generate much steam. Therefore the pressure of steam cannot be sufficiently augmented by turning the feed-water suddenly into an overheated boiler, to cause an explosion ; but the plates maybe seriously injured in this way, by the strain caused by sudden contraction after excessive expansion, and seam-rips are sometimes caused by the sudden contraction of the plates on filling the boiler with cold water while the bottom is hot after emptying. Explosions from overheating are generally caused by the plates softening and rupturing at the ordinary working-pressure of the steam. When a Boiler Explodes from Overheating, the crown-plates of the furnace-tube, having become hot and weakened, are forced inwards towards the furnace, and they usually bulge down, collapse, and rupture over the fire, as shown in Fig. 161. In other cases the top of the furnace-tube has bulged down and collapsed nearly its entire length, as shown in Fig. 162, from the weakening of the plates through shortness of water. The explosion of a marine-boiler caused by a deposit of salt is shown in Fig. 163. The boiler was worked with salt water, and, for want of sufficient knowledge, it BOILER EXPLOSIONS FROM WEAKNESS. 237 was not noticed that the salt had accumulated and caused collapse of the crown of the furnace-tube. These three examples present the usual appear- /T TT Fig. 161. Explosion of a boiler Irom ct.llapse of the furnace- tube from over-heat ng, due to shortness of water. 'ig. 162. Explosion of a Cornish- boiler from collapse of the furnace- tube from overheating, due to shortness of water. Fig. 163. CoV-. lapsed furnace- tube of a ma- rine-boiler which exploded from a deposit of tail. ance of a boiler furnace-tube collapsed from overheating of the plates from, deposit and shortness of water. Furnace-Plates in Fracturing from Overheating assume certain colours which denote the temperatures at which they were fractured. The fracture of the overheated plates becomes the following colours at the respective temperatures given: Bright yellow at 440 Fahr.. orange at 470, red at 510, violet at 530, blue at 560, green at 630 Fahr., and a dull bluish-grey colour at higher temperatures. The fracture of iron at temperatures between 212 and 360 Fahr. is of a clear, bright, whitish-grey colour, but these temperatures do not weaken iron. Shortness of Water may be due to inattention to water-gauges ; to. the feed-valve sticking fast or being out of order ; to failure in the supply of feed-water ; to excessive priming ; to leakage from fractured plates and pipes ; and to neglecting to shut the blow-off cock. Shortness of water was the cause of the explosion of the marine boiler shown in Fig. 164. The top of the combustion-chamber was so much weakened in this way* that it partially collapsed. Weak Furnace-Tubes have been the cause of many boiler explosions. The furnace-tubes of most old boilers are weaker than the shells, their cok Fig. 164. Explosion of a marine-boiler from collapse of combustion-chamber, due to shortness of water. Fig. 165. Explosion of a Cornish-boiler from,, a weak furnace-tube and overpressure. lapsing pressure being generally much less than the bursting-pressure of the shells. A weak furnace-tube was the cause of the explosion of the Cornish boiler shown in Fig. 165, the furnace-tube of which, being without: strengthening-rings, and much wasted by corrosion, collapsed in the manner shown, from over-pressure. 2$8 THE PRACTICAL ENGINEER'S HAND-BOOK. Over-pressure, relative to the strength of a boiler, may be due to either the safety-valve being overweighted, or to its sticking fast and being in- operative; to water freezing in the escape-pipe when the safety-valve, is bonneted, or to an accumulation of water in the escape-pipe ; to fixing the working-pressure of the steam too high for the condition of the boiler ; to overrating the strength of the boiler ; to ignorance of the quality of the plates ; and to the omission of making proper allowance for diminution of the strength of the plates from wear and tear. When a Weak Furnace-Tube fails from Over-pressure it usually collapses from end to end, and the bottom of the furnace-tube generally comes up to meet the top of the tube, that is, the tube collapses downwards at the crown and upwards at the underside at one and the same time. Weakness and over-pressure were the cause of an explosion of a Cornish boiler, the collapsed furnace-tube of which is shown in Fig. 166. The ' Fig. 166. Explosion of a Cornish-boiler from a weak furnace tube. rurnace-tube collapsed nearly from end to end, the bottom being forced upwards and ruptured. There were no strengthening rings, and the fur- nace-tube was so much reduced in thickness by corrosion that it was too weak to bear the ordinary pressure. When a Weak Boiler-Shell gives way from Over-pressure a rent may be made in the plate, or a piece of the shell may be blown out. Many boilers have been weakened and injured by shocks from the sudden opening and shutting of stop-valves ; from severe tensile strains from con- traction caused by the sudden impingment of cold water and cold air against hot plates ; by unequal contraction caused by introducing the feed- water at too low a point of the boiler; by the injudicious manner in which mountings are fixed on the boiler ; by frequent repairs, careless patching, and excessive caulking ; by emptying boilers under pressure and cooling them too hastily, and by emptying them while the surrounding brickwork is hot. Weakness from Wear and Tear has been the cause of numerous boiler-explosions. The defective condition of the boilers being due to their continuing at work too long, and being so much weakened by wear and tear as to be unsuitable for their working pressure, and they burst simply because the plates had worn too thin to any longer sustain the ordinary pressure. The explosions might have been prevented by reducing the working pressure to suit the age and condition of the boilers. Weak- ness from wear and tear was the cause of the explosion of the boiler shown in Fig. 167, the furnace-tube of which was so much reduced in thickness by long wear, that it was unable to bear the ordinary working pressure any longer, and it collapsed from end to end. Fractured Plates may be caused by overheating ; weakness ; brittb- DEFECTIVE MATERIALS OF BOILERS. 239 ness ; bad workmanship ; fatigue from long exposure to strains, due to variations of pressure ; unequal expansion of the material in different parts of the boiler ; want of freedom to expand and contract; and by sud- r . . ,_] J._ den contraction, due to / f " ! \~~^\ \ the impingement of cold -^ ' water or cold air on hot plates. Defects in the De- - ., i- v Fig. 167. Explosion of a Cornish boiler from collapse of the fur- Slg'll Ol Boilers Which nace-tube from weakness, due to wear ana tear. have led to explosions are : Impeded convection from crowded tubes ; defective circulation from crowded tubes ; defective circulation from cramped water-spaces ; insuffi- cient inclination of water-tubes ; omitting to provide holes in the shell, for manholes, domes, mudholes, and mountings, with strengthening rings ; oval manholes placed with the longest diameter in the longitudinal direc- tion of the boiler ; stays cut away to clear obstructions ; the use of cast- iron for mouthpieces and stand-pipes, or seatings for mountings, instead of wrought-iron or steel ; omitting to provide for expansion and contraction of the metal by heat ; errors in the arrangement of stays ; imperfect staying ; staying too rigidly ; omitting to stay flat surfaces ; stiffening flat end-plates instead of staying them ; omitting to strengthen furnace-tubes with strengthening-rings and flanged seams ; longitudinal seams placed in a continuous line from end to end, instead of being crossed. Defective Workmanship may be : Injuring, straining, or fracturing the metal in flanging, dishing, bending, hammering, or punching ; burning plates or rivets ; injuring or fracturing plates by drifting blind rivet-holes to force them in line ; careless caulking ; faulty riveting ; rivet-holes not fair, causing distorted rivets ; defective welding of stays and plates ; imper- fect threads on bolts and nuts, and in the holes for screwed stays ; and rivets not fitting their holes. Defective Materials may be : Weak rivets ; laminated, blistered or burnt plates ; plates of brittle, inferior, or hard quality, so much deficient in ductility, and of such an unyielding nature that they soon suffer under strain, and break instead of elongating as tough plates would do. It is essential that boiler-plates should be ductile, because when a plate is hard and unyielding, each rivet, and the plate between the rivet-holes, has frequently to bear an undue strain, which would be spread over a longer line in a tough plate. A severe strain may be caused by the giving-way of a rivet, or by the plate tearing between the rivet-holes, when the strain would come on the adjacent parts with a jerk. All steam-boilers should .be efficiently and periodically inspected by an independent authority. A Boiler, when not in use, may be preserved from corrosion by drying it thoroughly with brasiers of burning charcoal, and placing pans of quicklime inside, and afterwards closing all openings to prevent the admis- .sion of atmospheric air. The quicklime will absorb any moisture remain- ing in the boiler after it is closed. The boiler should be opened and the quicklime renewed at least twice a year. Another method is to fill the boiler quite full of water, if the water be not of a corrosive nature, and close all openings to prevent the admission of air. 240 THE PRACTICAL ENGINEER'S HAND-BOOK. Method of Testing a Steam-Boiler under ordinary working con- ditions. Connect the feed-pipe to a tank placed upon a weighing-machine, so that the water entering the boiler may be weighed. With the pressure of the steam and the level of the water in the boiler at the ordinary working- height, and the fires ready for stoking, clear out the clinkers and ashes, and note the condition and level of the fires and the level of the water in the water-gauge. Then commence the test: stoke the fires from a weighed heap of coal, and shovel into the furnaces all small coals and cinders which fall through the fire-bars during the trial. Regulate the draught by the damper to maintain a nearly uniform working-pressure of steam, without blowing off at the safety valves. Note the pressure of the steam and the temperature of the feed-water every half-hour. Towards the end of the test, allow the fires to burn down until ready for stoking, clear out the clinkers and ashes, and leave the fires as nearly as possible in the same condition at the end of the test as they were at the commencement. Weigh the clinkers and ashes and find the average of the steam pressures, and that of the temperature of the feed-water, and note the quantity of coal and water consumed. The results of the test may be calculated as shown by the following example : A Lancashire boiler 7 feet diameter, 28 feet long, with two furnace-tubes 33 inches diameter, having 33 square, feet of fire-grate surface, was carefully tested. It had heating-surface = internal Hues 398 square feet, Galloway tubes 56 square feet, external side flues 270 square feet, bottom 98 square feet, or a total of 822 square feet. The result being that, 2480 Ibs. of good small coal evaporated 20832 Ibs. of feed-water at 51 Fahr., to steam of 66 Ibs. per square inch average pressure, in five hours = 2480 Ibs. -r- 5 = 496 Ibs. of coal burnt per hour, and 496 Ibs.-f- 33 square feet = 1 5 Ibs. of coal burnt per square foot of fire-grate surface per hour. The weight of coal burnt per square foot of boiler heating-surface was = 496 Ibs. -r- 822 square feet = '63 Ib. per hour. The clinkers and ashes weighed 155 Ibs. = (155 x ioo)-r-248o Ibs. = 6-25 per cent, of the coal consumed. The water evaporated was 20832 Ibs. -7-5 hours= 4166-4 Ibs. per hour = 4166-4 Ibs. -f- 33 square feet = 126-25 Iks., or 126-25 Ibs, -*- 10 Ibs. = 12-625 gallons per square foot of fire-grate surface per hour; and =4166-4 lbs.-f-822 square feet of heating-surface=5 - o7 Ibs. of water per square foot of boiler heating-surface per hour. Then 20832 Ibs. of water -r- 2480 Ibs. of coal = 8-4 Ibs. of water evaporated per Ib. of coal. The total heat of steam of 66+15 = 81 Ibs. per square inch absolute pressure is, from table 79,= 1178 units, and the factor of evaporation is=(ii78 + 32) 51 temperature of feed water-f-966=r2, and 8*4 Ibs. of water x 1*2 = 10-08 Ibs. the equivalent quantity of water evaporated from and at 212 Fahr. The heat evolved during combustion was, = 2480 Ibs. of coal x icroS Ibs. of water x 966 heat-units per Ib. = 24i48454 units, and assuming the calorific power of the coal at i J.OOQ thermal units, the efficiency of this boiler is = Heat utilised 24148454 units. Heat supplied 2480 Ibs. x 14000 units y ' that is, presuming no water was carried with the steam from priming. By the rule on page 178, the power of this boiler is=(4 166-4 Ibs. per hour x 1-2 the factor of evaporation)-7-34'5 Ibs.= i67 actual horse-power. The nominal horse-power is = (4166-4 x 1-2) -f- 62-4 Ibs. per cubic foot = 80 nominal horse-power. SECTION III. STEAM, CONDENSATION, CONDENSERS, AIR- PUMPS, WATER-PUMPS ; SLIDE-VALVES, PISTON-VALVES, CORLISS AND OTHER VALVES ; LINK-MOTION AND OTHER VALVE-GEARS, ETC. SECTION III. STEAM, CONDENSATION, CONDENSERS, AIR- PUMPS, WATER-PUMPS ; SLIDE-VALVES, PISTON-VALVES, CORLISS AND OTHER VALVES ; LINK-MOTION AND OTHER VALVE-GEARS, ETC. STEAM : CONDENSATION : CONDENSERS AND AIR-PUMPS : WATER-PUMPS AND TANKS. The Pressure of Steam is equal in all directions, and it is usual to measure the pressure with reference to that of the atmosphere, which is equal to 147 Ibs. per square inch of surface, and is the measure of one atmosphere of pressure. Vapours, of which steam is one, do not follow the law peculiar to permanent gases, according to which the volume of a given weight is inversely as the pressure. It has been demonstrated on the contrary, that there exists a constant relation between the pressure, the density, and the temperature of steam ; such that the pressure cannot be raised above a given maximum, without, at the same time, a certain eleva- tion of temperature. Volume and Pressure of Steam. If the volume be forcibly reduced, and the vapour compressed, without any change of temperature, the com- pression has not the effect of augmenting the pressure, as would happen if air was similarly treated ; it only results in liquefying a portion of the steam, according as the volume is reduced, so that the volume, however reduced, will only contain so much proportionally the less of steam of the original pressure. In order to increase the pressure, the temperature must be raised. Point of Saturation of Steam. When the vapour has attained the limit of density and pressure, corresponding to the temperature, the steam is said to be saturated, and it is always in the state of saturation when in contact with water. For one pressure there is one density and one temperature ; and the higher the pressure, the greater is the density and the higher is the temperature. Expansion of Steam. When a quantity of steam is placed out of con- 244 THE PRACTICAL ENGINEER'S HAND-BOOK. tact with water, as in the cylinder of a steam-engine, it may be expanded, and again compressed up to the limit of saturation, and it will follow approximately, though not precisely, the law of Boyle or Mariotte ; that is to say, the pressure is nearly in the inverse ratio of the volume, insomuch that when the volume is doubled, the pressure is reduced to about one-half, and when the volume is trebled, the pressure is reduced to about a third. Superheated Steam. Superheated steam is amenable to the laws of permanent gases, and behaves as one of them, expanding and contracting in the inverse ratio of the pressure, when the temperature is constant, with- out the condensation of any portion of it. Density, Pressure, and Temperature of Steam. It follows from the above: ist. That one density and one pressure relative to one temperature are attained in a steam-boiler ; these several qualities are in equilibrium, and the steam is in a state of saturation. 2nd. That so long as the state of saturation corresponding to a given temperature is not attained, evaporation continues ; and when attained, evaporation ceases. 3rd. If the capacity of the boiler be increased, evaporation is resumed, until the state of saturation is again arrived at. Likewise, if the tempera- ture be increased, evaporation is resumed, and continues till the steam again becomes saturated. 4th. If the temperature falls, the pressure and the density fall also. 5th. If the boiler be closed, and the steam remain at the same temperature, the conditions remain unchanged. But, if an opening be made for the outflow of steam, the pressure will fall, and evaporation will be recommenced, until saturation is re-established. This new genera- tion of steam is very rapid, so much so that the pressure does not sensibly vary between and during the charges of steam taken from the boiler for each stroke of the piston. Economy in the production of Steam-power increases with the pressure of steam, because the total heat required to generate steam being the same for all pressures, the same quantity of fuel is required to evaporate a given weight of water whether the pressure be high or low, and the higher the pressure the greater the power. The relative value of steam of different pressures when used without expansion varies as the pressure x by the volume. Take for instance steam of 50 Ibs. and 150 Ibs. per square inch absolute pressure, and assuming an evaporation of 10 Ibs. of water per hour per Ib. of coal, then 10 Ibs. x 8*2 cubic feet per Ib. the volume of the steam x 50 Ibs. pressure = 4100, and 10 x 3 cubic feet per Ib. the volume of , 4500 4100 x 100 the steam X 150 Ibs. = 4500, or a gam of - = say 10 per cent. : if the steam were used expansively the gain by the higher pressure would be considerably greater, as the available rate of expansion increases with the pressure, and the percentage of back-pressure is less as the total mean-pressure is greater. Temperature of Saturated Steam. Steam when in contact with the water producing it, is at the maximum density consistent with that temperature and pressure, and is then called saturated steam, and its temperature is called the maximum temperature of saturation at the given pressure. A certain pressure accompanies a fixed temperature of steam and vice versd, so that one can not increase or decrease without a corresponding change in the other, as will be seen from Table 78. TEMPERATURE AND VOLUME OF STEAM. 245 Table 78. TEMPERATURE AND VOLUME OF SATURATED STEAM FROM THE EXPERIMENTS OF REGNAULT, FAIRBAIRN, AND TATE. Total Pressure o: the Steam in Ibs. per Square Inch, including the Pressure of the Atmosphere. Temperature in degrees, Fahrenheit. Volume or Number of Cubic Feet of Steam from one Cubic Foot of Water. Water = i at 39. Total Pressure of the Steam in Ibs. per Square Inch, including the Pressure of the Atmosphere. Temperature in degrees, Fahrenheit. Volume or Number of Cubic Feet of Steam from one Cubic Foot of Water. Water = i at 39. 1 102 17,985 41 269 6l 4 2 127 io,355 42 271 6OO 3 142 7,285 43 272 587 4 154 5,610 44 273 574 5 I6 3 4,567 45 275 562 6 171 3,852 46 2 7 6 55i 7 177 3'33 2 47 277 539 8 I8 3 2,93 6 48 279 529 9 189 2,625 49 280 5i9 10 194 2,375 50 28l 509 ii 198 2,167 51 283 499 12 2O2 ,994 52 284 490 13 206 ,846 53 285 482 14 2IO ,720 54 286 473 147 212 ,642 55 287 465 15 213 ,609 56 288 457 16 217 ,512 57 290 450 17 220 ,427 58 2 9 I 443 18 223 ,350 59 292 436 19 226 ,282 60 2 93 429 20 228 ,220 61 294 422 21 2 3 I ,165 62 295 416 22 234 >"3 63 296 410 23 2 3 6 ,067 64 297 404 24 2 3 8 ,024 65 298 398 25 240 985 66 2 99 39 2 26 243 948 67 300 387 27 245 9'5 68 301 382 28 247 883 69 302 377 29 249 854 70 303 372 3 251 827 71 34 367 3 1 253 801 72 305 362 3 2 254 767 73 306 357 33 2 5 6 755 74 307 353 34 2 5 8 734 75 308 349 35 260 7H 76 39 344 36 26l 695 77 310 340 37 263 677 78 310^2 336 38 26 4 660 79 3 11 S3 2 39 266 644 80 312 329 40 268 628 81 3*3 325 246 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 78 continued. TEMPERATURE AND VOLUME OF SATURATED STEAM. Total Pressure of the Steam in Ibs. per Square Inch, including the Pressure of the Atmosphere. Temperature in degrees, Fahrenheit. Volume or Number of Cubic Feet of Steam from one Cubic Foot of Water. Water = 1 at 39. Total Pressure of the Steam in Ibs. per Square Inch, including the Pressure of the Atmosphere. Temperature in degrees, Fahrenheit. Volume or Number of Cubic Feet of Steam from one Cubic Foot of Water. Water = i at 39. 82 314 321 125 345 2 2O 83 315 318 I 3 348 212 8 4 3 l6 3M 135 350 2O6 85 JIO'J 3 11 140 353 198 86 317 308 145 356 193 87 318 34 150 359 I8 5 88 3'9 301 155 362 1 80 89 320 298 1 60 364 175 90 320-2 295 165 367 170 9 1 321 292 170 3 6 9 I6 5 92 322 289 175 37i 1 60 93 3 2 3 286 1 80 373 I 5 6 94 323-3 284 185 376 152 95 324 281 190 378 149 96 325 278 195 380 H5 97 326 276 2OO 382 142 98 327 273 2IO 387 136 99 327-2 271 22O 390 130 100 328 268 230 394 124 105 S3 2 257 240 398 I2O no 335 246 2 5 402 "5 "5 338 238 275 410 109 I2O 342 228 3 00 418 97 The Properties of Saturated Steam are given in the following table. Table 79. WEIGHT, VOLUME, TOTAL HEAT, AND LATENT HEAT OF STEAM FROM THE EXPERIMENTS OF REGNAULT, FAIRBAIRN, AND TATE. TOTAL PRESSURE. WEIGHT. VOLUME. UNITS OF HEAT. UNITS OF HEAT LATENT. In Ibs. per Square Inch. In Inches of Mercury. In Ib. per Cubic Foot. Cubic Feet per !b. Total per ib. from 32 Fahr. Latent Heat per Ib. I 2-037 0034 289 III 3 1044 2 4-074 OO6O 1 66 II2I IO27 3 6-i 1 1 0086 117 1126 1016 4 8-148 'OII2 90 1129 1008 5 10*185 0137 74 II 3 2 1001 6 I2'22 Ol62 62 U34 996 7 14-26 0188 54 1136 8 16-29 0213 47 1138 987 1 WEIGHT AND VOLUME OF STEAM. 247 Table 79 continued. WEIGHT, VOLUME, ETC., OF STEAM. TOTAL PRESSURE. WEIGHT. VOLUME. UNITS OF HEAT. UNITS OF HEAT LATENT. In Ibs. per Square Inch. In Inches of Mercury. In Ib. per Cubic Foot. Cubic Feet perlb. Total per Ib. from 32 Fahr. Latent Heat per Ib. 9 I8'33 0238 42 II4O 983 10 20-37 0263 38 II4I 979 ii 22-4I 0288 35 H43 978 12 24-44 "OS'S S 2 1144 973 J 3 26-48 0338 30 1145 971 14 28-52 0363 28 1146 968 147 29-92 0380 27 "47 966 15 3055 0388 26 "47*5 965 16 32"59 0413 25 1148 9 6 3 17 34-63 0438 2 3 1149 961 18 36-67 0463 22 1150 959 !9 38-7I 0487 21 1151 958 20 40-74 0512 2O 1152 956 21 42-78 0536 J 9 "53 953 22 44-82 0561 1 8 "53*5 95i 2 3 46-85 0586 ?7 1154 950 24 48-89 0610 16-5 H55 948 25 50-93 0634 16 1156 946 26 52-97 0659 15-2 1156-5 945 27 55-00 0683 14-7 "57 943 28 57-04 0707 14-2 "57*5 942 2 9 59-08 0731 13-7 1158 940 30 6rn "0755 I3-3 "59 939 3 1 63-15 0780 12-9 1159-5 938 3 2 65-19 0804 12-5 IIOO 93 6 33 34 67-23 69-26 0828 0850 I2'I n-8 1 160*5 1161 935 934 35 71-30 0875 11-5 1161-5 933 36 73-34 0899 ira 1162 93i 37 75-38 0923 10-9 1162-5 93 38 77-4I 0947 10-6 1163 929 39 79-45 0971 10-4 1163-5 928 40 81-49 0994 lO'I 1164 927 41 83-52 1018 9-9 1164-5 926 42 85-56 -1041 9'7 1165 925 43 87-60 1065 9'4 1165-5 924 44 89-64 1088 9-2 1166 923 45 91-67 III2 9-0 1166-5 922 46 93-71 '"35 8-9 1166-8 921 47 95-75 1158 8-7 1167 920 48 97-98 1182 8-5 1167-5 919 49 99-82 -1205 8-3 1167-8 918 2 4 8 THE PRACTICAL ENGINEER'S HAND-BOOK, Table 79 continued. WEIGHT, VOLUME, ETC., OF STEAM. TOTAL PRESSURE. WEIGHT. VOLUME. UNITS OF HEAT, UNITS OF HEAT LATENT. In Ibs. per Square Inch. In Inches of Mercury. In Ib. per Cubic Foot. Cubic Feet perlb. Total per Ib. from 32 Fahr. Latent Heat per Ib. 50 101-86 1228 8-2 1168 917 51 103-90 1251 8-0 1168-5 916 52 105-93 1274 7'9 1168-8 9*5 53 107-97 1297 7'7 1169 914 54 IIO'OI I32O 7-6 1169-5 9*3 55 112-04 1343 7'5 1169-8 912 56 114-08 I 3 66 7'3 1170 911-5 57 Il6'I2 1389 7-2 1170-5 911 58 118-16 1412 7-1 1170-8 910-5 59 1 20*19 -I 434 7'o 1171 910 60 122*23 1457 6-9 1171-5 909-5 6* 124-27 1479 6-8 1171-8 909 62 126-30 1502 67 1172 908 63 128-34 1525 6-6 1172-5 907 64 130-38 -1547 6-5 1172-8 906-5 65 132-42 1570 6-4 H73 906 66 J 34'45 1592 6'3 1173-5 905 67 i3 6 '49 1613 6=2 1173-8 904 68 I38-53 1637 6' 1174 93 69 140-36 1660 6-0 1174-5 902 70 142-60 1682 5'95 1174-8 901 7i 144-64 1704 5-90 "75 900' 5 72 146-68 1726 5-81 "755 900 73 148-72 1748 573 1175-8 899-5 74 150-75 1770 5-66 1176 899 75 152-79 1792 5-60 1176-5 898 76 154-83 1814 5-52 1176-8 897-5 77 156-86 1836 5'45 1177 897 78 158-90 1858 5-40 1177-2 896-5 79 160-94 1880 5'3 2 1177-6 896 80 162-98 1902 5-26 1177-8 895 Si 165-01 1924 5'2i 1178 894 8s 167-05 1946 5-I5 1178-2 893 83 169-09 1967 5-10 1178-6 892-5 84 171-12 1989 5-03 1178-8 892 85 173-16 2OII 4-98 1179-2 891 86 175-20 2032 4-93 1179-6 890-5 87 177-24 2054 4'88 1179-8 889 83 179-27 2075 4-82 1180 888-6 89 181-31 2097 4-78 1180-2 888-2 90 183-35 2119 4-73 1180-5 888 9 1 185-38 '7140 4-68 1180-7 887-5 WEIGHT AND VOLUME OF STEAM. 249 Table 79 continued. WEIGHT, VOLUME, ETC., OF STEAM. TOTAL PRESSURE. WEIGHT. VOLUME. UNITS OF HEAT. UNITS OF HEAT LATENT. In Ihs. per Square Inch. In Inches of Mercury. In Ib. per Cubic Foot. Cubic Feet perlb. Total per Ib. from 32 Fahr. Latent Heat per Ib. 92 187-42 2161 4-63 Il8o'9 887 93 189-46 2l82 4'59 1181 886-6 94 I9I-50 2203 4'54 1181-2 886 95 '93'53 2225 4-50 1181-5 885-7 96 I 95'57 2246 4-46 1181-7 885-3 97 197-61 2268 4-42 1181-9 885 98 199-65 2288 4-38 Il82 884-6 99 201-68 2309 4'34 II82-2 884 100 203-72 233 4"3G 1182-5 8837 IOI 205-76 '235 1 4-26 1182-8 883 102 207-79 2372 4-22 1183 882-4 I0 3 209-83 2393 4-18 1183-3 882 104 211-87 2414 4-15 1183-6 881 105 213-91 '2434 4-11 1183-8 880 106 215-94 2455 4-08 1184 879-6 107 217-98 '2475 4-04 1184-2 879-5 108 220-02 2497 4-01 1184-5 879 109 222*05 2517 3-98 1184-8 8785 no 224-10 2538 3'95 1185 878 III 226-13 2559 1185-2 877-5 112 228-14 2571 3-88 1185-5 877 1J 3 230-20 260O 3-85 1185-7 876-6 114 232-24 -2621 3-82 1185-9 876 115 234-28 2640 379 1186 8757 120 244-40 2743 3-65 1186-7 874 I2 5 254-60 2843 352 1187 871 I 3 264-80 2942 3-40 1188 869 135 275-00 3041 3-29 1189 867 I4O 285-20 > 3 I 39 3 -I 9 1190 865 us 295-40 3236 3-10 1191 ^ 3 150 305-60 3332 3-00 1192 861 J 55 31573 3450 2-91 1192-4 860 i So 325-92 3548 2-83 1193 858 165 336-10 3674 275 "94 857 170 346-29 3770 2-67 1194-7 855 i75 356-48 3876 2-60 1195 853 1 80 366-84 3882 2-52 1196 852 185 376-85 4092 2-46 1196-5 850 190 387-03 4178 2-42 1197 849 J 95 397-22 4285 2-36 1197-6 847 200 407-40 4385 2-30 1198 846 2IO 427-77 4590 2'2O 1200 842 250 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 79 continued. WEIGHT, VOLUME, ETC., OF STEAM. TOTAL PRESSURE. WEIGHT. VOLUME. UNITS OF HEAT. UNITS OF HEAT LATENT. In Ibs. per Square Inch. In Inches of Mercury. In Ib.per Cubic Foot. Cubic Feet per Ib. Total per Ib. from 32* Fahr. Latent Heat per Ib. 22O 448-14 4800 2-10 1201 840 2 3 4D8-5I 5OIO 2'OO I2O2 837 240 4 88-88 52OO I'Q2 I2O3 8 34 250 509-25 5420 1-86 I2O4 832 275 560-18 5926 1-68 I2O6 825 300 6irio 6439 1-56 I2IO 820 35 9UW5 7452 J '35 1213 811 400 814-80 8457 I'2O 1218 801 Boiler-Pressure as shown by the Steam-gauge is the pressure of steam above the atmosphere. The Absolute Pressure of Steam is the total pressure of steam in Ibs. per square inch, reckoned from vacuum, or including atmospheric pressure, or the pressure shown by the steam-gauge plus the pressure of the atmosphere. Initial Pressure is the pressure of steam when admitted to the cylinder at the beginning of the stroke. Terminal Pressure is the pressure of steam when discharged from the cylinder. The Plow of Steam through an Orifice with a square edge is 15 per cent, less than through an orifice with a rounded edge. The Plow of Steam is neither increased nor diminished by reducing the outside pressure below about 58 per cent, of the absolute pressure in the boiler, for example the same weight of steam would flow from a boiler under 100 Ibs. pressure into steam of 58 Ibs. absolute pressure as into the atmosphere. The Weight of Steam that will Flow in 70 seconds into a space in which the pressure does not exceed 58 per cent, of the gross pressure of the steam, is equal to the gross pressure of the steam upon an area equal to the area of the orifice. Hence the loss of steam and fuel due to a crack in a cylinder, may easily be calculated. Example: Steam escapes through a crack, of 1-25 square inches area, in the metal between the exhaust port of the low pressure cylinder of a compound engine and the steam-jacket, which contains steam of 60 Ibs. pressure by the gauge. If i Ib. of coal produces 8 Ibs. of steam, what is the loss of steam and coal in 24 hours due to the crack ? Then 60 + 15 = 75 Ibs. per square inch absolute pressure of the steam, 75 x 1-25 x 60 minutes x 60 seconds and -= 4821-428 Ibs. of steam 70 seconds lost per hour; and 4821-428 x 24 hours = 11571^272 Ibs. of steam, or 115714-272 -f- 2240= 51*658 tons of steam lost in 24 hours, and 51*658 -"- 8 = 6-457 tons of coal lost in 24 hours. SUPERHEATED STEAM. 251 The Pressure of Steam when an engine is working at less than its normal speed may be found by the following Rule : normal pressure x (reduced revolutions) 2 (normal revolutions) g Example : An engine makes 62 revolutions, its normal speed when the pressure of steam is 70 Ibs. per square inch, the speed becomes reduced to 50 revolutions, what is the pressure of the steam ? Then 7 X 5 ^ 5 = 45.57 Ibs. pressure per square inch. Superheated Steam is steam which has been isolated from water, and further heated to form gaseous steam or steam-gas. Superheated steam is usually produced by means of a super- heater, composed of tubes placed be- tween the boiler and the chimney, and heated by the waste products of com- bustion which pass between and sur- round the tubes on their way to the chimney. The steam passes through the superheater before entering the cylinder. Fig. 167 A shows the plan of a super- heater attached to the steam-pipes of four marine boilers : A is the super- heater, over which stands the funnel ; B the uptakes leading the smoke from the smoke-boxes to the chimney; the stop-valves are shown at C. The Limit of Temperature of Superheated Steam is about 380 Fahr. ; at higher temperatures the packing of the glands becomes charred, the lubricants are destroyed, and the faces of the valves and cylinder become injured. Superheated Steam expands nearly at the same rate as a perfect gas, according to the experiments of Fairbairn and Tate, who give the following formula for the expansion of superheated steam: Where V = the volume of steam at the temperature /. V 1 = the volume of steam at the temperature t\ V _ 438 + / Vi 438 + /i This formula is a modification of that given below by the same authorities. The rate of expansion of a perfect gas, R, or the fraction expressing the increment of volume for one degree of temperature Fahr., may be found by the following formula, where / is the temperature of the gas : R = l - , thus at 212 Fahr., the rate of expansion of a perfect gas 459 + / is . ? = JL, and at 320 Fahr., it is = JL. 459 + 2I2 6 7 r 459 + 3 2 779 Fig. i67A. Superheater. 252 THE PRACTICAL ENGINEER'S HAND-BOOK. Superheating prevents partial condensation in the cylinder, and conduces to economy in the consumption of fuel. Mr. Fairbairn* gives the following table of the expansion of superheated steam : Table 80. EXPANSION OF SUPERHEATED STEAM FROM THE EXPERIMENTS OF FAIRBAIRN AND TATE. Maximum Temperatui e of Saturation. Temperatures between which the Expansion is taken. Co-efficient of Expansion of Steam. Co-efficient of Expansion of Air. Degrees Fahr. 13677 140 and 170 ^ T*T !55'33 160 190 Tie i -6T9- i59'3 6 159-36 170-2 TTcT eiir i59'3 6 170-20 209-9 i "6T4" eie 171-48 171-48 1 80 -2&0 tto 171-48 ISO'OO 200 ~erb~* Trhr 174-92 174-92 186 T*T eir 174-92 180-00 200 eir air 182-30 182-30 186 irio air 182-30 186 209-5 eio air 188-30 191 211 <&* aio 242-90 243 249 ifr r^ 255-50 257 259 STT rb> 255-50 257 264 tto Tir 267-21 268 271 f0 rh 267-21 271 279 aio rio 269-20 271 273 *** rio 269-20 273 279 T*T ria 279-42 283 285 ~2~1T8 TiT 279-42 285 289 5^3 rir 292-53 297 299 lir T*7T 292-53 299 302 i "eTs" ri Dr. Siemens found that steam of 212 Fahr., superheated but maintained at atmospheric pressure, augmented rapidly in volume until the temperature rose to 220, and less rapidly up to 230, or 18 degrees above saturation- point, from thence it behaved like a permanent gas. Ordinary saturated steam may be made gaseous by superheating it to from 10 to 25 degrees. A Separator is an apparatus for depriving the steam of any water it may have carried with it from the boiler. In its simplest form, it consists of a cast-iron cylinder, as shown in Fig. 168, having a diaphragm, or partition- plate, extending from the top to a little more than half the depth of the casting. It is connected to the steam-pipe between the boiler and the engine ; the steam enters at the top on one side and strikes against the partition-plate, which disengages the particles of water carried from the boiler with the steam which fall to the bottom of the separator. The steam passes under * See "Mills and Millwork," published by Longmans & Co., London. METHODS OF DRYING STEAM. 253 the partition-plate, and leaves the vessel at the opposite side to which it entered : a cock is fitted to the bottom of the separator for the purpose of drawing off the water, and a water-gauge is fitted to show the depth of Fig. 168. Separator. Fig. 169. Separator. water. Care must be taken to prevent the water rising too high and closing the passage for the steam. A Separator of another form is shown in Fig. 169. It has a grating at the bottom, through which the water is drained into a Hanson's steam-trap, by which the water is carried off automatically. A Separator of improved construction and very efficient in its action, is shown in Fig. 170. The steam traverses a spiral passage, which effects the disengagement of the particles of water carried with the steam. The water falls to the bottom of the vessel, whence it is drained off by a cock ; or automati- cally by connecting the drain- pipe to a steam-trap. The depth of water is shown by a water-gauge. A Steam -Drier, shown in Fig. 171, is an apparatus for evaporating the particles of water which the steam may have carried with it from the boiler. It dries and slightly superheats the steam, and pre- vents partial condensation in the cylinder. It is fixed between the boiler and the Fig. 171. Steam-drier. Fig. 170. Improved separator. chimney, and is heated by the gaseous products of combustion, part of which pass through the centre tube of the drier. The steam passes through the drier on its way to the cylinder. Condensation of Steam. The weight of water to be mixed with steam to produce water of a certain temperature may be found as follows : 254 THE PRACTICAL ENGINEER'S HAND-BOOK. Let S = Ibs. of steam of a given pressure. H = the number of units of heat in the steam from 32 Fahr. W = the weight in Ibs. of water per Ib. of steam used to condense with. / = the temperature of the water per Ib. of steam used to condense with. T = the temperature of the water produced. The steam loses S (H T) units of heat, and the water gains W (T /) units of heat. Then W = HZ!. Example : What weight of water at 50 Fahr. must be mixed with 10 Ibs. of steam of atmospheric pressure to produce water at 100 Fahr. The number of units of heat in steam of atmospheric pressure = 1178*6. Then II7 = 21-57 Ibs. of water for each Ib. of steam, and 10050 21.57 x 10 Ibs. of steam = 2157 Ibs. total weight of water required to be mixed with that weight of steam to produce water at 100 Fahr. The Temperature of the Condensed Water may be found as follows : The notation being the same as in the previous formula. Then T 1178-6 +(W x/) W + i Example: Required the temperature of the water produced from the mixture of water and steam given in last example. Then 1178-6 + (2r57 x 5o) = I00 o Fah the temperatur e O f the water 21-57 + i produced by that mixture of water and steam. Condensation of Steam. The following Rule is sometimes used for finding the quantity of water required to condense steam. Let T = the temperature of the steam. / = the temperature of the water to be produced. y 1 = the temperature of the water used to condense with. S = Ibs. of steam of a given pressure. W = the weight of water in Ibs. per Ib. of steam used to condense with. Example : Taking the particulars from the former example, the tempera- ture of the steam = 212 Fahr. Then this Rule will give IOO + ( 2I2 - IO ) 10050 = 22-22 Ibs. of water for each Ib. of steam, and 22*22 x lolbs. of steam, 222 -2 Ibs. of water required to be mixed with the given weight of steam. CONDENSATION OF STEAM. 2^5 The Temperature of the Water produced may be found by the converse of the previous Rule. X/ + T - Taking the particulars from the former I example, this Rule will give IOOO+ ^ *5) + 212 = IQQ temperature of the water produced by the mixture of water and steam. Condensation of Steam. The following Rule is sometimes used, although it is not strictly accurate, for finding the weight of water required to condense steam. One Ib. of steam when it is condensed, is considered to be capable of raising 1000 Ibs. of water i Fahr. Let T = the tempera- ture of the water to be produced, / = the temperature of the water used to condense with, W = the weight in Ibs. of water per Ib. of steam required to condense the steam. Then W = -- Taking the particulars from the previous example, this Rule will give - -- = 20 Ibs. of water required per Ib. of steam, and 20 x 10 Ibs. of steam = 200 Ibs. of water to be mixed with the given weight of steam. The Temperature of the Water produced may be found by the converse of the previous Rule. Thus T = I00 \~ ^-i Taking the particulars from the previous example, this Rule will give IOO + ^ X 5o) = 100 Fahr., the tempera- ture of the water produced by the mixture of water and steam. Condensation of Steam. The following formula is sometimes used for finding the weight of water required to condense steam : the notation being the same as in the previous formula. W = 5 ~ . Taking the particulars from the previous example, this Rule will give II 5~ IO _ 2I ^ s< o f wa ter required perlb. of steam,. 10050 and 21 x lolbs. of steam = 210 Ibs. of water to be mixed with the given weight of steam. The Temperature of the Water produced may be found by the converse of the previous Rule. Thus T = m+i W x / ). Taking the particulars from the previous example, this Rule will give T = " 5 + (zl X 5o) = 100 Fahr., the temperature of the water produced by the mixture of water and steam. 2$6 THE PRACTICAL ENGINEER'S HAND-BOOK. Efficiency of Steam in an Engine. It is not possible to convert all the heat-energy initially in the steam into mechanical energy even in the cylinder of a perfect engine, if such could be made. In a perfect heat- engine, the heat would be supplied at the highest temperature and dis- charged at the lowest. The zero of Fahrenheit's thermometer is 461 degrees above the point of absolute cold or zero, at which point both the volume and pressure of a gas shrink to nothing. If the highest temperature, or that of the initial absolute pressure of the steam be denoted by T i; and the lowest temperature, or that of the, steam as it enters the condenser or atmosphere, by T 2 , the efficiency, E, of a perfect heat-engine would be expressed by the following formula : T T E = rp * / . This represents the greatest theoretical efficiency which can possibly be obtained in any heat-engine, and it is the standard by which the actual efficiency of an engine should be compared. As an Example of the above formula : Required the efficiency of a perfect con- densing steam-engine, using steam of 90 Ibs. per square inch initial pressure, or 105 Ibs. per square inch absolute pressure, the final pressure or pressure of the steam when it is discharged from the cylinder into the condenser being 2 Ibs. per square inch, or 13 Ibs. below atmospheric pressure. Then the temperature of steam of 105 Ibs. per square inch absolute pressure is from Table 78 = 332 Fahr. : the temperature of steam of 2 Ibs. per square inch absolute pressure is = 127 Fahr., and -r-=. -2 5 8 5, or say 26 per cent., the percentage of the total heat in the steam which could be converted into work. It will be seen from Table 79, that each Ib. of steam of 105 Ibs. absolute pressure per square inch contains 1 183-8 units of heat, and as 26 per cent, of the heat would be utilised in a perfect engine, 1183-8 x -26 = 307788 units of heat would be converted into work for each Ib. of steam used. As one unit of heat is equal t- 772 foot Ibs. of mechanical energy, 772x307-788 units=2376i2'336 foot Ibs. would be obtained per Ib. of steam used, equal 237612-336 to r= = 7' 2 Horse-power. The Efficiency of an engine relatively to that of a perfect heat-engine, working between the same limits of temperature, may be found by this Rule : . Actual efficiency of the engine. Efficiency of engine = Efficiency of a perfect heat-engine." Final Temperature of Steam in a Cylinder or Condenser. In a -non-condensing engine, the exhaust port being open to the atmosphere, there is a back-pressure =15 Ibs. per square inch atmospheric pressure, plus 5 Ibs. per square inch, the power necessary to drive the engine against its own friction, and to expel the exhaust steam from the cylinder ; so that the lowest terminal absolute pressure is 20 Ibs. per square inch, and the lowest temperature 228 Fahr. In a condensing engine there is always vapour in the condenser of at least 3 Ibs. pressure per square inch, which, added to the power necessary to drive the engine against its own friction POWER OBTAINED BY USING A CONDENSER. 257 and to the resistance to the escape of the steam from the condenser due to the friction of the exhaust passages, equal to 5 Ibs. per square inch, gives 8 Ibs. per square inch, the lowest terminal absolute pressure and the lowest temperature is 183 Fahr. Therefore, if a non-condensing engine and a condensing engine were each worked with steam of 89 Ibs. per square inch initial absolute pressure, the temperature of which is 320 Fahr., the non- condensing engine would work between the limits of temperature of 320 and 228 Fahr., and the condensing engine between the limits of temperature of 3 20 and 183 Fahr. The theoretical efficiency of the steam in the con- densing engine would be * | = 1-48 times greater than that in the non-condensing engine. A Vacuum is an empty space, or a space void of all pressure. A vacuum in the condenser of a steam-engine means absence of pressure. The vacuum is never perfect in the condenser, owing to the presence of a small quantity of air and vapour, and it is influenced by the temperature in the condenser. The pressure of vapour at 32 Fahr. is -089 lb., there- fore the vacuum is nearly perfect at that temperature, the usual temperature of the water in the condenser is 100 Fahr., at which the pressure of vapour is '942 lb., or in round numbers i lb. Hence the degree of vacuum rapidly diminishes as the temperature of the water in the condenser is increased, and the temperature of the condenser will always show the state of the vacuum. The Loss of Vacuum due to an Increase of Temperature in the Hot-well may be calculated by the following Rule, where T = the greater temperature and / = the less temperature. Decrease of vacuum = (T-/) x (T- 5 o) x (/-so). Example: The normal temperature of the water in the hot-well is 103 Fahr., and the vacuum in the condenser is 12 Ibs., but owing to an accident the temperature of the water in the hot-well increased to 128 Fahr. What will the decrease of vacuum be and what will the vacuum be now ? (128103) x (128 50) x (103 50) Then 100000 r 33 lb- decrease of vacuum, and the vacuum will now be = 12 i'O33 = 10-967 Ibs. A Vacuum is produced by condensation of steam in the jet-condenser of a condensing engine, into which the steam passes from the engine- cylinder, where it comes in contact with a jet of cold water. The steam is condensed by the cold water, and falls in the form of hot water to the bottom of the condenser, and a vacuum is formed above the water. The water and any air it contains, or which may have entered with it, is pumped out of the condenser by the air-pump, leaving only a slight vapour in the condenser, say, of 3 Ibs. pressure, which, deducted from the atmospheric pressure, leaves 12 Ibs. as the pressure removed by the condenser, which opposed the advance of the piston, the resistance thus removed being equivalent to an equal amount of steam-pressure on the piston. The Power obtained by using a Condenser may easily be calculated. For instance, if a non-condensing engine with cylinder 18 inches diameter, length of stroke 3 feet, number of revolutions per minute 50, were con- 258 THE PRACTICAL ENGINEER'S HAND-BOOK. verted into a condensing-engine, the power gained by using a condenser would be as follows : Say the pressure in the condenser is 3 Ibs., then 15 Ibs. atmospheric pressure 3 = 12 Ibs. vacuum, equivalent to 1 2 Ibs. per square inch steam pressure, and 18 x 18 inches x 7854 x 12 Ibs. x (3 feet x 2 x 50)^ 6 Horge 33000 power gained by converting the non-condensing engine to a condensing engine. The Temperature of the Water in the Condenser is usually about 100 Fahr., at this temperature the steam is sufficiently condensed, and a minimum quantity of condensing water is lifted by the air-pump. If the water enters the condenser at a temperature of 50 Fahr. and leaves it at 100 Fahr., out of every unit of water 100" 50= 50 of cold are available for condensing the steam. The Quantity of Water required for Condensation in Condensing- Engines, taking the above temperatures, may be found as follows : Taking the total amount of heat in a given unit of steam at 1178 units Fahr. The heat imparted to each unit of water is ioo 50= 50 units. Of the 1178 units of heat in each unit of steam, it must give up 1178100 = 1078 units, and the units of water required will be io78-h5O=2i'56. A cubic foot of steam is produced by a cubic inch of water, therefore, each cubic foot of steam will require 21-56 cubic inches of water to condense it. And each cubic inch of water evaporated to steam will require 21 '56, or, say, 22 cubic inches of water at 50 Fahr. for condensation, and will form altogether 23 cubic inches of wate'r in the hot-well at 100 Fahr.; in practice rather more than this quantity is required, and it is usual to allow from 27 to 30 cubic inches of injection- water for every cubic inch of water evaporated to steam in the boiler. The Weight of Injection- Water in Ibs. required to Condense 1 Ib. of Steam may be found by this Rule : Condensing water in Ibs. = 1150 temperature of hot-well temperature of hot-welltemperature of injection- water' Example: If the temperature of the injection-water be 52 Fahr. and that of the hot-well 100 Fahr., how many Ibs. of injection-water will be required to condense i Ib. of steam ? Then, "50- lo g! = 2I -8 7 Ibs. of injection-water. The Quantity of Injection -Water in tons is frequently calculated by the following rule, where I. H.-P. = Indicated horse-power Tons per day = I. H.-P. x Ibs. of steam per I. H.-P. x 1000 x 10 hours. 2240 x (temperature of hot-well temperature of injection- water)' Example : The indicated horse-power of an engine is 800, it uses 20 Ibs. of steam per I. H.-P. per hour. If i Ib. of steam on being condensed gives cut sufficient heat to raise 1000 Ibs. of water i Fahr., and if the JET-CONDENSERS. 259 temperature of the injection-water be 52 Fahr. and that of the discharge- water 104, how many tons of injection-water are used in a day of 10 hours? ~, 800 H.-P. x 20 Ibs. steam x 1000 x 10 Then, - - - - = 1374 tons. 2240 x (104- 52) The Temperature of the Hot-Well may be calculated from the weight of injection-water used by the following Rule : 1150 + (Ibs. of injection-water x its temperature) Ibs. of injection-water -f i. Example : If the temperature of the injection-water be 68 P'ahr., what will the temperature of the hot-well be if 24 Ibs. of water be required to condense i Ib. of steam ? 680) =n 2 Fahr., the temperature of the 24+ i hot-well. The Increase in Evaporation due to an Increase in Tempera- ture of the Hot- Well may be found by the following Rule : T = the greater temperature, and / the less temperature of the hot-well, and E the rate of evaporation. Increase of evaporation = (noo + (T - /)) x E^ noo Example : The evaporation was 8| Ibs. of water per Ib. of coal, the temperature of the hot- well being 104 Fahr. If the temperature of the hot-well increased to 138 Fahr., what would the evaporation be? Then, ("co + (138 -.104) x 8-5 Ibs. = g fi ^ 1 100 poration is counterbalanced by the loss of vacuum. Jet-Condensers. One method of effecting condensation to produce a vacuum in a condensing-engine is to discharge the exhaust steam from the cylinder into an air-tight vessel, or condenser, where it comes in contact with a jet of cold water, which absorbs the calorific properties of the steam. A Vertical Jet-Condenser for a beam-engine is shown in Fig. 172. The exhaust-steam passes from the engine-cylinder through the pipe A, to the condenser u ; c is a valve for the admission of cold water into the condenser, where it is discharged through a rose at the end of the injection pipe ; D D are the foot-valves ; E is the passage from the con- denser to the air-pump F; G is the air-pump-bucket provided with valves ; H is the hot-well into which the air-pump delivers its water and air, through the delivery-valves at the top of the air-pump ; i is the suction- pipe of the boiler feed-pump, which takes its water from the hot-well ; j is the cold-water pump which delivers cold-water through the pipe K, to the cold-water cistern L, in which the condenser and air-pump are placed. The air-pump is single-acting. Horizontal Jet-Condensers. In horizontal engines the condenser, air-pump and hot-well are usually contained in one casting, as shown in Fig. 183. The condensed steam from the jet-condenser is delivered by s 2 260 THE PRACTICAL ENGINEER'S HAND-BOOK. the air-pump into the hot-well, from which it is discharged into the conden- sation-reservoir, in land engines, or into the sea, in marine engines. In marine engines using sea-water for injection, the contents of the hot- well will consist of a mixture of from 27 to 30 parts of sea-water to i of pure water derived from the condensed steam. As the heat in steam of high pressure rapidly deposits sulphate of lime, salt-water can only be used for Fig. 172. Vertical jet-condenser, mp and cold-water pump, for a beam-engine. producing steam of pressures under 40 Ibs. per square inch ; hence fresh- water is used for producing steam above that pressure. This is obtained by using surface condensers to condense the exhaust-steam without its coming in contact with water. The water derived from the condensed steam of salt- water contains no salt, and is returned to marine boilers to be re-evaporated to steam and used over and over again, the small quantity lost by leakage being replaced by fresh-water, obtained from distilled salt-water. The Capacity of the Condenser should equal from i to i times that of the air-pump. The Diameter of the Injection-Pipe may be equal to ^th the diametei of the cylinder for high-speed engines, and -j^ththe diameter of the cylindei for low speeds. The Size of Injection Pipe necessary for the supply of a given quantity of condensation-water, making allowance for friction, may be found by this Rule : Divide the quantity of water required in cubic feet per minute, by 1550, the quotient will be the area of the pipe in square feet. Air- Valve for Condensing-Engines. When the injection-cock is not closed properly on stopping a condensing-engine, the vacuum may cause water to be drawn into the cylinder and pipes, which would impede the re-starting of the engine. This may be prevented by using the air-valve shown in Fig. 173, the upper part of which, marked A, is connected to the steam-chest, and the lower part is connected to the exhaust-passages from SURFACE-CONDENSERS. 251 the cylinder to the condenser. So long as the engine is working, the pres- sure of the steam forces the flexible plate-valve on to tha top of the pipe c, and closes its opening. When the steam is shut off on stopping the engine, the pressure is relieved from the valve B, and it is forced open by the spring, the passage c being opened before the engine comes to a stand-still. Air is then admitted through the holes in the lower part of the valve-case to destroy the vacuum and prevent entrance of water. The Ejector-Condenser, shown in Fig. 174, is another form of jet-con- denser. It is used for stationary engines and steam-pumps, and it dispenses with an air-pump. In starting this condenser the central spindle is raised by turning a hand-wheel, and a jet of injection-water is discharged through the centre of the current of exhaust-steam from the en- gine, which becomes condensed and produces a vacuum within the con- denser. The water enters with a velocity due to the difference of pressure between the external atmosphere and the degree of vacuum maintained in the condenser plus the velocity due to the head of the injection-water. The water-jet rushes through the combining nozzle of the ejector and the discharge - tube, and issues into the atmosphere in a con- tinuous stream, carrying with it any air that may be mixed with the exhaust- steam, the action of the ejector being similar to that of an injector. The ejector-condenser is very efficient and rapid in its action, the vacuum being produced within 4 or 5 seconds of the time of opening the injection-cock. Surface-Condensers. In surface-condensers the steam is condensed by coming in contact with cold metallic surfaces without coming in contact or mixing with the water used for refrigeration. In some cases the water for refrigeration circulates through tubes, and the steam to be condensed is on the outside : in other cases, the steam passes through tubes, and the water for refrigeration circu- lates on the outside. \\ hen the steam passes through the tubes any grease which the steam may carry with it from the engine-cylinder is deposited on the front tube-plate and inside the tubes, whence it can be removed by using suitable brushes. When the steam is outside the tubes the grease is deposited on the tubes and casing, and it Fig. 173. Air-valve for coi densing-eng 262 THE PRACTICAL ENGINEER'S HAND-BOOK. may be removed by using a solution of soda, or it may be detached by working the condenser at a good heat and washing it out with a jet of water. The Circulation of the Water through Tubes to condense the steam on the outside is the most efficient way of condensing steam in surface-condensers, because the largest amount of cooling surface is exposed to the hot steam, and the tubes being capable of resisting a greater internal than external pressure, can be made as thin as possible ; no scale is deposited on the outside of the tubes which would prevent their being easily drawn when required, and if india-rubber packing be used for the ends of the tubes it is not liable to be injured by grease in the steam. Surface-con- densers are frequently fitted with an injection valve and rose, so that in case of accident they may be worked as jet-condensers. The Weight of Circulating Water passing through a Surface Condenser may be found by this Rule : Weight of water in Ibs. passing through the condenser = Ibs. of water raised i degree in temperature temperature of discharged water temperature of circulating water' Example : If i Ib. of steam raise the temperature of 1000 Ibs. of water i degree, and the temperature of the circulating water is 52 Fahr., and that of the discharged water 104 Fahr., how many Ibs. of circulating water pass through the condenser per Ib. of steam ? Then, 1000 Ibs. -4- (104 52) = 19-24 Ibs. of circulating water. Cooling Surface of Surface-Condensers. The rapidity of con- densation by cold metallic-surfaces depends upon the efficiency and rapidity of the circulation of the cooling fluid. Peclet found that water was about 10 times more efficient as a cooling fluid than air, and that with refrigerating water at an initial temperature of from 68 to 77 Fahr. one square foot of copper-plate would condense 2\\ Ibs. of steam per hour. Joule found that with a rapid circulation of the cooling water 100 Ibs. of steam might be condensed per hour per square foot of surface. The cooling surface in square feet required per pound of steam con- densed per hour, may be found by dividing the weight of steam condensed per hour by n. For instance, a steam engine of 1400 indicated horse- power using 17 Ibs. of steam per indicated horse-power per hour, requires a surface-condenser with (17 Ibs. -f- u) x 1400 = 2163 square feet of cooling surface. The Quantity of Steam Condensed by coming in contact with the cold surface of flat plates of metal \ inch thick, kept cool by flowing water at a temperature of 50 Fahr., expressed in pounds of steam per square foot of surface, has been found by experiment to be as follows : Ibs. Gun-metal plates condense 26 Phosphor-bronze plates condense 25 Copper-plates condense 24 Tin-plates condense 22 Glass-plates condense 40 Tiles condense 38 11. s. Cast-iron plates condense 4 1 Wrought-iron plates condense 39 Steel-plates condense 38 White-metal plates condense 32 Brass plates condense 27 Bell-metal plates condense 26 The temperature of the steam was 228 Fahr. corresponding to 20 Ibs. WEIGHT OF STEAM CONDENSED BY CONDENSER-TUBES. 263 pressure per square inch. Each pound of steam condensed by the above plates represents 1152 thermal units. In a test of the Kirkcaldy Surface-Condenser 128-34 Ibs. of steam were condensed per square foot of tube-surface per hour, the temperature of the circulating water was 40 Fahr., temperature of steam, 295 Fahr., and the temperature of the water from the condensed steam was 70 Fahr. The tubes were corrugated in the direction of their length, they were measured as if plain and circular; this makes a difference of 10 per cent., so that the actual quantity of water condensed per square foot of surface was 1 1 5 Ibs. The weight of steam condensed in surface-condensers depends upon the efficiency of the condenser. It considerably increases with the velocity of the water circulating through the tubes. The rate of condensation in some surface-condensers is from 10 to 12 pounds; but in others it is only from 3^ to 5 Ibs. of steam per square foot of the cooling-surface of the tubes per hour. Horizontal surface-condensers are generally from 20 to 25 per cent, more efficient than vertical surface-condensers. Surface-condensers are generally so arranged that the hottest water meets the hottest steam. The Relation of the Cooling-surface of the Surface-condensers of Marine Engines to the Heating-surface of the Steam Boilers varies considerably in practice, as will be seen from the following table. TABLE 81. SHOWING THE COOLING-SURFACE OF THE SURFACE-CON- DENSER OF TRIPLE EXPANSION ENGINES AND THE HEATING-SURFACE OF THE BOILERS OF A NUMBER OF STEAMSHIPS. Indicated Horse-power of the Engines. Cooling-surface of Surface Condenser. Heating-surface of the Steam Boilers Diameter of the- Cylinders of the Triple Expansion Engines. Length of Stroke. I.H.P. Square feet. Square feet. Inches. L.ches. Inches. Inches. 130 2C 9 350 8 + 13 + 21 15 5 00 1,016 i,3 l8 14 + 22 + 36 24 645 1,360 3,160 22 + 34 + 57 39 I,OOO 1,280 2,800 19 + 30 + 49 33 I,IOO 1,700 3,000 22 + 35 + 57 54 1,300 1.977 4,320 23 + 37 + 60 42 1,500 i, 600 4,125 20 + 31 + 52 36 1,700 2,800 6, 1 60 27 + 45 + 71 48 2,000 2,552 8,418 24 + 37 + 55 iQ 2,5OO 4,000 6,250 22 + 34 + 51 21 2,7GO 4,300 7,7i5 29 + 46 + 74 51 4,000 6,045 11,380 36 + 56 + 90 60 5,OOO 8,000 II,IOO 31 + 45 + 68 33 0,OOO 6,750 9,900 40 + 59 + 88 5 1 7,000 9,500 13,800 42 + 59 + 92 42 7,500 n,550 17,650 40 + 66 + 100 72 9.000 14,500 20,174 40 + 59 + 88 5i 10,000 14,600 25,920 42 + 62 + 02 46 1 1 ,000 18,500 31,025 43 + 62 + 96 5 1 16,000 10,300 47,000 44 + 67 + 106 63 20,000 33,000 50,250 45 + 71 + 113 60 ' 264 THE PRACTICAL ENGINEER'S HAND-BOOK. The Cooling-Surface per Indicated Horse-power usually provided in surface-condensers is from 2 to 2\ square feet of tube-surface ; but it is frequently less, and varies considerably in practice, as may be seen from Table 82, page 271, which contains the cooling-surface, and the quantity of cooling water provided in a number of marine engines. The Quantity of Water required for Efficient Cooling in Surface- Condensers is one-half more than that required for injection water in jet condensers : the quantity of water required may be found as follows : The heat given up by each pound of steam condensed was found in the case of jet condensers to be 1078 units. If the temperature of the circu- lating water be increased 21 degrees in passing through the condenser, then 1078 -4- 21 = 51*3 Ibs. of circulating water will be required per Ib. of steam. It is usual to provide from 40 to 50 Ibs. of cooling water per pound of steam supplied to surface-condensers. The Velocity of the Passage of the Cooling Water through the Surface-Condenser may be found by the following formula, where V = the velocity of the cooling water in feet per minute. L = the length of the tubes in feet. T = number of times the water circulates through the tubes. P = pounds of cold water per indicated horse-power. D = the internal diameter of the tubes in inches. S = square feet of tube-surface per indicated horse-power. ^ = 80 D S' Example : The internal diameter of the tubes of a surface-condenser is f inch : the tubes are 6 feet long, there are 2\ square feet of tube-surface per indicated horse-power, the water circulates three times through the tubes, the weight of cooling water per indicated horse-power is 800 Ibs. Required the velocity of the passage of the cooling-water Then 6 feet x 3 times x 800 Ibs. = 80 x 75 x 2-5 The Capacity of a Circulating-Pump for circulating the water in a surface-condenser is generally equal to from -5 to '67 of the capacity of the air-pump when single-acting, and one-half that size when double-acting. A circulating-pump, together with air-pump and feed-pump, is shown in Fig. 175 : the barrel is lined with gun-metal, and the pump-rod is of iron cased with brass ; the plunger and valve-seats are of brass ; the valves are of india-rubber, made of best caoutchouc, with no other ingredients than sulphur and white oxide of zinc, and capable of enduring a test with dry- heat of 270 F., and with moist-heat of 320 F. Condenser-Tubes are made as small as possible in diameter, and they are placed as closely together as possible in order to obtain the greatest amount of cooling surface in the smallest space. The external diameter of the tubes is usually inch for very small condensers : f inch for small : f inch for medium size : and i inch for large condensers. The thickness of the tubes varies from 20 to 16 I W G, or from '036 to '064 inch. The unsupported length of tube should not much exceed 100 times the external diameter of the tube : a supporting-plate for the tubes is frequently fitted in the middle of the condenser. PACKINGS FOR CONDENSER-TUBES. The Pitch of Surface-Condenser Tubes is generally from i| to if times the external diameter of the tube ; the tubes are usually placed hori- zontally, and arranged in zigzag rows, so that the tubes in one row divide the spaces in the next row, as shown in Figs. 177 and 181. Brass Tubes are the best for Condensers, copper tubes do not answer for this purpose, because the acids produced by grease, carried with the steam from the cylinders, dissolve copper and produce soluble salts of that metal which are carried into the boiler with the feed-water and injure the boiler-plates. The tubes are sometimes tinned as a protection against corrosion. The condenser tube-plates and all bolts and screws should be made of brass containing not less than 70 per cent, of copper in its composition : all the joints between the cylinder, condenser, air-pump, and framing, should be faced and firmly secured. Direct- ing-plates should be fitted to cause the circulating-water to pass over the whole of the tube-surface, and provision should be made for examining and cleaning the interior of the condenser. The thick- ness of the tube-plates varies from 1-25 to 175 times the external diameter of the tube, according to the description of packing used for the tubes. Condenser - Tubes are usually composed of 70 per cent, of best copper and 30 per cent, of fine spelter. Packings for Conden- ser-Tubes. Wood-ferrules, shown in Figs. 176 and 177, form cheap and efficient pack- ings for condenser-tubes. They are made of well-seasoned soft wood, such as willow or pine, and are made about an eighth of an inch larger in diameter than the holes in which they have to fit, and are compressed in a die to the proper size for driving into their holes. When wet they expand and fit tightly round the tube and in the tube-plate holes. A hydraulic-leather packing for tubes, shown in Fig. 178, can only be used when the tubes are placed horizontally, and where the water- Fig. 175. Vertical circulating-pump, air-pump, and feed-pump. Condenser-tubes packed with wood ft 256 THE PRACTICAL ENGINEER'S HAND-BOOK. pressure is inside the tubes : the pressure of the water expands the leather- washer and makes a tight joint. An indiarubber packing for condenser-tubes is shown in Fig. 179. The rings are driven into a recess in the tube-plate, this arrangement may be used when the water circulates through the tubes, as the packing-rings are then pressed into their place by the water, and they are not exposed to the action of grease. A stuffing-box and gland packed with tape or cord for each tube, r ig. 178. Hydraul'C- leather packing for Fig. 179. Indiarubber-packing condenser-tubes. for condenser-tubes. Fig. 180. Stuffing-box and gland packing for condenser-tubes. shown in Fig. 180, is the best method of packing condenser-tubes : the water may circulate either inside or outside the tubes, and the packing is not affected by heat. A plan I of the tube-plate showing the arrangement of the tubes with these iiu Ting-boxes is shown in Fig. 181. A Single-acting Vertical Air-pump draws the air and water from the condenser only in its upward stroke, and the air and water pass through valves in the pump-bucket during its downward stroke, and are dis- charged into the hot-well. Vertical air - pumps are usually single-acting, having valves in the buckets, and they are more efficient than Fig. i8t.- Tube-plate with stuffing-box and gland-packing, horizontal air-pumps With Solid plungers. A vertical air-pump and surface-condenser of a marine-engine are shown in Fig. 182. A Double-acting Air-pump draws the air and water from the con- denser at each stroke, and has no valve in its plunger or piston. It is usually placed horizontally, and has a set of inlet and delivery-valves at each end of the pump-barrel ; a double-acting air-pump for a stationary AIR-PUMPS AND CONDENSERS. 267 engine is snown at Fig. 183. The direction of the flow of water is con- J. 182. Vertical a'r-mimp and surface-condenser of a marine engine. Fig. 183. Double-acting horizontal air-pump. tinually changing in this class of pump, which impairs its efficiency, foi' which reason horizontal air-pumps are frequently made single-acting. 268 THE PRACTICAL ENGINEER'S HAND-BOOK. A Horizontal Plunger-Air-pump, with. Jet-Condenser, for a Stationary Engine, is shown in Fig. 184. Fig. 184. Horizontal plunger-air-pump for a stationary engine, A Horizontal Plunger-Air-pump for a Marine-Engine, together with feed-pump and surface-condenser, is shown in Fig. 185. Fig. 185. Horizontal plunger-air-pump with surface-condenser for a marine engine. TRUNK AIR-PUMP. 269 A Trunk Air-pump has a hollow cylinder attached to the bucket which passes through a stuffing-box in the air-pump cover, as shown in Fig. 1 86. It is used in confined places where the space does not admit of a cross-head or guides. In the down-stroke the trunk displaces a portion of the water contained above the bucket, equal in volume to the displace- ment of the trunk. The Difference between a Bucket Air-pump, a Piston Air- pump, and a Vertical Plunger Air-pump, is : A bucket air-pump Fig. 186. Trunk air-pump for a marine engine. is single-acting, and is fitted with foot and head-valves. The valves in the bucket open on the down-stroke to admit water through the bucket, and close on the up-stroke, the theoretical quantity of water lifted being equal to the capacity of the air-pump for one revolution of the engine. A piston air-pump may either be made single or double-acting as required. The piston is solid, without valves ; suction and delivery-valves r.re fitted in the casing. When made single-acting it discharges water at cr.ch double stroke of the engine, and when double-acting it discharges at 2/O THE PRACTICAL ENGINEER'S HAND-BOOK. each single stroke of the engine. The vertical plunger air-pump is a double-acting pump, the bucket being attached to a plunger instead of a rod, there are no head-valves ; the plunger displaces water contained above the bucket on its down-stroke, and water is discharged at both the up and down-strokes, whereas the bucket air-pump discharges only on its up- stroke. The Capacity of the Air-pump for a Jet-Condenser may be equal to from -i to | the capacity of the low-pressure cylinder when single- acting, and one-half that capacity when double-acting. Air-pump capacity | that of cylinder =diam. of cylinder x -5 fvvnen th< " f " " " v'H 5 ) half that of " * " " " X 67 ( the piston. When the stroke of the bucket is either more or less than one-half the stroke of the piston, the diameter of the air-pump may be found by this Rule : Square the given diameter, multiply by the length of stroke, and divide the product by the proposed length, the square root of the quotient will be the diameter of the air-pump. Example: An engine with a 4 feet stroke has an air-pump 28 inches diameter, and 2 feet stroke. Required the diameter of the air-pump if the length of stroke be increased to 30 inches. Then 2 A^ 8 _ X -^ in J^i = jj 627 = 25 inches, the diameter of 30 inches V the air-pump required. When the capacity of the air-pump is to be equal to th of the capacity of the cylinder, it may be calculated as follows : Example: The diameter of the cylinder of an engine is 56 inches. The length of stroke is 42 inches. The air-pump is 28 inches diameter, and 1 8 inches stroke. Is the air-pump large enough to comply with the previous Rule? Then 56 x 56 inches x 7854 x 42 inches = 103446 cubic inches, the capacity of the cylinder, and 103446 -f- 8 = 12930-75 cubic inches, the capacity the air-pump should be ; but the air-pump capacity is = 28 x 28 inches x 7854 x 18 inches = 110844 cubic inches, therefore it is of less capacity than the Rule in question gives. Air-pump Lever. An air-pump" for a vortical marine-er^-'.ne is worked by a lever, shown in Fig. 182, connected to the crossh'sad u- '.a? piston-rod. The weight on the centre-bearing of the lever may be calculated by this Rule : Weight on centre -bearing = Weight on pump-end of lever x its distance from centre-bearing Length of crosshead-end of lever from centre-bearing load on lever. Example : An air-pump lever sustains a weight of 5 tons at the pump- end of the lever which is 3 feet 10 inches from the centre-bearing, the crosshead-end of the lever is 5 feet 9 inches from the centre-bearing. COOLING-SURFACE OF SURFACE-CONDENSERS. 2/1 What will be the weight on the centre-bearing, exclusive of friction and of the weight of the lever and its connections ? Then 5 tons x 46 inches = 69 inches. tons 5 tons load on the lever == 8-33 tons, the weight on the centre -bearing. In Jet-condensers, the air-pump discharges the condensation-water, the water from the condensed-steam and the air. In surface-condensers, the air-pump discharges only the water from the condensed-steam and the air; therefore a smaller pump is required in the latter than in the former case. Surface-condensers are sometimes arranged to work also as jet-condensers in cases of accident, then the capacity of the air-pump is made the same as for a jet-condenser. The Passages and Valves of an air-pump should not be less than equal to one-fourth the area of the air-pump. The Velocity of the Water through the Passages and Valves of an Air-pump should not exceed 500 feet per minute. The Capacity of the Air-pump for a Surface-condenser, may be equal to -^ the capacity of the low-pressure cylinder. The capacity of the air-pump, the cooling surface, and also the quantity of injection water pro- vided, varies considerably in practice, as will be seen from the following Table collated from recent practice : TABLE 82. AIR-PUMP CAPACITY, COOLING SURFACE, AND QUANTITY OF CIRCULATING WATER PROVIDED FOR THE SURFACE-CONDENSERS OF MARINE-ENGINES. Indicated Horse- power of the Marine Engines. Cooling Surface of the Condenser, in Square Feet. Relative Capacity of the Air-pump to that of the Low-pressure Cylinder. Quantity of Circulating Water provided, per Square Foot of Condensing Surface. Cubic Feet. Lbs. of Water. 625 800 : 40-04 152 9-51 860 1695 54-83 l6 7 IO-42 IO25 1980 20-47 151 9-50 I2OO 3000 24-I3 241 I5-00 1400 3400 24-OO 226 14-14 !! 3865 1930 22-86 46-28 208 142 12-94 8-92 1980 4786 22-23 192 II-94 2285 78lO 3 6 '47 191 I2'OO 235^ 4850 25-00 187 1175 2525 2940 23-83 161 lO'IO 2650 5280 24-36 079 4-94 3400 5500 27-50 121 7-75 3800 5670 26-10 196 I2'CO 4550 5500 25-20 128 8-00 5600 Il6lO 27-25 215 13-25 8010 Il687 20-37 '222 13-80 IOOOO 25COO i 24-00 2 4 8 15-50 2/2 THE PRACTICAL ENGINEER'S HAND-BOOK. Air-pump- Valves. Indiarubber valves are suitable for moderate temperatures, they should be made of the best caoutchouc, with not more than 3 per cent, of sulphur, and 67 per cent, white oxide of zinc. They should not be employed where mineral oil is used for lubricating the cylinder, as it decomposes them. Several small valves are more effective Man one large one. Vulcanised-fibre valves are more suitable for high temperatures than indiarubber, besides being more durable, and not liable to injury from the action of lubricants, and they can be made much thinner than indiarubber. The lift of indiarubber and vulcanised-fibre valves is controlled by the perforated guard, shown in Fig. 187, in which, tor comparison, an indiarubber val/3 is shown on the left-hand side and a vulcanised-fibre valve on the right hand side. Flexible Metallic Valves for Air-pumps, shown in Fig. iSS, are Fig. 187. Au-pump valve. Fig. 188. Kinshorn's Metallic valves. made of a thin and elastic sheet of phosphor-bronze. They are neither affected by the hottest water, nor by the action of lubricants, and are efficient and durable. The valve in lifting bends gradually against the curved guard by which the lift of the valve is controlled. Rigid Metallic Air-pump Valves, shown in Fig. 186, consist of light castings of bronze ; the valve is rigid, and slides up the spindle when it lifts from its seat. Heat Carried off in Condensing- Water. The efficiency of a steam-engine is the ratio of the heat converted into work to the heat expended. Only a small portion of the heat supplied to an engine is converted into work, the remainder is lost by conduction and radiation, and by passing into the condensing-water of a condensing-engine, or by being discharged in the exhaust steam of a non-condensing engine. Therefore by measuring the quantity of heat carried off by the exhaust steam, the loss of heat, per horse-power developed, may be accurately ascer- tained. It is evident that of two engines receiving per minute an equal quantity of heat from the boilers, that one is the better of the two which converts the larger portion of this heat into work, and discharges the least into the condensing-water ; hence by a measurement of the qmntity of heat carried off by the condensing-water, a comparative estimate can be formed of the performance of the two engines. This method of measuring the condensing-water is adopted in engine-tests, to obtain the number of thermal-units or pound-degrees for each indicated Fig. 189 Thomson's metallic valves. MEASUREMENT OF WATER FROM CONDENSING-ENGINES. 273 horse-power exerted in any condensing-engine. It is a very ready method of testing the consumption of steam where the measurement of the feed- water is difficult or impossible, as steam-boilers are frequently used for other purposes than power. The quantity of the waste-water from the condenser and its increase of temperature simply are taken. Method of Measuring the Quantity of Water coming from the Air-pump of a Condensing-engine. It is important to measure this Fig. 190. Fig. 191. Fig. 192. Figs. 190192. Apparatus for measuring waste-water from condensing-engines. water in engine-tests, because it contains nearly all the heat and steam that passes through a condensing-engine. It may be measured by a simple apparatus shown in Figs. 190-192, which may be briefly described as follows * : The water is led into a tank or reservoir, having a series of transverse divisions or baffle-plates. By passing over some, under others, and * The Author is indebted to Messrs. B. Donkin & Co., engineers, Bermondsey, London, the makers of the apparatus, for this information, which was originally given in a paper read before the Institution of Civil Engineers, and also in ' ' Engineering. " T 274 THE PRACTICAL ENGINEER'S HAND-BOOK. through the last of these plates, the water can be made to flow very steadily and without undulations. Beyond these divisions the water should be perfectly smooth. Under the above conditions the quantity of water flowing over a weir is easily ascertained by the usual formula, Q = C L f v/ 2 g /t 3 , in which Q is the actual quantity, C the co- efficient of discharge, or the percentage of the actual over the theoretical quantity, L the length of the weir, and h the head of water on the weir taken some way back. The above formula becomes Q, cubic feet per second = C L $'3472 > :IQ in all cases these 2/6 THE PRACTICAL ENGINEER'S HAND-BOOK. intervals should be regular, as in dealing with considerable variations of power, an irregularity in the intervals between the observations, may lead to erroneous results. From the data obtained in an engine-test carried out in the manner above explained, the following facts can be derived : (i.) The mean indicated horse-power. (2.) The mean quantity of water discharged per minute from the con- denser, and (3.) The mean rise in temperature of the condensing-water. If the number of pounds of water discharged per minute be multiplied by the mean rise in temperature, and the product divided by the mean indicated horse-power, the quotient will be the number of pound-degrees, or units of heat discharged per minute per indicated horse-power, and this number forms a constant by which the performance of the engine can be judged, or from which the quantity of steam used by it can be calculated. To make this perfectly clear it may be illustrated by an example. Suppose the observations made on an engine show that the mean indicated horse- power developed is 130 horse-power; the average quantity of water discharged per minute from the condenser is 1250 Ibs. ; and that the mean rise in tem- perature of this water is 40 Fahr., then the number of units of heat discharged from the condenser per minute is 1250 x 40 = 50000 pound- degrees, and the engine "constant "or number of units of heat discharged per horse-power per minute is ~ = 384-6. This "constant" forms a 130 means by which the performance of the engine can be compared with that of any other engine tested on the same system ; the lower this constant is, the higher, of course, being the efficiency of the engine. The manner in which the quantity of steam used per horse-power per hour can be obtained from the " constant " can be readily explained by continuing the consideration of the example above given. Suppose, for instance, that the engine in question is supplied with steam of 50 Ibs. pres- sure, and that the temperatures of the injection-water and of the discharge from the condenser are 55 and 95 respectively. The amount of steam used will be made up of three quantities, namely, first, that to supply the heat converted into work ; second, that to supply the heat imparted to the condensing-water; and third, that to supply the losses by radiation, &c. For each horse-power developed there are converted into work 33 x 772 = 2564-5 units of heat per hour, and as the total heat of steam of 50 Ibs. pressure is 1207-8, and the discharge from the condenser takes place at 95, it gives in this case - 2 5 4 5 = 2-306 Ibs. of steam per hour required to 1207-8 95 account for the heat converted into work. Again, the discharge from the condenser, as shown by the "constant," carries off 384-6 x 60 = 23076 units of heat per hour, and to furnish this - __ - = 2 o 01 Ibs. of 1207-8 -55 steam have to be provided. It will be noticed that in this last calculation the divisor is the total heat of the steam less the temperature of the injec- tion-water, and not of the discharge from the condenser. This divisor must be taken, because the whole discharge from the condenser does WATER-PUMPS AND TANKS. 2J/ not consist of heated injection-water, but of that water mixed with the steam which has been condensed. This is allowed for by taking the divisor as given. Thus 2-306 + 20-01 = 22-316 Ibs. of steam per hour are accounted for, and to this amount an allowance must be added for losses by radiation, &c., which may be taken at 5 per cent., making the total amount of steam required per horse-power per hour = 23-48 Ibs. The quantity of steam required calculated as above must be true steam. If the boiler primes to the extent of 10 per cent. a by no means uncommon occurrence then the apparent evaporation from the boiler working the engine we have taken as our example, would be greater, or probably about 25! Ibs. of steam per horse-power per hour. It will be seen from the above, that when used in conjunction with a boiler trial, this system of testing affords a clear indication of the steam supplied to the engine, while it is evident that when used alone it gives results which are practically (although not absolutely) independent of priming, and which afford therefore a better criterion of the performance of the engine itself than can be obtained by any other mode of testing. WATER-PUMPS AND TANKS. Pumps. All pumps lift considerably less water than the theoretical quantity due to their size and speed. The efficiency or quantity of work realized in proportion to that applied, is called the modulus of a machine. Thus, if a pump only lifts one-half the quantity of water it is theoretically capable of lifting, its modulus will be -5. The Modulus or Efficiency of Pumps averages as follows : Centrifugal pumps, low lift -50 Common lifting pumps . . . . -50 Ordinary lifting and force-pumps . . . . -66 Air-pumps -56 to '56 In high-class pumps, such as are used for water-works, the quantity of water actually pumped is frequently from 80 to 94 per cent, of the theoretical contents of the pumps. Example i : How many cubic feet of water is a 6 horse-power steam-pump capable of lifting per hour to a height of 20 feet ? Then, the work applied per hour = 6 x 33000 x 60 minutes. The work done = 6 x 33000 x 60 x '66 modulus. The work in raising i cubic foot of water = 62-5 Ibs. x 20 feet. The number of cubic feet of water = 6 X 33QQQ x 60 x -66 = 62 _ bic feet per hour. 62-5 x 20 Example 2 : A 6 horse-power steam-pump lifts 6273 cubic feet of water per hour to a height of 20 feet, What is the modulus or efficiency of the pump ? The work done per hour = 6 x 33000 x 60 minutes. Total work done = 6273 x ^ 2 '5 x 2O ^ eet - The efficiency or modulus = Work done 6 x 33000 x 60 Air-i p-n = i ^ = '66 modulus. Work applied 6273 x 62*5 x 20 ...V , For much useful information on Pumps and Pumping see the author's work "The Works Managers Handbook," published by Crosby Lockwood & Son, London. 2/8 THE PRACTICAL ENGINEER'S HAND-BOOK. Example 3 : Required the indicated horse-power of an engine to pump 6273 cu bi c feet of water per hour from a depth of 20 feet. Then, work in raising the water per hour = 6273 x 62-5 Ibs. x 20 feet. Effective work of one horse-power per hour = 33000 x 60 minutes x -66 r , . 6273 x 62's x 20 c , modulus, and the power of the engine = '-* = 6 horse- power. 33000 x oo x -oo Example 4: A tank is 12 feet long, 6 feet wide and 6 feet deep ; the height from the water in the well to the bottom of the tank is 70 feet. In what time can the tank be rilled with water by a hand-pump, if the man performs 2600 units of work per minute and the modulus of the pump is 66 ? Then, weight of water the tank will hold =12x6x5 feet x 62-5 Ibs. = 27000 Ibs. Height to which the centre of gravity of the water is raised = + 70 = 73 feet. Work = 27000 Ibs. x 73 feet = 1971000. Effective work of the man per hour 2600 units X 60 minutes X '66 modulus = 102960. Then, - I97IOOO work = , h 102960 effective work A Vertical Pump, with ram, is shown in Fig. 193. The valves and seats are of gun-metal, and the casing of cast-iron. The Area of a Pump Barrel is = tiiameter 2 x 7854. The Capacity of a Pump- Barrel is = the area in square inches x the length of stroke in inches. The Quantity of Water in Cubic Inches delivered per Stroke is = the capacity x the fraction of the pump's efficiency. The Quantity in Cubic Inches delivered per Hour is = the net quantity of water delivered per stroke x the number of strokes per minute and by 60. The Quantity in Cubic Peet delivered per Hour is = the quantity in cubic inches Fig. 193. Vertical pump. divided by 1728. Example : How many cubic feet of water will be delivered per hour by a single-acting pump, 4 inches diameter, 12 inches stroke, number of strokes per minute = 20, the pump being two-thirds full at each stroke ? RULES FOR PUMPS. 279 Then 4 2 x 7854 = 12-566 the area of the pump-barrel in square inches. 12-566 x 12 inches stroke = 150-792 the capacity of the pump-barrel in cubic inches. 150-792 x f = 100-528 the quantity of water delivered per stroke in cubic inches. 100-528 x 20 strokes x 60 = 120633-6 the quantity of water delivered per hour in cubic inches. 120633-6 -4- 1728 = 69-81 the quantity of water delivered per hour in cubic feet. The Diameter and Length of Stroke of Pumps, the number of strokes per minute, and the quantity of water delivered, may be obtained by the following formulas : Let Q = the quantity of water in cubic feet delivered per hour. D = the diameter of the pump-barrel in inches. L = the length of stroke in inches. N = the number of strokes per minute. M = the modulus of the pump = in most cases f or '66. P = the quantity of fresh-water in tons. S = the quantity of sea-water in tons. -7854 D 2 L N M x 60 ^ 1728 ,-7854 L N M x 60. L _ 1728 Q 7854 D 2 N M x 60' N ^ 1728 Q 7854 D 2 L M x 60' M = 78^4"D 2 ~L~N^T6o* P= -7854 D 2 L N M x 60 1728 x 35-9 S = "7 8 54 D 2 L N M x 60 i 7 28"x" 3 5 Example: Required the diameter of a pump to deliver 69*81 cubic feet rf water per hour. Length of stroke, 12 inches; number of strokes per i .inute, 20. Then I7z8 x 6() ' 8l 2 = 16 and /i6 = 4 inches diameter. 7854 X 12 X 20 X f X 60 A vertical pump with an escape-valve attached to the delivery side of the pump is shown in Fig. 194. The escape-valve relieves the pipes of any strain due to the accidental obstruction of the delivery pipes : it is loaded with a spring, which may be adjusted to suit the pressure required. Ths v.T.tcr which passes the ecccipe-valve, is discharged into the suction-pipe. 280 THE PRACTICAL ENGINEER'S HAND-BOOK. The Time required to Pump a given Quantity of Water may be found by dividing the quantity of water in cubic feet to be pumped, by the number of cubic feet of water discharged per hour by the pump. Example : What length of time will be required to empty a tank containing 100 tons of sea-water, with a single- acting pump, 4 inches dia- meter, 12 inches stroke, mak- ing 20 strokes per minute, the pump being two-thirds full at each stroke. Then the quantity of water in the tank will = 100 x 35 cubic feet per ton = 3500 cubic feet. The quantity of water the pump is capable of discharging per hour as given in the previous example is 69-81, or say 70 cubic feet per hour, and 3500 -f- 70 = 50 hours. If the pump had been double-acting, only one- half the time, or 25 hours, would be required to empty the tank. The Time required to Pump a given Quantity of Water, when two or more pumps of different size are employed to empty a tank, may be found by the following : Rule : Divide the product of the time in which each pump will separately empty the tank, by the sum of the times required by each pump to separately empty the tank. Example : The water-ballast pump of a steamship will empty a tank in 3 -hours, and the boiler pump will empty it in 10 hours : In what time can the tank be emptied by both pumps working together ? Then 3 x IO _ 2 hours, 18 minutes. 3 + io The Quantity of Water required to be Pumped into a Boiler to raise the water-level a given height may be found by this Rule : Multiply the superficial area of the water-level by the required height and* divide by the quantity of water. Example : The surface-area of water in a boiler at the water-level is = 6 feet x 10 feet : How many tons of sea-water are required to be pumped into the boiler to raise the water-level in the water-gauge glass to the extent of 6 inches ? Then 6 -^-! ~~* = i?'i4 cwt. ; or if the dimensions be taken 35 cubic feet in inches, then 7* x 120 x_6mches = 35 cubic teet x 1728 inches Fig. 194. Vertical pump, with escape-valve. RULES FOR PUMPS. 28 1 For fresh water, use 35-9 as a divisor, instead of 35 in the above example. The Velocity of Water in a Pump in feet per minute, may be found by multiplying the length of stroke in feet by the number of strokes per minute. The velocity of water in pipes is in inverse proportion to their areas, or to the squares of their diameters. Example : A pump makes 50 strokes per minute. Length of stroke, 2 feet; diameter of ram, 6 inches; diameter of delivery pipe, 3 inches. Required the velocity of the water in the pump-barrel and in the delivery pipe in feet per minute. Then 50 strokes x 2 feet = 100 feet, the velocity of the water in the pump-barrel and ? inches x 6 inches x 100 = 4OQ f thevdodt of the 3 inches x 3 inches water in the delivery-pipe. In Calculations for Pumps, where accuracy is required, it is necessary, in addition to the load on the pump, to make allowance for the following resistances : i st. The friction of the ram in the gland, and of the bucket or piston against the sides of the pump. 2nd. The friction of the water in the pipes. 3rd. The resistance of the water in passing through the pump-valves. 4th. The weight of the valves. 5th. The force necessary to work the ram or bucket by itself. In well-proportioned vertical-pumps, the load to. be overcome in raising the pump-bucket or ram, including these resistances, independent of the weight of the ram or bucket and rod, may be found by the following formulae : When the force necessary to work the bucket is not taken into account, the load to be overcome in raising the ram or bucket is equal to 62-5 Ibs. x D 2 x 7854 x L x R. Where 62-5 = the weight in Ibs. of a cubic foot of water. D = the diameter in feet of the pump-barrel. H = the height in feet from the level of the water from which the pump draws its supply, to the point of delivery above. R = a co-efficient to provide for the above resistances = ri in most cases. Then 62-5 x 7854 x ri = 54, and the formula for the load to be overcome on the pump is simply 54 D 2 x H. When the force necessary to work the ram or bucket by itcelf is not known, it may in most cases be provided for by adding -06 to i i given above, and the co-efficient of the resistances becomes n6; then 62-5 x 7854 x ri6 = 57, and the formula in such cases for the load-to be over- come on the pump is 57 D 2 x H. In each case the weight of the pump-ram, or bucket and rod, must be added to the result obtained, in order to find the total load to be over- come in raising the ram or bucket in a vertical pump. As the weight of the ram or bucket assists its depression, less power is required to depress it than that necessary to raise it. 282 THE PRACTICAL ENGINEER'S HAND-BOOK. Example : Required the load in Ibs. to be overcome in raising a pump- bucket, 6 inches diameter, to lift water a height of 50 feei, from the water in the well to the point of delivery in a tank, the \veight of the bucket and rod not being taken into account. Then 57 x -5 x -5 x 50 = 7i2'5 Ibs. The Horse-power required to Work a Pump may be found by adapting the above formula as follows, where V is the velocity of the pump in feet per minute. Horse-power of a pump = 57_D a x H x V 33,000 Example : Required the horse-power of the pump described in the last example, if the velocity of the pump-bucket is 60 feet per minute. Th e n 57 x -5 x -5 x 50 x 60 = horse . power . 33,000 The Quantity of Water to be Pumped out of a Ship, flowing in through a hole in the bottom, may be found by the following formula, where Q = t ie quantity of water in cubic feet flowing in per second, and H = the depth in feet of the hole below the surface of the water. Q = Area of hole in square inches x 8 *J H H4 The Quantity of Water a Tank will contain may be found by the following Rule : Multiply the length, width, and depth together and multiply the product by 6-25, the product will be the number of gallons of fresh water the tank will hold. Example : How many gallons of water will a tank 4 feet long, 4 feet wide, and 3 feet deep contain ? Then 4 x 4 x 3 x 6-25 = 300 gallons, or 100 gallons per foot in depth. The Weight of Water a Tank will contain may be found by the following Rule : Multiply the contents of the tank in cubic feet by 62*5 for the weight in Ibs. of fresh water, or by 64 for the weight in Ibs. of sea- water. Example : Required the weight of fresh water that the tank named in the previous example will contain. Then 4 X4X 3 = 48 x 62*5 = 3000 Ibs. or 48-^35'9=i ton 6 cwt o qrs. 20 Ibs. This tank would hold 484-35 = 1 ton. 7 cwt. i qr. 19 Ibs. of sea- water. The Size of Tank to contain a given Number of Gallons may be found by the following formulas : the dimensions being expressed in feet. .. Number of gallons The depth of a tank = Lengthxwidth % 6 - 25 . The width of a tank = Number of gallons Length x depth x 6-25. The length of a tank = J""^ f rall ? ns Width x depm x 6' 2 5 . Example i : A tank 4 feet long, 4 feet wide, and 3 feet deep, contains 200 gallons of water : What is the depth of the water, and what is the distance of the surface of the water from the top of the tank ? RULES FOR TANKS. 2 83 , 200 gallons c <. A ^ c Then . _ _ = 2 feet depth of water in the 4 feet long x 4 teet wide x 6-25 tank, and the distance of the surface of the water from the top of the tank is 3 2=1 foot. Or 200 gallons-4-6-25 = 32 cubic feet of water in the tank. 4 feet long x 4 feetwide=i6 square feet surface of water. 32-4-16=2 feet depth of water in the tank. And 3 feet depth of tank 2 feet=i foot depth of the surface of the water from the top of the tank. Example 2 : A tank 4 feet long, 4 feet wide, and 4 feet deep is full of olive oil : required the consumption per day, if in 10 days the depth of oil is lowered 18 inches; and also the weight of oil in the tank. Then 4 feet x 4 feet x 4 feet = 64 cubic feet, the contents of the tank, and 4 feet wide x 4 feet long x 1-5 foot = 24 cubic feet, the quantity of oil used,24 x 6-25= 150 gallons, 1504-10=15 gallons consumption p^r day. The specific gravity of olive oil is -915 and 62-5 Ibs.x -915 = 57-19 Ibs., the weight of a cubic foot of oil, then 57-19 x 64 cubic feet the capacity of the tank=366o Ibs. the weight of oil. The Diameter of a Tank to contain a given number of Gallons, being given to find the depth, or the depth being given to find the diameter, all the dimensions being expressed in feet. The height of a circular tank= ^ Number of g allons Diameter 2 x -7854 x 6-25- The area of a circular tank= Number of ga llons^ Height x 6-25 The diameter of a tank = yarea-f-7854. Example \ : Required the height of a tank 4 feet 6 inches diameter, to hold 400 gallons of oil. Then 40Q gallons = ^ h ^ 4-5 x 4-5 x -7854x6-25 Example 2 : Required the diameter of a circular tank 4-02 feet high, to contain 400 gallons of oil. = 15-9 area in square feet and i5'9-7--7854= V 2 ' 2 4 = 4 feet 6 inches diameter. The Time a Tank will take in Filling, when a given quantity of water is going in and a given quantity going out in a given time, may be found by this Rule : Divide the contents of the tank, in gallons, by the difference of the quantity going in and that going out of the tank, and the quotient will be the time in hours that the tank will take in filling. Example : If 60 gallons per hour be pumped into, and 40 gallons per hour be pumped out of a tank capable of holding 400 gallons, in what time will the tank be filled ? Then 4 = 20 hours. 6040 28 4 THE PRACTICAL ENGINEER'S HAND-BOOK. SLIDE-VALVES, PISTON-VALVES, CORLISS-VALVES, LINK- MOTION AND OTHER VALVE-GEARS. The Slide-valve regulates the admission, expansion, and exhaust of the steam in the cylinder. The action of the slide-valve may be clearly com- prehended by constructing, with thin strips of wood, a working model of a slide-valve, arranged so that the valve may be moved over the ports of the cylinder, to show how communication is established alternately between each steam port and the exhaust port, and the position of the valve at various points of the stroke of the piston. A model of an ordinary single-ported slide-valve is shown in Fig. 195, Fig. 195. Model of an ordinary slide-valve. in which the slide-valve v is shown in the position it would occupy when the piston has moved in the cylinder to the end of one stroke, and is about to commence the return stroke, A being the port through which steam is entering the cylinder, and B the port through which the steam, which pro- pelled the piston on its previous stroke, is escaping into the exhaust port. The valve v is moving in the direction of the arrow, and opening the port, A, for the admission of the steam, and a communication is at the same time established between the port B, through which the steam is exhausting, and the exhaust port E. When the piston arrives at the other end of the cylinder the valve will have moved back again, and these conditions will be reversed ; the steam will be admitted to the cylinder through the port B, and it will escape or exhaust from the cylinder through the port A. The valve moves from its middle position to the end of its travel, and back again to its middle position, while the piston moves from one end to the other end of the cylinder. A similar model of an expansion slide-valve is shown in Fig. 196. The Fig. 196. Model of an expansion slide-valve. circle in each case represents the motion of the crank-pin, and P is a pointer to show the position of the crank when the valve is set to give the required lead. LEAD OF SLIDE-VALVES. 28 5 When the terms lap and lead are used, they are understood to refer to outside lap and lead only, unless otherwise expressed. Lead of a Valve is the width the port is open to steam at the beginning of the stroke, as shown in Fig. 197, in order to bring the full pressure of the steam on the piston as it commences its stroke. The steam thus admitted acts as a cushion upon the piston, and enables it to reverse its motion without shock, and pre- vents the jerk and strain which would come on the crank-pin if the piston were thrown upon the crank with Fig. ^.-Secti^cyiinder-portsand full force at its dead points ; it also ensures the quick getting-away of the piston irom the end of the stroke. Lead is effected by fixing the eccentric a little more than 90 in advance of the crank, as shown in Fig. 198, the throw-line A of the eccentric being placed in advance of a line B, at right angles to the centre-line of the crank c, the arrow denoting the direction in which the engine is to run. The Radius of the Eccentric is equal to one-half the travel of the valve. The angular advance of the eccentric 0, may be found approximately by this Rule : _ outside lap + outside lead = ~ half-travel of the valve. The Angle of Advance of the Eccentric is the value of 0, found by the last rule, added to 90. The positions of the eccentrics on the crank-axle of a locomotive engine Fig. 198. Crank and eccentric. Fig. 199. Locomotive crank-axle and eccentrics. are shown in Fig. 199, in which the angular advance of each eccentric is clearly shown. The eccentric is made in halves, united upon the axle by bolts : there are two eccentrics to each cylinder the forward and the backward. 2o6 THE PRACTICAL ENGINEER'S HAND-BOOK. Deficient and Excessive Lead of the Valve. If the lead of the valve is deficient or altogether wanting, the maximum pressure of the steam in the cylinder is not attained until after a portion of the stroke is traversed by the piston. When the lead of the valve is excessive, the steam is admitted so readily as to be momentarily compressed and to cause in some cases an unfavourable pulsatory action of the steam. The total absence of lead of the valve likewise occasions an unsteady pulsatory action of steam in the cylinder, as steam can neither enter nor leave the cylinder when the crank is on its dead centres. High-speed engines require more lead than engines of moderate speed. Compression of Steam or Cushioning, by giving the valve the proper amount of lead, and by closing the exhaust port a little before the termina- tion of the return stroke, enables the momentum of the piston to be efficiently balanced, and the play of the bushes or bearings to be taken up, by which means thumping and hot bearings are prevented. The compressed steam saves steam which would otherwise be wasted in filling the clearance and waste-room in ports and passages. The rise in temperature of the com- pressed steam re-evaporates any water condensed on the surfaces of the metal, and sufficient steam may be locked in the cylinder to raise the pressure at the end of the stroke to nearly that of the steam entering from the steam-chest. . Excessive compression pulls up, or retards the working of, the engine, and deficient compression leads to sudden shocks on the admission of steam, and irregularity in the working of the engine. Lap of a Valve is the amount the valve extends beyond the edges of each of the steam-ports, when the valve is in the position of half- travel, as shown in Fig. 200, and its effect is to cut off the supply of steam when the piston has only travelled a portion of its stroke, the remainder of the stroke being performed by the expansive force of the Fig. 200. Section of cylinder-ports and slide-valve. showing steam shut into the cylinder until the valve opens for exhaust. If the valve opens the exhaust-port too soon, the steam is released before it is fully expanded and deprived of its force, and if the valve opens the exhaust-port too late, it will cause back-pressure, and the engine will not run smoothly. High-speed engines require large measures of expansion, and an early release of the steam, to prevent back-pressure. The Lap of the Valve and opening of the steam-port may be ascer- tained approximately by drawing a diagram like Fig. 201. in which A B is the position of the crank, at the beginning of the stroke. The circle repre- LAP OF SLIDE-VALVES. 28 7 sents the path of the centre of the eccentric, which moves the slide-valve. The diameter B D is the whole travel of the valve, c is the point which the centre of the eccentric occupies when the piston is at the end of the stroke. Draw the line E perpendicular to B D from the point c. Then, neglecting the obliquity of the eccentric-rod, A E = the lap of the valve. E D = the opening of the steam-port. Table 84. LAP OF VALVE REQUIRED FOR VARIOUS GRADES OF EXPANSION OF STEAM. 1 Distance of the pis- ton from the ter- mination of its A A A A ir A A A stroke, in parts of the length of its or i or i or i or i or A stroke. Lap on the steam side of the valve, in parts of the length of the 289 270 250 228 204 177 144 -103 stroke of the 1 valve. J The Lap, Lead, and Travel of Locomotive-Engine Slide-valves, and Size of Ports, are frequently as follows : Lap of slide-valve, either Lead of slide-valve, either Maximum travel, either Steam-port, either . . Exhaust-port, either . . Thickness of bridge , , f inch, i inch, or i| inch. -^ inch, -^ inch, or ^ inch. 3f in., 4 in., 4^ in., or 5 in. 15 x 15- in., or 15 x i| in. 15x3 in., or 15 x 3! in. Exhaust-lap or inside-lap is the amount which the inside edge of the Fig. 202. Slide-valve with exhaust-lap. slide-valve covers or overlaps the steam-port when the valve is at half-stroke, as shown in Fig. 202. Its effect is to delay the release of the steam or period of exhaust, and to increase the amount of cushioning ; it is some- times applied to the slide-valves of quick- speed engines. 288 THE PRACTICAL ENGINEER'S HAND-BOOK. Negative Exhaust-lap, or inside clearance, is the amount which the inside edge of the valve clears the edge of steam-port, or is open to the exhaust when the valve is at half-stroke, as shown in Fig. 203. Its effect is to hasten the release of the steam, or period of exhaust, and to decrease the amount of cushioning. The closing of the Fig. 2o 3 .-Slide-valve with negative lap. ExhaUSt-pOrt tOO SOOn, is followed by excessive compression of the steam, or cushioning ; if it be closed too late, it is followed by back-pressure and deficient cushioning. The Point of Cut-off is the position of the piston at the instant the slide-valve has closed the steam-port, and cut off the admission of steam to the cylinder. The most economical point of cut-off is, theoretically, that which would leave the steam at the instant of its release from the cylinder no capacity for developing further power. The pressure of the steam would then have fallen during expansion to that of the back-pressure, and the release of the steam would take place when the final pressure equals one atmosphere in a non-condensing engine, and when it equals that of the condenser in a condensing-engine. In such cases the ratio of expansion is equal to the pressure of the steam on its admission to the cylinder, divided by the back-pressure, according to Marriotte's law of expansion, and the initial pressure multiplied by the initial volume will equal the final pressure multiplied by the final volume. j initial pressure final volume , c And i =--. ,- = ratio of expansion. final pressure initial volume This is theoretically the best adjustment of the point of cut-off, but in practice allowance must be made for loss of power by radiation of heat, cooling by expansion, and for friction, which necessitates a different adjust- ment of the point of cut-off. The Point of the Stroke at which the Slide-valve cuts off the Steam may be found by this Rule: Point of cut-off = i - ( kpxj_ Vtravel of valve Example : The travel of a slide-valve is 6 inches, the lap of the valve is \\ inches, at what part of the stroke will the slide-valve cut off the steam ? Then i - (I2L*. 6 ')'= 826=: of the stroke. The Distance of the Piston from the end of the Stroke when the Steam is cut-off may be found by this Rule : lap x 2 + leadV = f x length of stroke, travel ot valve / TRICK SLIDE-VALVE. 289 Example: The travel of a slide-valve is 8 inches, the lap is if inch, the lead is ^ inch, and the length of stroke of the piston is 40 inches. How far is the piston from the end of the stroke when the steam is cut off ? Then X 4 inches = 7 ' 942 inches ' the distance of the piston from the end of the stroke when the steam is cut off. The Travel of a Slide-valve necessary to open the steam-port its full width, is equal to twice the sum of the width of port and the lap of the valve. Thus, for a steam-port \\ inch wide, and i inch lap of valve, the travel of the valve will be \\ + i x 2 = 5 inches ; and if the length of port be 1 6 inches, the greatest area the valve is open for steam is 16 x i| = 24 square inches. The area of Opening given by a Slide-valve for the admission of steam when the travel of the valve is not sufficient to open the steam-port its full width, maybe found by this Rule: Deduct the lap from one-half the travel of the valve, which will give the width the steam-port is opened by the valve, multiply by the length of the port, and the product will be the area of the opening. Example : The steam-port of a cylinder is 24 inches long and 2\ inches wide; the lap of the valve is if inch, the travel of the valve is 6f inches : What is the greatest area of opening given by the valve for the admission of steam ? Then 6| ~ 2 = 3! inches, one-half the travel of the valve, 3! if = if inches, the width the valve opens, and 175 x 24 inches = 42 square inches, the area of the opening given by the valve for the admission of steam. A Trick Slide-valve, shown in Figs. 204 and 205, is a valve with a Fig. 204. - n Fig. 205. Figs. 204 and 205. Sections of a trick-valve. steam-passage through it, the steam being admitted from both ends of the steam-chest into the same port. By this means a large opening for the admission of steam is obtained with a small travel of the valve. A Double-ported Slide-valve admits steam to the cylinder through two steam-ports at each end of the valve-seating, as shown in Fig. 206, thus enabling the same quantity of steam to be admitted to the cylinder with one-half less travel of the valve than that required for an ordinary valve and a single port at each end of the valve-seating. This form of valve is adapted for large engines, and is largely used for marine engines. A Gridiron Expansion-valve has a number of bars which slide over corresponding openings in the valve-face, as shown in Fig. 207, a large area of opening for the admission of steam being obtained by this arrange- u 290 THE PRACTICAL ENGINEER'S HAND-BOOK. Fig. 206. Double-ported slide-valve. ment from a small travel of the valve. The travel of the valve is regulated by a link attached to the valve - spindle, worked by an eccentric from the crank- shaft as shown ; the travel of the valve being altered by moving the block in the link up or down, by which means the point of cut-off may be varied as required. This form of valve is usually employed when the ex- pansion-valve is required to work on an independent face, and it is also sometimes arranged to work on the back of a main slide-valve. A separate Expansion-valve works separately from, and is indepen- dent of, the main slide-valve. It is used in cases where an earlier cut-off of steam is required than can be obtained by lap on the ordinary slide- valve, or where va- riable expansion is required. It is worked by an independent eccentric and rod, and the cut-off can be arranged to suit any required portion of the stroke of the piston. A variable expan- sion- valve working on the back of a main slide-valve is shown in Fig. 208, in which the cut-off plates are placed upon a spindle having a right- and left - hand screw, by which their position on the back of the main slide-valve can be adjusted to re- gulate the point of Fig. 208. Cylinder with separate expansion-valve. cut-off at any point of the stroke of the piston. An expansion-valve prevents the expeditious starting or reversing of an engine. DIAGRAM OF A SLIDE-VALVE. 291 An Expansion- valve withafixed Cut-off is shown in Fig. 209. This arrangement gives a fixed rate of expansion, and only one cut-off plate is required, which works upon the back of the main slide-valve as shown. Fig. 209. Expansion-valve with a fixed cut-oft'. The action of cut-off plate can be regulated by altering the position of the eccentric on the shaft. The Principal Points in the Motion of a Slide -Valve are four in number, viz. : The Admission of Steam for a certain period. The Cut-off in the supply of steam to allow the steam already in the cylinder to propel the piston by its expansive force. The Release of steam or opening to the exhaust. The Compression of steam, or closing of the exhaust before the end of the stroke to cushion the steam behind the piston. The Motion of the Slide-valve may be illustrated by a diagram* of the slide-valve shown in Fig. 210. To find the Position of the Eccentric, the Points of Admission. Cut-off, release and compression : the travel of the valve, its lap, and lead being given. Draw the centre-line A B, in Fig. 210; from the point O describe a circle equal in diameter to the travel of the valve ; from the centre O mark the lap C and the lead D ; at D erect a line E, perpendicular to A B, cutting the circle at F ; join O F, and on this line draw a circle cutting the points F O. Draw a circle from O of a radius equal to the lap of the valve; draw a line from O through the point of intersection of the two circles at G to the point H in the large circle. Draw a line from O to K, which will represent the position of the crank, when the valve begins to open the port to admit steam. Then O H is the position of the cut-off, and the points of admission, release and compression are as shown. The position of the eccentric is not actually at O F., when the engine is running, as shown by the direction of the arrow, but is at an equal angular advance on the other side of the vertical centre-line, at the point I. The shaded portion of the diagram F J represents the amount of opening of the port from the point of the admission of the steam to the point of cut-off. An indicator diagram similar to that which this valve would produce is * The above and following Diagrams of slide-valves are constructed according to Zeuner's method, described in his work, "Die Schiebersteuerungen. " u 2. 292 THE PRACTICAL ENGINEERS HAND-BOOK. Fig. 210. Figs. 210 and 211. Diagram of a slide-valve. shown underneath the valve-diagram in Fig. 211, the points of admission, cut-off, release, and compression being projected from the valve diagram. To Find the Lap of the Valve and the Position of the Eccentric: the travel of the valve, the point of cut-off and the lead being given. Draw the centre-line A B, Fig. 212, ]L and from the point O describe a circle equal in diameter to the travel of the valve ; from B mark the lead L ; mark the point of cut-off C ; bisect the angle between L and C by line O D, on which draw a circle cutting the points O D, join C L. Then O E is the amount of lap of the valve re- quired, E F is the lap-circle, and A O D is the angle between the crank and the eccentric which will give the required cut-off. Fig. 212 Diagram showing lap of valve and position of eccentric. DIAGRAM OF AN EXPANSION SLIDE-VALVE. 293 The Motion of an Expansion Slide-valve working on the back of a main slide-valve, having two cut-off plates adjustable by a right-hand and left-hand screw, for cutting off the steam at any required portion of the stroke, as shown in Fig. 213, may be illustrated by the following diagram, Fig. 214. Diagram of an Expansion Slide-valve working on the back of a main slide-valve as shown in Fig. 213. Fig. 213. Expansion slide-valve, with variable cut-off. From the point O on the line A H in Fig. 214, describe a circle equal in diameter to the travel of the main slide-valve, on the centre line of which at the point A describe a small circle equal in radius to the lead of the main slide-valve. Let the line A O be the position of the crank when on its dead centre, and the line O B its position at the point where the steam Fig. 214. Diagram of an expansion slide-valve. is cut off by the main slide-valve. Draw the line C from B to D, and join O D, the line O D will represent the position of the crank when the main slide-valve is on the point of admission of the steam to the cylinder. Bisect the arc A B at E and join E O, then the angle E O F = G, and the centre line of the throw of the eccentric of the main valve will have an 2Q4 THE PRACTICAL ENGINEER'S HAND-BOOK. angular advance of the crank equal to H O E or = 90 + G. At the centre of the line O E describe a circle equal in diameter to one-half the travel of the valve, which will intersect the lines O D at I, and the line O B at J, and it will touch the line C at K. O I and O J will equal O K, which will represent the amount of lap on the steam side of the valve required to cut off the steam when the crank is in the position OB. A circle drawn from the point O will intersect the points I J K, which is called the lap-circle. To show the travel of the valve, suppose a radial arm or line to revolve round the centre O, then the amount of the travel of the valve from its middle position will equal the length of the radial line contained in the circle described on E O. For instance, if the crank moves from A to M the valve will move from its middle position a distance equal to the length intercepted O N, part of this length O P lies within the lap-circle, and the remainder or length N P represents the width of opening of the steam-port when the crank is in the position O M. When the crank is in the position O E the port is wide open, when it is at F it is closed to the extent of F Q, and when it is at O B the valve is closed and the steam is cut off. The Cut-off Valve is moved by an eccentric similar to the main slide, and in considering its action, the main slide may be supposed to be stationary, and the cut-off valve only movable. To find the travel and angular advance of the cut-off eccentric, and the position of the cut-off plates or length L in Fig. 215. On the centre-line O B in Fig. 214 describe a circle equal in diameter to one-half the travel of the main slide-valve. Draw from E the line E A parallel to O B, join E B and draw from O the line O A parallel to E B intersecting the line E A at A. Then O A represents in position and length the radius of the eccentricity of the eccentric for the cut-off slide-valve, and the centre line O A of the cut-off eccentric leads that of the main Fi piate I5 oV 7x P ansbn eccentric O E by the angle E O A. On the line O A as slide-valve. a diameter describe a circle cutting the points O A as shown, which will be the cut-off-valve circle, round the centre of which a revolving arm or line will show the travel of the valve from its middle position. Thus at the position O E of the crank, the cut- off plate has moved from its middle position a distance = O R. The distance L of the cut-off-plates from the middle position, as shown in Fig. 215, will be equal to the distance E K in Fig. 214, if it were required to cut off the steam at the position O E of the crank. The Friction of a Slide-Valve is very considerable, owing to the pres- sure of the steam acting on the back of the valve. The force required to move a slide-valve has, in some eases, been found to equal from th to ^rd the total pressure on the valve. The Friction of a Slide-Valve may be reduced by reducing the area of the back of the valve exposed to the pressure of the steam in the steam chest, by means of an equilibrating-ring recessed into the cover of the steam-chest, having springs adjustable by set-screws, as shown in SLIDE-VALVE RELIEF-FRAMES. 295 Fig. 216. The back of the valve works steam-tight against the ring, and the space inside the ring is connected by a pipe to the condenser, so that a vacuum is maintained within the ring, and the pressure is considerably relieved from the back of the valve. The springs on the back of the valve permit the valve to leave its seat to allow the escape of water from the cylinder, in case of priming. The area of the equilibrating-ring is generally made equal to the area of the exhaust-port. A Relief- Frame, shown in Fig. 217, is another method of relieving the pressure of the steam from the back of the valve, in order to reduce the friction. It consists of a cast-iron frame, attached to the back of the valve by means of a spring-steel diaphragm-plate; the space within the Fig. 216. Showing equilibrating- ring on the back of a slide-valve. Fig. 217. Dawe's slide-valve relief-fr; frame at the back of the valve is connected by a pipe to the condenser, so that a vacuum is maintained within the frame, and the pressure on the back of the valve is reduced ; the elastic diaphragm compensates for the wear of the rubbing surfaces. The Relief- Frame is frequently placed on the steam-chest cover, as shown in Fig. 218, instead of on the back of the slide-valve. The frame Fig. 218. Slide-valve relief-frame. is pressed against the back of the valve by a spring-steel diaphragm, the back of the valve working steam-tight against the frame. An enlarged view of a similar arrangement attached to a door in the cover of the valve-chest is shown in Fig. 219. 2 9 6 THE PRACTICAL ENGINEER'S HAND-BOOK. A Slide-Valve Relief- Frame of another kind is shown in Fig. 220. The valve has a circular spigot cast on the back, fitted with rings like a Fig. 219. Slide-valve relief-frame on steam-chest cover. piston to keep it steam-tight, which fits into a socket attached by a spring, in the form of a cross, to the back of the slide-valve. The spring presses the socket against the steam-chest cover, and the steam - pressure is partly relieved from the back of the valve, which is thereby nearly balanced. As devices of this kind are never perfect, slide-valves are never per- fectly balanced, but are only relieved of the greater portion of the pressure of the steam on their backs. A Balanced Slide" - Valve of another kind is shown in Fig. 221. It consists of a relief-ring fitted into a short cylinder attached to the cover of the valve-chest. The flange out- side the relief-ring forms the bottom of the recess B, which is packed with gasket, pressed down a junk-ring by means of the screws C, which pass " back f Fig. BACK Of SLIDE V i. Claparede's balanced slide-valve. through stuffing-boxes in the cover of the valve-chest, so that they can be tightened when the engine is working. The balancing space D, or BALANCED SLIDE-VALVES. 297 that to which steam cannot get access, is placed in communication with the atmosphere by a small cock. The valve is kept to its seat by the spring E, the tension of which can be regulated by the screw F, which passes through a stuffing-box G, on the lid H. A Balanced Slide-Valve, applied to a locomotive engine, is shown in Figs. 222 and 223. The slide-valve is attached by a link to a balance- Fig. 223. Fig. 222. Transverse Figs. 222 and 223. Urquhart's balanced slide-valve applied to a locomotive-engine. piston fitted with piston-rings to make it steam-tight, and a pipe is fixed to the balance-cylinder to carry off any steam which may escape past the piston. A Balanced Slide- Valve of another kind, for locomotive engines, is shown in Figs. 224 and 225. It consists of a rectangular frame, formed of Fig. 225. Section of valve. Fig. 224. Delancey's balanced slide-valve. strips of metal inch square, fitted into grooves in the back of the valve ; the strips are halved on to each other at the corners, and rest on springs fixed to the bottom of the grooves. A crown-plate, forming the top of the 298 THE PRACTICAL ENGINEERS HAND-BOOK. valve, rests on the top of the strips. The crown-plate works against an adjustable frame fixed in the steam-chest ; the frame rests on feet at its four corners, therefore the steam-pressure on its top does not affect the slide- valve. The small holes through the top of the slide-valve, shown in Fig. 225, are to allow any leakage of steam past the strips to escape to the exhaust cavity of the valve. The Air or Relief- Valve shown on the steam-chest in Fig. 224 is shown in enlarged views in Figs. 226 and 227. It opens inwards, and Fig. 226. Fig. 227. Figs. 226 and 227. Air-valve for sttam-chest. Fig. 228. Balanced slide-valve of a mark engine. admits the atmosphere when a vacuum is formed in the steam- chest, as it is found that, when the regulator is closed to shut off the steam, dust and ashes are liable to be sucked down the exhaust-pipe and are likely to cut the face of the slide-valve. The Slide-Valves of Vertical Engines are usually balanced by a piston fixed on the top of the valve-spindle, working in a small cylinder on the top of the steam-chest, as shown in Fig. 228, to which steam is supplied from the steam-chest ; the pressure of the steam on the balance-piston balances the valve, the area of the balance-cylinder being arranged to suit the weight of the slide-valve, rods, and gear. The Strain on a Valve-Spindle in moving a Slide- Valve depends upon the force with which the valve is pressed against the face of the cylinder by the steam in the steam-chest. This force is equal to the product of the pressure of the steam by the area of the back of the valve exposed to the pressure of the steam. PISTON- VALVES. 299 Example : The size of the back of the valve exposed to the pressure of steam of 60 Ibs. per square inch, is n inches by 16 inches. Required the strain on the valve-spindle due to the pressure of steam on the Lack of the valve. Then n x 16=176 square inches, the area of the back of valve, and 60 x 176=10560 Ibs., the total pressure on the back of the valve. Taking the ioe;6o x 100 frictional resistance at 10 per cent, of the pressure, it will give 1056 Ibs. frictional resistance, or strain on the valve-spindle. Where the friction due to either a large size of slide-valve, or to a high pressure of steam upon it, would be great, it is better to adopt a piston-valve, instead of a slide-valve with a relief- frame. Piston- Valves work in equilibrium, as the pressure of steam cannot force the valves against the sides of the casing Fig. 230. Fig. 231. Z7/7/7 Fig. 232. VAVA Figs. 230 232. Piston of pistcn-valve : and cylii.der-ports. in which they work. A piston-valve consists of a spindle or socket having a piston at each end ; steam is admitted from the outside of the valve, and it exhausts into the space between the pistons. Small piston-valves are fixed on a solid spindle, and the ends of the valve-chest are connected by a pipe, as shown in Fig. 229. Large piston- socket, through which the steam can Fig. 229. Piston-valve of a marine hollow valves are attached to a pass from end to end of the valve-chest. The pistons are fitted with rings of cast-iron or gun-metal, like an ordinary piston ; a simple arrangement of rings is shown in Fig. 230, in which there is one outside ring and one inside spring-ring of cast-iron. The rings are prevented from springing into the ports by diagonal bars placed across the ports, as shown in Figs. 231 .ind 232. The diameter of a piston-valve is frequently made equal to one-half the diameter of the steam-cylinder. Thorn's Piston- Valve, shown in Figs. 233 235, differs from ordinary piston- valves in that its working face is provided with a passage similar to the passage in a trick-valve, but having positive and negative exhaust-lap at the top and bottom of the cylinders, so that the negative exhaust-lap forms 3oo THE PRACTICAL ENGINEER'S HAND-BOOK. a communication between the opposite ends of the cylinders just before exhausting to the condenser, and so that steam at its terminal pressure is transferred from one side of the cylinder-piston to the other through the passage, such steam being then compressed nearly up to the initial Fig- 234- Figs. 233 233. Thorn's piston-valves applied to a marine-engine. pressure and used over again on the return stroke of the engine, and causing the engines at the same time to turn the centres, especially that of the low- pressure cylinder of compound engines, with less shock, due to having steam in the cylinder to compress. In Fig. 233 the valve is shown in the position in which a communication is formed between the two ends of the cylinder for a very brief period, the result being that a portion of the exhaust steam first released passes to the other end of the cylinder and assists in cushioning. Fig. 234 shows how the connecting-passage also serves to afford a double inlet for the steam, in the same manner as in the trick- valve. Fig. 235 is a section through the valve at A B in Fig. 233. VALVE-GEAR OF A CORLISS-ENGINE. 301 I Fig. 236. Double-beat valve. Double-beat Valves, shown in Fig. 236, work nearly in equilibrium, as the pressure of the steam is nearly equal on both the inside and outside of the valve. They are frequently used in place of slide-valves in low-speed engines, but they are difficult to keep steam-tight on account of the unequal expansion of the valves and seatings. This kind of valve is fully open when it is lifted a distance equal to one-fouith the diameter of the valve. Double-beat valves are also made in the form of two mushroom-shaped valves of different diameters attached to a spindle. If D be the difference of the areas of the valve-seats of such a valve, then, load in Ibs^on the valve = the pressure on the valves in Ibs. per square inch, and D x pressure in Ibs. per square inch = the load in Ibs. on the valve. Example : In a double-beat valve the internal diameters of the two valve-seats are 6 inches and 4^ inches respectively. The load on the valve, including the weight of the valve, is 108 Ibs. What is the pressure on the valve ? Then, the dif- ference of the areas of the valves is (6* - 4 2 ) x 7854 = 12-37 square inches, and 108 -f- 12*37 = 873 Ibs. per square inch, the pressure on the valve. Corliss-Valves, shown on page 409, are disc-shaped. The valve- gear of a Corliss-engine, having a steam- jacketed cylinder 20 inches diameter, and 4 feet length of stroke, is shown in Fig. 237, which exhibits the novel feature of open- ing the port wide during the first tenth of the stroke, and keeping it full open until it is tripped. Thus, for all grades of expansion beyond and including one-tenth, there can be no wire-drawing what- ever due to a contracted port. The valve-gear is driven by a side-shaft actuated by a bevel wheel on the crank-shaft. On this side-shaft there are two cams, one for each steam-valve. On the top of each cam there rides Fig. 237. Corliss valve valve-gear & Co., Boll by Hick, Hargreaves ton. an arm or bracket projecting from a casting which carries the tripping- gear, and slides upon a vertical rod connected to the valve. This casting rises and falls with the cam, the upward motion commencing when the engine is upon the centre, and being completed by the time the piston has 302 THE PRACTICAL ENGINEER'S HAND-BOOK. finished one-tenth of the stroke. There is then a " dwell " or pause due to a circular portion of the cam, and the casting remains elevated until it is again lowered by the cam. But in the meantime the trip- gear comes into action, and breaking the connection between the casting and the vertical rod upon which it slides, allows the valve to close with the suddenness peculiar to the Corliss valve-gear. The tripping- motion is worked b'y an eccentric on a side-shaft through two links and a rocking-lever. It consists of a block or catch on the vertical rod, a catch-lever which engages with this block, and a second lever which trips the first. The point of cut-off is determined by the governor, which turns a srmll rocking-shaft as it rises and falls. The rocking-lever, referred to above as forming part of the tripping-gear, is mounted upon this shaft, but not directly, an eccentric-bush being first keyed upon the shaft. The result of this arrangement is that when the governor rises, the centre of the lever is moved in such a way that the acting end of the tripping-lever is brought nearer to its work, and comes into contact with its companion-lever sooner than before, cutting off the steam at an earlier point. The vertical rod is connected to the lever of the steam-valve by a block working in a slotted crosshead, and is moved to close the valve by a spring, a dash-pot prevent- ing any concussion. The exhaust-valves are also worked from the side- shaft by eccentrics. The Motion of an Engine may TJC reversed by altering the position of the eccentric on the crank-shaft. This may be effected by attaching the Fig. 238. Reversing-plate for eccentric. eccentric to a plate fixed on the crank-shaft, as shown in Fig. 238. The eccentric is loose on the shaft, and is bolted to the reversing-plate with a bolt, sliding in a slot, thus enabling the position of the eccentric to be shifted to a similar position on the opposite side of the crank, thereby reversing the motion of the engine. This arrangement is used for portable and other engines which only required to be occasionally reversed. It necessitates stopping the engine for reversing, and it is not so convenient as a link- motion. Link-motion is used to effect the reversal of the motion of an engine. A link-motion with a shifting link is shown in Fig. 239. The crank is chown in its position when the piston is at the end of the stroke. Two LINK- MOTION. 3C3 eccentrics are keyed on the crank-shaft, the top one being the forward eccemric, and the bottom one the backward eccentric. The bottom of the link is connected to a lever, by means of which the link is moved up or down as required. When the link is lowered so as to bring the forward Fig. 239. Link-motion of a horizontal-engine. eccentric-rod in line with the valve-spindle, the motion of the slide-valve- is governed by the forward eccentric, and the engine goes forward. On the contrary, when the link is raised so as to bring the backward eccentric- rod in line with the valve-spindle, the motion of the slide-valve is governed by the backward eccentric, and the motion of the engine will be reversed. Only one eccentric works the valve at a time, and when the middle of the link is in line with the valve-spindle, the motion of neither eccentric is com- municated to the slide-valve. As the link is moved from the central position it causes more and more steam to be admitted to the cylinder, and when the link is shifted to bring the block up to the end of the link, full steam is admitted. The distance between the centres of the eccentric-rod-pins of the link is usually about three times the maximum travel of the valve, and the radius of the link is struck from the centre of the crank-shaft. The Expansion- Link of Locomotive Engines is generally either supported at the centre as shown in Fig. 240, or at the top from the pin of Fig. 240. Link-motion of a locomotive-engine. the forward eccentric-rod, as shown in Fig. 241, the reversing shaft being 304 THE PRACTICAL ENGINEER'S HAND-BOOK. below the motion and behind the link. The usual proportions of the valve- motion of locomotives are as follows : Length of expansion-link from centre to centre of pins = 17 inches. Thickness of expansion-link = 2\ inches. Diameter of motion-pins = i\ or if inch. Radius of expansion-link = 4 feet, 7 inches. Diameter of reversing-shaft == 3! inches at the centre and 3 inches at the bearings. Length of eccentric rod = 4 feet, 7 inches, centres. Diameter of eccentric-sheaves = 16 inches. Width of eccentric-sheaves=2f inches. Fig. 241. Link-motion of a locomotive-engine. Throw of eccentrics = 6\ inches. Angle of forward eccentric = 103. Angle of backward eccentric = 104. Lead of slide-valve = -jV mcn back and -^ inch front. Lap of slide-valve = i inch. Travel of slide-valve = 4-^ inches. The Stationary Expansion-Link, shown in Fig. 242, is another form of link-motion : the link is supported in a fixed position as shown, the changing of the gear being effected by moving up and down the expansion- Fig. 242. Link-motion with stationary-link. link a radius-rod connected to the sliding block at one end and to the valve- spindle at the other end. The curvature of the expansion-link is in the reverse direction to the shifting expansion-link previously described, to adapt it to the radial movement of the radius-rod of the valve-spindle ; the radius- rod of the valve-spindle is supported and moved by levers on the reversing shaft in front of the expansion-link. The Straight Expansion-Link, shown on Fig. 243, has parallel instead of curved sides, and is something like a combination of the shifting-link and the stationary link. The link and the radius-rod, connecting the link- block and the valve-spindle, are supported by links connected to the ends of arms of unequal length on the reversing-shaft as shown. The expan- EXPANSION-LINK OF A MARINE-ENGINE. 305 sion-linl; and the radius-rod are shifted in opposite directions, one being moved upwards and the other downwards, by one movement of the revers- ing. 244. Expansion-link of a marine-engine. Fig. 243. Link-motion with straight link. ing shaft. The advantage of this form of link-motion is, that by moving two pieces of the link-motion, the reversing of the engine may be effected with only one-half the vertical movement necessary when the movement is applied to only one of the pieces, as in the case of the ordinary link- motion shown in Fig. 239. Expansion - Links of Marine-Engines, when a single link is used, are gene- rally provided with adjustable bushes, as shown in Fig. 244, and the sliding block is also bushed, to facilitate repairs. Expansion-links of marine- engines ave frequently made double, as shown in Fig. 245. The sliding-block moves be- tween two radius-links; the ends of the eccentric-rods are forked to span the link ; and all the bearings are pro- vided with adjustable bushes. Liiiking-up means alter- ing the working position of the link, whereby the point of cut-off is altered and the steam is worked expansively. When the position of the link-block is moved from the extremity towards the centre or dead-point of the link, the travel of the valve is shortened, and it is equiva- lent to diminishing the throw of the eccentric and increasing its angular position, so that the points of lead and cut-off are earlier. Fig. 245. Expansion-link of a marine-engine. 306 THE PRACTICAL ENGINEER'S HAND-BOOK. Eccentrics and Eccentric-Straps for working the Slide-Valve of a Locomotive Engine, by means of the link-motion previously described, are shown in Figs. 246 and 247. The eccentric-sheaves are made in two Fig. 346. Figs. 246 and 247. Eccentrics and eccentric-straps of a locomotive-engine. pieces let into each other and bolted together as shown ; the larger piece of the sheave is generally made of cast-iron and the small piece of wrought- iron. The eccentric-strap is made of wrought-iron, lined with gun-metal tongued and grooved into the eccentric-strap. The eccentric has a projec- tion on its circumference which works between two flanges on the lining of the eccentric-strap. The eccentric-rod is flat in section and is forged solid with one-half of the eccentric-strap. An eccentric-strap for a locomotive engine, made of cast-iron, the pattern used on the London, Brighton and South Coast Railway is shown in Fig. 248. The sheaf is of cast-iron, and the wear and tear is very slight, as cast-iron works well upon cast-iron when efficiently lubricated. The eccentric-rod is made of wrought-iron, bolted to the strap by studs screwed into the strap as shown. An Eccentric and Eccentric-strap for a Stationary Engine is shown in Figs. 249 252. The eccentric is either made solid as shown in Fig. 249, or in two pieces let into each other and bolted together as shown in Fig. 251, the larger piece of the sheave being made of cast-iron and the smaller piece of wrought-iron. A number of plugs of anti-friction metal are let into the circumference of the wrought-iron piece for the purpose of reducing friction and assisting lubrication. The eccentric- ECCENTRICS AND ECCENTRIC-STRAPS. 307 strap is made of cast-iron, and is kept in its place on the sheave, by .sfwM- r <==S^- h'tH F*^i /*%" 1 Fig. 248. Eccentric-strap of a locomotive-engine. projection on the sheave which works in a groove in the eccen- tric-strap. The eccentric-rod is made of wrought-iron, bolted into a recess on the side of the strap, as shown. An eccentric and eccentric- Strap for a stationary engine in which the rod is provided with a flange and bolted to the end [_ of the strap is shown in Figs. 253 and 254; the strap is made of cast-iron, lined with gun- metal; the eccentric-sheaf is Fig. 249. Fig. 25 1. Fig. 252. Figs. 249 252. Eccentric and eccentric-strap of a stationary-engine. 303 THE PRACTICAL ENGINEER'S HAND-BOOK. recessed on each side to receive the flanges of the eccentric-strap as shown. A Set of Eccentrics and Eccentric-Straps for a Marine-Engine is shown in Fig. 255 ; the sheaves are of solid cast-iron, but they are f re- Fig- 253- Fig. 254. Figs. 253 and 254. Eccentric and eccentric-strap of a stationary-engine. Fig. 255. Eccentrics and eccentric- straps of a marine-engine. quently made in halves and bolted together, as previously described for stationary engines. The eccentric-straps are of solid gun-metal, or of wrought-iron or steel lined with gun-metal. Joy's Reversion and Expansion Valve-Gear. The essential feature of this valve-gear is that the movement for the valve is produced by a com- bination of two motions at right angles to each other, and by the various proportions in which these are combined ; and by the positions in which the moving parts are set with regard to each other, it gives both the reversal of motion and the various degrees of expansion required. Eccentrics are dispensed with ; the motion is taken direct from the connecting-rod, and by utilising independently the backward and forward action of the rod, due to the reciprocation of the piston, and combining this with the vibrating action of the rod, a movement results which is suitable to work the valves of engines allowing the use of any proportions of lap and lead desired, and giving an almost mathematically correct " cut-off " for both sides of the piston and for all points of expansion intermediately, as well as a much quicker action at the points of " cut-off " and " release " than is given by a link gear. The machinery for accomplishing this is less complicated than ths ordinary link-motion, and is shown in elevation in Fig. 256. Here E is the main valve-lever, pinned at D to a link B, one end of which is fastened to the connecting-rod at A, and the other end maintained in about the vertical by the radius-rod C. which is fixed at the point Ci. The centre or JOY'S VALVE-GEAR. 309 fulcrum F of the lever E, partaking of the vibrating movement of the con- necting-rod at the point A, is carried in a curved slide J, the radius of which is equal to the length of the link G, and the centre of which is fixed to be concentric with the fulcrum F of the lever when the piston is at either extreme end of its stroke. From the upper end of the lever E the motion is carried direct to the valve by the rod G. It will be evident thus that by one revolution of the crank the lower end of the lever E will have imparted to it two different movements, one along the longer axis of the ellipse, travelled by the point A, and one through its minor axis up and down, these movements differing as to time, and corresponding with the part of the movement of the valve required for lap and lead, and that part constituting the port opening for admission of steam. The former of these is constant and unalterable, the latter is con- trollable by the angle at which the curved slide J may be set with the vertical. It will further be evident that if the lever E were pinned direct to the connecting-rod at the point A, which passes through a prac- tically true ellipse, it would vibrate its fulcrum F unequally Fig. 256. joy's valve-gear. on either side of the centre of the curved slide J by the amount of the versed line of the arc of the lever E from F D ; it is to correct this error that the lever E is pinned at the point D to a parallel motion formed by the parts B and C, the point D per- forming a figure which is equal to an ellipse, with the error to be eliminated added, so neutralising its effect on the motion of the fulcrum F. Thus the " lap " and " lead" are opened by the action of the valve-lever acting as a lever, and the port-opening is given by the incline of the curved slide in which the centre of that lever slides, and the amount of this opening depends upon the angle given to that incline. Consequently, when these two actions are in unison, the motion of the valve is very rapid, and this occurs when the steam is being admitted. Then follows a period of opposition of these motions, during which time the valve pauses momen- tarily, this corresponding to the time when the port is fully open. Further periods of unison follow, at which time the sharp " cut-off" is obtained. The "compression" resulting with this gear is also reduced to a minimum, owing to the peculiar movement given to the valves (i.e., the series of acclerations and retardations referred to), as while the " lead " is obtained later and quicker, the port is also shut for " compres- sion " later and quicker, doing away with the necessity for a special expansion-valve, and allowing the main valve to be used for expansion, as the "compression" is not of an injurious amount, even with a "cut-off" reduced to 15 per cent., or about th of the stroke. Joy's Valve-Gear for Triple-Expansion Engines, is shown in THE PRACTICAL ENGINEER'S HAND-BOOK. Figs. 257 and 258, in which, instead of employing three distinct sets of valve-gears, one for each cylinder, a valve-gear is fitted to each outer cylinder, and these two are united by a floating lever, motion being taken for the valve of the third cylinder from about the middle of this lever, this motion being found to be correct in its character, for the purpose, and is under the same control for reversing and for expansion as the other two Fig. 257. Fig. 258. Figs 257 and 258. Triple-expansion engines with Joy's valve-gear. valve-motions. Being, moreover, the resultant of the other two motions, it is a mean between them, so .that the high-pressure cylinder may be set with a cut-off of, say, '65, and the low-pressure at -55 ; the resultant motion for the medium-pressure cylinder will be *6o. These proportions may be varied to suit circumstances, or all the valves may be set to cut- off alike, and within considerable limits also the cut-offs of the high and low pressure cylinders may be varied independently of each other to equalise the strains on the cranks, without affecting appreciably the cut-off of the intermediate cylinder. Thus a considerable saving in complication of the triple-cylinder engine is effected, a complete set of valve-gear being replaced by a single lever. Bremme's Valve-gear, shown in Figs. 259 261, is worked from only one eccentric, and it has consequently fewer working joints than a link- motion. Figs. 259 and 260 illustrate the mechanism of this valve-gear in its most elementary form. GH is a swinging link or radius-rod, pivoted at G to a bracket, and at H to an arm projecting from the hoop of the single eccentric. The bracket itself is centred at F, in the same horizontal plane as the centre line of the shaft C, and can be partially rotated around that centre by a THE BREMME VALVE-GEAR. worm or worm-segment (Fig. 260). The two extreme positions of the bracket are shown by dotted lines, and correspond to the two directions of motion of the engine. A modification in the arrangement of this valve-gear is shown in Fig. 261, which represents the engines of a steam-yacht, in which, instead of the toothed-bracket FG, a double bar is used, which is carried by a lever at one end and by a curved slot at the other the radius of each of these being the same as FG or GH (Figs. 259 and 260). The centre, G, of the swing- ing link or radius-rod GH, is thus, in reversing or varying the expansion, carried in the arc of a circle around the centre F, with a radius equal to FG Or GH. When the Crank is On Fig. 259. Diagram of Eremme's valve-gtar. the dead point at top and bottom, then F and H coincide, so that shifting the bracket does not then move the valve. The Bremme valve-gear gives at all grades of cut-off a uniform lead. Fig. sea- 's valve-gear. In reversing or altering the expansion there is no side-thrust put on the valve-spindle. It is simple in its action, and has very few working parts. 312 THE PRACTICAL ENGINEER'S HAND-BOOK. A well-made link-motion for one cylinder has two eccentrics, four double joints, and one single joint constantly working or eleven parts in all ; Fig. 261. Yacht-engines with Bremme's valve-gear, by Ross and Duncan, Glasgow. whereas a Bremme-gear for one cylinder, when constructed in its best form, as shown in Fig. 261, has one eccentric, and four single joints con- stantly working or five in all. SECTION IV. CONNECTING-RODS, COUPLING-RODS, CRANK- SHAFTS, CRANK - AXLES, SCREW - PRO- PELLER - SHAFTING AND BEARINGS, SCREW-PROPELLERS, PADDLE-WHEELS, AND JET-PROPELLERS, ETC. SECTION IV. CONNECTING-RODS, COUPLING-RODS, CRANK- SHAFTS, CRANK - AXLES, SCREW - PRO- PELLER - SHAFTING AND BEARINGS, SCREW-PROPELLERS, PADDLE-WHEELS, AND JET-PROPELLERS, ETC. CONNECTING-RODS, COUPLING-RODS, CRANK-SHAFTS, SCREW- PROPELLER SHAFTS, AND HOLLOW SHAFTING. Connecting-B-ods for Marine-Engines are usually made equal in length to from twice to three times the length of stroke of the engine ; the usual forms of the ends of the rod are shown in Figs. 262 265. The Fig. Fig. 264. Fig. 263. Fig. 263. s. 262 and 263. Marine-engine connecting-rod. Figs. 264 and 265. Marine-engine connecting-rod. THE PRACTICAL ENGINEER'S HAND-BOOK. strongest is that shown in Fig. 262, in which one-half of the end is forged solid with the rod, which forms a firm support for the cap-bolts. Bushes, Figs. 266 and 267. - Connecting-rod with fork-end. having packing-pieces, or liners for adjustment, are fitted and secured by a cap bolted to the solid end of the rod ; the bushes are sometimes lined with anti- friction metal. The connecting-rod shown in Fig. 264 terminates in a T-piece, into which a gun-metal block, forming the bushes, is partly recessed ; the bushes are retained by the cap and bolts as shown. The nuts on the bolts are each provided with a collar, recessed into the metal as shown, and a set-screw is fitted into a groove in the collar, by which the nut can be secured and prevented from working loose. A Connecting-Bod with a Fork-end is shown in Figs. 266 and 267, the end being forked to span the cross-head ; the large end of the rod has adjustable bushes with caps and bolts. The fork-end carries the pin for the crosshead ; the pin is fitted into tapered holes in the jaws of the fork- end. Another arrangement of the fork- end of a connecting-rod is shown in Fig. Fig. 268. Fork-end of a connecting-rod. 268; it is provided with caps, bolts, and adjustable bushes, the ends of the cross- head pin are fitted with links for working the air-pump lever of a marine- engine. CONNECTING-RODS. 3 1/ The Diameter of the Connecting- Bod at the Centre may be found by the following formula : Let D = the diameter of the cylinder in inches. P = the initial absolute pressure of the steam in Ibs. per square inch. C = the diameter of the connecting-rod at the centre, in inches. Then C = / // F 55 * Example : Required the diameter of the connecting-rod at the centre, for a marine-engine with a cylinder 42 inches diameter ; the initial absolute pressure of the steam being 90 Ibs. per square inch. Then 42 -4-55 = -76, and 2 fgo=g-4gx 76=7-22 inches, the diameter at the centre of the connecting-rod. The Diameter of the Connecting-Rod at the End may be found by the following formula, where the notation is the same as in the previous formula. Let E = the diameter at each end of the connecting-rod. Example : Required the diameter of the ends of the connecting-rod given in the previous example. Then 42-f-6o='7 and /9O = 9'49X'7 = 6*65 inches, the diameter of each end of the connecting-rod. The Diameter of the Cap-Bolts for the Connecting- Bod shown in Figs. 262 266 may be found approximately by the following formula, where the notation is the same as in the two previous examples. Let B = the diameter in inches of each cap-bolt. ThenB= ^ // F 125 V Example: Required the diameter of the bolts for the connecting-rod given in the previous example. Then 42 -^ 125 = '336 and if/go = 9-49 x '336 = 3'i8 inches, the diameter of each bolt. The diameter of the bolt-head should be one- half larger than the bolt. The Centres of the Cap-Bolts of the Connecting-Bod maybe=the diameter of the neck plus from 1-25 to 1*4 diameter of the bolt; they are generally placed as closely as possible. The Thickness of the Cap of the Connecting- Bod may be equal to one-half the diameter of the bearing. A Connecting- Bod for a Stationary Engine, the ends having a strap to secure the bushes, and gib and cotter, are shown in Figs. 269 and 270. 3?8 THE PRACTICAL ENGINEER'S HAND-BOOK. When the cotter is tightened to take up the wear of the brasses, the con- Figs. 269 and 270. Connecting-rod of a stationary-engine. necting-rod is shortened in length. The taper of the cotter is usually from f to f inch per foot. In the large end of the connecting-rod shown in Fig. 272. Fig. 273. Figs. 271 273. Large end of the connecting-rod of a locomotive-engine. Fig. 269 the cotter is locked by nuts on a screw forged on the head of the gib as shown, and in the small end the cotter is locked by a steel set-screw. LOCOMOTIVE-ENGINE CONNECTING-RODS. 319 Fig. 274- The number of turns required to be given to the nut on the screw of the cotter to draw the brasses a given degree closer, may be ascertained as follows : Supposing the screw to have 14 threads per inch, and the taper of the cotter = | inch per foot, it is required to find the number of turns to be given to the hexagon nut to draw the brasses -^ inch closer. Then -5Q4 inch taper of cotter inch for Qne tum Qf 14 threads x 12 inches required adjustment of brasses = T V or -0625 inch, and^ -^ = 2O'8 turns. "OO^ As the nut has six cants, it will require 20 turns and '8x6 =4^8 cants, or say 5 cants, to draw the brasses -^ inch closer. A Locomotive-Engine Connecting-rod, the pattern used on the Brighton Railway, is shown in Figs. 271 273. The large end of the con- necting-rod is fitted with a cap and bolts. The bolts are bored up for the greater part of their length so as to reduce their sectional area to that of the screwed portion, and thus secure equal elasticity. With these long bolts it is not found necessary to employ lock-nuts ; a small cotter is fitted in the ends of the bolts. The small end of the con- necting-rod, shown in Figs. 274 and 275, has a strap secured with a cotter and bolt, the butt-end of the rod is recessed to receive the brass- bush as shown. The taper of the cotter is i in 6. A locomotive engine con- necting-rod of another design, the pattern used on the Lon- don and North-Western Rail- way, is shown in Figs. 276 279. The large end of the connecting-rod, shown in en- larged view, Fig. 278, is open-ended, and secured at the end with a bolt passing through a block,, which forms an abutment for the bush in front of it. The brasses are adjustable by a cotter having double nuts at each end. Strips of anti-friction- metal are let into the brasses, as shown in Fig. 281. The middle of the con- necting-rod is flat-sided, as shown in Fig. 277; a boss is formed on the rod, which is bushed to receive a pin for coupling a link to work a rod connected to Joy's valve-gear. The small end of the rod is solid, without strap, and is bushed, as shown in Fig. 280. locomotive Engine Coupling-rods or Side-rods with adjustable bushes, are shown in Figs. 282 285. The large end is solid, without straps,. Figs. 274 and 275. Small end of the connecting-rod of a locomotive-engine. 320 THE PRACTICAL ENGINEER'S HAND-BOOK. and is provided with a cotter for adjusting the bushes. The small end is forked and fitted with an end-block, as shown, and a cotter for adjusting the brasses. The brasses of the small end are formed with a cap to cover in Tn Fig. 276- Fig. 277. -r 5-- 8 '-Centre to- Centre Figs. 276 and 277. Connecting-rod of a locomotive-engine. the end of the pin to protect it from dust, as shown in Figs. 283 and 284. A cross section of the large end of the rod is shown in Fig. 285. The ends of a set of coupling-rods or side-rods of another design, for a loco- motive engine, are shown in Figs. 286 and 287. They are fitted with solid Fig. 278, Figs. 278 and 279. Large end of the connecting-rod shown in Figs. 276 and 277. bushes, restrained from turning round by taper-pins. The ends of the rods are hardened, and the bushes are forced into place by hydraulic pressure. LOCOMOTIVE-ENGINE SIDE-RODS. 321 Fig. 280. Small end ot tnc connecting-rod shown in Figs. 276 and 277. Fig. 281. Bush of connecting-rod. Figs. 282 and 283. Locomotive-engine side-rods. Figs. 284 and 285. Cross- section of the ends of the side-rods shown in Figs. 282 and 283. Figs. 286 and 287. Locomotive-engine side-rods. %* For some of the above, and several other illustrations in this work, the author is indebted to " Engineering." Y 322 THE PRACTICAL ENGINEER'S HAND-BOOK. The bushes are bored ^V inch larger than their pins to allow for the play of the axle due to inequalities of the road. The middle or plain part of the rod is flat-sided. Crank-shafts of Marine-Engines are generally constructed in two or Fig. 288. Crank-shaft of a marine-engine. more parts, which are interchangeable, and connected together by flanged Fig. 289. Built-up crank-shaft of a marine-engine. couplings, a separate part being provided for each cylinder, as shown in Fig. 288 ; each part is a duplicate of the other, so that in the event ot a break-down only one part has to be renewed. The Marine-Engine Crank-shaft, shown in Figs. 289 and 290, is built of separate pieces; the two pieces of each part of the shaft, and also the cranks, are forged out of the best scrap-iron. A. forging of cast-steel is used for the crank-pin. In this method of building up the shaft in pieces, the forgings for engines of the largest size are of the simplest kind, and of such a size as to insure their being sound. A Crank-shaft for a Triple - expansion Engine, built up on a very simple and effective plan (J. P. Hall's patent), is shown in Fig. 291, the novel feature of: Fig. 290. End-view of the crank-shatt shown in Fig. THE PRACTICAL ENGINEER'S HAND-BOOK. frhich consists in bolting the centre crank-pin to the webs of the crank. The crank-pin is flanged at both ends, the flanges are recessed into the crank-webs and secured by bolts, as clearly shown in the sectional view. This arrangement is particularly adapted for the three-throw crank- shafts of triple-expansion engines, as the shaft then only consists of two pieces and a crank-pin, consequently only one-half a shaft need be carried as spare-gear, or provision for a break-down on a voyage. A shaft constructed on this principle is more flexible than a solid shaft, and it possesses all the advantages of a shaft made in three pieces and joined by flanged couplings, without losing the space occupied by such couplings. The application of this system to one of the cranks of a built- up shaft for marine engines of 1200 indicated horse-power, is shown in Fig. 291, but it may be applied to all the cranks of a similar shaft, and also to cranks having webs solid with the shaft. A number of crank-shafts are working with very satisfactory results, constructed on this principle, the pro- portions of a few of which are given in the following Table : Table 85. PROPORTIONS AND FINISHED WEIGHTS OF CRANK-SHAFTS BUILT ON MR. J. P. HALL'S SYSTEM ; THE SHAFTS BEING MADE OF WROUGHT- IRON AND THE CRANK-WEBS AND CRANK-PINS OF FORGED STEEL. Name of Vessel. Length Stroke. Diam. of Shaft. Length Over All. Diam. of Coupling Length of Crank-Webs Thick- ness of Webs. Weight Shaft. For H. P. & L. P. For I. P. Inches. Inches. Ft. In. Ft. In. Ft. In. Ft. In. Inches TnsCwt Earnwell 42 15 8 I 9l 3 5f 3 7 6 5 Earnmoor 42 I li 15 8 9i 3 5l 3 7 74 6 5 Era . . 39 io| 16 2 9 3 3f 3 5 7 6 i Hopetoun 39 I I j 15 ii 9l 3 4* 3 5r 7f 6 2 Starling. 33 9i 13 6 8 2 103- 2 11^ 64 4 S ,Alice Depeaux IOJ 14 2 9 3 \ 3 ! 6f 4 18 Cairnryan . . 36 10 14 2 8 3 s 3 i 6| 4 15 Drever . 36 ici 14 *J 8:7 3 1 3 2 71 5 5 Glanystwyth . Northwood . 103 10 H 7 14 2 8 i 8 3 1 3 8 3 2 3 i- 1 1 i 5 8 4 15 Cairntoul . 36 10^ 14 7 i 8| 3 1 3 2 I 7? 5 5 The Diameter of a Wrought-iron Crank-shaft for a Marine Engine may be found by the following formula : Let IHP = the indicated horse-power of the engines ; N = the number of revolutions per minute ; D = the diameter of the shaft in inches. Then D = 4-5 y (IHP -5- N). Example : Required the diameter of a wrought-iron crank-shaft, also the dimensions of the web of the crank for a marine engine of 2,400 indicated horse-power, making 60 revolutions per minute. Then 2400-7- 60= %/ 40= 3-42 x 4-5 = 1539 inches, or say 15! inches diameter of the shaft. The area of each web of the crank should at least be equal to that of the shaft, which is i5'5 2 x -7854= 1887 square inches; taking the width of each web at two-thirds the diameter of the shaft, or say MARINE-ENGINE CRANK-SHAFTS. 325 10 inches, the depth of each web will be 1887 -7-10= 18-87, or say 19 inches. Hence the area of the section of each web of the crank will be 10 x 19 = 190 square inches; the diameter and length of the crank-pin Fig. 292. Fig. 293. Figs. 292 apd 293. Crank-shaft of a marine-engine. may each be equal to the diameter of the crank-shaft, and with these pro- portions the crank-shaft shown in Figs. 292 and 293 is obtained. The Web of a Crank may be proportioned by the following rule, which gives nearly the same results as those obtained by the previous method. If w = the width and d = the depth of each crank-web, wd a should be equal to the cube of the diameter of the crank-shaft. Example : Required the dimensions of the web of the crank-shaft given in the previous example, 15^ inches diameter. Then the cube of the diameter of the crank-shaft (i5| 3 ) = 3724. If the width of the web be two-thirds the diameter of the shaft, or say 10 inches, it will give 3724 -f- 10 = 372-4 and V37 2 '4 = 19*3 inches, the depth, and 10 x i9'3 2 = 3724 as required by the rule, which makes the depth of the crank -3 inch more than that obtained by the previous method. The Diameter of a Solid Steel Crank-shaft for a may be found by the following formula : Let IHP = the indicated horse-power of the engine. N = the number of revolutions per minute. D = the diameter of the shaft in inches. Larmp-pn gine Then D =4*3 Example : Required the diameter of a solid steel crank-shaft for a marine-engine of 2400 indicated horse-power, making 60 revolutions per minute. Then 2400 horse-power + 60 = 40 and ^40 = 3-42 x 4-3 =14-7, or say 14^ inches, being 15' 5* -f- I475 3 =1*15 or 15 per cent, less in size than the wrought-iron crank-shaft found for the same power in the previous example. Journals and Couplings of Crank-shafts of Marine-engines are usually of the following proportions : Length of each journal or bearing of crank-shaft = diameter of crank- shaft x 1-25 to 2'5 ; the higher the speed the longer should the journal be. 326 THE PRACTICAL ENGINEER'S HAND-BOOK. Diameter of the coupling of crank-shaft = diameter of crank-shaft x r8 to 2. Thickness of each flange of the coupling = diameter of crank-shaft x 25 to -3. The Length of Bearings or Journals of a Crank-shaft suitable for a given pressure may be found by this Rule : Divide the initial pressure of the steam on the piston in Ibs. per square inch of its area, by the product of the given pressure in Ibs. on the bearing and the diameter of the bearing in inches. Example : The piston of an engine is 60 inches diameter, the initial pressure of the steam is 50 Ibs. per square inch, the diameter of each bearing of the crank-shaft is 14 inches : what should the length of each bearing be, if the pressure on the bearing is not to exceed 600 Ibs. per square inch ? Then 63Jcfokdbet2^ 5 4JL53!LP!* = 16-82 inches, the ooo Ibs. x 14 inches diameter length of each bearing required. The Bushes for the Journals of Crank-shafts are best made of good tough bronze or gun-metal, with strips of anti-friction metal let into the bearing-surfaces. The gun-metal for the bushes may be composed of : 88 parts of copper 10 parts of tin 2 parts of zinc. The strips of anti-friction metal may be composed of : 85 parts of tin 5 parts of copper 10 parts of antimony. The strips may be let into the bearing-surfaces in the manner shown in Fig. 281. The Proportions of the Crank of a Marine-engine are usually as follows : Width of each web of crank = diameter of crank-shaft x '67. Depth of each web of crank = diameter of crank-shaft x i'25. Diameter of crank-pin = diameter of crank-shaft x i to n. Length of crank-pin = diameter of crank-shaft x i to 1-25. The area of bearing of each crank-pin should not be less than = '2 square inch per indicated horse-power developed by the corresponding cylinder. The Strain or Pressure on a Crank-pin may be found by this Rule : Area of cylinder in ins, x maximum pressure of the steam in Ibs per sq. in. diametrical sectional area of the crank-pin in square inches The diametrical sectional area of the crank-pin is the product of the diameter of the crank-pin in inches by its length in inches. Example : The diameter of the low-pressure cylinder of a compound engine is 60 inches, the areas of the two cylinders are to each other as i is COUNTER-JBALANCE-WEIGHT OF A CRANK. 327 to 37, the effective pressure of the steam on the high-pressure piston is 85 Ibs. per square inch at the beginning of its stroke, and on the low- pressure piston the effective pressure of the steam is 23 Ibs. per square inch at the beginning of its stroke, the crank-pin is 14 inches diameter and 15 inches long. Required the diametral sectional area of the crank- pin in square inches ; and also the pressure in Ibs. per square inch on the surface of each of the crank-pins ? Then, the diametral sectional area of the crank-pin is 14 x 15 inches = 210 square inches. The area of the low-pressure cylinder is 60 x 60 x "7854 = 2827-44 square inches. The area of the high-pressure cylinder is 2827-44 -=- 3-7 = 764-17 square inches. The pressure on the low-pressure crank-pin is 2g2 7'44 x 23 Ibs. _ 210 area of crank-pin 309-67 Ibs. per square inch. The pressure on the high-pressure crank-pin is L_1_1Z_ 5 s - _ 210 area of crank-pin 309-30 Ibs. per square inch. The Weight of the Crank and of half the length of the Connecting-rod next the Crank-pin of high-speed engines should be accurately balanced by means of a counter-balance-weight revolving opposite to the crank, so that both may revolve in the same plane of revolution. The counter-weight may either be solid with the crank, or bolted on. When it is bolted on to the crank, the diameter of the bolts required may be found by the following formulas : Let R = the number of revolutions of the crank-shaft per minute. r = the effective radius of the balance-weight in feet. N = the number of times the weight is increased by centrifugal force. N = ^*-^- Area of bolt in sq. ins.= ___ yince^W number of bolts X working stress on the bolt in Ibs. Example : The counter-balance-weight of a crank weighs 1480 Ibs., its effective radius being r6 feet, the shaft makes 65 revolutions per minute. What should the diameter of each bolt be, if two bolts be used to bolt it to the crank, and the strain on the bolts is not to exceed 5000 Ibs. per square inch of section ? Then -5-^ L*_Lr = 2-3, the number of times the weight is increased 2935 by the centrifugal force, which multiplied by the weight of the counter- weight in Ibs., will give the stress upon the bolts, and 2*3 x 1480 Ibs. weight of counter-balance 2 bolts x 5000 Ibs. the strain allowed = 3-4 square inches the area of each bolt required, then V3'4 ** 7854 = 2 -08 inches, the diameter of each bolt. 328 THE PRACTICAL ENGINEERS HAND-BOOK:. The Boiler-Pressure of Steam suitable for a given Size of Shaft is sometimes found by the following Rule : Let D = the diameter of the low-pressure cylinder in inches. H = the diameter of the high-pressuie cylinder in inches. L = the length of stroke in inches. d = the diameter of the shaft in inches. f = a constant = 4936 for wrought-iron crank-shafts. = a constant = 5760 for wroueht-iron tunnel or propeller-shafts. Boiler-pressure of steam in Ibs. per square inch. B _ if; Example : What boiler-pressure of steam may be used for a compound engine having a wrought-iron crank-shaft 1 1 inches diameter ; diameter of the low-pressure cylinder 60 inches ; diameter of high pressure cylinder 30 inches ; length of stroke 36 inches. Then x 36x15 i bs . per square inch, the boiler- * 30 inches x 30* inches pressure of steam that may be used for that crank-shaft. A Crank- Axle for a Locomotive Engine with inside cylinders, single frames and single bearings, is shown in Figs. 294 and 295. The cylinders Fig. 294. Fig. 235. Figs. 294 and 295. Locomotive crank-axle. are 17 inches diameter, and the length of stroke is 26 inches; the journals are 7^ inches diameter and 7! inches long. The crank-pins are each 7! inches diameter and 4^ inches long ; their diametrical sectional area being 7f inches x 4^ inches= 34-88 square inches. Taking the maximum mean effective pressure of the steam in the cylinder at 100 Ibs. per square inch, the area of the cylinder being 17" x 7854 = 227 square inches, the total pressure that may be delivered on each crank-pin would equal 227 square inches x 100 Ibs. = 22700 Ibs. or a little more than 10 tons being at the rate of 22700 Ibs. -f- 34'88 = 623 Ibs. per square inch of diametrical section of the crank-pin. A pressure of 10 tons on each crank -pin would, when the cranks are in certain positions, result in a combined stress of 20 tons on the axle. The outside or thinner webs of the crank are 4j inches thick and 12 inches broad, the sectional area of each web being 12 x 4j = 51 square inches, the sectional area of each crank-pin is 7f 2 x LOCOMOTIVE CRANK- AXLES. 329 7854 = 47'i7; the sectional area of each journal is 7^ x 7854 = 44-17. Hence the thinner webs of the crank are of sufficient area, being a little greater than that of the axle. A Crank-Axle for a locomotive Engine with inside cylinders, double Fig. 296. Locomotive crank-axle. frames, and both inside and outside bearings, is shown in Fig. 296 ; outside cranks are provided for the coupling-rods or side-rods. Crank-Shafts and Crank- Axles frequently fail at the angle between the web of the crank and the crank-pin as shown in Fig. 297, and they sometimes fail by a ball-and-socket shaped fracture at the crank-pin which separates in this form from one of the crank-arms. The cause of failure in many cases being overstraining of the crank beyond the limit of its elastic strength. Crank-Axles of Locomotive Engines frequently fail from being kept running too long a time. It is considered that the maxi- mum mileage of iron crank-axles should not exceed 200,000 miles, and of steel 180,000 miles. In order that in the event of a breakage, the crank may hold together until the train is stopped or a station reached, each web of the crank is frequently hooped, and a Fig. 297. Broken crank hole is bored through the centre of the crank-pin into which a bolt is fitted to hold the webs together. A Crank-Shaft may be strained excessively by its bearings being out of line ; by the bearings giving or springing ; by slackness of the brasses ; by want of rigidity in the bed-plate ; or by the presence of water in the cylinder : and its tensile strength may be considerably diminished by long- continued excessive straining. When the bearings are so much out of line as to cause the necks or journals to become hot, the strain on the shaft is seldom less than one-third greater than that due to ordinary working in true bearings, it frequently is considerably more, and it may be from 50 to 100 per cent, greater than when the bearings are true. When the shaft is fractured by being out of line, it is frequently due to the strain produced by 330 THE PRACTICAL ENGINEER'S HAND-BOCK. the opening and closing of the jaws of the crank at each revolution of the crank-shaft. The slackness of the brasses, if slight, may be taken up gradually by cushioning, but where cushioning is defective, or absent, the pressure of the steam comes on the piston suddenly and causes an impulsive strain on the shaft which varies in intensity with the amount of slackness of the brasses. The presence of water in the cylinder may cause a severe bending strain on the crank-shaft. Steel Crank- Axles and Crank-Shafts should be made of mild, homo- geneous forged-steel, of which the following is an average analysis : Carbon -200 ; manganese '600 ; silicon -015 ; sulphur '060 ; phosphorus 050. The tensile strength should be about 28 tons per square inch; elongation 25 per cent. ; contraction 40 per cent. Crank-shafts are some- times made as steel-castings, but they are generally inferior to, and not so reliable as, forged-steel shafts. Bent Cranks, made from round bars of iron or steel, shown in Fig. 298, are used for portable-engines,pumps, thrashing-machines, looms, &c. ; the small sizes are bent by special ma- chines, and the larger sizes by hydraulic pressure in suitable presses, the ends being forced inwards while the throws are being formed, so as to Fig. 29 8.-Crank-shaft of a portable-engine. complete the crank with as few heats as possible and prevent deteriora- tion of the material. This is the cheapest method of making a crank-shaft, and it is also the strongest, because the fibre of the material runs along the arms and round the throw of the crank, whereas when the crank is forged in a solid block, the fibre runs across the webs and is severed by cutting out the throw. When a bent crank is required to work in a limited space, the webs, instead of being round are slightly flattened, or made oval-shaped. Three-Throw Cranks for Large Pumps are frequently made of cast- iron, and when made of good tough metal they work satisfactorily. The crank- pins or sling-bearings are usually made one-fifth larger in diameter than the main bearings, to compensate for the torsional strain being greater on the sling-bearings than on the main-bearings, owing to the peculiar form' of this kind of crank. A cast-iron crank-shaft will only bear two-thirds the torsional strain of that of a wrought crank-shaft of the same propor- tions. Thus if a wrought-iron crank-shaft be suitable for a strain of 30 horse-power, a cast-iron shaft of the same proportions would only bear a strain of 20 horse-power. Cast-iron Cranks for Large Pumps should be cast from good tough metal. The following is a good mixture of metal for this purpose : Scotch mixed brands, 5 cwt. Weardale, 7 cwt. Good clean scrap, 8 cwt. A test-bar of cast-iron cast from this mixture, i inch square, placed upon SCREW-PROPELLER-SHAFTING. 331 supports three feet apart, should bear a gradually applied weight of about 7^ cwt. with a deflection of about f inch. A Screw-Propeller Shaft is connected to the crank-shaft by several lengths of shafting with couplings forged solid with the shaft, as shown in Fig. 299. The foremost length of shafting has a journal fitted with thrust- Fig. 299. Screw-propeller-shafting. collars which work in recesses in a thrust-bearing, which receives the thrust of the propeller. The Diameter of a Solid, Wrought-iron Propeller-Shaft, or screw- shaft, may be found by the following formula : Let I H P = the indicated horse-power of the engines. N = the number of revolutions per minute. D = the diameter of the screw-shaft. . / T H P ' rr-ii -T--V A * tJ- -^ Then D = 4 AY =-= Example : Required the diameter of solid wrought-iron screw-propeller shafting for a pair of marine engines of 1500 indicated horse-power, making 62 revolutions. Then 1500-7-62= ^25" = 2^93 x 4=1172, or say nf inches diameter. The size of shaft obtained by this rule, although it agrees fairly with practice, does not allow a sufficient margin of strength for contingencies, the number of failures of these shafts prove that they are frequently made too light. They frequently fail from want of stiffness to resist the strain due to the continual bending and unbending action of the overhung weight of the propeller. Screw-Propeller-Shafting is exposed to an end-thrusting strain due to propulsion, a twisting strain from the engine, and a bending strain due to the weight of the propeller. The diameter of the shafting may be found by the following Rule, which provides for all these strains and allows a margin of strength for contingencies, to obviate fracture. D = Example : Required the diameter of the solid wrought-iron propeller- shaft, given in the previous example. Then ~? x 9 = */ 2016=12-96, or say 13 inches diameter of shaft, being i3 s -Mif s = i'35, or 35 per cent, larger than that obtained by the previous Rule. 332 THE PRACTICAL ENGINEER'S HAND-BOOK. Screw-Propeller Shafts of Large Size are best made hollow of Whitworth's Compressed Steel, as the weight of the shaft may thus be con- siderably reduced without diminishing the strength. Hollow-Shafting of Whitworth's Compressed-Steel for screw- propellers should be calculated, for the external diameter, by the last Rule given above for wrought-iron propeller-shafts, and the internal diameter should = the external diameter of the shaft x '56. Example : Required the internal diameter of a propeller-shaft of Whit- worth's Compressed Steel, of 14 inches external diameter. Then 14 x -56 = 7*84, or say 7! inches internal diameter. Couplings for Screw- Propeller Shafting consist of flanges forged solid with the shafts, one flange having a projection to fit into a recess in the other flange, in order to keep the shafts central, as shown in Fig. 300. The diameter of the flange or coupling = the diameter of the shaft x i '8 to 2 : the thickness of each flange = |th the diameter of the shaft. Fig. 300. -Coupling of propeller-shafting. Bolts for the Couplings of ScrCW- Fropeller Shafting are exposed principally to a shearing strain. The diameter of the bolts, D, may be found by the following formula, where N = the number of the bolts. D = T/!L x diameter of the shaft. Example: Required the diameter of the bolts for the couplings of a screw-propeller shaft of 12 inches diameter, the number of bolts to be six. Then ^6 = 2-45 and '55-4- 2'45 = '224X 12 = 2-69 inches, the diameter of the bolts required. If the number of bolts were eight, their diameter would be = ^78 = 2-83 and > 55-f-2 > 83 = 'i94 x 12 = 2-33 inches. The Shearing-Strain on the Bolts of the Couplings of Shafting may be found by dividing the power in foot pounds transmitted, by the distance travelled by the bolts in one minute. Example : Required the shearing-strain on the bolts of the coupling's of the shafting of a screw-propeller transmitting icoo indicated horse-power, making 60 revolutions per minute, the diameter of the circle of the centres of the bolts is 1 8 inches, and there are 8 bolts, 2 inches diameter, in each coupling. Then 1000 horse-power x 33000 Ibs. = 33,000,000 foot Ibs. transmitted and 1-5 feet pitch-circle of bolts x 3-1416 x 60 revolutions =282-744, the distance travelled by the bolts in one minute. The strain on all the bolts of the coupling will be = 33,000,000-7-282744=1 16,713*31 Ibs., the strain on each bolt will be = 116713-31-4-8=14,590 Ibs., the area of each bolt is 2 a x -7854 = 3-1416 square inches, and the strain on each bolt is 14590-7- 3-1416=4644 Ibs. per square inch of the sectional area of the bolt. The Strain on the Shaft of a Screw-Propeller due to the Over- hang of a Propeller may be found by the following formula : STRENGTH OF SHAFTING. 333 Let W = the weight of the propeller in tons. D = the distance in inches of the centre of the weight from the point of support. S = the maximum strain in Ibs. per square inch. ,p, g _ _ io'2 x Wx 2240 xD ~ (Diameter of the shaft in inches) 3 ' Example: Required the maximum strain in Ibs. per square inch on the shaft of a screw-propeller due to the overhang of a propeller weighing 5 tons, the centre of weight being 25 inches from the point of support and the shaft being 1 1 inches diameter. rr,, io - 2 X 5 tons x 2240 x 25 inches . , Then - 5 _Jt. ^ - = 2145-8 Ibs. per square inch. ii x ii x ii inches The Strength of a Shaft or Shafting, to resist Bending, is only equal to one-half of its strength to resist torsion or twisting. The Strength of Bound Bars or Shafts to resist a Torsional or Twisting Strain is in proportion to the cubes of their diameters. A bar of wrought-iron, i inch diameter, is twisted asunder by a weight or force of 800 Ibs. applied at the end of a lever 12 inches long, measured from the centre of the bar, and the relative resistance of different bars is usually expressed by stating the weight which twists them asunder when applied in this manner. Hence if the torsional strength of a bar i inch diameter be known, the strength of bars of other dimensions of the same material may be calculated from it. Example : As a bar of wrought-iron i inch diameter is twisted asunder by a force of 800 Ibs. .applied at the end of a lever 12 inches long from the centre of the bar, what force will be required to break a | inch diameter wrought-iron stud, applied at the end of a lever 16 inches long ? Then 16 inches : 12 : : 800 Ibs. = 600 Ibs. the force required to break a stud i inch diameter applied at the end of a lever 16 inches long. And i 3 : 75 3 : : 600 = 253-125 Ibs. the force required to break the f inch diameter wrought-iron stud at a leverage of 16 inches. The Torsioual Strain on Shafting may be found by the following formula : Let F = the force in Ibs. applied to the shaft. L = the leverage in inches through which the force acts. D = the diameter of the shaft in inches. S = the maximum strain per square inch of section of the shaft. Then S = Example : A shaft 10 inches diameter is subjected to a torsional strain by a force of 50,000 Ibs., acting with a leverage of 20 inches. Required the maximum stress per square inch of section of the shaft. 5o.ooolbs.X2oinchesxs-i = 10 x io section of the shaft. = ^ si ^ n Q mch of 10 x iox 10 inches 334 THE PRACTICAL ENGINEER'S HAND-BOOK. The maximum strain, S, per square inch on the transverse section of the shaft should not exceed the following : For wrought-iron crank-shafts, 5,000 Ibs. For mild steel crank-shafts, 5,500 Ibs. For all other shafts and shafting of wrought-iron, 9,000 Ibs. For all other shafts and shafting of mild steel, 10,000 Ibs. The Force, acting with a given Leverage, which may be applied to a Shaft may be found by the following formula, the notation being the same as in the previous formula : F = D3xS Lxs-i' Example i : Required the force in Ibs. which may be applied, at a /everage of 20 inches, to a shaft 10 inches diameter, which is capable of bearing a maximum strain of 5,100 Ibs. per square inch of section. Then IQ3 x 5> IQolbs - _ r O ,ooo Ibs., the force which may be applied to 20x5-1 the shaft at that leverage. Example 2 : If the maximum strain to be allowed on \vrought-iron be taken at 9,000 Ib. per square inch, what pressure may be applied at the end of a crank 20 inches long, to be transmitted by a shaft io| inches diameter. Then^-'5 8 _x 9.000 = IQ fi 20x5-1 The Diameter of a Shaft, subject only to a Torsional or Twisting Strain, suitable for a given force and leverage, may be found by the following formula, the notation being the same as in the two previous Examples : PI _ 3 / v x Lx 5-1 " V " ~s~ Example: Required the diameter of a shaft suitable for a force of 50,000 Ibs. applied at a leverage of 20 inches, the material of which the shaft is made being capable of bearing a strain of 5,100 Ibs. per square inch of cross section. rr,, 3 /50,000 X 20 X V I Then A/ * ? = 10 inches diameter. V 5,100 The Torsional Strain on a Crank Shaft may be found by the following formula : Let F = the force at leverage = the effective pressure of the steam in IDs. X length of crank in inches. A = the area of the cylinder in square inches. D = the diameter of the crank-shaft in inches. S = the torsional strain per square inch of section of the shaft. Fx Ax vi s = SCREW-PROPELLER-SHAFTING. 335 Example : The diameter of the cylinder of a marine engine is 42 inches, the length of stroke is 48 inches, the effective pressure of the steam is 60 Ibs. per square inch, and the diameter of the crank-shaft is 13 inches. Required the torsional strain on the crank-shaft per square inch of section. Then the area of the cylinder is 48* X 7854= 1305-45 square inches, , 1385*45 area x 60 Ibs. pressure x 24 inches crank x 5-1 _ , ., 13 x 13 x 13 inches the strain per square inch of section of the shaft. The End-thrust on the Shafting of a Screw-propeller, if the whole of the power were utilised by the propeller, may be ascertained by the following formula : Let IHP = the indicated horse-power of the engines. N = the number of revolutions per minute. S = the diameter of the screw-propeller in feet. T = the mean thrust in Ibs. on the propeller-shaft. TK IHP x 33 x I2 ~~~ Example: Required the end-thrust on the shafting driving a screw- propeller of 10 feet diameter, the indicated horse-power of the engines being 1000, and the number of revolutions per minute = 50. Then I00 x 33000 x_i 2 = 66ooQ lb the end . thrust 50 X 10 X 12 Main Tunnel and Propeller-shafts will not be passed by the Board of Trade if found less in diameter than that found by the two following rules ; but first-class makers generally put in larger shafts than those found by the following formulas :' Where S= diameter of shaft in inches, d*= square of diameter of high pressure cylinder in inches, or sum of squares of diameters when there are two or more high pressure cylinders, D 2 =square of diameter of low pressure cylinder in inches, or sum of squares of diameters when there are two or more low pressure cylinders, P= absolute pressure in Ibs. per square inch, that is boiler pressure plus 15 Ibs. C= length of crank in inches,/" constant from the following Table. For compound condensing engines with two or more cylinders, when the cranks are not overhung : s= For ordinary condensing engines with one, two, or more cylinders, when, the cranks are not overhung : tx/xS. 336 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 86. CONSTANTS FOR BOARD OF TRADE RULES FOR SHAFTING. For Two Cranks, For Crank an d Propeller For Tunnel Angle between Shal J Shaft. Cranks. 9 H. 1047 1221 100 ,-= * 966 1128 110 3 c o ^ 904 1055 120 f S . ^ 3 855 997 130 w ^f 1 P 817 953 I 4 JJJ w'S u 788 919 I 5 1 60 170 ^^S y ^Tij .. *- JC O C 766 75 1 743 894 877 867 1 80 h 740 864 For Three Cranks. IIIO 120 1295 NOTE. When there is only one crank the constants applicable are those in the table opposite 180. The four previous formulae are the only Board of Trade Rules for shafts. The Stern-shaft, or aftermost length of the propeller-shafting, marked A in Fig. 301, passes through the stern of the ship and drives the screw-pro- peller. In order to preserve the shaft from oxida- tion it is always covered or cased at the bearings with gun-metal, of from -| inch to f inch thick, and in some cases it is cased from end to end. When the casing is in seve- ral lengths, they are filletted into each other at the joints to prevent leakage. The casing is either cast on the shaft, or cast separate, and bored to fit the shaft tightly, on which it is forced by hydraulic pressure. The Stern-tube, marked B in Fig. 301, carries the bearings on which the stern-shaft revolves. It consists of a strong tube of cast-iron or gun- metal, having a flange on the forward end, or end of the tube inside the ship, by which it is bolted to the after-bulkhead ; this end is fitted with a stuffing-box and gland to prevent water entering the ship. The length of the stern-tube is determined by the distance between the after-bulkhead and the stern-post. The after or outer end of the stern-tube passes through the stern-post, to which it is secured on the outside by a strong nut screwed Fig. 301. Stern-tube and stern-shaft THRUST-BEARINGS OF PROPELLER-SHAFTING. 337 on the end of the tube. The bearing at the outside or after-end of the stern-tube, and sometimes at both ends, is fitted with strips of lignum-vitae recessed into the bush, as shown in Fig. 302, the strips being secured by a check-plate to prevent them working out. A pipe with cock is fitted for drawing water from the stern-tube to ascer- tain if the bearings are working cool. Lignum-Vitae Bearings, consisting of strips of lignum-vitse recessed into a bush as shown in Fig. 302, are the best and most durable bearings for the journals of shafts working in water; the space between the strips form watercourses by which the water circulates and efficiently lubricates the journals of the shafts. These bearings will stand a working pressure of as much as 2000 Ibs., being five times as much as can in many cases be safely carried by metal bearings. They are used for the outer-bearings of paddle-shafts and stern-shafts. Pltmiiuer - blocks for screw-propeller-shafting are usually of the form shown in Fig. 303. They are made of cast-iron, and lined with anti-friction- metal or white-metal. The plummer-blocks should be spaced as widely apart as possible, consistent with freedom from the shafts' sagging, in order Fig. 302. Section of Lignum- vitae bearing. Fig. 303. Plummer-block. Fig. 304. Thrust-bearing. to allow the shafting to yield to the strains in the hull due to the rolling of the ship, to prevent friction and diminish liability to fracture. A Thrust- bearing is shown in Fig. 304. It consists of a bush of either gun-metal or white-metal, made in halves; it is fitted into a cast-iron thrust-block. The bush is provided with a number of thrust-rings, which fit between corresponding collars on the thrust-journal; the rings are bored a little larger than the collars, so that the circumferences of the collars on the thrust-journal suf- pH ficiently clear the bottom of the re- cesses in the bush to prevent the weight of the shaft coming on the thrust-block, which should only take the end-pressure due to the thrust of the propeller. The wear takes place on the sides or fore and aft surfaces of the thrust-rings. An oil-tube is provided for lubricating each thrust-collar. An ordinary plummer-block is fixed close to the thrust-block to relieve it of the weight of the shafting and prevent vibration. Fig. 305. Thrust-bea 333 THE PRACTICAL ENGINEERS HAND-BOOK. A Tliriist-beariiig composed of separate Thrust-rings recessed into the Thrust-block is shown in Fig. 305. A Thrust-block provided with adjustable Thrust-surfaces is shown in Fig. 306. The thrust both ahead and astern is taken up as a Fig. 306. Thrust-bearing with horse-shoe rings. tensile strain by two strong bars screwed from end to end ; these bars are fitted at each end with nuts for taking the total strain against the bosses on the thrust-block, the thrust-surfaces of the shaft bear against horse-shoe- shaped cast-iron rings, which are faced with white-metal, each ring being adjusted and secured in position along the screwed bars by means of nuts and check-nuts. SCREW-PROPELLERS, PADDLE-WHEELS, AND JET- PROPELLERS. Screw-propellers are made with two, three and four blades. Pro- pellers with four blades cause less vibration, and are more efficient in a rough sea than those having a less number of blades. The blades are frequently cast separately and bolted to the boss of the propeller by a flange, as shown in Fig. 307. The bolt-holes are elongated to allow the position of the blades to be ad- justed when it is necessary to alter the pitch of the propeller. The flanges of the blades are frequently coated with cement, rounded off to follow the outline of the boss, to cover in the bolts and reduce the resistance of their surfaces to the water. Screw-propellers made of Cast- iron should be made from good tough metal, twice run. The fol- lowing is a good mixture of metal for this purpose, which should be melted and cast into pigs in order Fig. 3 07.-Screw-propeller with blades bolted tO mix properly : to the Boss. DELINEATION OF A SCREW-PROPELLER. 339 Hematite, No. 4 . 7 cw Gartsherrie, No. 3 ..... Clyde, No. 3 Weardale, No. 3 3 > 3 . Monkland, No. 3 . . 2 , A test-bar, cast from this mixture of cast-iron, i inch square, placed upon supports 3 feet apart, should bear a gradually applied weight of 8| cwt., with a deflection of about f inch. Screw-propellers made of Gun-metal can be made much thinner and lighter than when made of cast-iron. The following mixture makes a tough and durable gun-metal for this purpose : Copper 88 parts, tin 10, and zinc 2 parts. Another mixture for the same purpose is copper 87-7 parts, tin, 8-3 and Silesian spelter 4 parts. Delineation of a Screw-Propeller. A well-proportioned and very efficient screw-propeller, 15 feet 4 inches diameter, is shown in Figs. 308 310 ; it has four blades cast solid with the boss. Fig. 309 is a view looking forward in line with the axis of the propeller-shaft, the full line representing the projected shape of the propeller-blade as it will then appear, and the dotted line the shape of blade when developed or laid flat. Fig. 310 is a plan of the propeller-blade looking in direction of line A B (Fig. 309). Fig. 308 is a view of the propeller-blade in direction C D (Fig. 310); that is, a side view of blade. This propeller was fitted to s.s. ' Flamboro." After drawing an outline of the boss, the centre lines, and diameter of the propeller, the developed shape of the propeller-blade, as shown in Fig. 310, is usually determined next, and for the screw-propeller illustrated, the following is a general outline of the mode of procedure. In Fig. 309 draw any convenient number of arcs from the centre E with radii E F, E G, E H, etc., and E A, E F being the same as or slightly more than that of the boss, and E A the full radius of the propeller, the inter- mediate axes being equally spaced, or nearly so. In Fig. 310 draw the line M N parallel to D C at a distance correspond- ing with the aftermost part of the blade. On any convenient scale make O P = pitch, and P Q and P R = circumference of circles of radii E F and E A (Fig. 309), respectively. Draw O Q and O R. These will give the developed angles of blade near the boss and at periphery respectively. In Fig. 309 lay off round full arc at A a distance A S = T S, (Fig. 310), and round full arc at F lay off F U = T U ; (Fig. 310), join S U cutting the full arcs in V, etc. This line in a propeller of uniform pitch will pass through the centre of the shaft if produced. On line M N (Fig. 310) lay off T S ;/ = perpendicular distance of S from A B (Fig. 309). Horizontally in line with S (Fig. 309) mark point S ;// at a perpendicular distance from A B = O S /; (Fig. 310). With centre somewhere on line A B or A B produced, draw dotted arc passing through point A and S //; . On line M N (Fig. 310) lay off T U,, = perpendicular distance of U from A B (Fig. 309). Horizontally in line with U (Fig. 309) mark point U,,, at a perpendicular distance from A B = O U ;/ (Fig. 310). Developed edge of Bed Projected edge of Bed 'oped edge ofBl Projected edge of Blade DELINEATION OF A SCREW-PROPELLER. 341 With centre somewhere on line A B or A B produced, draw dotted arc passing through points F and U ;// . In Fig. 310 divide S^U,, into parts by points V /y etc., corresponding with points V etc. (Fig. 309) join O V /; etc. (Fig. 310). Horizontally in line with V (Fig. 309) mark point V /;/ at a proper distance from A B = O V,, (Fig. 310). With centre in A B or A B produced, draw dotted arc through J V //; . Draw the other dotted arcs in the same manner and then draw S y// U ;// through the points S //7 V ;// etc., and U //r All the other arcs should be continued on right side of A B as shown. These arcs correspond with those that will eventually be drawn on " bed " of the propeller-mould in the foundry, the projected edge of " bed" being represented by the full line S U, and the developed edge by the dotted line s,,, u,,,. The dotted arcs are approximately the development of parts of the helices wound round cylinders of radius E A and E F respectively, with pitch equal to that of the propeller. The figure A S //; U,,, F, and a similar figure on other side of A B show the limits with which the bhde must be drawn. On dotted curve F (Fig. 30:) mark point W /; at a perpendicular distance from A B = O W, (Fig. 3io),'this distance O W, being limited by the length of boss. Starting from point W ;/ (Fig. 309), and keeping within the prescribed limits, draw the outline of the blade as in dotted lines of such a shape and area as may be thought best. The projected outline (Fig. 309), may now be drawn from the develop- ment obtained, for example, mark point W on full arc F (Fig. 309) at a perpendicular distance from A B = perpendicular distance of W, from Y P (Fig. 310). This point W is the first point in projected outline. Then on line O V ;/ (Fig. 310) mark point X, at a distance from O = perpendicular distance of X y/ from A B (Fig. 309), then mark-X (Fig. 309) on full curve at a perpendicular distance from A B = perpendicular distance of X, from Y P (Fig. 310), or simply draw horizontal line X ;/ X, cutting full curve in X. All the other points for the projected outline may be obtained from the developed outline in the same manner, and the curve drawn through them. The plan may be drawn through the points X y etc., previously obtained from Fig. 309. Fig. 308 may be drawn through points obtained from Fig. 309 and 310 together. This method, in which a series of helices of different radii are developed, does not give the length of the edge S,,, U /;/ of the blade exactly, but the error is trifling, and by neglecting it the method is simplified. If the projected view of the blade (Fig. 309) is to be determined first, then part of the operation will simply require to be reversed. The blade is 8 inches thick at the root and tapers to f inch thick at the tip ; diameter of boss 2 feet 9 inches, depth of boss 2 feet 2 inches, taper of hole in boss i inch in 18 inches. Total developed surface 64'8 square feet. The Thickness of the root of the Blade of a Screw-propeller per foot in diameter of the propeller may be = \ inch for cast-iron, T V inch for 342 THE PRACTICAL ENGINEER'S HAND-BOOK. gun-metal, and f inch for mild-steel. The entrance-edge of the blade should be as sharp as practicable. The Velocity of the Blades of a Screw-propeller through the Water, consequent upon its revolution and the forward movement of the vessel, at different points from the centre of the boss : or the velocity or distance passed through the water each revolution by any point in the blade from the boss to the extremity may be found by this formula : y(27rr) ; T(P-S) 2 =D. D being the distance passed through by the point each revolution, P the e'tch of the propeller, and S the slip each revolution, or in other words : is = hypotenuse of a right-angled triangle where the base is = the cir- cumference of the circle of any diameter of the propeller, and the perpen- dicular is = the actual progress of the vessel each revolution of the propeller. Example : Required the velocity of the blades of a screw-propeller through the water, consequent on one revolution and the forward move- ment of the vessel, at a point in the blade 3 feet 4 inches radius or 6 feet 8 inches diameter, the pitch of the screw-propeller being 2777 feet and the slip 10 per cent. Then (3-1416 x 3-333 feet radius x 2) 2 =439'56. and (277710 per cent. slip) 2 =625. Then 4 / (439'56 + 625) = 32'62 feet the velocity for each revolution. The Pitch "of a Screw-Fropeller is the distance, in the line of the shaft, from one convolution to the next, or the distance the propeller would advance in one revolution if it worked in an unyielding or solid substance. To Measure the Fitch of a Screw-Fropeller. Let A B in Fig. 311 = the line of shafting, draw the angle ABC that the blade makes with the shaft at N feet from the centre of the shaft. Draw the line B D perpendicular to A B, and make B D equal in len ? tn to 2 N x 3-1416. From D draw the line C D propelkr. ' parallel to A B, then C D = the pitch of the screw- propeller. The Fitch of a Screw-Fropeller necessary to maintain a given speed of Screw with a given number of revolutions may be found by the following formula : Let K = the speed of the screw-propeller in knots per hour ; L = the length of a knot in feet = 6080 feet ; R = the number of revolutions ; P = the pitch of the screw-propeller in feet. Then P = *ii K. Example i : Required the pitch of a screw-propeller necessary to main- tain a progression of 10 knots an hour, if there were no slip, with 3000 revolutions. Then (10 knots x 6080 feet) -i- 3000 = 20*266 feet pitch. Example 2 : A ship is required to steam 10 knots per hour when the screw-propeller is making 58 revolutions per minute, what must be the pitch of the screw ? Then (iox6oSo)-r- (58x60) = 17-47 feet. PITCH AND SLIP OF SCREW-PROPELLER. 343 Wh3n the Pitch of a Screw- Propeller is altered, if the mean effective pressure of the indicator diagram remains unaltered, the product of the pitch by the square of the knots per hour is not altered. The Speed of a Steamship, if the Pitch of the Screw-Propeller be altered, the indicator diagram of the engine remaining the same, may be found by this Rule : Old pitch x old knots 2 . . _ New pitch " = new knots 2 , and Vnew knots a = knots. Example : The pitch of a screw-propeller is 20 feet, and the speed of the ship is 10 knots an hour. Required the speed, S, if the pitch be altered to 17 feet, the indicator diagram remaining the same. Then S 2 x 17 feet the new pitch= 10 knots 2 x 20 feet, the old pitch, And 20XI 2 = 2 /ii7-64=io-82 knots. I 7 When both the Pitch and the Speed of a Screw-Propeller are altered the speed of the ship may be found by the following Rule : knots = ^ Old pitch x old revolutions Example: The pitch of a screw-propeller is 20 feet, the number of revolutions per minute 60, and the speed of the ship 10 knots an hour. What would be the speed of the ship if the pitch were altered to 22 feet and the number of revolutions increased to 75 per minute, the slip of the screw remaining the same. Then 22 x 75 * 10 _ ^.^ the gpeed of the ghip after a j tering thg pitch and increasing the speed of the propeller. The Slip of a Screw-Propeller is the difference between the actual advance of the ship and that due to the speed of the propeller, or the amount of work lost from the screw working in a yielding substance. Slip varies from 10 to 25 per cent. Let v = the speed of the screw-propeller, and V = the speed of the ship. v V Then v V = the slip of the screw, and - , the slip of the screw expressed as a fraction. _, _ y /. -- x 100 = the slip expressed as a percentage of the speed. The Slip is calculated on the Speed of the Screw- Propeller. Example i : A ship is required to steam at the rate of 12 knots, and the crank-shaft of the engine is to make 76 revolutions ; what must be the pitch of the screw-propeller if 20 per cent, be allowed for slip ? Then if 20 per cent, be deducted from the speed it leaves-^ - 100 15*20, 76 i5'2O=6o'8 knots as the effective speed of the propeller, and = 20 feet, the pitch of the screw-propeller required. 60-8 x 60 344 THE PRACTICAL ENGINEER'S HAND-BOOK. Example 2 : A steamship has a screw-propeller making 63 revolutions per minute, the pitch of the screw is 18 feet, and the slip 15 per cent. Required the speed of the ship in knots per hour ? Then the speed of the screw-propeller per hour in feet = 18 x 63 x 60= 68240 feet. The speed of the screw-propeller, if there were no slip, would be in knots per hour= ] ^ - = 11-22 knots. Taking off 15 percent. slip, leaves -I, and the speed of the ship will be = l8 * 6 3 x 6 x ^5 100 6080x100 = 9-54 knots per hour. The Slip of a Screw-Propeller may be ascertained by comparing the distance steamed by the ship with the progression of the screw-propeller, or distance run by the engines. Example: A ship steamed a distance of 27 knots, the screw-propeller made 9120 revolutions, the pitch of the screw was 20 feet. Required the slip of the screw-propeller ? Then 9^0 revolutions x 20 feet pitch = 6080 feet The difference between the distance steamed by the ship and the pro- gression of the screw-propeller is 3027=3 knots, and the slip of the screw- propeller is 3 x I0 = 10 per cent. Negative Slip of a Screw-Propeller is the difference between the velocity of the screw-propeller and that of the ship, when a ship is propelled at a faster speed than would be obtained if the screw-propeller worked in an unyielding substance. Negative slip, when it exists, is probably due to the following cause : The propeller throws the water outwards and back- wards in the form of a hollow cone, this hollow is filled up partly by the stream following the ship, and partly by water which returns to fill up the vacuum caused by the centrifugal action of the screw-propeller : the water coming in these two directions impinges upon the screw-propeller and causes additional thrust. The Angle of a Screw-Propeller is the inclination of the thread of the screw to the horizon. The angle may be found from the tangent of the angle, which is obtained as follows : Tangent of the angle of the screw = . Circumterence Example : The diameter of a screw-propeller is 11-026 feet, the pitch is 20 feet. Required the angle of the screw. Then iro26x 3- 14 16 = 34-6410 16 feet, the circumference of the screw, and = , 7 5 tangent, ang,e= 3 o. The Fitch of a Screw-Propeller, when the angle and the diameter are given, may be found by the following Rule : Pitch of screw = tangent of angle x circumference of screw. SCREW-PROPELLERS. 345 Example : Required the pitch of screw-propeller in feet, when the angle is 30, and the diameter 11-026 feet. The tangent of angle 30= '5 773 5. Then 1 1-026 x 3-1416 = 34-641016 x -57735 = 20 feet, the pitch of the screw-propeller. The Thread of a Screw-Propeller is the distance along the edge of the blade. The Length of a Screw-Fropeller is the fraction of the pitch actually used. The Diameter of a Screw-Fropeller is the diameter of the circle described by the tips of the blades. The Area of the Blade of a Screw-Fropeller is the surface of the blade. The Disc- Area of a Screw-Fropeller is the area of the circle described by the tips of the blades. The Projected- Area of the Blade of a Screw-Fropeller is the area that would be traced by a pencil held parallel to the propeller-shaft, traversing the edge of the blade of the propeller, on a plane at right angles to the shaft. The Expanded- Area of the Blade of a Screw-Fropeller is the same as that of a sheet of paper which would cover the blade. The Boss of a Screw-Fropeller is generally bored to a taper of i inch in 18 inches, in propellers of moderate size, and to a taper of i inch per foot in large propellers. The boss is keyed on the shaft with one key, sunk into the shaft, for moderate-sized propellers, and with two keys for large propellers, as shown in Fig. 312, which represents a boss 3 feet \\ inch Fig. 313.- Diagram of the surface of a screw-propeller-blade. Fig. 312. Boss of a s rew-propeller. diameter, and 3 feet long, of a screw-propeller 18 feet diameter. The diameter of the large end of the tapered hole is 15^ inches, and the taper being i inch per foot, the diameter of the small end of the tapered hole will be i 5 i - (36 inches xi inch taper) = ^ incheSi A nut . g screwed 12 inches on the end of the shaft to tighten against the boss, and a check-plate is fitted to prevent the nut working loose. The width of each Key of a Screw-Fropeller, when fixed on the shaft, as shown in Fig. 312, should = diameter of shaft x -226, and the key should enter the boss to a depth, measured at the side of the key = diameter of shaft x -08. Hence each key of the above propeller should be 346 THE PRACTICAL ENGINEER'S HAND-BOOK. 15*5 x '226 = 3! inches wide, and the depth of each keyway in the boss should be 15-5 x '08 = i|- inch. The Surface of a Blade of a Screw-Propeller may be found approximately as follows : In Fig. 313, let AB be the pitch, BC the circumference, and AC the thread of the screw-propeller : then, if the blade be considered to be made up of a large number of triangles placed side by side, and if the part ABC be taken away, leaving AC to form the blade, then if the lengths of all the lines corresponding to AC were found, their sum divided by their number would give an average length, which, multiplied by the radius, will give the approximate area of the blade. In practice it is sufficiently correct in most cases to find only three of these lines, then by dividing by three and multi- plying by the radius, the area of the blade is obtained. In the above figure AB may be considered as the length of the screw to obtain the approximation. If BC be bisected in D, and AD joined, then AC represents the longest line on the surface of the blade, AB the shortest, and AD an intermediate one. Then the area of the blade of the screw-propeller= AB + AD + AC x radius. 3 Example : The diameter of a screw-propeller with two blades is 15 feet, the pitch is 20 feet, and the length 3 feet. Required the area of the com- plete screw, the surface of one blade, and the surface of two blades. Then BC =15 feet diameter x 3-1416= 47- 12 feet circumference. BD = one-half of 47- 12 = 23-56 feet. AB = 20 feet pitch. AC 2 = AB 2 + BC 2 = 400 + 2220-2944 = 2620-2944. .-. AC= 51. AD 2 = AB 2 + BD 2 = 400 + |th of 2220*2944 = 955736. .-.AD = 31. and AB = 20. AC = 51. AD = -3-- -f- 3 = 34 x 7' 5 radius =255 square feet, the area of the complete screw. The length being 3 feet, the area of one blade will = ^ of the area of complete screw. The area of the complete screw is =255 square feet. The area of one blade = 255 X 3 = 38-25 square feet. The area of two blades = 38-25 x 2 = 76-50 square feet. The Resistance of a Steamship to Propulsion by a Screw- Propeller may be found by this Rule : ' Resistance in Ibs. = in f ated horse-power x -6 x 33000 ^ pitch of screw x revolutions per minute Example : Required the resistance of a steamship to propulsion by a THRUST OF A SCREW-PROPELLER. 347 screv.-, driven by engines of 800 indicated horse-power, pitch of screw- propeller 18 feet, number of revolutions per minute =56. ~, 800 x '6 x 33000 Then -^ - : = 15714 Ibs. IB ieet pitch x 50 revolutions The Indicated Thrust of a Screw-Propeller may be found by this Rule : Thrust = pressure in foot-lbs. on the thrust x pitch x number of revolutions. . ,p, indicated horse-power x 33000 pitch x revolutions Example : Required the thrust of a screw-propeller 20 feet pitch, driven by engines of 1000 indicated horse-power at 60 revolutions per minute, slip 10 per cent. Then IOO x 33ggg _ 275OO I DS< thrust, being the total power exerted 20 X 60 by the engines, but in practice only about 38 per cent, of the indicated horse-power is utilised or effectively applied in the thrusting-force of a screw in propelling a ship. And the horse-power at the ") 1000 x 33000 x 38 r.nt.hWt will L 3-rr ^~ = IQ 450 Ibs. thrust. thrust-block will be . j 20 x 60 x 100 The loss by slip is .?21_5o_x_!2 = 1045 The actual power on the thrust . . . 9405 Ibs. The Indicated Horse-Power required to exert a given Thrust or power on a thrust-block, may be found by the following Rule : Indicated horse-power = pressure in Ibs. on the thrust-block x pitch x revolutions 33o Example : What indicated horse-power would be required to exert a force or thrust of 27500 Ibs. on a thrust-block, with a screw-propeller of 20 feet pitch, making 60 revolutions per minute ? Then 27500 Ibs. thrust x 20 pitch x 60 revolutions = IOOQ indicated 33000 horse-power. If the slip be 10 per cent., the power lost will IO - x IO _ IOO horse- 100 power, and the power actually employed will = 1000 100 = 900 indicated horse-power. The Percentage of the Whole Power which is applied to the Thrust-Block to push the Vessel ahead may be found as shown by the following example. Example : The power on a thrust-block is 16500 Ibs., the speed of the 348 THE PRACTICAL ENGINEER'S HAND-BOOK. ship is io'84 knots per hour, with a screw-propeller 20 feet pitch, making 60 revolutions per minute, the engines developing 1000 indicated horse- power. What percentage of the power as actually applied at the thrust- block in pushing the ship ahead, including the power lost as slip ? What power is applied at the thrust-block, and what power is lost by slip ? Then, the knots run by the engine are =25 ? = 1 1-84 knots. oooo feet The percentage of speed lost by slip is = ( ir8 4- 10-84) x 100 _ ^ The power used, in percentage of the available power, is= - x 100 = 60 per cent. The loss by slip = 6o X 8 ' 5 = 5-1 per cent. The actual power at the thrust-block, in percentage = 60 5-1 = 54-9 per cent. The actual power applied at the thrust-block = Z - "5*9 =^4Qhorse- power. The power lost by slip = - 1 - -^- = 5 1 horse-power. The Surface of a Screw-Propeller being oblique to the direction of the thrust, the area of the screw-disc is less effective for thrust than an equal area of feathering float with the same slip. The following" formula, given in another form by Rankine, gives approximately the area. A, of an equiva- lent pair of paddle-floats, which will be equal to the effective area of the screw-disc of a given diameter, when the pitch is between '9 D and 2'i D. Let P = the pitch of the screw-propeller. D = the diameter of the screw-propeller. B = the diameter of the boss. Then A = (7854 L-) x (D 2 -B 2 ); or A = 7854 - - (D + B) (D - B). Example : The diameter of a screw-propeller is 20 feet, and the pitch is 21 feet, the diameter of the boss is 4 feet: what is the equivalent area? Then 7854 ^ = -5754 and 2O 2 - 4 2 = 3 8 4> and -5754 x 384 = 3 X 2'J 220-9536. The Thrust in Ibs. of a Screw-Propeller, T, may be found by this Rule: T = 5-66 x the slip in knots per hour x speed of the propeller in knots per hour x the equivalent area of stream or column of water sent astern, which may be found by the previous rule. Example : The screw-propeller described in the previous example makes SCREW-PROPELLERS. 349 60 revolutions per minute, the speed of the ship is 10 knots an hour, and the equivalent area of stream is 220*95, as found in the previous example : what is the thrust in Ibs ? rp, 2 1 pitch x 60 revolutions x 60 . u j < , Then = 12-41, the speed of the propeller OOoO in knots per hour. And 12-41 knots 10 knots = 2*41, the slip in knots per hour. Then 5*66 x 2*41 slip x 12-41 speed of propeller x 220-95 equivalent area = 37468-46 Ibs. thrust. If fresh water, use a constant of 5*5 in the above rule instead of 5*66, which is for sea-water. Horse-Power lost by slip of a Screw-Propeller. In addition to other losses in effecting the propulsion of a screw-steamer, the yielding of the column of water on which the screw-blades act, is a loss of power equal to the product of the thrust by the difference between the advance of the ship and the speed of the screw. Applying this to the previous example, the loss of work by slip in actual horse-power is as follows : 2-4 1 slip x 6080 feet = the Jn feet m 60 minutes and 37468-46 IbS. tost X 244-21 =277 . 27 horse . power lQSt by slip . Horse-power required to drive a Screw- Propeller. Effective horse- power is the proportion of the indicated horse-power available for perform- ing useful work after deducting the power absorbed by friction. In the case of steamships it is found that only about 38 per cent, of the indi- cated horse-power is utilised or effectively applied in the thrusting-force of a screw-propeller in propelling a ship. The effective horse-power re- quired to drive the propeller described in the two previous examples may be found as follows : 21 feet pitch x 60 revolutions x 37468*46 Ibs. thrust _ ^ 33 effective horse-power required to drive the screw-propeller ; and the total or gross indicated horse-power required will be = 1430*64 x ^- = 3764-84 3 horse-power. Horse-Power lost in propelling a Ship with a Screw-Propeller . The difference between the effective horse-power and the indicated horse- power found in the previous example = 3764-84 1430-64 = 2334-2 horse- power represents the loss of power which takes place in propelling a screw- steamer though the water, equal to I43 4 X IO = 62 per cent, of the 2334-2 total power expended. The Resistance of a Ship's Model determines the resistance of the ship and the horse-power required to propel it. Mr. Froude found that for two vessels of similar forms, as, for instance, a ship and her model, the corresponding speeds are to one another as the square roots of the similar dimensions ; and at these corresponding speeds the resistances of the two 35O THE PRACTICAL ENGINEER'S HAND-BOOK. vessels are to one another as the cubes of the similar dimensions, or as their volumes. The resistances may be calculated as shown by the follow- ing example. Example : Required the resistance and horse-power necessary to propel a ship 3&o feet long, at a speed of 15 knots per hour. Then, if the model of the ship be, say, 12 feet long, its speed corresponding to that of the ship will be = 15 knots x /i 2 feet length ofm^el = . 2JJ knQt hour> Jf V 360 teet length of ship the resistance of the model at that speed = say 4'25lbs. the resistance of the ship at 15 knots per hour will be=f 360 feet length of ship_ x Vi2 feet length of model / 4-25 Ibs. = ii475olbs. ; or, 360-12 = 30, and 3Q* 30x30x4-2 5 Ibs. x 15 knots x 6080 feet = 33000x60 5281 effective horse-power. The Speed of a Steam-ship in Knots per Hour, due to a given Fitch and Speed of Screw-Propeller may be found by the following Rule : Multiply the pitch of the propeller in feet by the number of revolutions per minute and by 60, and divide the product by 6080. Example : The pitch of a screw-propeller is 20 feet, and its speed, or number of revolutions, is 62 per minute, how many knots will the ship go per hour, making no allowance for slip? The ship advances at each revolution of the screw 20 feet. The ship advances in one minute 20 x 62 = 1240 feet. The ship advances in one hour 20 x 62 x 60 = 74400 feet. The speed in knots per hour = s P e f in u fe f et P er miimtex6o = length of a knot m feet 20 feet x 62 revolutions x 60 = knotsper hour. 6080 feet. The Life of a Screw-propeller depends greatly upon its resistance to corrosion and corrosive-pitting, caused by air drawn down to the back of the propeller, the backs of the blades being most affected. Corrosion blunts the blades, increases friction, and causes loss of power. Gun-metal has great resistance to corrosion, and a gun-metal propeller may, excepting accidents, last as long as the ship. Cast-iron blades are liable to corrosive- pitting, and require to be renewed on an average every six years. Steel "blades are more liable to corrosive-pitting than cast-iron; and are. less true to form, owing to being liable to twist both in casting and annealing ; they require renewal on an average every three and one-half years. The Resistance of a Screw-propeller to Friction decreases as the sectional area of the blade decreases, and as the smoothness and accuracy of the blade increases. Fronde's Formulas for Screw-Propellers are as follows : Indicated thrust. Let i = indicated thrust ; M = mean piston-pressure ; T = total piston- travel per revolution ; p = pitch of screw-propeller ; N = number of revolu- tions ; IHP = indicated horse-power. _ MXT _ 33000 x IHP p PXN SCREW-PROPELLERS. 351 Indicated thrust is resolved into the following six elements : No. i. The ship's nett resistance, or useful thrust. No. 2. Augment of resistance due to negative pressure created about the ship's stern by the action of the screw. This is nearly pro- portional to the useful thrust. No. 3. Water friction of screw. This is also nearly proportional to the useful thrust. No. 4. Constant friction, or friction of engine without external load. This may also be taken as nearly proportional to the useful thrust. No. 5. Friction due to external load. This may be taken as constant at all speeds. No. 6. Air-pump and feed-pump resistance. This may be taken as nearly proportional to the square of the number of revolutions. The above six elements are force-factors, and when multiplied by the speed of the ship in feet per minute ^.^ ^ , g h Qwer ag 33000 fundamentally due to the progress. Let EHP = effective horse-power that is, the power due to the nett re- sistance of the ship; SHp=ship's horse-power ; iHP=indicated horse-power. Then the ship's horse-power due to the several elements is as follows : Ship's horse-power due to No. i = EHP. No. 2 = '4 EHP. No. 3 = 'I EHP. No. 4 = '143 SHP. No. 5 = '143 SHP. No. 6 = '075 SHP. Or in combination SHP=I'5 EHP + '361 SHP. So that '639 SHP = 1.5 EHP; Or, SHP = -*-5 EHP = 2*347 EHP ; ' 6 39 To this must be added Slip = *i SHP., making IHP = n SHP. Thus IHP = 2-582 EHP = IH2. EHP; or, EHP = '387 IHP. To convert the formula from one adapted to high speed only to one adapted to all speeds, it is necessary to keep the term involving constant friction separate from the rest, for it represents simply the effect of a constant resistance operating with the existing speed of the engine. In shaping the formula the co-efficient 27, derived from experience, will be adhered to, instead of the co-efficient 2-582, as the latter is built up from somewhat hypothetical data, assuming, however, that the constant friction is equal throughout to one-seventh of the maximum load. Of the 2 '7 EHP which make up the IHP at the maximum speed v, one- seventh part, or "385, is the part due to constant friction, leaving 2^315 as due to the other sources of expenditure of power. And to express the IHP due to constant friction at any other speed v, the coefficient must be altered in the direct ratio of the speed, so that the term becomes x -385 x EHP 352 THE PRACTICAL ENGINEER'S HAND-BOOK. at designed maximum speed. Thus the formula for IHP at any speed, v is as follows : IHP = 2-315 EHP + -385 x (EHP due to v) ; or, if the useful is finally severed from the collateral expenditure of power, it stands thus : IHP = EHP + I'3I5EHP +'385 x (EHP due to v). Thorn's Formulae for Screw-Propellers,* given below, are based upon the assumption that the area of propeller-disc should be proportional to the indicated horse-power, divided by the cube of the speed, and the same rule applies to the projected area of the propeller and also to the surface. In this way constants can be obtained for the disc-area, the projected-area and the expanded area as follows : Disc-area constant = Area of propeller disc x speed of ship in knot S 3 Indicated horse-power Projected-areaconstant= Projected-area of propeller x speedof shipinknot S 3 Indicated horse-power Expanded area ") _ Expanded-area of propeller x speed of ship in knots 3 constant j ~~ Indicated horse-power ' Table 87. PARTICULARS OF SCREW-PROPELLERS AND CONSTANTS. Ship. Length of Ship. Disc Constant. Projecting Surface Constant. Feet per Sec. Speed per 1 ips. Remarks. City of Rome . 542 220 6 9 4715 1 Normandie 459 250 66 4099 Furnessia . 445 223 69 3 6 54 Eden Yorouba . . Taygete . 300 270 260 211 213 2 3 8 64 63 56 3080 3202 3166 Single Screw- 1 propeller. Kow-shing . . 250 171 69 33 6 9 S. Y. Monarch 152 221 65 4040 ,, Aries 138 179 56 2986 j Twin-screw \ Fenella. ) 200 244 64 2890 Twin-screw ") C Estimated with a H.M.S. [ 22O 277 67 5O22 ) speed of 17-5 ] knots, and -n7o Fearless. ) I (^ I.H.P. The Speed of a Steam-ship may be found by the following formulae which are based on the assumption that the resistance offered by the water to the motion of a ship varies as the square of the speed, and that the power required to overcome this resistance varies as the cube of the speed, which is not quite correct, because the indicated power varies as a higher * See a Paper on " Atlantic Steamers : of Naval Architects. read by Mr. Wm. John before the Institution POWER REQUIRED TO PROPEL A SHIP. 353 power than the cube of the speed, but the Rules are useful for arriving at an approximation of the spee.l. I H P x constant Speed = - Displacemen 7T- I H P x constant ~~ Area of midship section Speed 3 x displacement l Constant= - flTT Constant^ Speed 3 x arearf midship section 1 rl r Where I H P = the indicated horse-power : Displacement 8 = ^(displacement) 2 . Example : Required the constants for a steam-yacht, fitted with engines of 800 indicated horse-power, having a speed of 12 knots an hour; a dis- placement of 850 tons ; the area of immersed midship section being 273 square feet Then constant = "' kn Q ots X 8 5 ' = i7*8 x 3/850 x 850^1728 x 9 o = 800 800 1 H P 800 104 constant. 1 2 3 knots x 2 73 square feet 1728x273 And constant = ~ Tu^ ~" = 5 9 constant. oOO 1 rl r oOO The Speed may be found with the above constants as follows : c , , 800 I H P x 194 constant 155200 155200 ,/ opeea = = 5-= i == =^ ^"1725 12 knots 5 displacement 3/850x850 90 Speed 3 = 800 I H Px 590 = 472ogg = . y 8=I , knots . 273 square teet 273 The Indicated Horse-Power required to Propel a Ship may be found by the converse of the previous formulae : Indicated horse-power of engines = Spee^x_displa_cemem Constant Indicated horse-power of engines= S P eed3 X area of midshi P section . Constant Taking the particulars from the previous example, the horse-power of the engines required to propel that steam yacht, will be = i 2 3 x 8 5 o> = , 728 x y-gsoxSFc^ 1728 x_ 9 p =8oo indicated hors er> 194 194 194 i2x 273 square feet = i728x2 7 ? = 8oo indicated horse . p ower. 590 590 The Indicated Horse-Power and Displacement of a number of Modern Steamships is given in Table 88*, which also gives the mid- ship-area, the speed on trial trips, the co-efficients for the lines both from the block or parallelopipedon, and also from the midship section prism, together with the length and angle of entrance obtained by Kirk's rule, the Admiralty displacement co-efficient, and the coal-consumption per day and per indicated horse-power per hour. This table contains particulars of some of the most important of the Atlantic steamers, and also of a * The Author is indebted for this Table to a paper on "Atlantic Steamers," read by Mr. \Vm. John before the Institution of Naval Architects. A A 354 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 88. DIMENSIONS, MOULDED DRAUGHT, MIDSHIP-AREA, DISPLACE- MENT, INDICATED HORSE-POWER, SPEED, BLOCK CO-EFFICIENT, MIDSHIP SECTION CO-EFFICIENT, AND OTHER USEFUL DATA OF MODERN STEAM- SHIPS. - . 1 ft 1 | g, Name. Length 1 if Ij 0; '5K Speed. |1 I'll m a-i % a I W 8 *IJ City of Rome . Normandie . . . Furnessia ft. in. 542 6 459 4 445 o ft. in. 49 ii 44 6 ft. in. 19 9! 22 2j 1031 892 893 11,230 7,975 8,578 11,890 6,959 4,045 18-235 16-66 33 682 925 90! '903 Arizona . . . 450 o 45 4 18 9 758 6,415 6,300 17 589 895 Orient Stirling Castle . . Elbe . . . Pembroke Castle . Umbriaand Etruria 445 o 420 o 420 o 400 o 500 o 46 o 50 o 44 9 57 21 4* 22 3 17 o 22 6 904 990 807 6 4 8 1090 7,770 7,600 6,350 5,433 I5-538 8,396 1 i8'4 5,665 j 16-571 2,435 i I3'25 14,321 20-18 621 569 "591 i 'III g Aurania . 470 o 57 o 2O O 8^800 8,500 *I7'5 '575 "942 America 441 8 5i 3 J - 6,500 Oregon . Servia . . . Scotia, P.S. . 501 o 515 369 o 54 2 52 o 47 6 23 8 23 3i 19 9 1150 11,000 1046 10,960 867 6,000 13,300 18-3 10,300 j *i6' 9 4,632 *i 4 - 3 i '599 610 605 18 92 Alaska . . . 500 o 50 o 21 949 9,210 614 904 Aller 438 o 48 o 21 907 7,447 7,974 17-9 590 899 Ems . . . . 430 o 46 10 20 ?i 877 7,030 7,251 17-55 '593 907 1*1 '1- Kirk's system. Coal con- sump- Cylinders. Boilers. i -n u 'el a k' g.>l tion. i Name. ismatic tion co F QM ^,0* 1| V 1 '3 Diameter. -J II A I &% ~ 3s < I I ~r. E2 ~^- I Inches. Ins. Ibs. City of Rome 702 255 201-3 161-27 8-29' 185 2-2 ill 6\ 7 2 =9,286 1393 90 Normandie . 68 1 265 219-5 146-41 8 44' I 4 8 '2 1 3 (I 35T I ! 67 21,404 756 85-2 Furnessia . . '755 284 273 108-7 10 28' 97 2-2 V-ioo 66 10,396 440 90 Arizona . 658 269-2 217 i53'79 7 3o' ; | i (* 62 ) 2 @ 90< 66 90 Orient . . 676 270-8 225 144-17 8 21 ' t I @ 60^ 2 @ 85 | 00 - - 75 Stirling Castle 639 286-8 233'7 151 '3 8 22' I @ 62! 2 @ 90 J 66 21,161 737 zoo Elbe . . . Pembroke '655 275-5 229 144-6 7 56' - - i ! @ 60J 2 @ 8 S j 60 - - - Castle . 692 284 258 122-9 8 49' 44 i '7 4 3 and 86 57 7,896 2S3 99 Umbria and r (fa ") Etruria . 637 >6o 191-8 184 6 52' 315 2-1 I 2 @ 105 ; 72 38,817 1606 no Aurania . 632 266 204*6 170 8 38' 215 ' 2'2 { i @ 68 ( 2 @ Oil 72 23,284 1001 America . . 1 ~ - - - ,8 S |- i I @ 63) 2 @ 91 i 66 - SS2 - Oregon . '67 227-9 190 164-3 9 39' 310 ; 2 "2 | I @ 70 | 2 @ 104 \ 72 38,047 1428 no Servia . . 71 231 192 1 45 '3 10 42' 205 2 j I @ 72 2 @ 100 78 27,483 1014 - Scotia, P.S. . 65 208-9 1 86 126-8 13 2l' 168 3'4 Alaska . . 679 160-23 8 2' - | i @ 68 ( 2 @ 100 \ 72 100 Aller . 656 277 225 150-6 8 10' - - { i @ 44") I @ 70 f I @ 100 J 72 22,630 799 150 Ems . . . 652 273 223 149-4 8 40' - I @ 62) 2 86 1 60 19,700 7 So 100 ! Mean speed of a voyage across the Atlantic Ocean. POWER RELATIVE TO SPEED OF A SHIP. 355 number of other typical ships. The co-efficient given in the fourth column of the bottom half of the table, viz. : Displacement f x speed 3 Indicated horse-power x y entrance ~ 10 generally comes out for ships of similar type more nearly a constant in the true sense of the word than the corresponding Admiralty constant. The Admiralty Knot = 6080 feet : i statute mile = 5280 feet. The length of a knot is sometimes taken at 6082-66 feet, and also at 6086 feet. The Speed of a Ship in knots X 1*15 = miles. The speed of a ship in miles x '87 = knots. The speed of a ship in feet per minute x -01 = knots per hour. One knot per hour = r688 foot per second. One knot per hour = -5144 metre per second. One metre per second = 1-944 knot per hour. One foot per second = -592 knot per hour One foot per second = '682 mile per hour. The most Economical Speed for a Steamer going up a River down which the tide is coming, is half as fast again as the tide. The pro- gress made by the ship per hour will be equal to the difference between the speed of the ship per hour and the velocity of the tide or current per hour. Example : A steamer is going up a river, down which the tide is coming at 3 miles an hour : how fast must she steam and what progress will she make per hour ? Then 3x^=4-5 miles per hour, the speed required, and the progress will be 4-5 3 = ii mile per hour. The Number of Revolutions of a Shaft vary as the Cube of the Speed. The following examples show the application of this Rule, which applies to all similar questions : Example i : The number of revolutions of the crank-shaft of a marine- engine are 40, and the speed of a ship is 8 knots per hour : what will the speed be if the number of revolutions be increased to 50 ? Let V be the required speed. Then -=5?. o 40 40 /. V= 3/640=8-617 knots. Example 2 : The horse-power of a pair of marine-engines is 500, and the speed of the ship is 9 knots per hour ; it is required to increase the speed to 12 knots: what power of engines will the ship require? Then 5oxi2 3 = 1I ^ horse-power. 9 3 Example 1 ^'. With a pair of marine-engines of 1185 horse-power a steamship has a speed of 12 knots an hour: what will be the speed of the ship when the engines are developing only 500 horse-power ? Then -^ _ \ = 3/729=9 knots per hour. ii 5 Example 4 : If a pair of marine-engines of 900 horse-power give a ship 356 THE PRACTICAL ENGINEER'S HAND-BOOK. a speed of 9 knots an hour, what speed will be obtained with new engines of 1 400 horse-power ? 3 = y 1 134= 10-428 Example 5 : A steamship has four boilers ; when two of them are in use the speed of the ship is 8 knots an hour : what will be the speed when three boilers are used, and also when all the four boilers are used ? Then 2_ - 1=^/768 = 9- 158 knots per hour,the speed with threeboilers. And 121jL = 3/1024= io'079 knots per hour, the speed with four boilers. The Number of Revolutions of a Screw-Propeller per Knot, if there were no slip, would be= ^ Pitch in feet The Number of Revolutions of a Screw-Propeller per Hour, if there were no slip, would be = - '-f x number of knots per hour. Pitch in feet The Number of Revolutions of a Screw-Propeller per Hour in- cluding Slip = 6080 x (100 + slip) x number of knots hour< Pitch in feetx 100 Example: A steamship is to have a speed of 14 knots per hour ; the pitch of the screw-propeller is 20 feet : at what speed must her engines run, assuming a slip of 1 5 per cent. ? Then, if there were no slip, the number of revolutions of the screw- propeller would be = - = 304 revolutions per knot. Assuming 15 per cent, slip the number of revolutions of the screw- propeller will be = 6o8 lL5 = 3 4 Q-6 revolutions per knot. 20 x 100 And 349'6 revolutions per knot x 14 knots=4894'4 revolutions of the screw-propeller per hour, or 4894'4-!-6o=8i'57 revolutions per minute, the speed at which the engines must run. Twin Screw-Fropellers, shown in Fig. 314, are used when the draught of water is not sufficient to permit a single screw of sufficiently large diameter to be used. One advantage of twin-screws is, that in case of accident to one of them, the other screw can be used for propelling the ship at a reduced speed : another is, that by working one of the screws ahead, and the other astern, the ship can be turned in her own length, and in case of loss of the rudder the ship can be steered by the engines. Feathering Screw-Fropellers are so Fig. 314. Twin screw-propellers. arranged that the blades can be moved to a nearly fore and aft position, without stopping the ship, in order to remove the resistance which the screw-pro- peller would offer to the advance of the ship when under sail. The boss PITCHOMETER FOR SCREW-PROPELLERS. 35? of the propeller, and also the propeller-shaft, is made hollow. Each blade is fitted to the boss with a round shank, to which a lever is fixed, and connected to a shaft inside the screw-propeller shaft ; the forward end of the shaft is connected to a collar, which can be moved along the shaft by a nut screwed on the outside of the propeller-shaft. A Pitchometer, shown in Fig. 315, is an instrument for measuring the W READING BAR Fig. 315. Pitchometer for screw-propellers. pitch of a screw-propeller in its place : it enables the pitch to be quickly ascertained without calculation. It is based on the ordinary rule used in measuring screw-propellers, that is : Fraction of Pitch Fraction of Circumference Whole Pitch Whole Circumference If then, the angle between the legs of the instrument be made, a certain definite fraction of the whole 360, the fractional pitch, as measured by in- serting the reading bar at A and B, and taking the difference of the distances to the face of the propeller, will bear the same ratio to the whole pitch. In the device, as actually constructed, the angles are 7^ and 15, or ^-g-th and T T T th of the whole circumference, so that the fractional pitch measured will be T yh or -^th of the whole pitch. Since this is always the case, if the reading-bars be graduated to scales of |in.= i foot, and | inch = i foot, the whole pitch in feet and inches can at once be read off. For example, suppose the readings at A and B are actually 6 inches, and 358 THE PRACTICAL ENGINEER'S HAND-BOOK. iz\ inches, the difference is 6 inches; and as the ratio here is J F , the whole pitch = 25 feet. With graduated scale of inch = i foot, the readings would have been 24 feet, and 49 feet, or pitch = 25 feet. This instrument can be used for screws of uniform pitch, or pitch expanding from the boss to the periphery, but not for those where it expands from the entering to the leaving edge of the blades. A Screw-Steering Propeller or Rudder-Screw is shown in Fig. 316. It consists of a small screw-propeller placed exterior to and aft the rudder. The shaft of the rudder-screw is carried in a bearing fixed on the rudder ; it is cased with gun-metal and runs in lignum-vitae bushes. The thrust of the screw is taken, through gun-metal collars and lignum-vitae bearings, by the rudder. The rudder-screw makes revolution for revolution with the screw-propeller of the ship, the shaft of each propeller being coupled by a universal-joint, which enables the axis of the rudder-screw to be placed, by a force acting on the rudder, at any angle less than 55 degrees with the axis of the screw-propeller of the ship. A rudder-screw enables a ship to be turned quickly and to make a complete circle in about one-half the diameter required with a rudder alone. A rudder acts by resistance, and only while the ship . is in motion : a rudder-screw is a motive power in turning the hull the instant the shaft revolves, and before the ship attains the speed necessary to bring the rudder into play, and it gives great manoeuvring power to a ship. Radial Paddle- Wheels have floats fixed rigidly to their arms. The resistance offered by radial floats on entering and leaving the water is considerable : the whole of their faces is presented to it, and they lift a quantity of water ; and as each float can only give a direct sternward motion to the water when in a vertical position, their propulsive efficiency is very small. If the water did not yield to the pressure of the floats, the distance the ship would be propelled at each revolution of the paddle-wheel would be equal to the diameter of the circle of the centre of pressure of the floats x 3' 1416 : the point of maximum pressure or centre of pressure is at one- third the depth of the float from the outer edge. The slip of radial paddle- wheels is from 20 to 25 per cent., and they are not nearly so efficient as feathering paddle-wheels. Feathering Paddle- Wheels have the floats arranged to move so that they may enter and leave the water in a nearly vertical position. The floats are hung, and turn on pins fixed on the side of the wheel, to which arms are attached, connected by radius-rods to an eccentric-strap, which works loose on a feathering-stud fixed in a position eccentric to the wheel, on the outer sponson on the side of the ship. All the radius-rods are jointed by pins to the boss except one, the driving eccentric-rod, which is bolted 316. Kunstadter's screw-steering propeller, or rudder-screw. 360 THE PRACTICAL ENGINEER'S HAND-BOOK. rigidly to the eccentric-strap and drives the strap round the feathering- stud. By this arrangement the floats are so governed by the eccentric that their faces, while immersed, are nearly at right angles to the surface of the water, and very little power is lost, as the force applied to the float is nearly all expended in direct fore- and aft-thrust on the water. The centre of the eccentric-strap and the feathering-stud is placed forward, or in advance of the paddle-shaft, and a little below a horizontal line with the centre of the paddle-shaft, as shown in Fig. 319, in which the feathering-stud is two inches below the line of the paddle-shaft. A Feathering Paddle-wheel, 17 feet diameter, is shown in elevation in Fig. 317, and in cross-section in Fig. 318. The arms carrying the floats are forged in dies in one solid piece ot iron without weld, and are machined all over the bearing-surfaces ; they are also planed parallel where they fit into the boss, the grooves of the boss being slightly tapered and the edges of the arms correspondingly bevelled, so that as each arm is drawn into its place by the bolts it is fixed very securely. The bolts are relieved from strain by joggles forged on the arms, which clip the ring. The arms are if inch thick, and the ring is 8| inches wide and ij inch thick. The floats, which are 9 feet 6 inches long and 3 feet 7^ inches wide, are curved to the same radius as the wheel, and are provided at each end with an angle-iron to prevent the escape of the water laterally. The upper edge of each float, in its lowest position, is immersed 18 inches with the steamer at load-draught, and there is a space of 12 inches between the inner edges of the floats and the sides of the vessel. There are 9 floats to each wheel, six of which are f inch thick ; while of the other three, the centre one is i inch thick, and the two others i inch thick, the thick floats being used to balance the engines. The feathering- stud is fixed two inches below the line of the paddle-shaft, and 15 inches in advance. The joints of the feathering - gear are all bushed with lignum-vitae. The curvature given to the floats enables them to enter at a better angle and tends to prevent the back-action on leaving the water, reducing the evil effects due to the fact that every part of the wheels below the centre-line of the shaft has a different forward velocity. These paddle-wheels are fitted to several steamers noted for their high speed, they do not lift the water at the back when running at full speed, and if the door at the side of the paddle-box is opened it is found that the box only contains a slight mist. The Diameter of a Feathering Paddle-wheel, as shown in Fig. 162, may be found by the following formula : Let S=the speed of the ship in knots per hour. R=the number of revolutions per minute. D=the diameter in feet of the paddle-wheel at the centres of the axes of the floats. Then D = ? x 3 J. R Example : Required the diameter of a feathering paddle-wheel for a steamer to make 17^ knots an hour, with engines making 33 revolutions per minute. Then 1715_ > 11 2 = T7 feet diameter. 33 HYDRAULIC-PROPULSION. 361 The Number of Floats may be found by dividing the circumference cf the wheel in feet by 6. Hence the above wheel will require * 7 feet X 3' HI 6 = 8-9, or say 9 floats. The Length of each Float is usually equal to about | the breadth of the steamer ; if the latter be 28 feet 6 inches the length of float for the above wheel will be 28-5 -f- 3 = 9 feet 6 inches. The width of float may be equal to the length of float x -382, and the float for the above wheel will be = 9-5 x -382 = 3^629 feet, or say 3 feet i\ inches wide. The Number of Revolutions of a Paddle-wheel required per minute for a given speed of a steamer, may be found by this Rule : Revolutions per minute = " ^?^pei^ourx6o8o jeet Circumference of wheel in feet x 60 minutes' Example : Required the number of revolutions per minute of the engines of a steamer, with paddle-wheels 17 feet diameter,-to make 17^ knots per hour. Then T 7 5 x ^ -^ =33 revolutions per minute. 17x3-1416x60 Tha Speed of a Paddle-steamer in knots per hour with a. given diameter of paddle-wheel and a given number of revolutions per minute, may be found by this Rule : Speed in knots ) _ Circumference in feet of paddle-wheel X revolutions x 60 per hour ) ~~ 6080 leet in a knot Example : Required the speed in knots per hour of a steamer with paddle-wheels 17 feet diameter making 33 revolutions per minute. Then 17x3-1416x33x60 = knots hour 6080 feet in a knot The Speed of a Paddle-Steamer in knots per hour may be found approximately, by multiplying the circumference of the paddle-wheel in feet by the number of revolutions per minute and dividing the product by 100. Example : Required the speed of the paddle-steamer given in the previous example ? Then I7*3'*4i6x33 = 17-63 knots per hour. Jet-Propellers : The propelling power in hydraulic propulsion is derived from the reaction of jets of water. The water is drawn through orifices at the bottom of the vessel by a centrifugal pump, and is discharged through orifices either at the sides or stern of the vessel. The quantity of water projected astern should be as large as possible and its velocity should be as small as possible, in order to obtain the utmost efficiency. In a jet-propeller considerable power is lost in imparting to the water which enters the pump, a velocity equal to that of the ship : and also from friction. A trial of hydraulic propulsion was made with the French boat "Nautilus," 362 THE PRACTICAL ENGINEER'S HAND-BOOK the arrangement of the machinery of which is shown in Figs. 319 and 320 : the following were the leading dimensions : The length of boat=i4 metres, width of beam im. 80, immersed section 78 sq. m., mean draft '54m. The propeller was a Maginott's pump, P, 60 centimetres at its largest diameter, driven by an inverted cylinder engine with a single cylinder 2ocm. diameter and i5cm. stroke. The suction takes place through the pipe A, and the delivery at the stern through a conical Fig. 320. Figs. 319 and 320. Jet-propeller. copper pipe, B, ending in the mouthpiece, C, which has a bore of 241 millimetres. The pipes D are auxiliary pipes for going astern, and two other pipes E are for turning the vessel on the spot ; valves being used for changing the flow of the water. The complete turn by 180 degrees was effected in 45 seconds, and a complete stoppage in a distance of about 14 metres when the boat was going at the rate of 14 kilometres per hour. The results of the trial are as follows : Horse-power developed by the engine . 3-09 io'i5 Speed of jet, metres per second . . 4-40 6-55 Speed of boat 2-46 3*30 Ratio 1-8 -2 Efficiency of pump . . . .'60 *6o Efficiency of jet -715 '66 Total efficiency -425 '40 7-80 3-83 2-04 66 66 '435 12-27 9'55 4-22 2-28 80 613 49 The total efficiency reached as high as 49 per cent., or nearly the same as that usually assumed for screw-propulsion. The efficiency of the pump increased considerably with an increased speed, but that of the jet decreased greatly at the same time. SECTION V. HORSE-POWER; EXPANSION OF STEAM IN A CYLINDER; PROPORTIONS OF THE CYLIN- DERS OF STEAM - ENGINES ; PISTONS, PISTON-RODS, AND CROSS-HEADS; MILL- ENGINES; DOUBLE-EXPANSION, TRIPLE- EXPANSION, AND QUADRUPLE - EXPAN- SION MARINE-ENGINES, ETC, SECTION V. HORSE-POWER; EXPANSION OF STEAM IN A CYLINDER; PROPORTIONS OF THE CYLIN- DERS OF STEAM - ENGINES ; PISTONS, PISTON-RODS, AND CROSS-HEADS; MILL- ENGINES; DOUBLE-EXPANSION, TRIPLE- EXPANSION, AND QUADRUPLE - EXPAN- SION MARINE-ENGINES, ETC. POWER OF STEAM AND HORSE-POWER OF STEAM-ENGINES. Heat is the Source of the Power of Steam, and the elastic force of steam is due to its inherent heat-energy. Steam in performing work in the cylinder of an engine gives up heat, and the difference in the economy of fuel between any two engines is measured by the quantity of heat turned into work. If loss from radiation and condensation be not taken into account, the heat which leaves the cylinder in the exhaust-steam is less than that which entered it, in the proportion of one unit for every 772 units of work done by the engine. The quantity of heat theoretically capable of being transferred to motion, or the maximum amount of work that can be got in a heat-engine out of any gas or vapour, such as steam, is expressed by the following formula : Let M = the mechanical value of heat. T -= the highest absolute temperature of the gas or steam. / = the lowest absolute temperature of the gas or steam. The zero of Fahrenheit's thermometer being 46 1 above the point of absolute cold or zero, /will for condensing engines = 100 Fahr., the temperature of the hot-well, + 461 = 561 Fahr., and for non-condensing engines / will = 212 Fahr., the temperature of steam of the pressure of the atmosphere, + 461 = 673 Fahr. Taking the maximum temperature of the combus- tion of coal at 3000 Fahr., if the whole of the available heat were absorbed by the furnace-plates and transferred to the water in a boiler, it would give 772 x 3 ~ 5 _ jj 2 x .g ol _ 6i8'37 units of work, or foot-pounds, 366 THE PRACTICAL ENGINEER'S HAND-BOOK. the value or mechanical equivalent of the heat ; but there are no means available for using such a high temperature in a steam-engine. The highest satisfactory working temperature is probably 400 Fahr., the mechanical value ofwhichistheoretically=:772 (40 + o 46l) ~ 561 = 772 x -348 = 268-65 foot-pounds. By comparing the theoretical value or efficiency of the heat with the efficiency actually obtained with engines in practice, the mechanical equiva- lent of the heat used may be accurately estimated. For instance, if an engine use say 20 Ibs. of steam per indicated' horse-power per hour at the highest feasible temperatuie, or 400 Fahr., the total heat of steam of this temperature is (400 x "305) + 1082 = 1204 units per Ib. of steam, = 1204 X 20 Ibs. = 24080 units in 20 Ibs. of steam, and 24080 x 268*65 foot- pounds, the theoretical value of the heat, = 6469092, the units of work theoretically available in 20 Ibs. of steam. Then as one indicated horse-power is the expression of 33000 foot- pounds of work done per minute, 33000 x 60 = 1980000 units of work per hour, and '9JJ 0000 units f wo * P er , ho " r = -306, the efficiency of the 0469092 units or work available engine, or less than one-third the theoretical efficiency. One Horse-power is equivalent to 3 3000 foot-lbs. _ 6 th j 772 foot-lbs. units per minute, which multiplied by the number of indicated horse-power of an engine will give the thermal equivalent of the work done by that engine. Example : Required the number of thermal units in a marine-engine with cylinder 60 inches diameter, length of stroke 3 feet, number of revolutions per minute 70, mean pressure of steam 34 Ibs. per square inch : and what would be the coal-consumption per hour and per day per indi- cated horse-power. Then 6o x 6o inches x ' 7854 x 34 lbs " x (3 feet x 2 x 7o) = *oo-* 772 foot-lbs. thermal units per minute, or thermal equivalent of the work done by that engine ; or 6ox6ox7854X34lbs.x(3feetxax 7 o) = indicated 33000 lbs. horse-power x 42746 = 52300^3 thermal units per minute, the thermal equivalent of the work done by that engine. If i Ib. of good coal give out at the piston, say 1200 thermal units, the consumption will be = 5 2 33 ^.^g lbs. of coal burnt per minute, or 43*58 x 60 = 2614-8 lbs. per hour, and 26u ' 8 = 2-13 lbs. of coal per indicated horse-power per hour, or 2-13 x 24= 51-12 lbs. of coal per indicated horse-power per day of 24 hours. Nominal Horse-power is a commercial term for denoting the size of an engine without regard to the actual power it will develop. Marine- engines work up to from 4 to 8 times their nominal horse-power; the NOMINAL HORSE-POWER OF STEAM-ENGINES. 367 average actual or indicated horse-power in merchant-steamers being proba- bly 4 times the nominal. The Nominal Horse-power of ordinary Condensing Steam- engines of the low-pressure type, in which the mean effective pressure of the steam in the cylinder is assumed to be 7 Ibs. per square inch, and the speed of the piston is either 128 times the cube root of the length of stroke, or 220 feet per minute, may be calculated by the following Rules : (i.) Nominal horse-power = area of piston in square inches x 7 Ibs. x (128 x Vstroke in feet) 33000 Ibs. (2.) Nominal horse-power = diameter of cylinder in inches 2 x Vstroke in feet 47 , N XT . ,, diameter of cylinder in inches 2 , . -r, , (3.) Nominal horse-power = 3 - ; this Rule gives 30 circular inches of area of piston per nominal horse-power. (4.) Nominal horse-power = area of piston in square inches x 7 Ibs. x 220 feet piston speed 33000 Ibs. (5.) Nominal horse-power = diameter of cylinder* 20 (6.) Nominal horse-power = diameter of cylinder 2 x speed of piston in feet per minute 6000 These Rules may be illustrated by applying them to the following Examples. Required the nominal horse-power of a low-pressure con- densing steam-engine, with cylinder 30 inches diameter, and length of stroke 3 feet. Then bv Rule (rt 3<> * 3<> * 7854 x 7 x (128 x l/3~=the piston speed) 33000 = 27-68 nominal horse-power. Rule (3). Rule (4). 3 x 3 = 30 nominal horse-power. 3 30 x 30 x 7854 x 7 x 220 _ r . 98nominal hore power. Rule (5). 3_2_ _32 = 32-14 nominal horse-power. Rule (6). Assuming the number of revolutions per minute of this engine to be 37 , 3 * V x (3 ^stroke x 2 x 37) == 3 3' 3 nominal horse-power. 368 THE PRACTICAL ENGINEER'S HAND-BOOK. The Speed of a Piston in feet per minute = twice the length of stroke in feet multiplied by the number of revolutions per minute. The Admiralty Rule for finding the horse-power of a low-pressure type of steam-engine is that given above in Rule (6), and to which it still applies. The divisor 6000 is obtained as follows : _33^22 s '_ = in round numbers 6000. 7854 x 7 Ibs. Hominal Horse-power of modern Condensing Steam-engines. The following Rules are suitable for the high pressures of steam and increased piston speed now used. (7.) Nominal horse-power = diameter of cylinder in inches 2 X \/ stroke in feet 28 (8.) Nominal horse-power = diameter of cylinder in inches 2 x V stroke in feet 24 Applying these Rules to the previous examples, it gives : by Rule (7). 3 x 3 x VT-. ^.^ nom inal horse-power. 2o Rule (8), 3^_3Q x V 3 _ 54 nominal horse-power. Nominal Horse-power of Non-condensing Steam-engines. The following are a few of the Rules used in different districts for calculating the nominal horse-power of non-condensing steam-engines. Nominal horse-power of small steam-engines = area of cylinder in gq. ing. 8 This Rule only applies to steam-engines having a cylinder-area of not exceeding 100 square inches, and a length of stroke = diameter of cylinder x i'4 to 1-5. Example : Required the nominal horse-power of steam-engines with cylinders of 6| inches, 7| inches, 9 inches, io| inches, and lof inches diameter. Engine with a cylinder 6f inches diameter = 6 '375 x 6 '375 x '7^54 _ 8 4 nominal horse-power. Engine with a cylinder 7$ inches diameter = 775 x 775 x '7^54 _ 8 6 nominal horse-power. Engine with a cylinder 9 inches diameter = 9 x 9 x '7^54 _ g nom j_ 8 nal horse-power. Engine with a cylinder io| inches diameter = IO ' I2 5 x IO ' I2 5 x '? 8 54 8 = 10 nominal horse-power. NOMINAL HORSE-POWER OF NON-CONDENSING ENGINES. 569 Engine with a cylinder lof inches diameter = IO 75 * io^75 * 785.4 _ 1 1 nominal horse-power. For steam-engines having a cylinder-area larger than 100 square inches, the following are a few of the Rules used by makers of engines. N XT . , i diameter of cylinder in inches 2 .,. r> , ( i.) Nominal horse-power = , this Rule gives :o circular inches of area of piston per nominal horse-power. , N VT i - diameter of cvlinder in inches 2 .,. -r, , (2.) Nominal norse-power = - , this Rule gives 12 circular inches of area of piston per nominal horse-power. (3.) Nominal horse-power = area of cvlinder in square inches x j/ stroke in ieet 12 (4.) Nominal horse-power = area of cylinder in square inches X 3 */ stroke in feet 14 (5.) Nominal horse-power = area of cylinder in square inches x ^/ stroke i n inches 27 (6.) Nominal horse-power = area of cylinder in square inches x *(/ stroke in inches 30 (7.) Nominal horse-power = area of cylinder in square inches x j/ stroke in inchei 40 (8.) Nominal horse-power = area of cylinder in square inches X */ stroke in inches 46 (9.) Nominal horse-power = area of cylinder in square inches x V stroke in feet ITS (10.) Nominal horse-power = area of cylinder in square inches x i/ stroke in feet 20 The Nominal Horse-power of Modern Non-condensing Engines may be found by the first rule given above when the engines are small, with cylinder-area not exceeding 100 square inches, and for large engines by Rule (3). These two Rules represent probably the average modern practice of engine-makers for the high pressures of steam and high speed of piston now used. These Rules may be illustrated by applying them to the following : Example : Required the nominal horse-power of a steam-engine with a cvlinder 12 inches diameter, length of stroke 2 feet. B B 370 THE PRACTICAL ENGINEER'S HAND-BOOK. Then by Rule (i) 2 = 14-4 nominal horse-power. Rule (2) I2 X I2 = 12 nominal horse-power. Rule (3) =ii . 8 nominal horse _ power> Rule ( 4 ) ==lo . l nominal horse . power . Rule (5) " x 12 x 7854 xt/a 4 inches =I2 nominal horse _ power. Rule (6) "XiaxT^xg/aTin^Ees^ io . g nominal horse _ 3 power. Rule (7) I2 ^- I2X '78.54X^4 mchej = ^ nominal ho ^_ 40 power. r> i /0 x 12 x 12 x 78^54 x U 24 inches . , , Rule (8) - - '* X - = 7-! nominal horse- = ^ nQminal horse _ Rule (10) 4 e = ^ nominal horse _ power. The Effective Mean Pressure of Steam Required for a given Nominal Horse-power may be found by this Rule : Effective mean pressure in Ibs. per square inch = Number of foot-pounds Cylinder area in square inches per nominal horse-power x speed of piston. Example : If 30 circular inches be considered equal to one nominal horse-power, what is the effective mean pressure of the steam required to indicate four times the nominal horse-power with a piston speed of 420 feet per minute. Then 30x7854 = 23'562 square inches of cylinder area per nominal horse-power and __|3??L4 _ T 3. 338 Ibs. the effective mean pressure per square inch. The Number of times the Indicated Horse-power of an Engine is larger than the nominal horse-power may be found by the converse of the above Rule. Example : The speed of the piston of an engine is 420 feet per minute, with an effective mean pressure of steam of 13.338 Ibs. per square inch: 30 circular inches have to be given per nominal horse-power. How many NOMINAL HORSE-POWER OF COMPOUND-ENGINES. 371 times will the nominal horse-power be greater than the indicated horse- power. Then 30 circular inches x -7854 = 23-562 square inches per nominal horse-power, and 23-562 square inches x 13*338 Ibs. mean pressure x 420 feet_ 33000 Ibs. ~ 4> the number of times the indicated horse-power is greater than the nominal horse-power. The Speed of an Engine required to develop a given Number of horse-power may be found by this Rule : Number of revolutions of an engine per minute = Number of foot-pounds Area of cylinder in inches X pressure in Ibs. x twice length of stroke in feet. Example i : An engine was specified to have 30 circular inches of cylinder per nominal horse-power, and to indicate five times the nominal horse-power. Length of stroke 39 inches. Effective mean pressure of the steam 30 Ibs. per square inch. How many revolutions per minute must it make to fulfil the contract. Then 30 circular inches x '7854 = 23-562 square inches, area of cylinder. 5 _ _ _ _____ _ 23-562 square inches x 30 Ibs. pressure x 3-25 feet x 2 35-91 revolutions per minute. Example 2. An engine with a cylinder 41 inches diameter and 3 feet 6 inches length of stroke, is required to develop one thousand horse-power, with steam of 50 Ibs. per square inch effective mean pressure, how many revolutions must it make per minute ? Then - - __330ooxiooo - - , = revolutions 41 X4i inches x -7854 x 50 Ibs. x 3-5 feetx 2. per minute. Nominal Horse-power of Compound or Double-expansion Marine Steam-engines. A number of rules are used for calculating the nominal horse-power of marine-engines, the results obtained from which vary con- siderably, and are not proportional to the actual or indicated horse-power. The following are a few of the rules used by makers of engines to determine the nominal horse-power of compound, or double-expansion, condensing marine-engines : where HP=high pressure cylinder, and LP= low pressure cylinder. (1) Nominal horse-power = (Diameter of HP cylinder) 2 -}- (diameter of LP cylinder) 2 25 circular inches (2) Nominal horse-power = (Diameter of HP cylinder) 2 + (diameter of LP cylinder) 2 x y stroke in feet 38 (3) Nominal horse-power = (Diameter of HP cylinder) 2 -f (diameter of LP cylinder) 2 x Vstroke in inches ~~~~ 372 THE PRACTICAL ENGINEER'S HAND-BOOK. (4) Nominal horse-power = (Diameter of HP cylinder) 3 + (diameter of LP cylinder) 2 30 circular inches gives 30 circular inches of area of piston per nominal horse-power. These rules may be illustrated by applying them to the following example : Example: Required the nominal horse-power of a compound con- densing-engine with a high-pressure cylinder 30 inches diameter, and a low-pressure cylinder 60 inches diameter. Length of stroke 3 feet. Then by Rule (i) (3QX 30) + (60x60) = igo nominal ho ower> 25 circular inches Rule (2) (3ox 3 o) + (6ox6o)x VT =I71 nominal horse . 3 y power. Rule (3) (3Q x 3 o) + (fox 60) x = i;i nominal horse- power. Rule ( 4 ) (3Q x 3Q) + (60 x 60) = I50nominalhorse . pow er. 30 circular inches The Number of Circular Inches of Cylinder-Area per JTominal Horse-power of compound, or double-expansion condensing-engines, may be found by dividing the sum of the squares of the diameters of the cylinders by the nominal horse-power Example : The cylinders of a compound engine are 41 inches diameter, and 70 inches diameter; the nominal horse-power is 250. How many circular inches is that per nominal horse-power, and what is the ratio of the cylinders ? Then _(4J x 41) + (70 x 70) _ z6 circular inches of cylinder-area 250 nominal horse-power per nominal horse-power. The proportion of circles to one another is as the squares of their diameters. And 4i 2 :7o 2 : : i : 3-915 the ratio of the cylinders. The cylinder-area of triple-expansion engines may be found as follows: Example: The cylinders of a set of triple-expansion engines are 21 inches, 35 inches, and 57 inches diameter; the nominal horse-power is 224: How many circular inches of cylinder-area is that per nominal horse-power, and what is the ratio of the cylinders ? Then ("*") + (35X 3 5) + (57X57) = circular inchesof 224 cylinder-area per nominal horse-power. And 21 2 : 57 2 : : i : 6-859 tne rat i f tne high-pressure cylinder to the low-pressure cylinder. 35 2 : 57 2 : : i : 2-469 the ratio of the intermediate cylinder to the low-pressure cylinder. Mr. Parker and Mr. Milton, engineer-surveyors of Lloyd's, in their report on nominal horse-power for the information of the Committee of Lloyd's, in order to show the great diversity of practice, prepared the following table, which contains a number of Rules used for calculating the nominal horse-power of double-expansion marine-engines, and the nominal powers of three double-expansion engines of different sizes calculated by them. NOMINAL HORSE-POWER OF MARINE-ENGINES. 373 Table 89. CONTAINING 18 DIFFERENT RULES USED IN PRACTICE FOR OBTAINING THE NOMINAL HORSE-POWER OF DOUBLE - EXPANSION MARINE STEAM-ENGINES, AND GIVING THE NOMINAL POWERS OF 3 DIFFERENT SIZES OF DOUBLE-EXPANSION ENGINES CALCULATED BY THEM. Engines Engines Engines No. Formulae for Nominal Horse-power of Compound, or Double-Expansion, Engines. "Cylinder 42 in. of 33 & 62 Cylinder 19 in. of 33 & 62 Cylinder 45 in- Remarks. Stroke. Swoke. Stroke. A B C I (D 2 + d 2 ) + 33 = . 199 149 I 49 2 (D 2 + d 2 ) -- 32 = . 205 154 154 3 (D 2 + d 2 ) - 30 = 219 I6 4 I6 4 ( Rule of makers \ of Engine B. 4 (D 2 + d 2 ) -7- 28 = . 2 35 I 7 6 I 7 6 5 (DS + d 2 ) -r 2 7 = 243 182 182 6 (D 2 + d 2 ) -T- 26 = . 253 190 190 7 (D 2 + d 2 ) x y S, inches _ 22 9 167 175 IOO 8 (D 2 + d 2 ) x */ S, inches _ 254 I8 5 195 9 9 ((D 2 + d 2 ) x *,' S, feet) -=- 40 250 1 80 191 10 (D 2 x yS,feet) -33= - 222 172 1*1 ii 840 cubic inches of cylinder = . 2 5 8 1 80 207 12 800 to 700 cubic inches of j cylinder = . . . J 271 to 310 189 to 216 218 to 249 13 Area of H.P. cylinder 4- 5 = . 262 171 171 H ((D 2 + d 2 ) x S, feet) 4- 90 = 2 5 6 178 204 T r (D 2 + d 2 ) v /q , -\ / I 7O 18* ! Rule of makers ,- ,. - , , *3 20OO ^ i /'-' 10 j of Engine C. 16 (D- + d 2 ) v rQ _,_ ^^ 235 1 68 183 2016 17 (D 2 + d 2 ) x speed of piston _ 462 288 328 ( Rule given in J proposed Mer- | chant Shipping lAct, 1871. 6oco 18 Actual registered horse-power = 2^6 1 60 200 D = Diameter of Low-pressure Cylinder, and d = Diameter of the High-pressure Cylinder. S = Length of Stroke. H.-P. = High-pressure Cylinder. The Nominal Horse-Power of Triple-Expansion Engines may be found by the following formula : Let D = the diameter of each cylinder in inches ; S = length of stroke in inches ; N = nominal horse-power of the engines. 90 Example : Required the nominal horse-power of a set of triple-expansion engines with cylinders 33, 54, and 86 inches diameter. Length of stroke 60 inches. Then 33 2 + 54 3 + 86 2 x y 60 90 496 nominal horse-power. 374 THE PRACTICAL ENGINEER'S HAND-BOOK. The Nominal Horse-Power of Triple-Expansion Surface-Con- densing Marine-Engines may be found by the following formula, which assumes a boiler-pressure of 150 Ibs. per square inch above the atmo- sphere : Let H P = the diameter of the high-pressure cylinder in inches. M P = the diameter of the intermediate cylinder in inches. L P = the diameter of the low-pressure cylinder in inches. Then nominal horse-power = H P' Where x = the number of times the indicated horse-power is required to be greater than the nominal horse-power. Example : In a set of triple-expansion engines the high-pressure cylinder is 21 inches diameter, the intermediate cylinder is 35 inches diameter, and the low-pressure cylinder is 55 inches diameter; the engines were guaranteed to work up to, and indicate, four times their nominal horse- power : What is the nominal horse-power of the engines, and what power should they indicate ? Then x=4 And ("X2i)-K35X 3 5) + (55X55l . 22 nominal horse .power, and 5-5X4 these engines should work up to, and indicate 213-22 x 4=852*88, or say 853 horse-power. If the nominal horse-power of the above engines were calculated at 30 circular inches of area of piston per nominal horse-power, their power would only be = (" xai) + ( 3 5X 35) + (55X 5 5) = 156-36 nominal horse- 30 circular inches power, and they would require to work up to -7 = 5 '45 times the nominal horse-power, to develop 853 indicated horse-power. The Nominal Horse-Power of Quadruple-Expansion Surface- Condensing Marine-Engines may be found by the following formula, which assumes a boiler-pressure of 170 Ibs. per square inch above the atmosphere. Let L P = the area of the low-pressure cylinder in square inches. H P = the area of the high-pressure cylinder in square inches. A = the area of \\iefirst intermediate cylinder in square inches. B = the area of the second intermediate cylinder in square inches. Then, nominal horse-power = Lp2 + H P 2 +A 2 +B* 4-5x0: Where x = the number of times the indicated horse-power is required to be greater than the nominal horse-power. Example: In a set of quadruple expansion-engines the high-pressure cylinder is i6| inches diameter, the first intermediate cylinder is 23! inches diameter, the second intermediate cylinder is 33 inches diameter, and the low-pressure cylinder is 45 inches diameter; the engines were guaranteed ACTUAL OR INDICATED HORSE-POWER. 375 to work up to and indicate four times their nominal horse-power : What is the nominal horse-power of the engines ? Then x 4. And OS'S x i6-5) + (2 3 -5 X2 3 - 5 ) + ( 3 3 x 33 ) + (45 x 45) = 2 lg . 8 nominal 4-5x4 horse-power, and these engines should work up to and indicate 213-8x4= 875*2, or say 876 horse-power. If the nominal horse-power of the above engines were calculated at 30 circular inches of area of piston per nominal horse-power, their power would only be - ( l6 '5 * 16-5) + (23-5 x 23-5) + (33 x 33) + (45 * 45) _ 30 circular inches 131-28 nominal horse-power, and they would require to work up to '--=. 6-67 times the nominal horse-power to develop 876 indicated horse-power. The Indicated Horse-Power of an engine is the effective power calculated from an indicator diagram, or the power imparted by the steam in the cylinder to the piston. Actual or Indicated Horse-Power. One actual horse-power is equal to 33000 Ibs. raised one foot high in one minute, or 550 Ibs. raised one foot high in a second. The power imparted to the piston by the steam in a cylinder, or the actual horse- power, is the quotient of the effective work done in the cylinder in foot-pounds per minute divided by 33000. The effective work is found by multiplying the area of the piston in square inches by the effective mean-pressure in Ibs. per square inch, by twice ihe length of stroke and by the number of revolutions per minute of the crank-shaft. The following formulae are used for calculating the actual or indicated horse-power, the diameter of cylinder, the effective mean -pressure, and speed of steam- engines ; the working friction of the engine not being taken into account. Let=IHP = the indicated horse-power of the engine. D = the diameter of the cylinder in inches. P = the effective mean pressure of the steam in Ibs. per square inch. L = the length of stroke in feet. R = the number of revolutions of the crank-shaft per minute. Then, area of piston = D 2 x -7854. Pressure on the piston = D 2 x -7854 x P. Number of units of work in one revolution = D 2 x -7854 x Px 2L. Number of Ibs. lifted one foot high per minute ) r, 2 v .-Q- v p v ?T *K Or number of units of work done per minute j " (i.) Indicated horse-power, I H P = U"its of work done per minute 33000 (2.) The speed of the piston in feet per minute = Lx 2 X R. ( ^ Indicated horse- ") _D 2 x -7854 x Px speed of piston in ft. per minute U') power, I H P j - 33000 3/6 THE PRACTICAL ENGINEER'S HAND-BOOK. (4.) Indicated horse-power, I H P = D 2 x 7854 x Px (Lx 2 x 33000 (5.) Diameter of cylinder in inches,D = (7.) Length of stroke in feet, L = (8.) Number of revolutions per minute, R =- 33 o l / D 2 X785 4 xPx(2 L) These Rules may be illustrated by applying them to the following 1 example : Example : Required the actual or indicated horse-power of a non-con- densing steam-engine, with cylinder 16 inches diameter, length of stroke 2 feet, number of revolutions per minute 80, mean pressure on the piston 50 Ibs. per square inch. Then by Rule (i.) IHP = units of work done per minute 33000 16 x 16 x 7854 x5OX2X2x8o_ 33000 97-454 indicated horse-power. Rule (2.) 2 feet stroke x 2 x 80 revolutions per minute = 320, the speed of piston in feet per minute. Rule (3.) IHP = l X l X 7 g Q X 5 X 32 = 97-454 in- dicated horse-power. Rule f* ^ IHP l6 x l6 x ' 754 x 5 x 2 x 2 x 80 33000 97-454 indicated horse-power. Rule (5.) D = - ____ = ^ = fi 7854 X 50 X 2 X 2 X 80 inches diameter of cylinder. Rule (6.) P = . 3300Q xor454 - = Ibs . 16 x 16 x 7854 x 2 x 2 x 80 per square inch mean pressure of steam on the piston. Rule (7.) L - - - 33000 x 97-454 - = 2 f 16 x 16 x 7854 x 50 x 2 x 80 length of stroke. Rule (8.) R = -= _ 33000 x 97354 _ = So revc^ ID X l6 X 7854 X 50 X 2 X 2 lutions per minute. EXPANSION OF STEAM IN A CYLINDER. 377 Friction of Steam-Engines. The power absorbed by friction depends upon the load on the journals and guides ; the alignment and finish of the rolling and sliding surfaces, and the efficiency of their lubrication. It averages from 10 to 20 per cent, of the total power developed by an engine when fully loaded. No allowance is made for friction in the above Rules for finding the actual or indicated horse-power of steam-engines. It will be necessary to deduct from the horse-power obtained by these Rules 12 per cent, for a non-condensing engine, and 25 per cent, for a condensing engine, to allow for the power absorbed in driving the engine when fully loaded, against the resistance due to its own friction, and in working the pumps, the remainder will be the actual or available motive power, or the effective horse-power of the engine. For the friction of an engine without pumps, a deduction may be made from the effective mean pressure of 1 1 Ib. per square inch for large engines, 2 Ibs. for medium sized, and 3 Ibs. for small engines. EXPANSION OF STEAM PROPORTIONS OF THE CYLINDERS, PISTONS, PISTON-ROUS, AND CROSS-HEADS, OF STEAM- ENGINES. Expansion of Steam in a Cylinder. When steam is cut-off in a cylinder after the piston has travelled a portion of its stroke, the steam expands for the remainder of the stroke, the piston being driven by the expansive force of the steam, and its pressure at any part of its stroke during expansion is nearly in inverse proportion to its volume. For instance, if steam of 100 Ibs. pressure per square inch be admitted to a cylinder, and cut off when the piston has travelled one-fourth the length of its stroke, the remaining three-fourths of the stroke will be performed by the expansive force of the steam, which will increase in volume to four times its initial volume and be reduced to about one-fourth its initial pressure, or to about 25 Ibs. per square inch. It is therefore usual to assume the pressure of expanding steam to be inversely as its volume. The terminal pressure of the steam is equal to the product of the initial pressure by the grade of expansion. The method of calculating the pressure by these Rules is shown in the following example : Example : Steam of 66 Ibs. pressure per square inch is admitted to the cylinder of a steam-engine having a 6 feet stroke, the steam is cut off after the piston has travelled 2 feet of its stroke. Required the terminal pressure, the average pressure throughout the stroke, and the saving effected by working the steam expansively. The terminal pressure of the steam is : The grade of expansion is * feet admission of steam = i and 66 x i = 6 feet length of stroke 22 Ibs. per square inch, the terminal pressure of the steam ; initial pressure whole stroke ' terminal pressure ~~ part of stroke .._ = -.. ,r=22 Ibs. per square inch, the terminal pressure. X 2 THE PRACTICAL ENGINEER'S HAND-BOOK. The average pressure of the steam throughout the stroke is : Pressure of the steam during the first foot in length of the stroke second third fourth fifth sixth = 66 = 66 =66xf=44 =66x*= 33 =66x1=26-4 257-4 the total pressure, and 257*4 -4- 6 = 42-9 Ibs. per square inch, the average pressure of the steam throughout the stroke. The saving effected by working expansively is : If the steam had been admitted throughout the whole length of stroke, the average pressure would have been 66 Ibs. per square inch ; by working expansively the average pressure was 42-9 Ibs. per square inch, showing a saving of 66 42-9 = 23' i Ibs. per square inch = = 35 per .. cent, effected by working expansively. The average pressure of the steam throughout the stroke may also be found by constructing a diagram as shown in Fig. 321, which represents the cylinder described in the previous example. AB represents the initial pressure of the steam = 66 Ibs. per square inch, and BD the length of stroke, which is divided into six equal parts by the lines e,f, g, h, i, equal in depth to the pressure of the steam at these points of the stroke, as obtained in the previous example. For instance, the depth of trie line, g^ is frds that of AB, because the steam is cut off at f, and when the piston arrives at the position marked g the pressure of the expanding steam will be reduced to 66 x f = 44 Ibs. per square inch. The curve drawn through the points thus found is Ad. T_ Of. E'xpan Fig. 321. Diagram of steam-pressure. hyperbola : it represents the falling pressure of the steam during ex- pansion. The average pressure of the steam throughout the stroke may be calculated approximately by Simson's Rule : To the sum of the extreme or- dinates add four times the sum of the even ordinates, and twice the sum of the odd ordinates. This sum, multiplied by one-third the common distance between the ordinates, will give the area of that part of the diagram marked k,j, ~D,f, and therefore the steam pressure. Then the area = -i (66 + 22 + 4 (44 + 26-4) + 2 x 33} = 145-2 Ibs. The work done before the steam was cut off is 66 x 2 = 132 Ibs., the total work done is 145*2 + 132 = 277-2 Ibs., and the average pressure throughout the stroke is 277-2 -=- 6 = 46*2 Ibs. per square inch, or 46-2 EXPANSION OF STEAM IN A CYLINDER. 379 42-9 = 3'3 Ibs. per square inch more than the pressure found by the previous rule. The Maximum Economy of Steam is obtained, theoretically, when the whole of the work is done in the cylinder by the elastic force pro- ceeding from the expansion of steam. Therefore, to obtain all its useful work, steam should be expanded as many times as will reduce its final pressure to the lowest point consistent with doing useful work. When expansion ceases to do useful work it ceases to be of any practical value. As the temperature changes with the pressure of ?team, the reduction of pressure at the end of the stroke is accompanied by loss of heat and cool- ing of the cylinder, which causes the condensation of a portion of the steam which enters at the following stroke. This loss of heat limits the number of times steam can be economically expanded in one cylinder ; and wide variation of pressure in a cylinder produces irregular rotational force on the crank-pin. The less the difference between the highest and lowest temperature in a cylinder, the less is the loss of heat and power from the cooling of the cylinder at the end of the stroke. Consequently, when large measures of expansion are used, the highest economy, derived from the expansion of steam, will be obtained by expanding the steam in two or more cylinders, according to the grade of expansion used, by which means the range be- tween the highest and lowest pressure in each cylinder is diminished as much as possible, and loss of heat and power is prevented. A Steam-Jacket keeps the metal of the cylinder at a uniform tempera- ture, and prevents initial condensation of the steam. It also prevents con- densation during expansion by imparting heat to the expanding steam. The heat abstracted from the steam during expansion is in proportion to the work performed and a part of the steam is condensed ; the greater the measure of expansion the greater is the loss of heat and the greater the necessity for supplying the expanding steam with the heat lost in the per- formance of work. The heat corresponding to the steam condensed in an efficient steam-jacket, is according to Mr. Anderson's theory approxi- mately equal to the amount of heat converted into work. If H=the total heat of the absolute pressure of the steam in the jacket, from Table 79, and T = its temperature, from Table 78, the heat-units, U, converted into work per minute are, U = (IHPx 33ooo)-f-772, and the weight of water in Ibs., W, from the steam condensed in the jacket per hour, is approximately, 60 minutes. For instance, if the pressure of the steam in the ) r jackets of a steam-engine of 1200 indicated horse-power be 150 Ibs., or 150 + 15 = 165 Ibs. per square inch absolute pressure, the heat converted into work per minute is=(i2oox 33Ooo)-r772 = 5i295 units, and the quantity of 51295 x 60 minutes water from the steam condensed in the jackets 13=?* , 2 <>, 6 = = 3i861bs.-f-iolbs.=3i8'6 gallons per hour, when reduced to the standard temperature, from and at 2i2Fahr. ; and = 3186 Ibs. -f- 1200 = 2*66 Ibs. of water per indicated horse-power per hour. THE PRACTICAL ENGINEER'S HAND-BOOK. The Pressure of Steam in a Cylinder when it opens to the Exhaust may be found by this Rule: Terminal pressure = initial absolute pressure x length of steam-stroke distance travelled by the piston when the exhaust opens. Example : The length of stroke of an engine is 6 feet, initial pressure 65 lbs. per square inch, steam is cut off when the piston has travelled i foot of its stroke. Required the pressure in the cylinder when it opens to the exhaust, which is 3 inches before the piston arrives at the end of its stroke. Then - i j - = 14 lbs., the terminal absolute pressure. The Absolute Mean Pressure of Steam in a Cylinder and the Final Pressure maybe found by the graphical method shown in Fig. 322. oibs. Draw two lines, CB and AG, at right angles. Using any convenient scale, make the length AB = the initial abso- lute pressure of the steam, and AC = one - fourth the length of AB. With C as a centre and CB as a radius, draw the line B, F, G. The length of the line AG will repre- sent the stroke of the piston, plus the clearance measured in terms of the stroke. Find a point D, Fig. 322. Diagram of the mean-pressure of steam in a cylinder. on the line AG, so that DA clearance in terms of the stroke length of stroke. In DA take E, so that = = cut-off, and draw the perpendicular line EF. The length EF, measured on the same scale as AB, will equal the absolute mean pressure of the steam, from which deduct 15 lbs. in non- condensing-engines and 3 lbs. in condensing engines, and the remainder will be the effective mean pressure. Join the corners BG by a straight line, then the length from E to where the diagonal line cuts EF at H, measured on the same scale as the other pressures, will equal the final absolute pressure of the steam. Make the distance from G to D so that DG_ volume of clearance __ DA volume of cylinder swept by the piston in one stroke. The initial absolute pressure of the steam shown in the diagram Fig. 322, is 67 lbs. per square inch, the steam is cut-off at one-third of the stroke. EFFECTIVE MEAN PRESSURE OF STEAM. 381 The volume of one steam-port plus the clearance space between the piston and the cylinder-cover when the piston is at the beginning of its stroke, is equal to -^th the stroke of the piston, therefore GD is -^th part of DA. The diagram gives a mean absolute pressure of 48^ Ibs. per square inch, and a final absolute pressure of 24 Ibs. per square inch. The Effective Mean Pressure of Steam on the Piston may be found approximately without the aid of hyperbolic logarithms by the following formula : Let P = the absolute pressure of the steam in Ibs. at the beginning of the stroke. R = the number of times the steam is expanded. Then, the effective mean pressure of the steam = P x f 1 - 8 ^! -+ '*) -back-pressure. \ 40 R ) Example : Required the actual or indicated horse-power of an engine with cylinder 62 inches diameter, length of stroke 39 inches, pressure of steam in the cylinder at the beginning of the stroke 55 Ibs. per square inch, cut off at 13 inches of the stroke, number of revolutions per minute 64, back-pressure 3-06 Ibs. Then, the steam is expanded 39 inches stroke t imes,the ab- 13 inches point of cut-off solute pressure of the steam is 55 Ibs. + 15 Ibs. = 70 Ibs. per square inch, and f 1 ~ 3 +--JJ = -658 x 70 Ibs. = 46-06 3-06 back-pressure = 43 Ibs. per square inch, the effective mean pressure of the steam on the iston and ^ 2 x ^ 2 inches diameter x -7854 x 43 Ibs. x 3-25 feet x 2 x 64 33000 Ibs. = 1636-55 actual or indicated horse-power. The Effective Mean Pressure of the Steam on the Piston throughout the Stroke may be found by this Rule : To the hyperbolic logarithm of the total number of expansions add i, divide the sum by the total number of expansions, and multiply the quotient by the initial absolute pressure of the steam that is, the boiler pressure shown by the steam-gauge plus 1 5 Ibs. which will give the average pressure of the steam expanded the given number of times, from which deduct the back-pressure, and the remainder will be the mean effective pressure on the piston throughout the stroke. Example: Required the mean pressure of the steam in a compound engine, the initial pressure of the steam in the high-pressure cylinder being 69 Ibs. per square inch, and the final pressure in the low-pressure cylinder 12 Ibs. per square inch. Then the initial absolute pressure of the steam is 69 + 15 = 84 Ibs. per square inch, and 4 Ibs. initial absolute pressure = ^ ^ number of 12 Ibs. final pressure expansions, or number of times the steam is expanded. 382 THE PRACTICAL ENGINEER'S HAND-BOOK. The hyperbolic logarithm of 7 is from Table 90, =1-9459, which added to I = 2 '94 50, then = -4208 x 84 Ibs. absolute pressure = 7 expansons 3 5 '34 Ibs. per square inch, the average pressure of steam of 84 Ibs. absolute pressure expanded 7 times, and if 3*34 Ibs. be deducted for back-pressure, it leaves 32 Ibs. per square inch, the effective mean pressure. Table 90. HYPERBOLIC LOGARITHMS. Number. Logarithm. Number. Logarithm. Number. Logarithm. Number. Logarithm. I i 22 3 I 6 I-7 9 l8 iof 2-3749 16 2-7726 l 4054 6* 1-8326 II 2-3979 :6| 2-8034 If *559 6 6i 1-8718 Ilf 2-420I 17 2-8332 2 6931 6| I- 9 095 III 2-4430 irt 2-8621 2j 8l09 7 1-9459 III 2-4636 18 2-8904 2 \ 9162 7f 1-9810 12 2-4849 i8f 2-9173 4 ron6 7* 2-0149 "i 2-5052 J 9 2-9444 3 1-0986 7f 2-0477 I2| 2*5262 i 9 i 2-9703 si 1-1787 8 2-0794 I2f 2-5455 20 2-9957 3t 1-2528 8i 2'II02 J 3 2-5649 21 3-0445 3f 1-3217 8^ 2-I40I 13* 2-5840 22 3-09II 4 1-3862 8| 2-1691 13! 2-6027 2 3 3" X 355 4? 1-4469 9 2-I972 I3l 2-62II 24 3-1781 4i 1-5040 9i 2-2246 H 2-6391 2 5 3-2189 4| 1-5581 9* 2-2513 14* 2-6567 26 3-2581 5 1-6094 9l 2-2773 14! 2-6740 27 3-2958 5* 1-6582 10 2-3026 I4| 2*6913 28 3-33 2 2 si 1-7047 ioi 2-3279 15 2-7081 2 9 3-3 6 73 5* 1-7492 io| 2-3513 i5 2-7408 3 3-4012 Mean Pressure of Steam in the Cylinder. The lowest economical final pressure in a low-pressure cylinder is in practice from 10 to 12 Ibs. per square inch. The mean pressure of steam in the cylinders of steam- engines worked expansively, with various initial pressures of steam worked down to a final pressure of 12 Ibs. per square inch, is given in Table 91, which has been calculated by the previous rule with hyperbolic logarithms, but no allowance has been made for back-pressure, which must be deducted to obtain the effective mean pressure throughout the stroke. When the back-pressure is not known it will be sufficiently near in most cases to assume it to be 3 Ibs. per square inch. The Table shows the pressure of steam required for a given number of expansions, the point of cut-off required, and the mean pressure of the steam throughout the stroke. For instance, if it be required to expand steam 10 times, steam would be required of 120 Ibs. initial absolute pressure, the point of cut-off from the commencement of the stroke would be at ^th of the length of stroke, and the mean pressure of the steam would be 39-62 Ibs. per square inch. MEAN PRESSURE OF STEAM IN THE CYLINDER. 333 Table 91. SHOWING THE MEAN PRESSURE OF STEAM IN THE CYLINDERS OF STEAM-ENGINES WORKED EXPANSIVELY WITH VARIOUS INITIAL PRESSURES OF STEAM WORKED DOWN TO A FINAL PRESSURE OF 12 LBS. PER SQUARE INCH. 4 S| x|j> Absolute Pressure. Ij qj |lj! Absolute Pressure. '8 Ez< tJD^ O " BB fe SjU 1 - iji Hi $ |4 J| Hi ~ "SO: 4> 111 I" 1 , 1? |*f Number Steam i ill J-Bs 1 jili P P 3W lill JSJI |is.l ill lis |.st Ibs. Ibs. Ibs. Ibs. ;j I 5 9933 9875 13-5 15 13-40 14-81 10 * 3302 3246 1 2O 123 39-62 49-92 ii 1 9641 16 15-42 io| A 3191 126 40-20 13 9488 17-1 l6'22 ioi -3139 129 40-49 i ii 3 9369 18 16-88 ii ^ 3089 I 3 2 4077; If A 9090 20 18-18 Hi A 3040 135 41-04! 9 8912 21 1871 5-3 2993 138 2 i -8465 24 20-31 113 3? 2947 141 4''55| 2 k a 8048 27 2173 12 4 2904 144 41-81 2 ll & 8010 26-18 20-95 I2j 2861 147 42-05 2$, 1 7664 30 22-99 I2| I 2821 42-31 2 I A 73" 33 24-12 12^ 5*1 2780 I 53 42-53 3 i 6995 36 25-18 13 A 2742 156 4277 3i 3s 1 6703 6618 39 40 26-14 26-47 Ja I 2704 2668 '59 162 42-99 43-22 i 4 f 6436 6191 5965 42 27-03 27-85 28-63 14 Hi 2633 2599 2566 ^68 171 43'44 43-66 4k '5757 51 2936 I4f 1 2533 174 44-07 4 | -5463 54 29-50 14^ i 2502 177 44-28 4i TO 5385 57 30-69 5 1 1 5 2472 180 44-49 5 i 5218 60 31-30 3 2 1 2412 186 44-86 Si * 5063 63 31-89 16 10 2358 192 45 '37 5| 4917 66 32-45 16^ 33 2305 198 45-63 * 4781 69 32-98 17 T? 2255 204 46-02 6 1 4653 72 33-50 17* 3*? 2206 2IO 46-32 6i A 4532 75 33-99 18 * 2160 216 46-65 64 j! 4418 78 18^ 2112 222 46-88 6| 27 4310 81 34-9I 19 I 2076 228 4733 7 } 4208 84 35-34 lp| * 2036 234 47-64 7i / 4111 85 34^4 20 1998 240 47-95 74 A 4002 90 i 36-01 21 51 1926 252 48-53 7i 3932 93 36;56 22 23 1860 264 49-10 8 i 3849 96 23 1800 2 7 6 49-68 A '3779 99 37-32 24 2 1741 288 50-14 A 3694 3621 102 105 38-02 3 I 1687 1638 300 3" 50-61 51-10 9 i 3486 108 in 3836 38-69 3 1 1547 9 5I-54 5I-97 9-> -& 3422 114 39-01 29 1506 348 52-40 9l 3% 117 30 * 1467 360 52-81 The Back-Pressure, usually 3 Ibs. per square inch, must be deducted 34 THE PRACTICAL ENGINEER'S HAND-BOOK. from the mean pressure of the steam given in the above Table, and the remainder will be the effective mean pressure throughout the stroke. Number of Times the Steam is Expanded. If the number of expansions be carried out in two or more cylinders, as in double-expansion, triple-expansion, and quadruple-expansion engines, the final pressure of the steam is the same as in a single cylinder engine, and this table applies to all steam-engines in which the steam is worked expansively. The total expansion is equal to the number of cubic feet of space behind the low- pressure piston when the exhaust opens, divided by the space behind the high- pressure piston at the point of cut-off ; or=final volume -4- initial volume. The Diameter of the Cylinder of a Steam-Engine may be found from Table 91, as shown by the following example Example: Required the diameter of a cylinder for an engine of 800 indicated horse-power, with an initial pressure of steam of 90 Ibs. per square inch, above the atmosphere, with a speed of piston of 420 feet per minute, back-pressure 3-02 Ibs. per square inch, the steam to be expanded 8| times ? Then the initial absolute pressure of the steam will be = 90+ 15 lbs.= 105 Ibs. per square inch, the mean pressure of which with 8| expansions is according to the Table=:38-o2 Ibs. per square inch, from which deduct the back-pressure, and it leaves 38-02 3-02 = 35 Ibs., the effective mean pressure of the steam throughout the stroke. The total pressure on the piston to develop 800 horse-power will be = 33000 x 800 IHP = 62762lbs ., and _^_76 2 Jbs_ = 420 feet per minute 35 Ibs. pressure inches area of the cylinder, and A/ ^.Ssay 48 inches diameter. The Diameter of a Cylinder suitable for a given size of Crank- Shaft, for a low-pressure steam-engine using steam of under 35 Ibs. initial pressure per square inch, may be found by the following formula : Let D = the diameter of cylinder in inches ; d = the diameter of the crank-shaft in inches ; L = the length of stroke in feet. Then D = Example: What diameter of cylinder is suitable for an engine using steam of 30 Ibs. per square inch initial pressure, the diameter of the crank- shaft being 13^ inches, and the length of stroke 4 feet? 6-55 x irs x 13-5 x 13-5 inches ,/ , . - . / f. _ 5^ inches, the diameter of cylinder required. Diameter of Cylinder of Non-Condensing Steam-Engines. The area of the piston should be in proportion to the pressure of the steam and the speed of the piston. The piston-area per nominal horse-power may be 8 square inches for very high pressures and speed, 9^ to 10 square inches for high pressures and speed, and 1 1 square inches for moderate pressures and .speeds. Diameter = y(area in square inches -f- 7854). Diameter of Cylinder of Condensing Steam-Engines. The area of the piston per nominal horse-power may be from 13 to 16 square inches CYLINDERS OF COMPOUND ENGINES. 385 for very high pressures of steam, from 18 to 20 square inches for high pressures, and from 22 to 25 square inches for low pressure steam. Diameter of Cylinder, per Nominal Horse-Power, of Double Expansion Compound Steam-Engines, with one high-pressure cylinder and one low-pressure cylinder. Diameter of high-pressure cylinder = V nominal horse-power x 26 V ratio of the areas of cylinders. Diameter of low-pressure cylinder = diameter of high-pressure cylinder x Vratio of cylinder-capacity. Example : Required the diameter of the cylinders of a compound steam- engine of 250 nominal horse-power, the ratio of the cylinder areas being 4 to i. Then 2 ^ x 2 = ^625 = 40^32 inches, diameter of high-pressure cylinder ; and 40-32 x v X !T= 8o'64 inches, diameter of low-pressure cylinder. The Diameter of Cylinder required for a given Actual or Indicated Horse-power may be found by the following Rule : Diameter of cylinder = 33000 x number oFmdlcated horse-power 7854 x mean pressure of steam in Ibs. x speed of piston in feet. Example : Required the diameter of cylinder for an engine with steam of 42 Ibs. per square inch mean pressure, length of stroke 2 feet, to develop 25 indicated horse-power when making 70 revolutions per minute. Then /i:i33ggox 25 horse-power " ^ inch V -7854 x 42 Ibs. x (2 feet x 2 x 70) of cylinder required for that engine. In Compound Engines the steam, after performing work in one cylinder, is exhausted into and performs work in another, or in several cylinders. The expansion of the steam being carried out in two or more cylinders, the loss from cooling produced by extreme variation of temperature is diminished as much as possible by dividing the extreme range of temperature of the steam between several cylinders. The economy effected by using a double expansion compound engine, with one high-pressure and one low-pressure cylinder, instead of a simple engine, is about 25 per cent, of fuel. The expansion of the steam is carried out in two stages in two cylinders in double-expansion compound engines, in three stages in three cylinders in triple-expansion engines, and in four stages in four cylinders in quadruple- expansion engines. The Ratio of the Capacities of the Cylinders of Compound or Double-expansion Engines depends upon the initial pressure of the steam in the high-pressure cylinder. The area of the low-pressure cylinder of a compound engine is calculated as if all the power were to be developed in that cylinder. When the diameter of the low-pressure cylinder would be excessive, the capacity of the low-pressure cylinder is divided between two cylinders, and the cylinders are arranged to act on a three-throw crank, with crank-pins placed at equal angles of 120 apart, in order to secure equality of strains and power and uniformity of turning-effort. The diameters of the c c 386 THE PRACTICAL ENGINEER'S HAND-BOOK. cylinders of a double-expansion compound condensing engine, with one high-pressure cylinder and one low-pressure cylinder, for a given actual or indicated horse-power may be found by the following Rule : Let IHP = the indicated or actual horse-power of the engines. E = the effective mean pressure of the steam in Ibs. per square inch. S = the length of stroke in feet. R = the number of revolutions of the crank-shaft per minute. LP = the area of the low-pressure cylinder in square inches. HP = the area of the high-pressure cylinder in square inches. Then LP= 33000 x IHP E x (S x 2 x R) HP=- LP initial absolute working-pressure x '042- Example : Required the diameters of the two cylinders of a marine compound condensing engine to indicate 1402 horse-power, length of stroke 3 feet 9 inches, number of revolutions per minute 56, the working- pressure of the steam by the steam-gauge being 90 Ibs. per square inch, and the mean pressure 37 Ibs. per square inch. Then the absolute pressure of the steam will be 90 -f 15 = 105 Ibs. per square inch. and - _33 _J40O _ square inches, the area of the low- 37 Ibs. x (375 x 2 x 56) pressure cylinder. 2 9?3 _ 6-r square inches, the area of the high-pressure 105 Ibs. x -042 cylinder. Then //-1|Z3_ = S ay 62 inches, the diameter of the low-pressure cylinder. A/ 1^ = say 29! inches, the diameter of the high-pressure V 7854 cylinder. In order to provide for the loss due to the fall in pressure of the steam in passing from one cylinder to the other, their areas found by the above Rules should be increased to the extent of from 10 to 20 per cent. The Proportion of the Cylinders of Triple-Expansion Engines depends upon the initial pressure of the steam in the high-pressure cylinder. The diameters of the cylinders of triple-expansion surface-condensing marine engines may be calculated by the following formulae : Let IHP = the indicated horse-power of the engines. E = the effective mean pressure of the steam in Ibs. per square inch. S = the length of stroke in feet. R = the number of revolutions of the crank-shaft per minute. LP = the area of the low-pressure cylinder in square inches. TRIPLE-EXPANSION ENGINES. 387 HP = the area of the high-pressure cylinder in square inches. M = the area of the intermediate cylinder, in square inches Then LP = -33g*> * IHP_ E x (S x 2 x R) HP= LP initial absolute working-pressure x '042 M = HPx 2-5. Example: Required the diameters of the three cylinders of a triple expansion engine to indicate 1000 horse-power, length of stroke 3 feet 6 inches, number of revolutions per minute 60, the working-pressure of the steam by the steam-gauge being 1 50 Ibs. per square inch, and the mean pressure of the steam 30 Ibs. per square inch. Then the absolute pressure of the steam will be 150 + 15 Ibs. = 165 Ibs. per square inch, ooo x 1000 , ----- r-z 2620 square inches, the area of the low-pressure cylinder, rF = 379 square inches> the area of the hi s h -p ressure cylinder, and 379 square inches x 2'5 = 948 square inches, the area of the inter- mediate cylinder. Then A/____ = 58 inches, the diameter of the low-pressure cylinder, " A/- 94 = 35 inches, the diameter of the intermediate cylinder, "1 li_ A/-aZ2_ =22 inches, the diameter of the high-pressure cylinder. The proportion of these cylinders is in round numbers i : 2\ : 7, which is correct for this initial pressure of steam. All the cylinders, or at least the high-pressure cylinder, should be steam-jacketed to obtain the utmost economy. The best arrangement of the Cranks to ensure uniformity of rotative pressure on the crank-shaft is to place them at equal angles of 1 20 apart ; and to make the crank of the high-pressure cylinder the leading crank, the low-pressure crank should follow and the intermediate crank should be last. The economy effected by using a triple-expansion engine instead of a double- expansion or compound engine averages 25 per cent, in the best engines; in some cases as much as 33 per cent, saving of fuel has been effected. The Economy of Triple-Expansion and Quadruple-Expansion Engines is due, partly to the utilization of the principle of expansion in using steam of the highest pressure and expanding it as many times as possible in the most efficient manner, the extreme range of temperature being divided between several cylinders ; and partly to the means afforded for the effectual re-evaporation of the initial condensation of steam, the steam condensed in the small cylinder being re-evaporated to steam of a lower pressure in each larger cylinder and used expansively upon its piston. 388 THE PRACTICAL ENGINEER'S HAND-BOOK. The Diameters of the Cylinders of Quadruple-Expansion Surface- Condensing Marine-Engines may be found by the following formula: Let IHP = the indicated horse-power of the engines. E = the effective mean pressure of the steam in Ibs. per square inch. S = the length of stroke in feet. R = the number of revolutions of the crank-shaft per minute LP = the area of the low-pressure cylinder in square inches. HP = the area of the high-pressure cylinder in square inches. A = the area of the first intermediate cylinder in square inches. B = the area of the second intermediate cylinder in square inches. Then LP = 33QQQ x I H P E x (S x 2 x R) Hp== _ Lj; _ Initial absolute working pressure x '042 ' A = HPX2. B = Ax 2. Example : Required the diameters of the four cylinders of a quadruple- expansion engine to indicate 500 horse-power. Length of stroke, 2 feet ; number of revolutions, 105 ; the working pressure of the steam by the steam-gauge being 165 Ibs. per square inch, the steam to be expanded 15 times. Then the absolute of the steam is 165 + 15 = 180 Ibs. per square inch; the mean pressure of which, when expanded 15 times, is, according to Table 91, = 44*49 ^s., and if 3-09 Ibs. be deducted for back-pressure, it leaves 44*49 ~~ 3'9 = 4 r 4 ^s., the effective mean pressure. And 33000 Ibs. x 500 _ g re . nch h area f h j 41-4(2 X2X 105) pressure cylinder. n 94 93 __ j 25-52 square inches, the area of the high- 180 x -042 pressure cylinder. 125*52 x 2 = 251*04 square inches, the area of the first intermediate cylinder. 251*04x2 = 502-08 square inches, the area of the second inter- mediate cylinder. Then l/^L^L 34 i O r say 35 inches, the diameter of the low- v 7854 pressure cylinder. 2/_5p2_8__ 2^ Qr ga y 25 | i nc hes, t he diameter of the second v '7054 intermediate cylinder. 3/25 1 -04 _ I7 ^ Qr sa y ig j nc j ieSj t h e di ame ter of mediate cylinder. THICKNESS OF CYLINDER-LINERS. 389 = i2f, or say izf inches, the diameter of the high- pressure cylinder. The proportion of these cylinders is in round numbers, 1:2:4:7^, which is correct for this initial pressure of steam. Cylinders should be cast from hard close- ; grained cast-iron, perfectly free from honey- comb. The cylinders of marine-engines are usually fitted with a liner of either Whitworth's compressed steel, or hard cast-iron, having a flange at one end by which it is bolted to the cylinder, as shown in Fig. 323. The space between the liner and the cylinder-casting is from i inch to i| inches, forming a jacket which can be filled with steam from the boiler to prevent condensation. Cast-Iron Liners for Cylinders should be cast from tough, hard, close-grained metal; the following is a good mixture of metal for this purpose White ...... 3 cwt. Summerlee ...... 3 ,, Weardale ...... 2 Scotch Mixed Brands, No. 3 . . . 6 Good Clean Scrap . . . . 6 melted and cast into pigs in order to be properly mixed. A test-bar of cast-iron cast from this mixture, i inch square, placed upon supports 3 feet apart, should bear a gradually applied weight of about 7| cwt., with a deflection of about i inch. The Thickness of a Cast-Iron Liner for a Cylinder may be found by the following formula : Let D = the diameter of the cylinder in inches. P = the initial pressure of the steam in Ibs. per square inch. C = a constant divisor = 2400 for cast-iron. T = the thickness of the liner in inches. Fig. 323. Cylinder-lir Example : Required the thickness of a cast-iron liner for a cylinder 60 inches diameter ; initial pressure of the steam 70 Ibs. per square inch. Then 6 -^-7? = I75 inc h. 2400 The Thickness of a Steel Liner for a Cylinder may be found by the above Rule by using a constant divisor, C, of 350x3. Example : Required the thickness of a steel liner for a cylinder 40 inches diameter ; initial pressure of the steam 75 Ibs. per square inch. Then 40X ?5 = -86 inch. 3500 The Thickness of Metal for Marine-Engine Cylinders may be found by the following formula : 390 THE PRACTICAL ENGINEER S HAND-BOOK. Let D = the diameter of the cylinder in inches. P = the initial pressure of the steam in Ibs. per square inch. T = the thickness of the cylinder in inches. 6. 3000 Example : Required the thickness of a marine-engine cylinder 50 inches diameter ; initial pressure of the steam 70 Ibs. per square inch. 50 x 70 Then -^-=ri 7 +-6= 177. Locomotive-Engine Cylinders are usually f- inch thick when 17 inches diameter, i inch thick when 18 inches diameter, and \\ inch thick when 19 inches diameter. In locomotive cylinders a considerable allow- ance is necessary for re -boring, to provide for wear and tear due to high piston speed, and for the liability of the cylinders to become scored by ashes drawn into the cylinder through the exhaust-passages, when the engine is running with the steam shut off. A plan of the cylinders of a passenger locomotive engine is shown in Fig. 324. The cylinders are METAL FOR ENGINE-CYLINDERS. 391 made of the best close-grained cast-iron, twice run, as hard as can be worked, and free from honey-comb. The front cover of each cylinder is dished to correspond to the piston, and the back cover is provided with lugs for carrying the front ends of the slide-bars. The cylinders are 18 inches diameter, and 2 feet 4^ inches centre to centre, length of stroke 26 inches : they are attached to the frames by flanges, and secured by turned bolts, driven into rose-bitted holes. The tops of the cylinders are generally covered with thin fire-brick or cement. The pistons are of tough cast-iron, the packing rings are of cast-iron, turned \ an inch larger than the cylinder, and then cut and sprung into their places. The piston-rods are made of mild steel 2| inches diameter. The steam-ports are i| inches wide and 15 inches long, and the exhaust-port is 35 inches wide; thickness of bridges, i inch. The slide-valves are made of hard gun-metal, the slide- valve spindles are of best Yorkshire iron. The slide-bars are made of mild cast-steel, and the slide-blocks are of chilled cast-iron; the cross- head and gudgeons are of best Yorkshire iron; the gudgeons are case- hardened, and forced into the cross-heads by hydraulic pressure. The taper of the cone in the cross-head is i in 16, and in the piston i in 6 : the number of threads per inch of the screwed end of the piston-rod = 6. Locomotive-engine cylinders should be cast from metal of the following mixture, or equal quality : Pontypool Cold Blast, No. 4 Clyde No. 4 Coltness No. 4 10 cwt. 7 ,. 3 .. melted and cast into pigs, in order to be properly mixed. The Cylinder of a Horizontal Stationary-Engine is shown in Fig. Fig. 325. Cylinder of a horizontal stationary-engine. 325. It is provided with a liner of cast-iron. Stationary-engine cylinders should be cast from metal of the following mixture, or equal quality : Pontypool Cold Blast, No. 4 . . . .8 cwt. Monkland No. 4 . . . . 6 Clyde No. 4 . . . . 6 melted and cast into pigs, in order to be properly mixed. 392 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 92. PROPORTIONS OF THE CYLINDERS OF HORIZONTAL AND VERTICAL- NON-CONDENSING SATIONARY-ENGINES. LIGHT ENGINE WITH SHORT STROKE. STRONG ENGINE WITH LONG STROKE. Nominal Horse- Diameter of Length of Speed in Revolu- Nominal Horse- Diameter of Length Approxi- mate power. Cylinder. Stroke. tions per Minute. power. Cylinder. Stroke. Weight. Inches. Inches. Inches. Inches. Cwts. 4 4* 7 2I 5 3 5 IO 13 2 4f 8 1 80 4 6 12 16 H 5i 8 1 80 5 7 14 2 3 3 4 1 8 10 1 80 150 6 7 8 9 16 18 30 41 5 7f 12 125 8 10 20 62 6 8f 12 125 10 ii 22 72 7 8| 12 125 12 12 24 33 8 9^ 12 125 14 13 26 9 2 9 lot 12 125 16 H 28 IOO 10 io| 14 110 18 15 3 116 12 12 H 110 20 16 32 132 14 I2 I 16 IOO 25 18 36 174 16 I3t 20 80 30 20 40 2IO Table 93. PROPORTIONS OF THE CYLINDERS OF COMPOUND, OR DOUBLE- EXPANSION, CONDENSING MARINE-ENGINES.- Nominal Horse- power. Dhmeter of High- pressure Cylinder. Diameter of Low- pressure Cylinder. Length of Stroke. Nominal Horse- power. Diameter of High- pressure Cylinder. Diameter of Low- pressure Cylinder. Length of Stroke. Inches. Inches. Inches. Inches. Inches. Inches. 8 7 J 3 9 I 2O 28 52 36 IO 8 H 12 135 29 56 36 25 12 24 H 140 30 57 36 40 16 30 22 155 S 2 60 39 50 17 34 24 175 36 62 42 55 18 36 2 4 220 38 70 45 70 21 40 24 280 45 78 48 85 23 44 3 320 48 84 48 IOO 25 48 30 360 50 90 60 ,,0 27 50 33 480 56 105 72 The Cylinders of a Set of Triple-Expansion Surface-Condensing Marine-Engines are shown in Fig. 326. The high-pressure cylinder is 19 inches diameter, the intermediate cylinder is 30 inches diameter, and the low-pressure cylinder is 50 inches diameter, length of stroke 36 inches. The high-pressure cylinder is fitted with a piston-valve 9 inches diameter, the intermediate and low-pressure cylinders are fitted with double-ported slide- TRIPLE-EXPANSION ENGINE-CYLINDERS. 393 valves. The weight of the slide-valve of the low-pressure cylinder is counterbalanced by a balance-cylinder at the upper end of the valve-spindle. These engines indicated 800 horse-power, the boiler-pressure of the steam being 150 Ibs. per square inch. Fig. 326. Cylinders of a set of triple-expansion marine-engines. Marine-engine cylinders should be cast from metal of the following mixture, or equal quality Gartsherrie, No. 3 3 cwt. Monkland No. 3 3 ,, Coltness No. 3 3 ,, Summerlee, No. 3 3 ,, Clyde No. 3 3 Good clean scrap 5 ,, melted and cast into pigs, in order to be properly mixed. A test-bar cast from any of the above cylinder-mixtures of cast-iron, i inch square, placed upon supports 3 feet apart, should bear a gradually-applied weight of from yf cwt. to 8 cwt., with a deflection of from f inch to f inch. The Velocity of Steam through the Cylinders of Triple-Expan- sion Engines should not exceed 300 feet per second, and the velocity of the exhaust-steam should not exceed 170 feet per second. The velocity of the steam in feet per second may be found by this Rule : -y. , . area of cylinder x piston-speed in feet per second area of the opening of the port. The initial velocities of the steam in triple expansion engines are frequently as follows : High-pressure Intermediate Low-pressure Cylinder. Cylinder. Cylinder. Initial velocity of steam per | = IQQ ft> ^ ^ ft> second . . . . ; Initial velocity of exhaust-) steam per second . . ) 394 THE PRACTICAL ENGINEER'S HAND-BOOK. In some cases the velocity of the exhaust-steam in the low-pressure cylinder is as high as 160 feet per second without detrimental effect. Table 94. PROPORTIONS OF THE CYLINDERS OF TRIPLE-EXPANSION SUR- FACE-CONDENSING MARINE-ENGINES, COLLATED FROM RECENT PRACTICE. WORKING-PRESSURE OF STEAM, FROM 150 TO 160 LBS. PER SQUARE INCH. Name of Vessel. Diameter of High- Cytfnder. Diameter of Intermediate Cylinder. Diameter of Low- pressure Cylinder. Length of Stroke. Inches. Inches. Inches. Inches. Roseland .... 6 9 16 12 Cassandra 9 14 22 15 Condor ii i6| 3 21 Somalie '3i 21 34 24 Elgiva 15 24 40 33 Warrior 16 24 40 24 J. Joicey .... 16* 26 43 36 Charles I 7z 2 9 47 33 Teresa 18 3 48 36 Fijian i8| 3i 49 36 Cairnryan .... 1 8* 3 1 51 36 Gloamin . ... '9 3 50 42 Mandalay .... 20 33 54 36 Drever 20 33 54 36 Bleville 21 33 52 42 Era 21 34 57 39 Obeona 21 35 57 39 Thames 2l\ 33 54 36 Loch Etive .... 2\\ 34 56 42 Northenden .... 2l| 35 57 39 Indian Prince . . . . 2l a 37 58 39 Flamboro .... 22 35 58 42 Clitus 2 3 37 61 42 Rosemorran .... 2 3a 38 62 42 Saint Oswald . . . . 24 39 64 42 Euterpe 24 42 69 48 Dunbrodie 4* 39 62 42 Chingtua .... 25 40 62 48 Anglian 26 42 69 42 Argus 26 43 70 45 MethleyHall . . 27 44 7i 48 28 43 77 ci PortPirie 29 T'O 44 / / 74 48 Locksley Hall .... 29 47 7 6 5 1 Monmouthshir : . . . 30 47 70 51 Buffalo . ... 33 54 86 60 Lusitania 3 6 60 96 48 Orizaba 40 66 100 72 Orinoco 42 66 96 66 Ormuz ..... 46 73 112 72 NUMBER OF BOLTS IN CYLINDER-COVERS. 395 The indicated horse-power of the engines given in the previous Table may be calculated approximately by taking the average piston-speed and mean-pressure of the steam in the cylinders of triple-expansion engines in merchant-steamers. It may be assumed that the effective mean-pressure of the steam of the three cylinders reduced to the low-pressure cylinder, averages one-fifth of the initial absolute pressure, and that the average piston-speed is 500 feet per minute for engines of moderate speed, and 770 feet per minute for high-speed engines : the latter being the piston- speed of the engines of some Atlantic steamers. Take for instance the engines of the steamer Thames : the working-pressure of the steam is 1 50 Ibs. per square inch = 150 + 15 = 165 Ibs. per square inch absolute pressure, and 165 x i=33 Ibs., the assumed effective mean-pressure, the low- pressure cylinder is 54 inches diameter, then, if working at the moderate piston-speed assumed, the engines would develop = 54 x 54 inches x 7854 x 33 Ibs. x 500 feet piston-speed _ . ,. cated horse-power. 33' Again, the engines of the large steamer Orizaba, if working at the highest piston-speed assumed, would develop = IOQ x IPO inches x 7854 x 33 Ibs. x 770 feet piston-speed _ , . ,. cated horse-power. 33 Cylinder Escape- Valves, shown in Fig. 327, are fitted to cylinder-covers to allow the escape of water from con- densation or priming, which, in case there were no relief- valves and the drain-cocks were closed, could only escape from the cylinder by forcing the slide-valve from its seat. The diameter of the escape-valve may be equal to one- sixteenth the diameter of the cylinder. Bolts of Cylinder-Covers. The working-strain on the bolts of cylinder-covers should not exceed 2000 Ibs. Fi s- 327- Cylinder per square inch of section. The number of bolts required for a cylinder-cover may be found by this Rule: XT , c u U area f cylinder x pressure of steam iNurnDcr 01 Doits ^ V*"*"?"" r~* * i area of one bolt x working-strain on bolts. Example: How many bolts \\ inches diameter are required for the cover of a cylinder of 56 inches diameter, the initial pressure of the steam being 90 Ibs. per square inch, the working-strain on the bolts not to exceed 2000 Ibs. per square inch of section of the bolts ? Then 56 x 56 inches x 7854 x 90 Ibs. pressure = 6 Qr fi boltg i'5 x 1-5 inch x 7854 x 2000 Ibs. strain will be required for that cylinder-cover. The number of bolts when the diameter and pitch are given, maybe found by the following Rule : Number of bolts - diameter of pitch circle of bolts x 3-1416 pitch of the bolts 396 THE PRACTICAL ENGINEER'S HAND-BOOK. Example : The diameter of a cylinder-cover is 33 inches, the centres of the bolts are \\ inches from the edge, the pitch of the bolts is 35- inches. How many bolts should there be in the cover? Then 33 (\\ x 2) = 30 inches, diameter of pitch circle of bolts. 30x3-1416 8 bolts _ 3-25 inch pitch The Most Economical Piston-Speed is attained when an engine is run at as high a speed as its design and condition will permit with freedom from vibration and heated bearings, because a piston with a given pressure, upon it will exert power in proportion to its speed. The speed of a piston in feet per minute is found by multiplying twice the length of stroke in feet by the number of revolutions of the crank-shaft per minute. Piston-speeds vary considerably in practice, they range from 300 to 1200 feet per minute. The piston-speed of double expansion compound-engines averages 420 feet per minute, triple expansion engines of moderate speed average 500 feet per minute, and of high-speed from 750 feet to 800 feet per minute, and torpedo-boat engines average from 1000 feet to 1200 feet per minute. The highest piston-speed is obtainable with the least wear and tear where the rotational force is most uniform ; a nearly uniform turning-effort is obtained by dividing the application of the power between three cranks placed at equal angles of 120 apart on the same shaft, with an equal initial stress on each crank. Piston-Displacement is the space swept through by the piston in a single stroke of an engine. It may be found by multiplying the area of the piston by the length of stroke. Example : Required the piston-displacement of an engine with cylinder 30 inches diameter, length of stroke 3 feet, making 70 revolutions per minute. Then 2-5 x 2-5 feet diameter x 7854 x 3 feet == 14726 cubic feet piston-displacement; or, 2*5 x 2-5 feet diameter x 7854 x 3 feet stroke x 2 x 70 = 206 1 '64 cubic feet piston-displacement per minute. The Pressure on a Piston may be found by this Rule : Pressure on a piston in Ibs. per square inch = 33000 x indicated horse-power area of cylinder x speed of piston. Example : The indicated horse-power of an engine is 1 80, the diameter of the cylinder is 1 7 inches, the length of stroke is 2 feet, and the number of revolutions per minute of the crank-shaft is 80. What is the pressure on the piston in Ibs. per square inch ? Then 3300Q xiSoIHP = 8i . g ^ in 17 X 17 X 7854 X (2 X 2 X 80) pressure on the piston. The Diameter of a Piston may be found, when the total pressure and the effective pressure per square inch is known, by the following Rule : Diameter of piston in inches = 2 / total pressure in Ibs. on the piston v effective pressure in Ibs. per square inch x 7854 LOCOMOTIVE-ENGINE PISTON. 397 Example : The effective pressure per square inch on the surface of a piston is 60 Ibs., the total pressure is 7 tons. What is the diameter of the piston ? Then 2 /7 tons total pressure x 2240 Ibs. V 60 Ibs: effective pressure Pistons. The simplest form of piston is one fitted with Ramsbottonrs spring-rings or packing-rings, as shown in Fig. 328. Three separate grooves are turned in the circumference of the piston, into which elastic rings of from 4 to f inch square steel or gun-metal are fitted. Each packing-ring is turned to a diameter a little larger than that of the cylinder, a short piece is cut out and the rings are sprung over the piston into the grooves, which are slightly deeper than the rings. The rings break joint, and the elas- ticity of the packing-rings maintains a nearly uniform outward pressure against the sides of the cylinder and renders the piston steam-tight. A Piston for a Locomotive-Engine Cylinder. The pattern used on the London, Brighton and South Coast Railway is shown in Fig. 330. The body of the piston is made of gun-metal, and is cone-shaped, in Fig. 328. Piston with Ramsbottom's. rings. Fig. 329. Fig. 330. Figs. 329 and 330. Piston of a locomotive-engine. order to obtain the necessary strength with a light section. It is fitted with two cast-iron packing-rings, each f inch wide, placed in separate grooves spaced i inch apart. The piston fits on a steep cone, forged on the end of the piston-rod, shown in Fig. 329, so that it can be easily removed from the rod when required. A Piston fitted with one broad packing-ring pressed outwards by spiral springs placed in holes radiating to the centre of the piston is shown in Figs. 331 and 332. The packing-ring shown in Fig. 332 is sprung over the body of the piston into its place. A Piston, in which the packing- rings are expanded by a steel coil, is shown in Fig. 333. There are two packing-rings as shown, each having a 39? THE PRACTICAL ENGINEER'S HAND-BOOK. flange ; the flanges form a recess in which the coil is placed, and also act as abutments for the coil-ends. The packing-rings are pressed against the flanges of the piston, and also against the sides of the cylinder by the elas- ticity of the spring-coil, which is shown in Fig. 334. A Piston provided with three packing-rings, two narrow outside rings Figs. 331 and 332. Piston with ring expanded by spiral-springs. Fig. 333. Section of piston, with Mather's steel-coil spring. Fig. 334. Piston-spring. which fit the cylinder, and one broad inside ring, is shown in Fig. 335. A number of springs, shown in Fig. 336, are placed round the circumference of the piston, which abut on the body of the piston and press against the Fig. 335. Piston of a stationary-engine. Fig. 336. Piston-rings and springs. inside ring, which expands and presses the outside rings against the sides of the cylinder. A Piston provided with adjustable packing-rings is shown in Figs. 337 and 338. It is fitted with three packing-rings, two outside rings which fit the cylinder and break-joint, and one inside ring, which receives the pressure of a number of springs placed round the piston ; each spring has a tongue-piece at the back, which fits into a recess, as shown. The springs are adjusted or set out to expand the packing-rings, by a gun-metal key driven PISTON WITH ADJUSTABLE PACKING-RINGS. 399 Fig- 337- into the recess behind the tongue-piece of each spring, which provides a solid abutment for the back of the spring, so that the pressure of the springs cannot vary when the piston is working. When this piston is used for a horizontal-engine, the bot- tom spring is removed and replaced by a metal block, which carries the weight of the piston. A guard-ring is fitted be- tween the heads of the bolts, as shown, to prevent their working loose ; the nuts of the bolts are gun- metal, let into the casting. A Piston in which the packing- rings are ex- panded by a spiral-spring, which acts against two packing- rings, each having a flange, the spring being placed in a recess formed by the flange of each packing-ring, is shown in Fig. 339. The packing- rings are pressed against the sides of the cylinder, and also against each flange of the piston, by the elasticity of the spring, which is clearly shown in Figs. 340 and 341. The bolts of the piston-cover are screwed into gun- metal nuts let into the casting, and a guard-ring is fitted between the heads of the bolts to prevent their working loose. To prevent Steam escaping past the joint of Packing-Rings a plate is inserted as shown in Fig. 342, the joint being covered by another, or inside ring. Another way of preventing the escape of steam, suitable for single rings, is shown in Fig. 343, the joint being covered inside the ring by a plate having a tongue-piece which fits into a slot in the piston-ring as shown, the screw-holes are slotted on one side of the joint to allow the ring to expand. Packing-Rings for Pistons are turned to a diameter equal to | inch larger than the cylinder for every foot in diameter of the cylinder, this being necessary in order to make them spring out and fill the cylinder, a Figs. 337 and 338. Piston with adjustable rings. 4oo THE PRACTICAL ENGINEER'S HAND-BOOK. piece being afterwards cut out of the ring to make it the proper size. The ring is cut in an oblique direction, as shown in Fig. 342, in order to prevent the ends, or joint, scoring the cylinder. The length of piece required to Fig. 339- Figs. 339 341. Piston with Buckley's spring. Figs. 342 an-! 343. Joints 01 piston-rings. be cut out of the ring, is equal to the difference between the external circumference of the ring and the circumference of the cylinder. Example : A packing-ring for a piston is 6o| inches external diameter before being cut, the diameter of the cylinder is 60 inches. How much should be cut out of the circumference of the ring to make it exactly fit the cylinder when sprung in ? Then (60*625 x 3-1416) (6ox 3'i4i6) = i-9635 inches. Or 60-625 60 = -625 x 3*1416 = 1*9635 inches. The Diameter of a Piston-Rod may be found by the following formulae : Let D = the diameter of cylinder in inches. p _ { tne initial absolute pressure of the steam in Ibs. per square \ inch, or the pressure shown by the steam-gauge plus 1 5 Ibs. d = the diameter of the piston-rod in inches. s = the diameter of the screwed end of the piston-rod. To find the diameter of the piston-rod, d : Single piston-rods, d = Double piston-rods, d STRAIN ON A PISTON-ROD. 40 1 To find the diameter of the screwed end of the piston-rod, s : Single piston-rods, s = yFT " , 8 5 Double piston-rods, s = - J/PT" 120 v Example : Required the diameter of a piston-rod for a cylinder 60 inches diameter, the initial pressure of steam in the cylinders being 65 Ibs. per square inch. If the piston be fitted with two piston-rods, what diameter should they be ? Then 65 Ibs. initial pressure + 15 Ibs. = 80 Ibs. absolute pressure of the steam. , , 60 inches diameter ^ /n rc . , ,. And 60 constant ^ = 944 mches diameter of single piston-rod. 60 inches diameter , 5 n ^ 5 X\/QO Ibs. = 0-413 inches diameter of the 5 screwed-end of single piston-rod. If the piston be fitted with two piston-rods, the diameter will be : 60 inches diameter /* -r- , . , ,. , , rr x V8c ibs. = 6708 inches diameter of each OO double piston-rod. 6ojnches_diame.e_r x -^ = incheg diameter Qf the I2O screwed end of each double piston-rod. The Taper of the Cone on the Piston-rod, on which the piston is fitted, should not be less than i inch per foot, and there should be either a shoulder or collar on the rod at the bottom of the cone, to prevent splitting of the piston, and ensure its easy removal when required. To Prevent the Nut which secures the Piston on the Piston- rod working loose, it may be fitted in an octagonal recess in the piston, equal in depth to one-fourth that of the nut, having the space between the sides of the nut and of the recess filled up with white-metal. The Strain on a Piston-Rod may be found by dividing the maximum strain on the piston per square inch of its area, by the sectional area of the piston-rod, in inches. Example i : The diameter of a cylinder is 33 inches. The diameter of the piston-rod is 5*75 inches. The maximum working-pressure of the steam on the piston is 90 Ibs per square inch. Required the tensile strain per square inch on the piston-rod. Then 33 x 33 inches x 7854 x 90 Ibs. = 7697*7 Ibs. the strain per square inch of the area of the piston ? And 76 97 7 Ibs. strain on the piston = fi lb e inch ^ 575x575 inches x 7854 strain on the piston-rod. Example 2 : The diameter of a piston-rod at the smallest part is ^ O f D D 4O2 THE PRACTICAL ENGINEER'S HAND-BOOK. the diameter of the piston. What is the tensile strain per square inch on the piston-rod when the pressure on the piston is 60 Ibs., the back-pressure is 3! Ibs., and the diameter of the body of the piston-rod is the diameter of the piston ? Then, if the diameter of the piston be supposed to = 12 inches, the least diameter of the piston-rod will = i, and the diameter of the body of the piston-rod = | of 12 inches = i^ inches. And *3 2 -iVxj8j4X(6o-3- 5 rbs.) = 8oo . g7 lbs _ per square inchj lhe tensile strain on the piston-rod. Metallic-Packing for Piston-Rod and other Glands. The glands of triple-expansion and other engines using steam of very high pressure Fig. 344. Metallic- packing. 345 and 346. -Locomotive-engine crosshead. require to be packed with metallic-packing, as ordinary packing rapidly becomes charred by the high temperature of the steam. A simple and very efficient arrangement of metallic-packing is shown in Fig. 344. It consists of a number of V-shaped rings of anti-friction metal, in two pieces, arranged one above the other as shown, and tightened by a gland fitted to the stuffing-box with studs and nuts in thtr same way as for hemp packing. The following is a good mixture of anti-friction metal for the packing- rings. Tin 82 parts. Lead 14 Copper 4 STRENGTH OF COTTER AND PIN OF CROSSHEAD. 403 A piece of round canvas-packing, lubricated with a mixture of plumbago and tallow, is placed above the metallic-packing at the top of the stuffing- box, in order to prevent the escape of any steam which might leak through the joints of the metallic-rings, and also to give elasticity to the packing. The Crosshead of a Loco motive-Engine is either forged on the piston-rod, as shown in Figs. 345 and 346, or the end of the piston-rod is tapered into, and secured to the boss of a separate crosshead with a cotter, as shewn in Fig. 347. The boss of the crosshead, in Fig. 347, is bored conically to a depth of Fig. 347. Crosshead and slide-blocks of a locomotive-engine. 5f inches, to fit the tapered end of the piston-rod, the large end of the hole is 2\ inches diameter, and the taper being i inch in 1 1 inches, the diameter ii inches = 2-353* of the small end, or bottom of the tapered hole, is 2-875 - or say 2 inches. The Strength of the Cotter of the Crosshead shown in Fig. 347, may be ascertained as follows. The cotter is made of steel,, f inch thick, and 2\ inches wide at the middle, and being in double-shear it has a shearing section of '625 inch thickX2'25 inches wide x 2 = 2-8125 square inches for resisting a maximum working pressure of steam of, say, 140 Ibs. per square inch on the piston. If the diameter of the piston be 17 inches, the area will be 17 x 17 x 7854 = 226-98 square inches, and the maximum strain will be 226 '9 8 square inches.x 140 Ibs. = g6 tong 2240 Ibs. inch, equal to 14' 186-4- 2 '8 125 square inches, the shearing section of the cotter, =5*008, or say 5 tons strain per square inch of section of the cotter. Taking the ultimate shearing strength of the steel at 30 tons per square inch, the strength of the cotter will be = 30 -=- 5 = 6 times as great as the maximum working stress upon it. The piston-rod is 2| inches diameter, made of steel, and it has to resist a maximum working strain of Q 14-186 tons =2 . lg tons inch> 2-875 X 2-875 X -7854 The Strength of the Crosshead-Pin may be ascertained in a similar way to the above. The crosshead-pin shown in Fig. 347 is 2f inches diameter between the jaws of the crosshead, at the bearing for the connecting-rod, and the length of the bearing is 2\ inches. The diametral sectional-area being 2-75 inches diameter x 2-875 inches length = 7*857 square inches and the pressure on the crosshead-pin is 14-186 tons 4- 7-857 square inches = 1-806 tons per square inch of diametral section of the crosshead-pin bearing. A Crosshead for a Horizontal Stationary-Engine is shown in Fig. 404 THE PRACTICAL ENGINEER'S HAND-BOOK. 348, the pin projects on each side of the crosshead and carries the slide- blocks, which work between ' flat slide-bars, the wear being taken up by ad- justing the pillars between the ends of the bars. A Crosshead for a sta- tionary-engine of another design, is shown in Figs. 349-351. The slide-bars are concave, the sliding surfaces of the slide-blocks being convex. A cotter is fitted lengthways under the slide-block, as shown, adjustable by nuts to take up the wear. A Crosshead for a sta- tionary-engine of another Figs. 348 354. Crossheads of stationary-engines. design is shown in Figs. 352-354. The crosshead-pin is fixed in the forked-end of the connecting-rod, and the pin works in bushes in the CROSSHEADS OF MARINE- ENGINES. 405 crosshead, which are adjustable by a cotter, the sliding surfaces of the slide- blocks are convex, and they work between concave slide-bars, each slide-block being ad- justable by a cotter fitted crossways as shown. A Crosshead for a Marine - Engine, forged solid on the end of the piston-rod, is shown in Fig. 355. The crosshead-pin is fixed in the forked-end of the connecting-rod, and works in bushes in the crosshead, which are secured by a cap and bolts, as shown. The diameter of the crosshead-pin may be diameter of piston-rod x ri8 to 1*25, and its length may be = diameter of piston-rod x 1-5 to 175. The diameter of each bolt for the cap may = diameter of piston-rod x '55 to '6. Thus for a piston-rod 7 inches diameter, the diameter of each bolt for the cap would be = 7 x -57 = 4 inches : the ratio of the area of the cap-bolts to the area of the piston-rod would be = (7x7 inches) -=- (4 x 4 x 2 bolts) = 1-531 and the ratio of the area of the piston-roJ to that of the bolts would be (4 x 4 x 2 bolts) -H (7 x 7 inches) = '653. Marine-Engine Crossheads vary considerably in design, a few of the most generally used designs are given in Figs. 356-361, in which different 355- Crosshead of a marine- engine. Figs. 356, 357- Crosshead of a marine-engine. methods are shown of attaching the shoe to the crosshead. The area of the shoe is frequently made = one-tenth that of the piston. Then 60 x 60 x 7854 = 2827-44 square inches, the area of the piston. 2827-44 -T- 10 = 282-744 square inches, the area of the shoe. 282-744 -T- 15 inches = i8 - 85 inches, the length of the shoe. 40<5 THE PRACTICAL ENGINEER'S HAND-BOOK. Fig. 359- Figs. 358 360. Crosshead of a marine- engine. The Shoes of the Crossheads of high-speed engines. should have strips of anti-friction metal let into their sliding surfaces. A good anti- friction metal for this purpose is com- posed of tin 1 6 parts; copper i| parts; antimony 2 parts. Mill-Engines driving spinning ma- chinery- require to run with ftie utmost uniformity of velocity, because both the quality and quantity of th products of a factory are considerable-Increased by an exact and unvarying engine-speed, therefore uniformity of turning-effort is the first consideration, and economy of fuel the second. The variation in the speed of best modern mill-engines does not exceed from one quarter to one half per cent., and the consumption of coal averages from if to 2 Ibs. per indicated horse-power per hour of actual work, and from 2\ Ibs. to 2f Ibs. per indicated horse-power per hour, inclu- ding the coal used in getting up steam, in keeping it up during meal-times, and in heating the mill when required. Fig. 361. Crosshead of a marine-engine. STATIONARY NON-CONDENSING ENGINE. 407 The types of steam-engines used for driving modern factories are The horizontal or vertical simple engine of high speed, using steam of from 60 to 80 Ibs. pressure per square inch. The horizontal or vertical com- pound condensing engine, with a high-pressure cylinder and a low-pressure cylinder coupled to one shaft with their cranks at right angles, so that when one crank is on its dead-centre, the other crank is in the best position for rotating the shaft. The horizontal or vertical single compound condensing tandem-engine, that is, with the pistons of both cylinders attached to one piston-rod. The horizontal or vertical double compound tandem-engine, thai; is, a pair of single compound tandem-engines coupled to one shaft with their cranks at right angles. A Horizontal Stationary Non-Condensing Simple Steam-Engine is shown in Fig. 362. It has a high-speed governor, an equilibrium throttle- Fig. 362. Horizontal stationary non-condensing engine. valve, and wide bearings; the frame is girder-shaped of a depth equal to the diameter of the cylinder. The crank is cast on a disc having a counter- weight opposite to the crank, to counter-balance the rotating parts, the weight of the counter-weight is equal to the sum of the weights of the crank and pin, and the weight of half the length of the connecting-rod next the crank-pin. The momentum of the piston and other reciprocating parts is balanced by compression of steam in the cylinder. An engine balanced in this manner may be run at a high speed without vibration, and a high speed is conducive to uniformity of velocity, as the efficiency of a fly-wheel in producing regularity of motion varies, other things being equal, as the square of its angular velocity. An engine fitted with a slide-valve and controlled by a throttle-valve, works with con- siderable variation in speed, and is not so suitable for driving spinning- 408 THE PRACTICAL ENGINEER'S HAND-BOOK. machinery as an engine fitted with Corliss valve-gear, in which the steam is controlled automatically by a high-speed governor, with the slightest possible variation in speed. Corliss Engines are largely used as mill-engines. The cylinder of a horizontal Corliss engine is shown in Fig. 363. It is a built-up-cylinder on a simple and effective plan, with separate end-valve chambers, separate internal cylinder-liner and jacket-casing. The Corliss-valves are shown in position ; the two top valves are the steam admission-valves ; the steam ports and passages are made very short and direct, to avoid undue clearance-spaces. The lower valves are the exhaust- valves, and, as they are placed below the cylinder they drain it thoroughly, which is an advantage of considerable importance. This method of building a cylinder enables the cylinder-liner to be made a simple casting of sound, hard, close metal. The steam and exhaust-valves are shown separately in section, with their spindles. The piston, piston-roa and crosshead are shown in their place. The engine-frame is bolted to the front of the cylinder, so that it takes the strain direct and in the best possible manner. The valves are actuated by a central disc or wrist-plate, the steam-valves are arranged with liberating gear to cut off the steam instantaneously, the point of cut-off being controlled by the main-governor. The engine is also fitted with one of Knowles' supple- mentary governors, by which an almost uniform speed can be maintained, even with considerable variation in the steam-pressure, or in the load, an important advantage in spinning mills. This governor has a friction-pulley, fitted between two flanges on its socket. At the normal speed of the engine neither of the flanges touches the friction-pulley, but should any increase or decrease take place, one or other of the flanges presses upon and causes the friction-pulley to rotate -in one direction or the other, which operates by means of cord-pulleys, one of which is fixed on- a nut which moves a vertical rod, in two pieces, one piece being screwed with a right- hand and the other with a left-handed thread, attached to the forked- lever of the main-governor. The clearance between the flanges and the friction-pulley is so small, that the slightest variation in speed brings the supplementary-governor into operation, which is thus continuously resisting, automatically, any tendency to change of speed in the engine. The con- sumption of steam in Corliss-engines is usually from 17 to 18 Ibs. per indicated horse -power, corresponding to about 2 Ibs. of coal per indicated horse-power per hour. In a test of one of these engines, having a single- cylinder of 52 inches diameter, 6 feet stroke, making 60 revolutions per minute, or a piston-speed of 720 feet per minute, with a vertical air-pump 36 inches diameter, and 30 inches stroke and condenser: it drove by belts from the fly-wheel about 1800 indicated horse-power. The steam used per indicated horse-power was 17' 45 Ibs., and the consumption of coal was 2' 14 Ibs. per indicated horse-power per hour. Automatic Barring-Engine. Mill-engines frequently stop in such a position that it is necessary to turn them partly round by means of a bar before they can be re-started, and it is sometimes necessary to bar them round slowly when putting on belts or doing repairs in the factory. It being difficult to bar large engines by hand-power, a barring-engins, shown in Fig. 364, is used for this purpose, which is provided with a simple arrangement for automatic disengagement when the engine begins to run 4 io THE PRACTICAL ENGINEER'S HAND-BOOK. Fig. 364. Barring-engine, by Hick, Hargreaves and Co., Boltun. quicker than the barring-engine. The pinion which acts as driver to the fly-wheel is shaped as a worm-wheel on one side of the tooth and as a spur- wheel on the other, to gear with an internal toothed-wheel on the fly- wheel, the motion being communicated to it by a worm fixed on the crank- shaft of the barring-engine. The pinion is keyed on to a shaft which works in a slot, thus allowing a certain lateral motion. When it is desired to throw the pinion into gear a brake is held against the bottom edge by a lever, and the result is that th^ pinion is thrown into gear by the action of the worm, the point where the brake is applied becoming the fulcrum. As soon, however, as the fly-wheel becomes the driver the action is reversed, the worm becomes the fulcrum and the pinion falls back automa- tically, its axis moving along the slot referred to, and the wheel is retained in its out-of-gear position by a spring. This is a perfectly safe and auto- matic arrangement, and is a compact and well-contrived device with a small amount of mechanism. A Vertical Tandem Compound Mill-Engine is shown in Fig. 365. The high-pressure cylinder is 14 inches diameter, the low-pressure cylinder is 24 inches diameter, and the length of stroke is 2 feet, when running at 80 revolutions per minute it develops 1 20 indicated horse-power with steam of IOD Ibs. per square inch working-pressure. The high-pressure cylinder is rigidly supported by two wrought-iron pillars and the rectangular pipe connected to the low-pressure cylinder. The high-pressure cylinder is fitted with Corliss-valves and the low-pressure cylinder with a slide-valve, the spindle of which is carried through the upper end of the casing to work the Corliss exhaust-valves. The air-pump and feed-pump are worked by a lever coupled to the crosshead. One of the frames acts as a condenser : an air space is left between the frame and the slide-plate to prevent the slide- block heating. Non-Condensing Simple Engines frequently discharge the exhaust- steam into the atmosphere before it has been thoroughly deprived of all its available heat and power. In order to expand the steam in the most economical manner and leave it no capacity for developing further power, and also to equalise the strains and secure greater uniformity of turning- effort, non-condensing engines are sometimes compounded, and have their cranks placed at right angles. A Non-Condensing Compound Engine, compact in design, accessible to inspection, occupying small space, and requiring only a slight foundation, is shown in Fig. 366. The frame or bed of the engine is formed of two strong wrought-iron girders, firmly braced together by cross-stays. The cylinders are bolted, at the bottom to the frame, and at the top to the smoke-box of the boiler. The crank-shaft is of steel, bent from a single bar; it is balanced, and carries a heavy fly-wheel. The cylinders are each formed by a separate- barrel of hard metal forced into the main casing, Fig. 365. Vertical tandem compound mill-engine, by Douglas and Grant, Kirkcaldy. 412 THE PRACTICAL ENGINEERS HAND-BOOK. a space between the barrels forms jackets which surround the cylinders. The steam is admitted to the high-pressure cylinder by a double-ported expansion-valve working on the back of the main slide-valve, and automati- cally controlled by the governor, so as to vary the admission from any point up to one half the stroke, according to the power required. The expan- sion-valve is very prompt in action, and is actuated in a simple manner by a radius-rod working in a rocking slot-link driven by a separate eccen- tric, the raising or lowering of the governor-balls, by changing the posi- tion of the radius-rod in the slot-link, shortens or lengthens the travel of the expansion-valve, causing it to cut-off steam earlier or later as required. The governor shown in Fig. 367 is of the crossed-arm type with heavy balls and is very sensitive. An oil-cylinder is provided to prevent any tendencv to " dance," the piston of which has a simple arrangement for regulating the flow of oil, and consequent promptness of movement. The steam is usually cut-off in the high-pressure cylinder when the piston has travelled nearly one half its stroke, and is expanded a little more than twice, it then passes into the low-pressure cylinder, which has two and one- half times the capacity of the high-pressure cylinder, where it is expanded Table 95. RESULTS OF TRIALS OF A 12 NOMINAL HORSE-POWER NON- CONDENSING COMPOUND ENGINE. ist Trial. and Trial. 3rd Trial. Working boiler-pressure maintained 120 Ibs. 1 20 Ibs. 1 20 Ibs. Average revolutions per minute of the engine . . . . . I2 9 I30-8 129-7 Average piston speed per minute . 301 ft. 305 '2 ft. 302-6 ft. Effective horse-power on brake . . . 29-64 3O-26 29-92 Kind of coal used Welsh. Welsh. Welsh. Amount consumed during the trial 168 Ibs. 300 Ibs. 300 Ibs. Amount consumed per brake horse- power per hour 2-54 Ibs. 2-63 Ibs. 2-7 Ibs. Amount of feedwater supplied . . . 1330 Ibs. 2328 Ibs. 2408 Ibs. Amount of feedwater per brake horse- power per hour 20-09 Ibs. 20-46 Ibs. 21-63 Ibs. Temperature of water as supplied . . 56 F. 57 F. 55-4 F. Temperature of water forced into the boiler 155 F. 151 F. 152-8 F Increase of temperature from water- heater 99 F. 94 F. 97'4 F. Amount of exhaust-steam condensed per hour per horse-power .... 1-97 Ibs. 1-93 Ibs. 2'12 Ibs. Steam (exclusive of that condensed in the jackets) used per hour per brake horse- power 22-06 Ibs. 22-49 Ibs. 23-75 Ibs. Water evaporated per hour per pound of coal from feed temperature . 8-68 Ibs. 8-49 Ibs. 8-69 Ibs. NON-CONDENSING COMPOUND-ENGINE. 413 nearly four times, and finally escapes to the chimney, reduced by a six-fold expansion to a pressure of 8 Ibs. per square inch above the atmosphere, or at a final absolute pressure of 23 Ibs. per square inch. Several trials were made of one of these engines, of 12 nominal horse-power, with a high-pressure cylinder 7 inches diameter, and a low-pressure cylinder ii inches diameter, length of stroke of both cylinders 14 inches. The results of the trials are given in Table 95. 4 I4 THE PRACTICAL ENGINEERS HAND-BOOK. The consumption of 2 '63 Ibs. of coal per effective horse-power per hour on the second trial was equal to about 2-4 Ibs. per indicated horse-power per hour, an extremely low consumption for a small non-condensing steam- engine ; the saving effected being about 40 per cent, over a non-condensing simple engine. Fig. 367. Automatic expansion-gear of the engine shown in Fig. 366. Marine-Engines are of two classes, engines driving screw-propellers called screw-engines, and engines driving paddle-wheels, called paddle- engines. The chief consideration in a marine-engine is, the greatest power on the least weight, in the smallest space, from the smallest consumption of fuel. The weight of steam-engines in comparison with the power developed varies considerably in different classes of engines. The weight of steam-engines per indicated horse-power averages as follows : Weight per indicated horse-power in Ibs. . 800 Small vertical-engines attached to vertical boilers Stationary-engines, condensing Stationary-engines, non-condensing, strong Portable-engines . . . . . 750 700 620 TRIPLE-EXPANSION MARINE-ENGINES. 415 Weight per indicated horse-powet in Ibs. Stationary-engines, non-condensing, light . . . .560 Compound-engines of merchant-steamers . . . . 480 Triple-expansion-engines of merchant-steamers . . . 450 Royal navy engines, with natural draught . . . . 360 Special engines for light-draught vessels . . . .280 Royal navy despatch vessels, Surprise and Alacrity class . 240 Royal navy engines, with forced draught . . . 200 Locomotive-engines, heavy class 200 Locomotive-engines, light class 150 Torpedo-boat engines 60 These weights include that of pipes, fittings, and water in the boiler, that is, all in working condition. A Fair of Compound Surface-Condensing Screw-Engines of 35 nominal horse-power, of a type much used for yachts, cargo-vessels, and tugs, is shown in Fig. 368. The high-pressure cylinder is \\\ inches, diameter, the low-pressure cylinder is 28 inches diameter, and the length of stroke of both pistons is 22 inches. The surface-condenser forms the base of the back-columns, being cast in one piece with them. The air-pump,, circulating-pump and bilge-pumps are worked by rocking-levers from the cross-head of the low-pressure cylinder. The reversing-gear is link-motion, and being of a size easily handled, the position of the link is controlled by a hand-lever. The design of the engine is compact and substantial, and it admits of easy access to all the working parts. The vessel for which the engines were made is 95 feet long, 18 feet beam, and 9 feet moulded depth. A Set of Triple-Expansion Surface-Condensing Screw-Engines of 1 200 indicated horse-power is shown in the frontispiece. The cylinders are three in number, of hard close-grained cast-iron. The first, or high-pressure cylinder, is 22 inches diameter, the second, or intermediate cylinder, 35 inches diameter, and the third, or low-pressure cylinder, is 58 inches in diameter, all with 42 inches stroke, and fitted with escape-valves, indicator- cocks, and drain-cocks, with handles to starting-platform. The high-pres- sure cylinder is steam-jacketed by means of a liner, and all cylinders are neatly covered with felt and teak secured by brass screws. The first and second cylinder valve-chests are in line with the cylinders. The low-pressure cylinder valve-chest is in front of the engines. The first, or high-pressure cylinder, has piston-valves fitted with loose liners, the second and third cylinders have ordinary D valves. A valve is fitted so as to admit steam to the steam-chest of the second and third cylinders, its handle being reached from the starting-platform. A relief-valve is fitted to the steam-chests of the second and third cylinders to prevent the possibility of high-pressure steam being let into these cylinders. The valves are of hard cast-iron. A piston-valve is fitted to the first cylinder, a single ported-slide-valve to the second cylinder, and a double ported-slide-valve to the third cylinder. The pistons are of cast-iron. The piston of the first cylinder is fitted with three cast-iron Ramsbottom-rings. The pistons of the second and third cylinders have ordinary cast-iron packing-rings, with junk-rings of 416 THE PRACTICAL ENGINEER'S HAND-BOOK. cast-iron, held down by wrought-iron T-headed bolts and brass nuts, so arranged that the bolts and nuts can be easily taken out without drawing the piston ; the junk-ring bolts have patent guards. The piston-rods are of hammered-iron secured to the pistons by nuts, with solid forged-heads fitted with adjustable cast-iron shoes for working on the guides. The recesses in the piston-rod-heads for the gudgeon-brasses are Hat-bottomed for convenience in lining-up ; the piston-rods are duplicates of each other. The guides are bolted to columns on the condenser, and are provided with oil-boxes and lubricators. The connecting-rods are forged of best scrap-iron with solid double-eye and gudgeon of large size at the top end, and are fitted with flat brasses at the bottom end. The brasses are lined with white-brass. The length of the connecting-rod is equal to 2\ times the length of the stroke. The crank-shaft makes 70 revolutions per minute. It is n| inches diameter, built with three double-cranks of iron, with forged-steel pins set at angles of 120, constructed in two pieces coupled in the centre-crank, and fitted with the pin bolted to each part. The shaft is interchangeable. The shafting is of the best hammered-iron, having solid couplings forged upon each piece, and properly jointed with turned bolts. The intermediate lengths are lof inches diameter in the body, and n inches diameter in the bearings. The propeller-shaft is \\\ inches diameter, lined-up with brass in way of lignum-vitse bush and stuffing-box. The valves are worked by link-motion, of which all the principal bearings are made adjustable for wear. The eccentric-sheaves are of cast-iron, and the eccentric-straps are of solid gun-metal. The studs for securing the eccentric-rods to the eccentric- straps are left f inch above the top nut to allow for adjustment of the valves. The starting and reversing-gear is very powerful, and is conveniently arranged with regard to the working-platform, which is on a level with the engine bedplate. The air-pump is single acting, 18 inches diameter and 18 inches length of stroke, of solid brass fixed in a cast-iron casing. The bucket, foot and delivery valve-seats are of brass, fitted with metallic-valves. The pump-rod is of iron cased with brass. The circulating-pump is double-acting, 12 inches diameter, 18 inches length of stroke, of solid brass fixed in a cast-iron casing, and arranged to force the water through the condenser. The bucket, foot-valve and delivery-valve seats are of brass with india-rubber valves. The pump-rod is of iron cased with brass. The pump is arranged to draw from the sea or bilge. The air-pump and circulating-pump-levers are of forged-iron fitted to a weigh-shaft working in pillar-blocks having adjustable brasses. The levers are worked off the after-engine, and are fitted to the connecting-rod-gudgeon and pump-crosshead by links having adjustable brasses. The feed-pumps are two in number, each 3^ inches diameter and 18 inches length of stroke, of cast-iron with brass rams, worked from the air and circulating-pump crosshead, each pump is capable of supplying the boiler with water when the engines are working at full speed. They are fitted with MARINE-ENGINES. 41.7 brass suction and delivery-valves, and escape-valves of brass with steel spiral springs ; each pump is capable of being worked independently of the other. Fig. 368. Compound surface-condensing marine-engines, by Ross and Duncan, Glasgow. The bilge-pumps are worked from the air-pump and circulating-pump crosshead, and are similar in construction to the feed-pumps, but larger in size, being 4} inches diameter and 18 inches length of stroke, and arefitted with cast-iron rams and brass suction and delivery-valves and seats. All the steam-pipes, and pipes under pressure, are made of copper, of 4lS THE PRACTICAL ENGINEER'S HAND-BOOK. thickness varying from 3 to 14 wire-gauge. The bilge-pipes are of lead, The bed-plate is of ample strength, and is provided with recesses having square bottoms to receive the crank-shaft brasses ; the brasses are held down by wrought-iron keeps and bolts, and are fitted with syphon-lubricators. The columns are made of cast-iron, of ample strength to support the cylinders on the starboard side ; there are also hollow cast-iron standards cast on the condenser to support the cylinders on the port side. The surface-condenser is placed on the port side; it has a cooling-surface of 1500 square feet in 582 brass-tubes of f inch external diameter; all the joints between the cylinders, framing, condenser, air-pumps and bed-plate are carefully faced and firmly secured. The tubes are placed horizontally ; they are packed with wood ferrules in brass tube-plates. A soda-cock is fitted. The engines are provided with a governor. The steam drives the pistons of the first and second cylinders during 60 per cent, of the stroke, and the piston of the third cylinder during 55 per cent, of the stroke. The engines are supplied with steam of 150 Ibs. pressure per square inch by two single-ended boilers, 13 feet diameter and 10 feet 6 inches long, with six furnaces 3 feet 2 inches diameter. Smoke-tubes 3^- inches diameter outside and 7 feet long and No. 8 W. G. thick. The boilers are made entirely of Siemens-Martin steel except the stays and tubes, which are of wrought-iron. The total heating-surface is 3310 square feet, and the total fire-grate surface 97-5 square feet. Diameter of funnel 6 feet. The consumption of coal is i^ Ibs. per indicated horse-power per hour. The vessel in which these engines are fitted is 265 feet in length, 39 feet 6 inches in breadth, and 24 feet 7 inches in moulded depth : gross tonnage 1936, net register tonnage 1261. Conversion of Compound Engines to Triple-Expansion Engines. The economy derived from triple-expansion warrants the conversion of existing compound or double-expansion engines to triple-expansion engines. This may be effected, in inverted-cylinder engines, in three different ways : (i.) By adding another cylinder, tandem-fashion, to the top of either the present existing high-pressure cylinder, or low-pressure cylinder. This is the simplest way, but it has the objection of causing an unequal initial stress on each crank, and want of uniformity of turning-effort on the crank-shaft. (2.) By placing another cylinder on the top of both the high-pressure cylinder and the low-pressure cylinder, and carrying out one of the three stages of expansion in two cylinders instead of in one cylinder. This tandem-arrangement permits the attainment of a nearly equal stress on each crank, and approximate uniformity of turning-effort. (3.) By lengthening the bed-plate of the engine, and adding another crank and cylinder. This arrangement of cylinders on three cranks in- creases the length of the engine-room, but it ensures equality of initial stress on each crank, and greater uniformity of turning-effort and steadi- ness than either of the previous methods of conversion, besides minimising wear and tear. Space may be economised by placing the steam-chests at the side, which enables the cylinders to be placed close together, and the total length of the engine becomes no greater than that of a compound-engine. Triple-Expansion Engines, with Cylinders arranged on Two Cranks, do not run so sweetly as those arranged on three cranks, and are QUADRUPLE-EXPANSION MARINE-ENGINES. 419 Fig. 369. Quadruple-expansion surface-condensing marine-engines, by Rankin and Blackmore, Greenock R E 2 42O THE PRACTICAL ENGINEER'S HAND-BOOK. inferior to them in uniformity of motion, freedom from vibration, and economy in wear and tear. The Conversion of a Compound-Engine to a Two-Crank Quad- ruple-Expansion Tandem-Engine may be effected by adding another cylinder to each of the present existing cylinders. ' A Set of Quadruple-Expansion " Disconnective " Screw-Enginec of 528 indicated horse-power is shown in Fig. 369. There are three high- pressure cylinders, placed tandem-fashion over the first and second inter- mediate and low-pressure cylinders; the respective diameters being 7 inches, 7 inches, 7 inches, 16 inches, 22 inches, and 34 inches : and the length of stroke of pistons is 24 inches. The reason why six cylinders were adopted in this case instead of the four-cylinder arrangement was, that the engines were required to run sometimes very slowly, or not exceeding 15 revolutions per minute. But the capacity of the six cylinders was made the same as would have been required with the four-cylinder arrangement. Another motive for distributing the power equally over three cranks was to make the engines work as sweetly as possible, this being a matter of the first import- ance in a yacht. Again, by admitting steam to the three high-pressure cylinders simultaneously, prompt handling is insured and starting- valves are dispensed with, as the three cranks are set at angles of 120 apart. Further, this combination of cylinders enables the so-called " disconnec- tive " arrangement to be applied in a singularly efficient way, as each high- pressure cylinder forms a natural starting-point for the three principal subdivisions of the engine when working single tandem, for which purpose auxiliary exhaust-pipes have been provided. The high-pressure cylinders are also utilised for heating-up the lower cylinders in a very simple manner by allowing the hot water and steam to drain into them instead of into the bilges as usual. The chief objection to this type of engine as compared with the ordinary triple-expansion working on three cranks is the increased friction of the additional cylinders; but there is not so much in this as might be supposed at first, as owing to the number of stages, the high- pressure pistons (which with their rods form guides for the larger pistons in a heavy sea-way), and indeed the others, also, can be made so easy a fit that no oil need be used unless just before stopping the engines, as the steam itself will do all the necessary lubrication, and any portion which may escape will be worked up in the next stage. The "disconnective "- gear affords security against a complete breakdown, or in the event of any part requiring to be overhauled ; say, for example, if the white-metal often employed for crank-pin bushes should give out, it would only be the work of a few minutes to uncouple the connecting-rod and set the remaining two- thirds, or one-third if need be, of the engine to work, thus allowing ample time for refilling the bushes at leisure. The high-pressure cylinders are provided with liners of hard cast-iron, and their pistons are fitted with Ramsbottom packing-rings, while the inter- mediate and low-pressure pistons have Buckley's rings and springs. The high-pressure and first intermediate piston-rods and valve-spindles have their stuffing-boxes filled with/ metallic packing, ordinary packing being used for the others. The valve-gear is of the ordinary link-motion type, with all the working parts made very large and easily adjustable ; the valves are all of the common locomotive description. OSCILLATING MARINE-ENGINE. 421 422 THE PRACTICAL ENGINEER'S HAND-BOOK. The valves of the high-pressure cylinders are driven by their spindles coupled to rocking-levers, one end of each of these levers working on a fixed fulcrum, while the other is coupled to a prolongation of the corresponding low-pressure (or intermediate cylinder) valve-spindle. The high-pressure valves are thus given a travel equal to half that of the valves of the larger cylinders below. The air-pump, circulating-pump, feed-pump, and bilge-pumps are worked from the after division of the engine by levers. Steam of 180 Ibs. pressure is supplied to the engines by a return-tube boiler n feet 6 inches in diameter by 9 feet 10 inches long, having two corrugated furnaces 3 feet 5 inches internal diameter, and firebars 5 feet 9 inches long. A large stop-valve is fitted to the forward high-pressure cylinder, to the bottom branch of which is bolted the main steam-pipe connected to the boiler, and on its upper branch is placed a small stop-valve for the admis- sion of steam to the forward high-pressure cylinder. Similar small stop- valves are also attached to the other two high-pressure cylinders, so that, in the event of the vessel running short of coal, one or two of the high-pressure cylinders could have the steam shut off. The first stage of the expansion of the steam is carried out in the three high-pressure cylinders, which is virtually one cylinder subdivided into three. Steam is admitted to the high-pressure cylinders simultaneously, through a pipe with branches which connect these cylinders together, and it impels their pistons during thirteen- sixteenths of the stroke, when the engines are working up to their full power of 528 indicated horse-power. Steam is exhausted through a horizontal curved pipe placed at the back of the engines, c.nd connected to each high- pressure cylinder by branches, which conducts the steam to the first inter- mediate cylinder beneath, in which the second stage of expansion is carried out, from which it is exhausted into the second intermediate cylinder in which the third stage of expansion is conducted, and whence it is exhausted into the low-pressure cylinder, where the fourth and last stage of expansion is conducted, and it is finally discharged into the condenser. The steam drives the pistons of each intermediate cylinder, and of the low-pressure cylinder during three-fourths of the stroke. The engines when tested developed 528 indicated horse-power, when making 113 revolutions per minute, and expanding the steam twelve times, the boiler-pressure of the steam being 170 Ibs. per square inch. When the engines made 103 revolu- tions per minute, with steam cut off in the high-pressure cylinders at three- fourths of the stroke, the valves of the first and second intermediate, and low-pressure cylinder cutting off the steam at eleven-sixteenths of the stroke, they developed 412 indicated horse-power, and the consumption of hand- picked Penrikyber Welsh coal was only i| Ib. per indicated horse -power. An Oscillating Compound Surface-Condensing Paddle -Engine of 2000 indicated horse-power is shown in Fig. 370. The upper-end of each piston-rod is fitted with brasses, which work on the crank-pin. The cylinders are supported by, and oscillate on, trunion-bearings, which enable the piston-rods to accommodate themselves to the motion of the crank. Steam is admitted to, and exhausted from the cylinders through the hollow trunions. The high-pressure cylinder is 47 inches diameter, the low- pressure cylinder is 85 inches diameter, and the length of stroke is 6 feet. MARINE-ENGINE GOVERNORS. 423 The crank-shaft, crank-pins, and piston-rods are forged from ingots of Siemens-Martin steel. The crank-shaft bearings are 16 inches diameter, and 25 inches long, the crank-pin bearing is n inches diameter, and 18 inches long, and the brasses are lined with antifriction-metal. The paddle- shaft-bearing is i6| inches diameter, and 2 feet 9 inches long, the paddle- wheels are of the feathering type, the floats are made of iron, and are curved on the face. The area of the tube-surface of the surface-condenser is 3980 square feet. The air-pump, centrifugal circulating-pump, feed- pumps and bilge-pumps are worked by a pair of small independent com- pound engines. This arrangement permits the main engines to be run as slow as six revolutions per minute when required, and makes their prompt handling certain under any conditions. The links are reversed by one of Brown's patent engines, and the motion of both reversing and telegraph- handles coincides in direction with that of the ship. Steam of 85 Ibs. per square inch working-pressure is supplied to the engines by two double- ended steel boilers 14 feet 3 inches mean diameter, and 16 feet i inch long, having three furnaces at each end, or twelve turnaces in all, each pair of fore and aft furnaces opening into one combustion-chamber ; the diameter of each furnace is 3 feet 4 inches, and its length is 6 feet 6 inches. The fire-grate surface is 200 square feet, the heating-surface of the tubes is 5662 square feet, and the heating surface of the fire-boxes is 966 square feet. The total heating-surface being 6628 square feet. The boilers produce an ample supply of steam with easy firing. The vessel in which these engines are fitted is 270 feet long over all, 31 feet 3 inches broad, and 15 feet 6 inches deep to main deck, the height from the main-deck to the promenade-deck being 7 feet 9 inches. Marine-Engine Governors are used to prevent the racing of the engines when the sea is rough ; a very efficient and sensitive governor of this description is shown in Fig. 371. The performance of this governor is limited to working the slide-valve of a small steam-cylinder, the piston-rod of which is connected to, and moves the throttle- valve of the marine-engine, from which the governor is driven by a band, so that both work in unison. The governor consists of a small fly-wheel, with two weighted arms, hung dia- metrically opposite, and geared to a bevel- pinion cast on the driving-pulley. The inertia of the fly-wheel and arms allows the driving- pulley to overrun them on any increase of speed, and the centrifugal force of the weights keeps the position ; the motion so attained is Fig> conveyed through a sleeve and levers to a valve on the governor's steam-cylinder which admits and exhausts the steam, the piston in the cylinder moving in unison with the movement of the valve. This is accomplished by attaching the piston-rod end to the end of the valve-spindle by a link, so that the motion of the piston moves the simll valve laterally and shuts off the steam. Thus the angular motion of the valve, derived from the governor, opens the steam and exhaust-ports, and 424 THE PRACTICAL ENGINEER'S HAND-BOOK. the lateral motion of the piston closes the ports again. The governor is connected to the main engines by a band, it runs in unison with them, and should any increase of speed take place, produced by the sea leaving the propeller of the ship, it causes the fly-wheel to be overrun by the driving-pulley of the governor, and the weighted arms expand and move the sleeve along the spindle, and the small valve is turned in its seat, thereby opening the steam and exhaust ports in the governor's steam- cylinder and causing the piston to move inwards, and as the clutch on the end of the piston-rod is connected by a rod to the steam throttle-valve of the main engines, the throttle-valve is thereby closed. The opening action is the reverse of that of closing, that is, the piston moves outwards. The great sensitiveness of this governor prevents racing by closing the throttle-valve on any sudden increase of speed, and prevents the sudden shocks caused by the immersion of the propeller after it has been out or partly out of the water, by opening the valve again so quickly that practi- cally a uniform speed is maintained in the heaviest seas. The loss of efficiency of the Steam Engine is due principally to the small range of temperature through which it works, to heat lost by radiation, and to condensation of steam during its admission to the cylinder. The loss from initial condensation of Steam averages from 1 5 to 45 per cent., being proportional to the area of metal exposed to the steam up to the point of cut-off, and also to the difference of temperature of the steam at the point of cut-off, and that of the exhaust-steam, hence the earlier the cut-off the greater the loss. Therefore, the quantity of steam shown by an indicator diagram is generally less by at least 1 5 per cent, than that actually used, and the steam thus lost should be added to the weight of steam deduced from a diagram, to obtain the quantity of steam actually used by the engine. This may be illustrated by an example : An engine of 900 indicated horse-power with a high-pressure cylinder 22 inches diameter, length of stroke 42 inches, cutting off steam at two-thirds the length of stroke, makes 63 revolutions per minute ; temperature of feed- water 104 Fahr., pressure of steam shown by the indicator diagram 90 Ibs. per square inch. Required the consumption of steam per indicated horse- power per hour, and the quantity of water evaporated from and at 2 1 2 Fahr. per Ib. of fuel ? Then 22 x 22 x 7854 x 42 x 2 x 63 x 60 minutes x * 666 ? cubic feet 1728 X 3 denominator ot cut-off of steam used per hour. The weight of one cubic foot of steam of 90+15 = 105 Ibs. per square inch absolute pressure is, from Table 79, = '2434 Ib. and (46566-37 x -2434)-f-9OoLH.P. = 12-56 Ibs. of steam shown by the diagram per indicated horse-power per hour. The total heat in the steam is, from Table 79=1183-8 units, and (1183-8 + 32) iO4_ 966 the factor of evaporation, x 12-56 lbs.= 14-444 Ibs., the equivalent evapora- tion from and at 212 Fahr. Assuming the steam lost by initial conden- sation to be 16 per cent., then i4'444Xioo lb the wdght of 04 steam actually used by this engine per indicated horse-power per hour. SECTION VI. STRENGTH AND SPECIFIC GRAVITY OF STEEL AND WROUGHT -IRON PLATES AND BARS; CAST-IRON, GUN - METAL, BRASS, AND OTHER ALLOYS ; TIMBER AND OTHER MATERIALS, ETC. SECTION VI. STRENGTH AND SPECIFIC GRAVITY OF STEEL AND WROUGHT -IRON PLATES AND BARS ; CAST - IRON, GUN - METAL, BRASS, AND OTHER ALLOYS ; TIMBER AND OTHER MATERIALS, ETC. STRENGTH AND SPECIFIC GRAVITY OF MATERIALS. The Strength of Materials is measured by the resistance they oppose to alteration of form and rupture when subjected to strain or load. Tensile Strength or Tensile Stress is the resistance offered by a body to being pulled or drawn asunder. Jt produces elongation. Shearing Strength or Shearing Stress is the resistance offered by a body to being severed or cut through. It produces deflection and elongation. Compressive Strength or Compressive Stress is the resistance offered by a body to being crushed. Its effect is to compress, shorten, and produce lateral deflection. Transverse Strength or Transverse Stress is the resistance offered by a body to a lateral pressure tending to bend and break it across. It produces lateral deflection. Torsional Strength or Torsional Stress is the resistance offered by a body to being twisted asunder. It produces angular deflection. Working-Strain or Working-Stress Is the utmost strain or stress to which it is considered safe to subject a body, during its ordinary use as part of a machine or structure. Ultimate Strain is the utmost strain or stress, or alteration of shape, which a body can bear without breaking. Working-Load is the load which produces the working-stress. Proof-Strength, Proof Strain, or Proof Stress, is the utmost strain or stress which a body can bear without suffering any diminution of stiffness or strength. Proof-Load is the load which produces the proof stress. 428 THE PRACTICAL ENGINEER'S HAND-BOOK. Bead-Load, means one that is put on by degrees and remains steady. Live-Load, means one that is put on suddenly and accompanied with vibration. The effect of a live-load upon a structure is much more injurious than that of a dead-load. Set is the permanent strain or alteration of shape of an imperfectly elastic body which remains after a load has been removed. Stiffness is measured by the intensity of the stress required to produce a certain fixed quantity of strain. Pliability is the inverse of stiffness, and is measured by the quantity of the strain produced by a certain fixed stress. Modulus of Elasticity is the reciprocal of the direct pliability when the stress does not exceed the proof-strength. The modulus of elasticity is the measure of the elastic force of any sub- stance. It may be expressed as the force in Ibs. required to stretch a bar to double its length, if its elasticity remained perfect. A stretching-force was applied, in an experiment, to a bar of good wrought-iron, 10 feet long, which produced an extension in inches equal to -a-s-g-Woth P art f tne weight or force in Ibs. required to stretch it, and the modulus of the elasticity of this iron is = 233500 x 120 inches length of bar = 28020000 Ibs. per square inch. The modulus of elasticity, or resistance to stretching, of metals and woods, averages as follows : Cast-steel, hardened . . 37500000 j Teak . . , . 2167000 . 1714500 , . 1610000 . i 600000 . 1593 . 1525000 . . 1500000 . 1421000 . . 1343000 . i 3 i 6000 . . 1134000 . 1086750 . . 1036000 924750 837000 800000 The Stress or Full in Ibs. per Square Inch required to Elongate a Bar may be found by multiplying the strain by the modulus of elasticity. The Strain produced by a given Direct Stress may be found by dividing the stress, or pull in Ibs. per square inch required to elongate a bar, by the modulus of elasticity. Spring or Resilience, is the greatest quantity of work which a body can bear in the form of a blow or shock without injury. It is Cast-steel, not hardened . 33000000 Oak Mild steel .... 30000000 Ebony Wrought-iron . 28020000 Birch . Iron-wire . . . . 25000000 Mahogany, H. Homogeneous metal 23830000 Ash . . Platinum-wire . . . 22000OOO Pine . Cast-iron I 80OOOOO Box Copper-wire . . . 14500000 Elm . Cast-iron, weak I4OOOOOO Beech . Phosphor-bronze . . I35OOOOO Poplar, white Brass-wire 13500000 Alder . Gun-metal 9500000 Sycamore . Brass .... 9OOOOOO Chestnut Tin 45OOOOO Walnut . Lead, sheet . 720000 Blue-gum TEST-STRIPS OF WROUGHT-IRON AND STEEL. 429 equal to one-half of the product of the proof strength of the body by its proof strain. Direct Extensibility, or compressibility, is the amount of direct strain produced by each pound on the square inch of direct stress. Elastic Strength or the Elastic limit is the utmost amount of stress which a body can bear without set. The elastic limit of good mild steel- plates averages 17 tons per square inch -either along or across the grain, and of good wrought iron-plates it averages 13 tons per square inch either along or across the grain. The elastic limit of iron and steel-bars and plates may in a general way be taken at one-half the breaking weight. A stress of one ton per square inch applied to a bar of wrought-iron will produce an elonga- tion of approximately T ^^oth part of its length, and each additional ton of strain applied will stretch the bar another To ^ 00 th part of its length, until the limit of its elasticity is reached. The Fatigue of a Metal is the disturbance of its component particles under strain or stress within the limits of its elastic strength. The Refreshment of a Metal is the re-adjustment of its com- ponent particles after fatigue, or the restoration of the metal to its original state. The Patience of a Metal is the time required for its restoration after fatigue. The Endurance of a Metal is its power of resisting a prolonged strain or stress. The endurance of a metal has no fixed relation to its tensile strength, or its power of resisting a tensile strain for a short period. The Factor of Safety is the ratio in which the breaking-strain on a piece of material exceeds the working-strain. breaking-strain Factor of safety = rWg _^ rr Breaking-strain = working-strain x factor of safety. The factor of safety for a live-load is usually 6 in metals, 8 in masonry, and 10 in timber. The factor of safety for a dead-load is usually one-halt that required for a live-load. A Test-Strip of Steel, about i inch wide and from 6 to 9 inches long, cut either lengthways or crossways of the plate or bar, after being heated to a low cherry-red and cooled in water at a temperature of 82 Fahr., should stand bending double round a curve of which the diameter is not more than three times the thickness of the piece to be tested, without fracture. The fracture of a broken test-strip of steel should be silky. A Test-Strip of Wrought-iron 2 feet long and 2 square inches of sectional area of the iron used for crank-shafts, should not fracture until twisted at least five complete turns, and the fracture should be fibrous. It should also double up cold, quite close, without fracture. The edges of the test-strip should be planed in the direction of the grain : when planed across the grain it is liable to fracture in the tool-grooves. A good Steel Casting should bend through a right angle before breaking, and it should be composed of '28 carbon, -3 silicon, and '69 manganese. 430 THE PRACTICAL ENGINEER'S HAND-BOOK. Eteel-Plates, Wrought-iron Flates, and Bars, should be well and cleanly rolled, and free from scales, blisters, laminations, cracked edges, or other defects. They should be of such quality and strength as to be equal to the tensional strains given in the following table, and to indicate the per-centages of elongation and of contraction of the area at the point of fracture therein given. Table 96. TENSILE STRENGTH OF STEEL AND IRON PLATES AND BARS. Description of Plates and Bars. Tensional Breaking Strain per Square Inch in Tons. Percentage of Contrac- tion of Area of Fracture. Siemens-Martin mild steel boiler-plates, either along or across the grain. With an elongation of 20 per cent, in 8 inches ; not to be less than . Or more than Steel-rods for making rivets ; not to be less than Or more than Siemens-Martin mild steel-plates for girders, bridge- plates, channel, angle or flat bars, either along or across the grain, with an elongation of 20 per cent, in 8 inches ; not to be less than . . . Or more than Mild hoop-steel . . . . . . Mild steel for piston-rods and valve-spindles . Mild steel plates for fire-boxes Steel-castings, with an elongation in 10 inches of not less than 18 per cent. ; not to be more than Best Yorkshire wrought-iron plates, along the grain Best Yorkshire wrought-iron plates, across the grain Wrought-iron bolts, nuts and rivets Wrought-iron boiler-plates, along the grain . . Wrought-iron boiler-plates, across the grain . Wrought-iron ship-plates and bridge-plates, along the grain Wrought-iron ship-plates and bridge-plates, across the grain ........ Wrought-iron round and square bars, and flat bars under 6 inches wide Wrought-iron angle, channel, "|~ bars, and flat bars 6 inches wide and upwards . Hoop-iron Wrought-iron rolled-joists Wrought-iron crank-shafts . . ... Tons. 26 3 25 28 27 3 1 28' 2 5 3 24 22 23 21 18 20 17 24 22 22 24 25 Per cent. 2O 30 40 40 2O 20 12 30 50 45 15 12 25 IO 5 4 20 Mild Steel for Fire-box Flates should have very little phosphorous and no sulphur in its composition, as they reduce the heat-enduring power of steel. STRENGTH OF IRON PLATES AND BARS. 431 Table 97. AVERAGE STRENGTH OF IRON AND STEEL BARS AND PLATES, CULLED FROM THE TEST-BOOKS OF SEVERAL NOTED MANUFACTURERS. Description. Tensional Breaking Strain per Square Inch in Tons. Percentage of Contrac- tion of Area of Fracture. Tons. Per cent Wrought-iron bars made at the Earl of Dudley's Round Oak Iron Works, Dudley : L. W. R. O. bars, elonga- tion .... 28-3 ( P er cent. in 1 ( 10 inches. ) 24-94 4 8-2 L. W. R. O. bars, elonga- (percent, in] tion . . . ' > (io inches, j 26-57 44 Best bars, elongation per cent, in 4 10 inches. 24-67 453 Best, best, bars, elongation 297 P er . cent in y ' 10 inches. 23-35 45-2 Best, best, best, bars, elon- " gation . \ 30-7 (Per. cent, in \ ' ( 10 inches. 23-60 46-9 Best, best, best, C bars, elongation . . . I 2T , (percent, in I ' J \ 10 inches. 26-42 47-9 Best rivet-iron bars, elon- gation .... I 26-6 (Per. cent, in 1 (. 10 inches. 24-75 45-7 Best, best, rivet-iron bars, elongation . . . I g per cent, in I * 10 inches. 24-75 47'2 Best, best, best, rivet-iron ' bars, elongation . 27-4 Per cent, in i ' * 10 inches. 24-26 47-2 Best, best, best, rivet-iron ) o.o per cent, in " special bars, elongation j 10 inches. 24-40 473 Best cable-iron bars, elon- " gation . . . . I 25-0 Per cent, in | i D y 10 inches, j 24-28 45'3 Best, best cable-iron bars, 1 . per cent, in ] elongation . i 2 ^ J 10 inches, j 23-25 49-1 Best, best, best, cable-iron bars, elongation . . > C per cent, in ) 2 9'7 i 10 inches. 23-94 47'3 The average tensile breaking-strain of the above bars, per square inch of fractured area was 46*2 tons. Wrought-iron plates and bars made by the Shelton Iron and Steel Co., Limited, Stoke-on-Trent : Best boiler-plates | inch thick, lengthways . . 22*3 10-3 a ,, ,, , , crossways l8'7 4-6 Elongation in 1 2 inches = f inch lengthways, and | inch crossways. 432 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 97 continued. AVERAGE STRENGTH OF IRON AND STEEL BARS AND PLATES, BY SEVERAL NOTED MANUFACTURERS. Description. Tensional Breaking Strain per Square Inch m Tons. Percentage of Contrac- tion of Area of Fracture. Wrought-iron plates and bars made by the Shelton Iron and Steel Co., Limited : Best, best, boiler-plates -^ inch thick, lengthways ,, ,, ,, ,, crossways . Elongation in 12 inches = i-^ inch lengthways, and | inch crossways. Best, best, boiler-plates | inch thick, lengthways ,, ,, crossways . Elongation in 12 inches = i inch lengthways, and ^~ inch crossways. Rivet-iron. Elongation in 12 inches = 35- inches, or 27 per cent. Bolt-iron. Elongation in 12 inches = 3! inches, or 30-2 per cent Angle-iron. Elongation in 12 inches = scinches, or 27 per cent Cable or chain-iron. Elongation 31*8 per cent. . Tons. 23 '6 2O'IO 2 3 -II 2O'0 25 23-14 26-5 24-5 Per cent. 16-2 10-4 H'3 JO'S 40 47 34'i 40-6 Wrought-iron bars and plates made by the Butterley Company, Alfreton : Best round and square bars .... Best, best, round and square bars . . . . Best, flat, angle, and ""["-bars .... Best, best, flat, angle, and "["-bars . . . . Best plates, lengthways crossways best plates, lengthways .... ,, ,, crossways 23-9 2 5 -I 21-6 24'5 20-63 16-17 22-83 19-26 24'Q2 Wrought-iron and steel-plates and bars made by W. Beardmore & Co., Parkhead Works, Glas- gow : Best, best, wrought-plates, ") ( per cent, in ") elongation . . . j (8 inches, ) Best triple-crown wrought-") Cpercent.ini iron plates, elongation . . j (_ 8 inches. ) 21 22\ STRENGTH OF IRON AND STEEL BARS AND PLATES. 433 Table 97 continued. AVERAGE STRENGTH OF IRON AND STEEL BARS AND PLATES, BY SEVERAL NOTED MANUFACTURERS. Description. Tensional Breaking Strain per Percentage of Contrac- tion of Area Square Inch in Ions. of Fracture. Tons. Per cent. Wrought-iron and steel-plates and bars made by W. Beardmore and Co., Parkhead Works,. Glas- gow : Best wrought-iron bars, elon- ") C per cent, in | gation . . . . ) 1 8 inches. } 23 25 Best, best, wrought-iron bars, ") ( per cent, in ") . elongation . . . . j 2 -> 1 8 inches. ) 24i 3 2 Angle-iron, elongation . . j 23 I gYnches'. m } 24| Rivet-iron, elongation . -[2511 gYnches' m 24i Iron-forgings, elongation . > \2\ \ e . r c f n ' m 22\ Steel boiler shell-plates, elon- 1 x C per cent, in \ gation . . . . j 2 |8 inches. j 2 9 Steel internal boiler-plates, V . i J P e r cent, in j , elongation . . . j 4 * ( 8 inches. ) 2 ?2 Steel ship-plates, elongation | i8J | sYnches m ] 30| Steel-ancles and bars, elon- j ^ per cent, in ' gation . . . ) 8 inches. 3 1 Rivet-steel, elongation . . j 33 g^^" 1 2 1\ Steel bridge-plates, elonga- ") C per cent, in ) tion . . . . ) 2 ^ ( 8 inches, j 29 Steel-forgings, elongation j St 1 sYnches'. '" } *9i Wrought-iron and steel-plates and bars made by John Brown and Co., Limited, Sheffield : Iron boiler-plates, best, best, lengthways 2O Iron boiler-plates crossways . . . 17 Iron boiler-plates, best, best, best, lengthways 22 Iron boiler-plates ,, crossways . . 18 Steel-plates and bars ; not less than . 26 Or more than . . . . . 3 Rivet-steel and boiler-stay bars ; not less than 26 Or more than 3 Steel-shafts and axles ; not less than . 3 Or more than 35 434 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 97 continued, AVERAGE STRENGTH OF IRON AND STEEL BARS AND PLATES, BY SEVERAL NOTED MANUFACTURERS. Description. Tensional Breaking Strain per Square Inch in Tons. Percentage of Contrac- tion of Area of Fracture. Wrought-iron and steel-plates and bars made by John Brown and Co., Limited, Sheffield : Steel-tires ; not less than Or more than Tons. 26 50 226 22- 9 23-2 2 3 -8 23-5 24 25'5 257 28 9i 29! 27 28 to 30 Per cent. 45 46 44 35 5 45 45 27 45 40 40 50 50 Wrought-iron bars made by N. Hingley and Sons, Netherton Iron Works, Dudley: Netherton crown-best bar-iron, elongation 30 per cent Netherton crown-best bar-iron, elongation 19 per cent Netherton crown-best bar-iron, elongation 22 per cent Netherton crown-best bar-iron, elongation 24 per cent. ........ Netherton crown-best rivet-iron, elongation 20 per cent Netherton crown-special best, best, cable-iron, elongation 23 per cent Netherton crown-special best, best, cable-iron, elongation 23^ per cent Netherton crown-special best, best, 2 T 9 g- inch cable-iron, elongation 14 per cent. . Steel-plates, bars, &c., made by the Bolton Iron and Steel Company, Limited, Bolton : Steel-plates and bars for ") ( per cent, in ") boilers, elongation . . } -* ( 8 i nc hes. j Steel bridge-plates, elonga- \ \ per cent, in \ tion ) 20 1 8 inches. ) Steel-angles, tees, bulb-beams, S ( . ) &c., for bridge and ship- 20 ] g er c nt - m building, elongation . . ) ( 8 mches ' ) Rivet-steel, elongation . . ] 30 { jj?^; in ] Steel locomotive-crank-axles") ( t . ~) and straight axles, elonga- j 30 | P 6 ^ m j STRENGTH OF STEEL PLATES AND BARS. 435 Table 98. BREAKING STRENGTH OF STEEL-PLATES AND BARS, AND OF STEEL- WIRE IN LBS. PER SQUARE INCH. Description. Tenacity in Ibs. per Square Inch. Authority. Lengthway. Crossway. Siemens-Martin mild-steel boiler- plates, highest average 64OOO 64000 Siemens-Martin mild-steel boiler- plates 6OOOO 6OOOO Siemens-Martin mild-steel boiler- plates 58150 58150 Siemens-Martin mild-steel boiler- plates 57850 57850 Siemens-Martin mild-steel boiler- plates, lowest average 53000 53000 The above steel-plates will probably average an elastic limit of 40000 Ibs. per square inch tension, with an elongation of 20 per cent, in 8 inches, and a contraction of area of fracture of 20 per cent. in 8 inches. Mild-steel plates and bars contain- ing "13 per cent, of carbon with an elongation of 26 per cent, in 8 inches 62OOO 62OOO Mild-steel plates, stamping grade . 58240 58240 ,, bars, average of number 59000 59OOO bolts .... 80640 80640 ,, rivets . . . . 6272O 62720 Cast-steel castings 65000 65OOO Hadfield's manganese-steel, ham- mered . . . 94080 ... Homogeneous metal-bars . IOO99O ... W. H. Barlow. 5) 93000 Fairbairn. ,, ,, . . 90647 ... Kirkaldy. ,, ,, . 89720 ... , } Bessemer-steel bars, rolled and 1^2012 Wilmot. Bessemer-steel bars, rolled and mymy*m forged III46O ... Kirkaldy. Cast-steel bars, rolled and forged . I34OOO Rennie. 132900 Kirkaldy. ,, ,, ,, 92OI5 ... n Shear-steel bars, rolled and forged II8468 ... Soft-steel plates, tempered . . I2I7OO Tresca. not tempered 8l700 ... > 43^ THE PRACTICAL ENGINEERS HAND-BOOK. Table 98 continued. BREAKING STRENGTH OF STEEL-PLATKS AND BARS, AND OF STEEL-WIRE IN LBS. PER SQUARE INCH. Description. Tenacity Squar n Ibs. per e Inch. Authority. Lengthway. Crossway. Hard-steel plates, tempered . . IO30OO ... Tresca. Hard-steel plates, not tempered . 74300 ... H Puddled-steel bars, rolled & forged 116330 ... W. H. Barlow. i >j j 95 2 33 ,, 94760 ... Mallet. > 900OO Fairbairn. , ,, , 71480 ... Kirkaldy. > i 62760 ... j> Spring-steel bars ,, , 72529 Whitworth's compressed-steel 89600 SirJ.Whitworth. ,, ,, . . 152320 ... )} Whitworth's steel, tempered in oil 107968 ... 5} J) J> J) 93000 Fairbairn. }> )) 5) )' 90647 ... Kirkaldy. ,, ,, ,, 89724 ... j> Cast-steel plates .... 96280 97150 3> .... 75590 69082 ,, hard . I029OO ... Fairbairn. ,, soft . . . 85400 . Puddled-steel plates . IO259O 85360 Kirkaldy. > ... 7I53 67685 ,, Soft cast-steel for guns, not tem- pered 77930 ..i Anderson. Cast-steel tempered in oil . . 120467 ... v Krupp's cast-steel bolts 91840 Kirkaldy. ,, steel crank-shaft . . 93640 Cast-steel for drifts 116480 ... Kirkaldy. for taps . . . . 103040 for tools 134400 M Large crank-shafts, steel-castings, not forged 92600 ... Large crank-shafts, steel-castings, not forged 72300 Manganese-steel . 64300 ... Mild hoop-steel . . . . 95000 ... 82OOO 74000 Bessemer-steel tyres, hammered . 78400 Steel Committee. axles, 74816 ... >! rails, ,, 74368 ... Crucible-steel tyres, hammered . 79520 ... M axles, 9l6l6 " STRENGTH OF STEEL-WIRE AND IRON-WIRE. 437 Table 98 continued. BREAKING STRENGTH OF STEEL-PLATES AND BARS, AND OF STEEL-WIRE IN LBS. PER SQUARE INCH. Tenacity in Ibs. per Square Inch. Description. Authority. Lengthway. Cross way. Crucible-steel rails, hammered 85430 ... Steel Committee. Cast-steels for chisels . . . Il8l82 ... Siemens-steel plates, not annealed ,, ,, annealed 69880 64520 69440 64300 Kirkaldy. jy annealed and hardened .... 64650 ... Tenacity in Ibs. per Description. Diameter. Square Inch. Authority. Lengthway. Cross way. Steel pianoforte-wire 035 268800 Dr. Percy. Steel-wire OIQ 358400 ... Steel-wire . . . 030 360416 ... jj Steel-wire, John Fowler & Co.'s special . Steel-wire, John Fowler 093 344960 ... & Co.'s special . I 3 2 257600 ... Steel-wire, John Fowler & Co.'s special . 159 224000 ... Steel-wire, John Fowler & Co.'s special . . I 9 I 2OI6OO ' Fowler's special steel-wire is hard, tough, and rigid. It is used for making steel-wire-ropes for ploughing-tackle, and is composed of '828 per cent, of carbon, -587 per cent, manganese, -143 per cent, silicon, -009 per cent, sulphur, and of '030 per cent, of copper. Table 99. BREAKING STRENGTH OF WROUGHT-!RON BARS AND PLATES, AND OF IRON-WIRE IN LBS. PER SQUARE INCH. Tenacity in Ibs. per Square Inch. Description. Authority. Lengthway. Crossway. Iron-wire, very strong . II4OOO Morin. strong . . . . IOOOOO Gordon. medium 86000 Telford. ,, weak . . . 71000 Morin. average 80640 ... Barlow. 433 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 99 continued. BREAKING STRENGTH OF WROUGHT-!RON BARS AND PLATES, AND OF IRON-WIRE IN LBS. PER SQUARE INCH. Description. Tenacity in Ibs. per Square Inch. Authority. Lengthway. Crossway. Iron-wire, Warrington, not an- nealed 8OOOO ... Barlow. Iron-wire, Warrington, annealed . 53000 ... t) Good wrought-iron bars, average . 60OOO 5IOOO ,, plates, average 5OOOO 42000 ,, Wrought-iron bars, rolled or forged,. mean .... 57550 Kirkaldy. Wrought-iron bars, Yorkshire . . 66390 ... ,, 5> 60075 jj Rivet-iron, Yorkshire and Stafford- shire 59740 Fairbairn. Charcoal bar-iron 63620 )} Wrought-bars, Staffordshire, Lion Brand, best, best . . . 53760 47000 Wrought-bars, Staffordshire, Lion Brand, best, best 50000 426OO Wrought-iron bars, Staffordshire, best, best, average . . . 52267 45000 Wrought-iron bars, Staffordshire . 62230 Kirkaldy. ,, 56715 J( Lancashire 601 10 ,, ,, 53775 ... ,, Lanarkshire . 64795 ,, 5*327 >} Swedish 48933 ... ,, 41250 Russian 59096 49564 Staffordshire (S.C. Crown) 65400 ... T. Lloyd. Staffordshire (S. C. Crown) 5353 ... j> Wrought-iron boiler-plates, Staf- fordshire ..... 4394 37676 Edwin Clark. Wrought-iron plates, average of a large number of tests . 45000 38000 Wrought-iron plates for steam C Board of Trade boilers .... 47000 4OOOO ( estimate. Best scrap rivet-iron f inch dia meter 53760 }) Bushelled-iron from turnings 55878 ... Kirkaldy. Hammered scrap-iron 53420 ... " STRENGTH OF WROUGHT-IRON BARS AND PLATES. 439 Table 99 continued. BREAKING STRENGTH OF WROUGHT-!RON BARS AND PLATES, AND FORCINGS IN LBS. PER SQUARE INCH. Description. Tenacity in Ibs. per Square Inch. Authority. Lengthway. Crossway. Wrought-iron bars, Staffordshire (S. C. Crown) .... 50400 ... Steel Committee. Wrought-iron bars, best Yorkshire 52200 jj Lowmoor . . 55550 ... }> V )> J> 64750 M Angle-iron from various districts . 6l26o Kirkaldy. j> ' i 50056 ... }> Cleveland . . . 51800 ... Wrought-iron plates, mean . 50737 46171 Kirkaldy. ., Lowmoor 6420O 62490 Fairbairn. ,, Yorkshire . 58487 55033 Kirkaldy. 52OOO 46221 > Wrought-iron plates, Yorkshire bridge-iron 4993 43940 Fairbairn. Wrought-iron bridge-plates, Cleve- land 52810 41400 Wrought-iron bridge-plates, Cleve- land 46860 4OOOO Wrought-iron plates, ordinary good Staffordshire .... 56996 5*251 Kirkaldy. Wrought-iron plates, ordinary good Staffordshire 46404 44760 ,, Wrought-iron plates, Staff crdshire best, best .... 59820 54820 Fairbairn. Wrought-iron plates, Staffordshire best, best 49945 46470 ,, Wrought-iron plates, Staffordshire best 61280 53820 Wrought-iron plates, Staffordshire best, best, charcoal . . . 45010 41420 Wrought-iron plates, Staffordshire good common .... 52825 50820 n Wrought-iron plates, Staffordshire bridge-iron 47600 443 8 5 Wrought-iron plates, Lancashire . 48865 45015 1} ,, Lanarkshire 53 8 49 48848 Kirkaldy. )> ,, ,, 43433 39544 ., ,, Durham 5 I2 45 46712 J? Pieces cut out of large wrought- iron forgings . . . . 47582 44578 Pieces cut out of large wrought- iron forgings .... 43759 36824 " 440 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 99 continued. BREAKING STRENGTH OF WROUGHT-!RON BARS AND PLATES, AND OF HOOP-!RON IN LBS. PER SQUARE INCH. Tenacity in Ibs. per Square Inch. Description. Authority. Lengthway. Crossway. Effects of cold-rolling, black bar 58627 ... Fairbairn. Effects of cold-rolling, black bar turned . . . . 60747 ,, Effects of cold-rolling,, black bar cold rolled . 88229 Effects of cold-rolling, plate cold- rolled . . ... II49I2 ... ,, Hoop-iron, best, best . 64000 ,, ... S3000 ,, average . . . 48000 Description. Authority. Loss of strength in screwed and chased bolts, from 7i to 33l P er cent Kirkaldy. Loss of strength in welded-joints, from 15 to 30 per cent. Increase of strength of steel by hardening in oil, 12 to 79 per cent . " Table 100. ULTIMATE TENSILE AND COMPRESSIVE STRENGTH OF CAST- IRON FROM THE EXPERIMENTS OF FAIRBAIRN, HODGKINSON, AND OTHERS. Description. Tensile Strength in Ibs. per Square Inch. Compressive Strength in Ibs. per Square Inch. Authority. Cast-iron, No. i cold-blast . 12690 5645 ( Fairbairn and \ Hodgkinson. , ,, ,, . 17460 80560 5> , No. i hot-blast . I343 72193 ,, , ,, ,, . l6l25 88740 ,, , No. 2 cold-blast . J 3345 68530 ,, , ,, . . 18855 IO24O8 )t hot-blast . 13500 82730 , ,, ,, . . 17800 IO203O ,, , No. 3 cold-blast . 14200 76 9 00 ,, , - . 15500 II540O ,, , hot-blast . 15278 IOl83O , 23468 104880 TENSILE AND COMPRESSIVE STRENGTH OF CAST-IRON. 44! Table 100 continued. ULTIMATE TENSILE AND COMPRESSIVE STRENGTH OF CAST-IRON. Description. Tensile Strength in Ibs. per Square Inch. Compressive Strength in Ibs. per Square Inch. Authority. Toughened cast-iron . 23460 129870 C Fairbairn and ( Hodgkinson. ,, ') 25760 II9457 jy Cast-iron, No. 3 hot-blast after first melting . . o8?oo Cast-iron, No. 3 hot-blast after yu^ww twelfth melting . . . 163740 Cast-iron, No. 3 hot-blast after eighteenth melting . I97I2O Cast-iron, weak . . . . 13400 82OOO Hodgkinson. ,, average 16500 II2OOO strong . . . . 29OOO I45OOO ,, ,, very strong . 34000 Anderson. Pieces cut from cast-iron guns ") . ... 35000 }J began to yield, or give way at ) . Cast-iron, mean of 16 various sorts, 40700 12 inches high ... 85547 Hodgkinson. Cast-iron, Lowmoor, No. 3 C. B. . 14538 fj Devon, No. 3 H. B. 2l68q ,, cold-blast average of ww o various . 16845 99232 ,, hot-blast average of various . . 15300 IO25O2 American iron, effect of re-melting and retaining the metal in a state of fusion for 4 hours. Pigs 13440 Major Wade. ist melting ..... 20870 ... 2nd ,, . . . . . 24770 3rd ...... T" / / 26790 4th 27888 Samples from 100 gun-heads 33376 ... ' )} A lot of pig-iron in the crude state 12678 ... M Twenty-seven guns cast from this pig-iron, 3rd melting . . . 35280 ... Stirling's metal, a mixture of cast- iron and wrought-iron, average . 24500 I25OOO Hodgkinson. Cast-iron average strength of good 15680 107520 medium quality . . 13440 94080 A Test-Bar of good Cast-Iron, 3 feet 6 inches long and 2 inches by i inch in section, placed edgeways upon supports 3 feet apart, should not break -with a less weight than 30 cwts. gradually applied in the middle of the bar. 442 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 101. BREAKING STRENGTH OF METALS AND ALLOYS IN LBS. PER SQUARE INCH. Tensile Compressive Description. Strength in Ibs. per Strength in Ibs. per Authority. Square Inch Square Inch Aluminium-bronze ") . 73^5 I32OOO Anderson. 90 copper 10 aluminium j . . 96320 ... t) Tin, cast ..... 4600 Rennie. Zinc, 6900 ,, sheet 6lOO ... Lead, cast 1814 Rennie. sheet .... 1920 pipe ...... 224O ... Jardine. Brass I800 IO3OO Rennie. Brass, fine, 2 copper: i zinc . . 2890 Anderson. 7 copper : 3! zinc 28940 ... Alloy of copper 10 : iron 10 : zinc 80 parts 6988 ... ,, Gun-metal or bronze 12 parts cop- per : i part tin ... 29OOO }J Gun-metal or bronze 1 1 parts cop- per : i part tin . . . . 30700 ... 5> Gun-metal or bronze 10 parts cop- per : i part tin ... 33000 ... 5 Gun-metal or bronze 9 parts cop- per : i part tin . . . . 38000 tf Gun-metal or bronze 8 parts cop- per : i part tin ... 36OOO Gordon. Gun-metal or bronze 6 parts cop- per : i part tin . . . . 43800 ... Gun-metal, average strength of good bronze .... 33000 ... Anderson. Gun-metal from American guns . 23900 Major Wade. ,, ,, ,, ,, 35480 n Phosphor-bronze 56OOO Muntz-metal . . . . . 49300 ... Austrian sterro-metal . 59900 Major Wade. Sterro-metal, copper 60, zinc 39 ) 43120 ... Tin i -5 : iron 3, cast in sand ) 48160 ,.. j? Sterro-metal, copper 60, zinc 35, tin 2, iron 3 .... 85120 ... Copper, wrought 33600 ... cast I9OCO t) j> j> 26000 ... 5 j bolts 33COO ... cast .... I9OOO Rennie. sheet, rolled . . . 30000 STRENGTH OF WIRES OF VARIOUS METALS. 443 Table 101 continued. BREAKING STRENGTH OF METALS AND ALLOYS IN LBS. PER SQUARE INCH. Description. Tensile Strength in Ibs. per Square Inch. Compressive Strength in Ibs. per Square Inch. Authority. Copper, sheet, hammered . . ,, bolts .... ,, wire . . . . 33600 30000 6OOOO 64200 I47H3 265000 160540 137340 40320 ... Rennie. Fairbairn. Anderson. Kirkaldy. Wertheim. Fairbairn. Phosphor-bronze wire . . . Platinum-wire, hard . Coleford gun-metal, strongest . . ,, ,, mean of 10 sorts Gold, pure A Test-Bar of Good Tough Gun-Metal, i inch square and 15 inches long, placed upon supports 12 inches apart, should not break with less than four blows from a monkey of 50 Ibs. weight dropped from a height of 5 feet, which will cause a permanent deflection of from 2\ inches to 3 inches. Table 102. TENSILE STRENGTH AND RESISTANCE TO TORSION OF VARIOUS WIRES, THE RESULTS OF EXPERIMENTS BY MR. KIRKALDY. TWISTS IN s IN. PULLING STRESS, WIRE AS DRAWN. As An- Drawn. nealed. Description of Wire. Stress. Mean Dia- meter. Area. Per Square Mean of Three. of Three. Total. Inch. Inch. Sq. Inch. Ibs. Ibs. Twists. Twists. Phosphor-bronze . 0655 0640 003367 003216 340 389 100980 120957 22-3 9* 5 2 3> O60O OO2827 352 1243*3 7'0 87 'O6lO OO2922 379 129705 8*3 98 0595 002778 336 I2O950 13-0 124 >> 0585 002655 395 I47H3 7'5 97 5) 0640 OO32l6 1595*5 *3'3 66 Copper . . . . Brass .... 0640 O6O5 OO32l6 002871 203 233 63122 81156 867 147 96 57 Steel, ordinary . . O6OO 002827 342 120976 22-4 79 Iron galvanized, best- best C. . . 0580 002643 170 64321 26-0 44 Iron, galvanized, best Charcoal E. . . 0580 002643 174 65834 48-0 87 444 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 103. TENSILE STRENGTH AND CONDUCTIVITY OF SILICIUM-BRONZE AND PHOSPHOR-BRONZE WIRE, FOR ELECTRIC APPLIANCES, ROPES, &c. Description of Wire. Tensile Strength in Tons per Square Inch. Conductivity per Cent. From to Silicium-bronze telegraph and electric-light | wire. High conductivity . . . . j 2 9 33 9 9 6 Silicium-bronze telephone-line wire for long) distances ) 45 50 34 40 Silicium-bronze telephone (local) and spring- ) wire ) 5 65 20 30 Phosphor-bronze wire 40 65 20 30 Table 104. TENSILE STRENGTH, ELECTRICAL RESISTANCE AND RELATIVE CONDUCTIVITY OF VARIOUS WIRES, THE DIAMETER IN EACH CASE BEING ONE MiLLiMETRE='c>3937 INCH. Description of Wire. Tensile Strength in 'J ons per Square Inch. Resistance per mile in Ohms. Relative Conduc- tivity. Pure copper -1778 33' 1 IOO Silicium-bronze (telegraph) . . . 28-57 34'5 9 6 Silicium-bronze (telephone) 48-25 103 34 Phosphor-bronze (telephone) . . . 4571 124 26 Swedish galvanized-iron .... 22-86 216 16 Galvanized Bessemer-steel . . . . 25-40 249 J 3 Siemens-Martin steel .... 26-67 266 12 Table 105. BREAKING STRENGTH OF TIMBER FROM THE EXPERIMENTS OF BEVAN, HODGKINSON, FOWKE, AND OTHERS. Description. Tensile Strength in Ibs. per Square Inch. Compressive Strength in Ibs. per Square Inch. Authority. Abele, European 72OO 5I2O [ Bevan and ( Hodgkinson. Acacia ,, .... I6OOO Bevan. African oak, teak 6730 5270 Alder, European . . . . I4l8o 68 95 Apple-tree, European . I95OO 6500 ( Bevan and 1 Hodgkinson. Ash, English 3640 2974 TENSILE AND COMPRESSIVE STRENGTH OF TIMBER. 445 Table 105 continued. BREAKING STRENGTH OF TIMBER. Description. Tensile Strength in Ibs. per Square Inch. Compressive Strength in Ibs. per Square Inch. Authority. Ash, European .... I/OOO 9OOO ( Bevan and ( Hodgkinson. Aspen IOl8o Bamboo, Southern Asia 6300 Bevan. Baracara . . . . 88l8 Fowke. Bartaballe 88l8 Baywood, Newfoundland . . 2800 6OOO Beech II500 9360 ( Bevan and \ Hodgkinson. Birch I5IOO 6402 Hodgkinson. ,, American black . Il66o M Bitter-wood, West Indian . . ... 5510 Fowke. Blue-Mahoe .... ... 8820 Blue-gum, Australian . . . ... 8820 Box, European .... 2OOOO 10300 ( Bevan and V Hodgkinson. ,, Australian . . ... 8820 owke. Broadleaf, West Indian ... 7720 V Brown-ebony, Guianaian 12566 Buckati . 9920 ,, Buhuradda ,, . . I2I2O Bullet-tree, West Indian U330 ,, ,, bastard . . . ... IIO2O ,, red ... 99 20 ,, Cabacalli, Guianaian . . . 9920 ,, Cabbage-bark, West Indian 9920 ,, Calabash . . ... 55 10 ,, Cedar of Lebanon, North African II4OO 5860 C Bevan and ( Hodgkinson. Chestnut, European . . . 10500 Bevan. Chow, West Indian 6780 1 2 100 Cogwood, West Indian . . . I2I2O Fowke. Crab-tree, English 19800 6980 Cypress, European . . 6OOO ... Dantzic-fir ,, . . . . 3400 3OOO Deal IOOOO 5OOO Dogwood, West Indian ... IIO2O Fowke. Ducaliballi, Guianaian . . . I322O j> Ebony, West Indian . 18960 J? Elder, European . . . . 10230 8466 Hodgkinson. Elm, English . . . .... 5200 ... ( Bevan and ,, European . . ... 14400 10330 | Hodgkinson. 446 THE PRACTICAL ENGINEERS HAND-BOOK. Table 105 continued. BREAKING STRENGTH OF TIMBER. Description. Tensile Strength in Ibs. per Square Inch. Compressive Strength in Ibs. per Square inch. Authority. Fiddle-wood, West Indian . 66lO Fowke. Fir, red-pine, Norway . . . 14300 5375 ( Bevan and ( Hodgkinson. ,, Norway spruce I24OO ... Bevan. ,, American pitch-pine . . 7800 ,, larch, Northern Europe IOOOO 55oo French oak 7700 8000 Fustic, West Indian . I2I2O Fowke. Greenheart, yellow, Guianaian 8000 12 I 2O black : 543 Hawthorn, European . . . 10500 Bevan. Hazel 18000 tl Hickory, Australian . . . 7050 Fowke. Holly, European 16000 Bevan. Hornbeam . . . . 20240 8500 ( Bevan and 1 others. Iron-bark, Australian . 9920 Fowke. ,, rough-leaved, Australian 13220 5> Ironwood, West Indian 17630 M Kakaralli, Brazilian . . . I322O ti Kauri, New Zealand . 3900 IIOOO Laburnum, European 10500 ... Bevan. Lancewood, West Indian 23400 6610 C Bevan and { Fowke. Letterwood ,, . . . 14100 Fowke. Lignumvitae ,, . . 11780 9860 Lime-tree, European . . . 23500 Bevan. Locust, North American 16000 ... j} Mahogany, Spanish, West Indian 21000 8198 C Bevan and (_ Hodgkinson. ,, Honduras, Central | America . j 2800 6000 Maple 5IOO Mora 9920 Fowke. Mountain- Ash, Australian . . ... IIOIO Oak, British, average . IOOOO 10055 C Bevan and | Hodgkinson. ,, ,, very strong . . 19800 Bevan. ,, Dantzic .... 12650 7650 ,, red, North American . . IOOOO 5800 Orange-tree, wild, West Indian . ... 13230 Fowke. Pear-tree, European 13000 Bevan. Pine, pitch, European . . . 3970 6000 1 STRENGTH AND SPECIFIC GRAVITY OF TIMBER. 447 Table 105 continued. BREAKING STRENGTH OF TIMBER. Description. Tensile Strength in Ibs. per Square Inch. Compressive Strength in Ibs. per Square Inch. Authority. Pine, yellow, European 2340 3860 Plane, occidental, North American II7OO Be van. ,, common, European . . ... Plum-tree ,, II300 9300 . Poplar ,, . . . 72OO 5 I2 4 ( Bevan and | Hodgkinson. Quassia, West Indian . 55*0 Fowke. Rock-elm, American 8700 8200 Sabicu, West Indian . 4980 79 6 5 Satin-wood, West Indian . . 12560 Fowke. Saul, Asian .... 9640 Silverballi, Guianaian . . . 7716 Fowke. Small-leaf, West Indian ... J 543 J; Snakewood ,, . . ... 14000 Spruce 3820 Sweetwood, West Indian . . ... 9920 Fowke. Sycamore, European . ... Teak, South-Eastern Asian . . I5OOO I2IOO C Bevan and ( Hodgkinson. Wallaba, Guianaian . ... 6614 Fowke. Walnut, Western Asian . . . 8000 66OO Water-gum, Australian ... IIO2O Fowke. White-cedar, Guianaian . . . ... 9920 }} Willow, European Yellow-sanders, West Indian . . 6614 Fowke. Yew, European .... 8000 ... Bevan. Table 106. SPECIFIC GRAVITY OF TIMBER. Description. Specific Gravity. Water= i. Description. Specific Gravity. Water = i Abele .... '5 I 5 Beech .... 687 Acacia . . . . 710 Birch .... 710 African oak . 985 Canadian . . 603 Alder .... 558 Bitterwood . "557 Apple-tree . 790 Blackbutt, Australian . 7 80 Ash .... 755 Blue-gum . . . 910 Aspen .... 600 Blue-mahoe . '535 Bamboo . . . . 400 Box .... Q^S Baracara 808 Broadleaf 770 Bartaballi . . . 642 Brown-ebony(Guianaian) I'03O Baywood 560 Buckati . . . . 810 448 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 106 continued. SPECIFIC GRAVITY OF TIMBER. Description. Specific Gravity. Water = i. Description. Specific Gravity. Water = i. Buhuradda . 8l 5 Locust . . . . 710 Bullet-tree . . . I'027 Mahogany, Spanish 850 Cabacalli . 890 Maire, black . . . n6o Cabbage-bark . '943 Manuka, New Zealand . '944 Calabash . '555 Maple . . . . 670 Cedar of Lebanon . . 487 Mora .... 920 Canadian . 400 Moreton-Bay or hoop- Cherry-tree . . . 700 pine . . . . 470 Chestnut '535 Mountain-ash, Australian 1-070 Chow . ... I'lIO Mulberry . . . . 870 Cogwood 960 Oak, British, average '935 Cowrie, New Zealand . 580 Olive-tree . . . 690 Crab-tree 800 Orange,wild,West Indian 890 Cypress . . . . 658 Pear-tree 690 Dantzic-fir . 590 Pine, pitch . . . 663 Deal, white . . . 4 60 red . 655 yellow 553 white, Canadian . 446 Dogwood . . . '935 Plane . . . . i -642 Ducaliballi . 907 Plum-tree 780 Ebony, West Indian . . I' I 90 Poplar . . . . '5 X 5 Elder .... 700 Quassia '557 Elm .... 550 Rata, ironwood " . . i '046 Fiddle-wood 710 Rimu, red -pine, New Fir, red pine . . . 680 Zealand . 564 American pitch-pine 700 Rock-elm . . . 750 ,, red, Canadian . . 54 6 Sabicu .... 912 ,, larch . . . 530 Saul . ... 950 Flooded-gum . . . 683 Silverballi . 550 Fustic .... 960 Small-leaf, West Indian 1-165 Greenheart, yellow . . 1-050 Spruce . . . . 482 Hawthorn 912 Canadian . 416 Hazel .... 863 Stringy-bark, Australian 860 Hemlock, Canadian 504 Sweet-wood 968 Hickory . . . . 750 Sycamore '595 Holly .... 760 Tallow-wood, Australian 790 Hornbeam . . . 765 Teak, Indian 770 Iron-bark 1*030 African . . . 985 Iron-wood 985 Totara, New Zealand . 560 Kauri .... *557 Wallaba . . 1-030 Kowhai, New Zealand . 88 5 Walnut 675 Laburnum . . . 924 Water-gum . . . 998 Lancewood . . . 950 White-cedar . 510 Letterwood . '994 Willow .... 400 Lignumvitae . 1-327 Yellow-Sanders, W. Ind. 865 Lime-tree 765 Yew .... 800 SPECIFIC GRAVITY OF METALS AND ALLOYS. 449 Table 107. SPECIFIC GRAVITY OF CAST-IRON, WROUGHT-IRON, STEEL BRONZE, BRASS, TIN, LEAD, ZINC, AND OTHER METALS. Description. Specific Gravity. Water = i. Description. Specific Gravitv. Water = i. Lithium 58 Alloy, copper i, tin i . 8-00 Potassium . . . 8 4 Manganese . . . 8-04 Sodium '95 Pure iron by electro-de- Rubidium I- 5 posit (Dr. Percy) . 8-14 Calcium I '60 Bell-metal (small bells) . 7'5 Magnesium . . . 175 White-metal . 774 Glucinum 2-15 Muntz-metal . . . 8-22 Strontium 2-50 Yellow brass 8'33 Aluminium, cast . 2-60 Alloy, copper 2, zinc i . 8-34 ,, wrought 2-70 Brass, cast, good . . 8-40 Titanium 5'35 Brass-wire . 8-55 Arsenic . . . . 5-84 Cobalt .... 8-55 Chromium . 6-06 Nickel, cast . 8-30 Tellurium . . . 6-15 hammered . . 870 Antimony . . . 6-76 Ruthenium . 8-64 Zinc, cast 6-90 Gun-metal 8-65 ,, sheet . 7-20 Bronze 878 Alloy, tin 3, zinc i . . 7-22 Copper, cast . . . 870 Cast-iron, weak . 6'95 sheet 8-80 average . . 7*12 ,, hammered bars 8-88 ,, strong . . i 7-30 ,, wire 8-92 ,, white . . 7-50 Molybdenum . 8-66 Pewter .... 7-32 Cadmium . . . 874 Tin 7-40 Bismuth . . ^. . 9-86 Speculum-metal . 7H5 Osmium lO'IO Aluminium-bronze . . 7-67 Alloy, copper i, lead i . 10-35 Wrought-iron, common Silver, cast . . . 10-48 bars . . . . 7-50 ,, hammered . 10-58 Wrought-iron, puddled ,, wire . . . 10-65 slab .... 7-56 Rhodium 10-68 Wrought-iron rails . . 7-60 Lead, cast . . . 11-30 ,, bars, aver- pipe . 11-36 age good . 7-70 ,, sheet . 11-42 Wrought-iron, Lowmoor 7-80 Palladium . . 11-87 Steel, common 7-30 Thallium t I2'OO blister . . . 7-80 Mercury IS-SS compressed . 7-84 Tungsten . . . 17-70 Bessemer 7-85 Uranium 18-50 ,, Siemens-Martin . 7-85 Iridium . . . . 18-75 ,, crucible 7-86 Gold, cast . . 19-25 cast . . . 7-86 ,, hammered . . *9'37 i Homogeneous metal . 7.89 Platinum 2I'OO 450 THE PRACTICAL ENGINEER'S HAND-BOOK. Table 108. SPECIFIC GRAVITY OF VARIOUS MATERIALS AND LIQUIDS. Description. Specific Gravity. Water = i. Description. Specific Gravity. Water = i. Red iron-ore 5'2I Lancashire coal, Hay- Magnetic iron-ore . . 5-00 dock Rushv Basalt . . 2 '47 to 3-00 Park . . 1-32 Granite . . . . 2-95 Wigan cannel . I '2 3 Mica .... 2-85 Wigan 4 feet . t 1*20 Puzzolano . . . 2-84 Newcastle coals, West Limestone . 2-84 Hartley main I- 3 Slate .... 2-83 ,, Broomhill . . 1-25 White Parian-marble 2-83 Derbyshire coal, Staveley 1-27 Green-marble . . . 275 Parkgate 1-30 White Carrara-marble . 273 Welsh coal, Merthyr I- 3 Florentine-marble . . 2-50 Ebbw Vale 1-27 Jasper .... 275 Watney's Alabaster . . . 275 anthracite I- 39 Plate-glass . 270 Scotch coal, Eglington . 1-25 Pure rock-crystal . . 2-66 Dalkeith . 1-27 Quartz .... 2-65 ,, Kilmarnock 1-24 Purbeck-stone . . . 2'6o Patent coal, Warlich's . 1-15 Flint .... 2-59 ,, Livingstone's 1-14 Portland-stone . . . 2-58 Wylam's no Chalk .... 2'55 Average of a number of Crown-glass . . . 2-50 samples of Forest of Paving quartz 2-50 Dean coal 1-29 Yorkshire paving-stone . 2-47 Average of a number of Common glass 2-45 coals from various dis- Lias . . . . 2-40 tricts . . . . 1-31 Rock-salt 2'22 Mud-deposit from har- Bath-stone . . . 2'20 bour 1-50 Graphite 2-16 Plaster, cast . . . 1-29 Sandstone 2'12 Wine .... "00 Potash .... 2-08 Resin-oil . . . . *QO Sulphur . . . . 2-00 Castor-oil 96 Clay .... rQI Wax .... '95 Ivory . . . . I-9I Gunpowder . '94 Common salt, solid 1-90 Whalebone . . . '94 Sand, pure . 1-90 Ice .... '93 Tiles .... I-8 4 Linseed-oil . . . '93 Stone, mean of various . 2 'CO Sweet almond-oil . '93 Brick .... 2-00 Cotton-seed oil . . 92 Brickwork . 177 Whale-oil . 92 Mortar . . . . 170 Lard-oil . . . . 91 Lancashire coal, Ince Neatsfoot-oil 91 Hall Py I'34 Nut-oil .... 91 SPECIFIC GRAVITY OF SOLIDS AND LIQUIDS. 451 Table 108 continued. SPECIFIC GRAVITY OF VARIOUS MATERIALS AND LIQUIDS. Description. Specific Gravity. Water = i. Description. Specific Gravity. Water = i. Olive-oil QI Sea-water, ordinary . . I-O26 Rape-seed oil . . . QI Nitric-acid . I-27I Petroleum '89 Sulphuric-acid . . . 1-840 Sperm-oil . . . 88 Muriatic-acid I'200 Naphtha 85 Bromine . . . . 2-970 Benzine . . . . 83 Fluoric-acid . ro6o Wood-spirit . 80 Citric-acid . . . 1-034 Coke, hard . . . "QO Essential oil of cinnamon 1-043 Peat, hard "oO of lavender . 894 ,, soft . . . . 5 of turpentine 870 Wood-charcoal 24 ,, of amber 868 Water of the Baltic . . 1*015 Alcohol 835 Water of the Dead Sea . 1-24 Ether, nitric . . . 908 Milk .... 1-032 Proof spirit . 922 Cider .... 1-018 Vinegar . . . . 1*009 I Table 109. SPECIFIC GRAVITY OF GASES AND VAPOURS AT 32 FAHR. UNDER ONE ATMOSPHERE OF PRESSURE. Description. Specific Gravity. Air = i. Description. Specific Gravity. Air = i. Vapour mercury, ideal . 6-974 Carbonic-acid gas . . 1*527 Vapour of bromine . . 5-542 jj Nitrous-oxide gas . . 1*527 Chloroform . 5-297 Oxygen . . . . 1 i'io6 Vapour of turpentine . 4-694 Air .... I'OOO Hydriodic-acid gas 4'340 Nitrogen . . . . '974 Acetic-ether . . . 3-000 Carbonic-oxide 968 Vapour of benzine 2-695 Olefiant-gas . . . 967 Vapour of sulphuric Prussic-acid gas . '937 ether 2-579 Steam of water . . . '623 Vapour of ether . . j 2-557 Ammoniacal-gas . . '590 Chlorine-acid gas 2-500 Light carburetted hy- j Sulphurous-acid gas 2-500 drogen . . . -553 Cyanogen 1-805 Coal-gas . . . . '43 8 Alcohol . . . 1-613 Hydrogen . . . '069 The Specific Gravity of a Body may be found by dividing the weight in Ibs. of a cubic foot of the body by 62-355, the weight in Ibs. of a cubic foot of pure water at 62 Fahr. The Specific Gravity of a Solid Body heavier than Water, may be found by weighing it in the air, and again immersed in pure water at G G 2 452 THE PRACTICAL ENGINEER'S HAND-BOOK. 62 Fahr., and dividing the weight in the air by its buoyancy, or the loss of weight when immersed in the water. The quotient is the specific gravity. The Specific Gravity of a Solid Body lighter than Water may be found as follows : Weigh the body in the air, then load it with a body heavier than water, and large enough to sink the light body, and weigh them together in water ; also weigh the heavy body separately in air and in water. Subtract the buoyancy of the heavy body from that of the two bodies together, the remainder will be the buoyancy of the light body singly, by which its weight in air is to be divided. The quotient is the specific gravity. The Specific Gravity of a Solid Body which is soluble in Water may be found as follows : Weigh it in a liquid in which it is not soluble, divide its weight in air by the loss of weight in the liquid, and multiply the quotient by the specific gravity of the liquid. The product is the specific gravity required. The Specific Gravity of a Liquid may be found approximately as follows : Weigh a solid body in the given liquid, also in air and in water, divide the buoyancy, or loss of weight in the liquid, by the buoyancy or loss of weight in water. The quotient is the specific gravity. The Weight of a Cubic Foot of a Body may be found by multi- plying its specific gravity by 62-355. Table no. WEIGHT IN LBS. OF ONE CUBIC FOOT OF VARIOUS METALS. j Weight of Description. One ! Cubic Foot. Description. Weight of One Cubic Foot. Ibs. Ibs. Lithium 36 Steel-plates . . . 489 Potassium . . . 54 Steel, average 490 Sodium 61 Homogeneous metal 492 Rubidium 94 Manganese . . . 49 8 Calcium 99 Pure iron, by electro de- Magnesium . . . 109 posit (Dr. Percy) . . 508 Glucirum 130 Bell-metal (small bells) 509 Strontium . . . 1 59 White-metal . . . 5" Aluminium, cast . 159 Muntz-metal 512 wrought 168 Yellow brass . . . 520 Titanium 332 Brass, cast . 527 Arsenic . . . . 362 Brass-wire . . . 53 1 Chromium . 376 Cobalt .... 532 Tellurium . . . 380 Nickel, cast . . . 5i5 Antimony 420 ,, hammered 540 Zinc, cast . . . 428 Ruthenium 535 sheet . 450 Gun-metal . 540 Cast-iron . . . . 45 Bronze . . . . 545 Pewter .... 454 Copper, cast 538 Tin 456 sheet . . . 548 Speculum-metal . 464 hammered bars 555 Aluminium-bronze . . 480 ,, wire 554 Wrought-iron 480 Molybdenum . . . 535 WEIGHT OF STONE AND MINERAL SUBSTANCES. 453 Table no cont. WEIGHT IN LBS. OF ONE CUBIC FOOT OF VARIOUS METALS. Description. Weight of One Description. Cubic Foot, | Weight of Cubic^oot. Ibs. Ibs. Cadmium 542 Thallinum . 743 Bismuth . . . . 6l 7 Mercury, fluid . . . 848 Osmium 624 solid 977 Type-metal . . . 6 5 4 Tungsten . . . 1096 Silver, cast . 6 5 6 Uranium 1146 standard. . . 658*4 Jridium . . . . 1166 hammered . 660 Gold, standard 1102-9 Rhodium . . . . 661 Gold .... 1203 Lead .... 708 Gold, hammered . I2IO Palladium . . . 736 Platinum . . . . 1340 Aluminium is a remarkably light metal, its specific gravity being onlv about one-third that of steel. It is strong, ductile, easily wrought, and not liable to rust. The addition of a small quantity of aluminium to gun-metal and steel, greatly increases their strength. The tenacity of aluminium- bronze depends upon the purity of its copper ; it averages from 30 to 36 tons per square inch with 5 per cent, of aluminium, and from 40 to 48 tons per square inch with 10 per cent, of aluminium. Table in. WEIGHT IN LBS. OF ONE CUBIC FOOT OF STONE AND MINERAL SUBSTANCES. Description. Weight of One Cubic Foot Solid. Description. Weight of One Cubic Foot Solid. Ibs. Ibs. Coal, bituminous . 80 Flint and felspar . 165 ,, anthracite . . IOO Rock-crystal . . . 166 Earth and plaster . 9 Quartz and talc 169 Sand, dry . . . 9 Glass, crown . . . 156 damp . 1 20 plate . 169 Portland cement . . 92 flint . . . 187 Mud .... 105 Marble, Egyptian green 167 Mortar . . . . 109 Carrara . . 170 Brickwork . . . ! 112 Porphyry and trap 170 Marl and clay . . . 119 Limestone 170 Sulphur and tiles . 125 ,, magnesian . 179 Concrete . . . . 128 Granite . . . . 170 Potash . . -130 grey . 190 Rock-salt .. . . i 136 Slate . . 178 Masonry 140 Serpentine . 176 Sandstone . . . J 57 Basalt .... 188 Chalk . . . . . I 59 Iron ore, brown . 245 Shale .... 162 red . 328 454 THE PRACTICAL ENGINEERS HAND-BOOK. Table 112. WEIGHT AND BULK OF STONE. Description. Weight of One Cubic Yard. Number of Cubic Feet in One Ton. Ibs. Chalk 3170 I 9l 475O 13 Sandstone 3900 16 ,, ...... 22OO 14 Shale 4300 13^ Felspar 4370 13! Flint 445 I 3a' Limestone 4560 *34 ...... 4730 I2 4 ,, Magnesian . . . . 4800 12^ Quartz 4450 13^ Granite 4450 I 3 ,, ...... 4650 13 Basalt 5070 12 1 Table 113. WEIGHT IN LBS. OF ONE CUBIC FOOT OF DRY TIMBER. Description. Weight of One Cubic Foot. Description. Weight of One Cubic Foot. ' I Ibs. Ibs. Elder-pith . 5 Sycamore 35 Charcoal from pine . . T 3 Silverballi . . . 35 Charcoal from oak 15 Calabash 35 Cork .... 15 Bitterwood . . . 35 Poplar, Lombardy 24 Alder .... 35 Bamboo . . . 25 : White-deal, English . . 35 Willow 26 I Mahogany, Cuban 35 Pinaster . . . . 27 Red-pine, Norway . . 3 fi Poplar, Abele 27 Totara, New Zealand . 3* Lime-tree . . . 28 Cedar, Jamaica . . 37 Yellow-pine, American . 29 Cowrie 37 Weymouth-pine . . 29 Rimu, New Zealand. 37 : White-spruce, American 29 Crabwood, Guiana 38 Red-pine, Russia . . 30 Vine-tree . . . . 38 Larch .... 3 1 Aspen-tree . 38 Cedar of Lebanon 3i Spanish-chestnut . . 38 Norway-spruce 32 Poon . . . . i 40 Chestnut . ... 34 Swamp-oak 40 Blue-mahoe . 34 Bartaballi . . . i 40 Elm .... 34 Walnut, American . . 40 Memel-fir 34 Jungle-teak, Indian 40 Baywood . . . . 35 Yacca .... 40 WEIGHT OF DRY TIMBER. 455 Table 113 cont. WEIGHT IN LBS. OF ONE CUBIC FOOT OF DRY TIMBER. Description. Weight of One Weight of Description. One Cubic Foot. Cubic Foot. Ibs. Ibs. Plane-tree, occidental . 40 Buckati 51 ,, common 41 Yew . . . . 51 Maple .... 41 American white-oak 5 2 Cypress . . . . 41 Spanish-mahogany . . 53 Green - Mahogany, Ja' 42 Beech, Jamaica . 53 J arrow 42 Burute . . . . 53 Kullum . . . . 42 Hazel .... 54 Pitch-pine 42 Yellow-sanders, Jamaica 54 Riga-masts 42 Prune-tree ,, 54 Service-tree . 42 Stringy-bark 54 Walnut, brown . . 43 Oak, American 54 Lancewood . 43 Bibla .... 54 Locust-tree . . . 43 Kaieeriballi . 54 Purple-heart . 43 Sissoo . . . . 54 Olive-tree . . . 43 Tamarind, Jamaica 55 Prickle, yellow 43 Teak, Indian . . . 55 Cos 43 Cashaw 55 Beech .... 44 Blue-gum . . . 55 Lemon-tree . . . 44 Blackbutt, Australian . 56 Cartan .... 44 Kowhai, New Zealand . 56 White-cedar . . . 44 Mulberry 56 Orange-tree . 45 Blackwood . . . 56 Fiddle-wood . . . 45 Ducaballi . 56 Locust-tree, Guiana 45 Gymp . . . . 56 Birch .... 45 Ironbark, rough, AustTn 57 Teak, China 45 Cabacalli . ... 57 Cherry-tree . . . 45 Tallow-wood 57 Pear-tree 46 Wild orange-tree, Ja- Apple-tree . . . 46 maica . . . . 57 Crab-tree 47 Hawthorn 57 Hickory . . . . 47 Gray-gum . . . 57 Fir, Norway pine . 47 Mora .... 57 Dantzic-oak . . . 47 Laburnum 58 Oak sap-wood 47 Oak, English 58 Hornbeam 48 Walnut, green . . . 58 Holly .... Green-elm . . . 48 48 Monkey-pot . Mahogany, Australian . 58 58 Moreton Bay, AustTn . 48 Manuka, New Zealand . 59 Matai, New Zealand 49 : Dogwood . . . 59 Sweet orange-tree . 50 Flooded-gum, AustTn . 60 Rock-elm . . . 5 Puriri, New Zealand 60 Baracara 5 Sabicu .... 60 Acacia . . . . 51 Satin-wood . . . 60 456 THE PRACTICAL ENGINEER S HAND-BOOK. Table 113 con/. WEIGHT IN LBS. OF ONE CUBIC FOOT O.F DRY TIMBER, Description. Weight of One Cubic Foot. Description. Weight of One Cubic Foot. Ibs, Ibs. Cog-wood 60 Paloo .... 66 Mee .... 60 Rata, New Zealand . . 66 Sal .... 60 Greenheart . 67 True-box . . . 60 Kakaralli. . . . 68 Sweet-wood, Jamaica . 6l Bastard-box . 70 Fustic ,, 61 Mountain-ash, Australian 70 Oak, European . 61 Ebony . . . . 7i Tonka . . . 61 Caluvere . . . . 72 Erroul . 61 Small-leaf . 72 Iron-wood . . . 62 Lignumvitse, Jamaica . 73 Teak, African 62 Ironbark, white, AustTn 73 Woolly-butt . . . 62 Box, Ilwarra . . . 73 Letter-wood, Guiana 63 Maire, black 73 Lance-wood . 42 to 63 Oak, heart of . . . 73 Water-gum . 64 Oak, black . 75 Wallaba .... 64 Ebony, black . . . 75 Brown ebony, Guiana . 65 green 76 Boxwood . . . . 65 Boxwood of Holland 83 Rosewood 65 Lignumvitse . .41 to 83 Bullet-tree . . . 65 Pomegranate . . . 85 Table 114. WEIGHT OF LIQUIDS AT 32 FAHR. Description. Weight of One Cubic Foot. Weight of One Gallon. Ibs Ibs. Ether, sulphuric 44'9 7'2 Alcohol, pure 49'3 7-9 proof spirit .... 57'4 9*2 Wood, spirit 49'9 O'O Oil, linseed 587 9'4 ,, olive 57-1 9-15 ,, whale 57'4 9-2 ,, turpentine 54'3 8-7 Naphtha 53' 1 8'5 Petroleum 54'9 8-8 Wine, Burgundy . 61-9 9-9 Sea-water, ordinary 64-05 10-3 Milk 64-30 10-3 Acetic acid, maximum concentration 67-4 10-8 Nitric acid 76-2 I2'2 Water of the Dead Sea . . . . 77'4 12'4 Sulphuric acid, maximum concentration 114-9 18-4 Mercury 848-75 136-0 INDEX. A BERDARE-COAL, composition of, , evaporative power of, 106. Absorption, 96. Acid water, to purify, 212. Action of flame in boiler furnace-tubes, 93. of injectors, 200, 203. Actual or indicated horse-power, 375. evaporative efficiency, 103. evaporative power of coal and other fuels, 107. power developed by combustion, 92. Adamson's flanged seam, 215. Admiralty allowance for the bulk of coal, 52. knot, 355. Air, 3, 10. , compression of, 4 6. consumed per Ib. of combustible, in experiments with boilers with natural draught, 121, 122. , effect of an excessive supply of, to a furnace, 122. , force of, 10, n. , heat in the, 6. , hot, evolved by combustion, 84 , increase in volume of, due to eleva- tion of temperature, 6, 7- or relief-valve for a steam-chest, 298. , quantity chemically consumed, 82. , quantity and temperature of, in boiler-furnaces, 84. required for combustion, 82. , specific heat of, 41. supplied to boiler-furnaces, 84, 121. , temperature of, 6. , vitiation of the, by the products of combustion, 83. , warm forced draught with, 126 128. , weight of, 4. , weight of, required for combustion per Ib. of coal, 82, 121. Air-pressure in stokeholds, effect of, 1 1 2, "3- , influence of, on evaporation and combustion, 112, 113.. Air-pump, method of measuring the quantity of water delivered by an, 273, 274. capacity, cooling-surface, and quan- tity of circulating-water provided for the surface-condensers of marine-engines, 271. lever, 270. valves, 271, 272. Air-pumps, capacity of, for jet-condensers, 270. , capacity of, for surface-condensers, 271. , horizontal, 267, 268. , vertical, 266, 267, 269. and condensers, 264 272. Air-space round steam-pipes, 98, 99. Air-valve for condensing engines, 260, 261. Alcohol, vapour of, 84. Alder and ash, 428, 444, 445, 447. Alloys for fusible-plugs, 224. Alloys, strength of, 442, 443. Aluminium, 449, 452, 453. , specific gravity of, 449. Aluminium-bronze, strength of, 442, 453. Ammoniacal gas, weight and volume of, 85- Analysis of coal, 54, 55. of steel for crank-axles and crank- shafts, 330. of water-gas and coal-gas, 62. Aneroid barometer, 9. A ngle of a screw-propeller, 344. Angle-iron, strength of, 430, 432, 439. hoop for furnace-tubes, 215. Angle-steel, strength of, 430, 433, 434. Annealing steel-plates, 1 54. Anthracite-ash coverings for steam-pipes, 99- coal, 50, 52, 91, io5. Antifriction-metal, 326, 402, 406. Apparatus for measuring water from con- densing-engines, 273. Area, projected and expanded, of screw- propellers, 345, 352. of blade of screw-propeller, 345. of chimneys, 229, 230. of cylinder per nominal horse-power, 37 2 - of disc of screw-propellers, 345. of fire-grate, power developed by a given, 114 1 1 6. of fire-grate surface per Ib. of coal burnt, 114. of opening given by a slide-valve, 289. of pump-barrels, 278. of safety-valves, 186, 195, 196. of tubes of feed-water heaters, 2IO. Asbestos coverings for steam-pipes, 98, 99- Ashes, heat-conducting power of, 97. Asphalte, evaporative-power of, 106. 458 INDEX. Atmosphere, mean pressure of the, 7- , temperature of, 6. Atmospheric air, 3. , weight of, 4. , weight and volume of, 84, 85. Atmospheric-pressure, 7, 9. Atmospheric-resistance, 8. Automatic barring-engine, 408, 410. expansion-gear of non-condensing compound engine, 414. injectors, 201 207. Axial Girard-turhine, 32. Axles, crank, of locomotives, 328, 329. "DALANCED cranks, bolts for the ** balance-weight of, 327. slide-valves, 295 298. Balls for safety-valves, 185. Barker's fuel, 52. Barometer, aneroid, 9. , ordinary, 8, 9. Barring-engine, 408, 410. Bars and plates of wrought-iron and steel, strength of, 430 440. Basketfuls of coal burnt on a steam-ship, Bays, measurement cf water flowing over, 23, 24, 274, 275. Beech, birch and box, 428, 445, 447. Bending, strength of shafting to resist, 333- Bent cranks, 330. Benzine, vapour of, weight and volume of, 85. Bessemer-steel, strength of, 435. Bituminous coal, 50, 52, 91. Blade of screw-propeller, surface of, 346. Blast-pressure in a chimney, effect of, 108. Blow-off, silent, for marine safety-valves, 197- cocks, 224, 225. Blowing off, 19 22. , feed-water, required when, 18. , loss of heat by, 21. Blown-out rivet, 225. Blue-gum-leaveo for preventing scale in steam-boilers, 212. Board, notched, measurement of flowing water by a, 23, 24, 274, 275. Board of Trade, proportions for riveted- joints, 133, 134. rules for propeller-shafting, 335. rules for safety-valves, 186188. rules for safety-valves, illustrations of, 188190. rules for steam-boilers, 145 160. Boiler blow-off cocks, 224, 225. , egg-ended, 95. , evaporative performance of, 108 113, 177, 178. -explosions, 230 240. -explosions, causes of, 230 232. Boiler-furnace-tubes, collapsing pressure of 144. furnaces, temperature in, 95. -plates, arrangement of, 129. plates, soundness of, 130. plates, strength of, 129, 130. -plates, steel, 130. plates, steel, strength of, 430, 432 -plates, wrought-iron, strength of, 430, 433, 438, 439- scale, 211, 212. -setting, 216. -shells, 142, 143. -tubes, 174 176. tubes, action of flame in, 94. Boilers, arrangement of plates, 129. , bursting-pressure of, 143. , butt-straps, B. T., 150. , circular furnaces, B. T. , 151. , collapsing-pressure of the furnace- tubes of, 144, 145. , compressive stress on tube-plates, B. T., 147, 155, 159. , construction of, 213 224. , Cornish, construction of, 213, 214. , corrosion of, 232 235- , corrugated furnaces, B. T., 152. , defects in the design, workmanship and material of, 239. , diameter of rivet, B. T., 150. , diameter of shell of, 142. , dished-ends, B. T., 150 , effect of feeding with cold water, 206, 207. , efficiency of, 104, 108, 177, 178. , equivalent evaporation, 104, 105, 178, 1 80. , evaporative performance of, 108 113, 121, 122, 128, 129, 240. , expansion hoop for furnace-tubes, 215. , feed-water, consumption in, 178, 199. , feed-water heaters for, 208211. , feed-pumps for, 199, 200. , fire-box, roof-stays of, 146, 154, 156, 171, 172. , fire-grate-surface, and heating-sur- face of, 114 1 20. , flat-ends of, B. T., 153. , flat-surfaces of, B. T., 147. , Galloway, 216, 217. , girders for flat-surfaces, B. T., 146. , horse-power of, 178 180. , illustrations of the Board of Trade rules for, 156 160. , illustrations of Lloyd's rules for, 165 -167. , injectors for, 200207. , Lancashire, construction of, 214. , Lancashire, test of, 240. I , Lloyd's rules for, 160 169. i , locomotive, 218, 219. INDEX. 459 Boilers, locomotive, evaporative perform- ance of, 1 08, in. , manholes and openings, B. T., 150. , marine, 115, 116, 220 224. , perforated steam-pipe of, 176. , proportions of riveted -joints of, 130 141. , quantity of water evaporated by dif- ferent types of, 108 113, 121, 122, 128, 178. , safety-valves for, 180198. , stays of, B. T., 146, 158. , steam-space, 176. , steel, B. T., 153, 155. , steel, compressive stress on tube- plates, B. T., 154, 155. , steel, constants for flat surfaces, B. T., 154. , steel, furnaces, plain and corrugated, B. T., 154. , steel, perforating and annealing, B. T., 154. , steel, plate and rivet section, B. T., J 55- , steel, stress on stays, B. T., 154. , steel, tensile stress, B. T., 153, 154. , steel, tests, B. T., 153. , steel, welding, B. T., 155. , strength of the joints of, B. T., 150. , strength of plates, 129, 130. , strength of shell of, 142. , strengthening-rings for furnace-tubes, 215. , strengthening-ring for manhole, 215. , superheaters, B. T., 152, 153. , thickness of furnace-plates of, 173, 174. , thickness of plate for flat surfaces of, 173- , thickness of shell-plates, 172. , thickness of tube-plates of, 173, 174. , to preserve when not in use, 239. using vegetable-refuse fuel, fire-boxes of, 77. , vertical, 217. , water to be pumped into to raise the water-level, 280. , water-tube, 226 228. , working-pressure of, B. T. , 145. , working-pressure of boiler-shells, 142. , working-pressure on screwed stays for flat surfaces, 158. , working-pressure of furnace-tube, 144. , working-pressure on roof-stays of combustion-chamber or fire-box, 146. , zigzag riveting, B. T. , 1 50. , method of testing, 240. Boiling-points of sea- water, 17. Bolt-iron, strength of, 430 432. tolls for couplings of screw-propeller- shafting, 332. for cylinder-covers, 395. Boss of screw-propeller, 345. Brass, strength of, 442. Brass-wire, strength of, 443. Brass and bronze, specific heat of, 41. Breeze, evaporative power of, 79. , pressure of, n. Bremme's valve-gear, 311, 312. Brickwork of combustion-chambers burn- ing liquid-fuel, 72. Bridge-plates, strength of, 430, 439. Brighton Railway, consumption of coal on, per ton of train, 89. , evaporative performance of locomo- tive-engine-boilers on' the, 109. Brine, pressure of steam to expel, 20. , saturated, 17. British unit of heat, 40. Bronze or gun-metal, strength of, 442. , aluminium, strength of, 442, 453. , phosphor, strength of, 442, 443. , silicium, wire, strength of, 444. Uuckets of turbines, 30, 32, 34. of water-jet motors, 34. Built-up crank-shafts, 322. crank-shafts for triple expansion en- gines, 322324. Bulk of coal, 52. of coke, 52. of gunpowder, 53. of petroleum-refuse, 53. of wood, 53. Bunkers, coal, 53, 54. , to find the dimensions of, 53. Burning coal-dust, coke-dust, breeze and similar refuse-fuels, 78 80. liquid-fuel, 69 74. refuse-fuel, 67 74, 7680. straw, 77. vegetable-refuse-fuel, 76, 77- Bursting of steam-boilers, examples of, 230 240. Bursting- pressure of cylindrical boilers, H3- Bushes for crank-shafts, metal for, 326. Butt-straps, 150. /"* ABLE-IRON, strength of, 431, 432. ^ Calculations for pumps, 2SI. Calorific power of coal-gas, 59, 62. of combustibles, 5759, 62, 65, 66. of water-gas, 62. Calorimeters, 42, 43. Canals, evaporation from the surface of water in, 15. Capacity for heat, 42. of air-pumps for jet - condensers, 270. of air-pumps for surface-condensers, 271. of a pump-barrel, 278. of circulating-pumps, 264. of condensers, 260. stowage of fuels and stores, 53. 460 INDEX. Carbon, 54, 56. , heating-power of, 57. Carbonate of lime in feed-water, 211, 212. Carbonic-acid, 3. -oxide gas, 84. Carburetted hydrogen, 85. Castings of steel, composition of, 429. , strength of, 430, 435. Cast-iron cranks for large pumps, 330. Cast-iron, expansion of by heat, 48. liners for cylinders, 389. , specific heat of, 41. , tensile and compressive strength of, 440, 441. Cast-steel, strength of, 435, 436. fire-box roof-stays, 172. Causes of loss of efficiency of turbines, 27. of steam-boiler explosions, 230 232. Chaff-coverings for steam-pipes, 99. Chain-iron, strength of, 431, 432. Chalk-waters, to purify, 212. Charcoal iron-wire, strength of, 443. Chemical composition of combustibles, 57. Chimney, effect of air-blast in a, 108. , effect of a steam-blast in a, 108. draught, 85, 86. Chimneys for steam-boilers, 228 230. , size of, for factory-boilers, 229, 230. , temperature of the gases in, 94. Chisel-steel, strength of, 437. Chloroform, weight and volume of, 85. Circular-furnaces of boilers, 151, 152. Circulation of water in boilers, loo. Circulating-pumps, 264, 265. -water for condensers, 262, 264, 271. Classes of turbines, 26. Clay-coverings for steam-pipes, 99. Clear-burning coal, 5- Closed stokeholds, 112. Coal and other fuels, 50. , anthracite, 50, 52, 91. , anthracite, cost of per train-mile in locomotives, 91. , anthracite, bituminous, clear-burning, flaming, fuliginous, Newcastle, Welsh, 50. , bituminous, cost of per train-mile in locomotives, 91. burnt on a voyage, 87, 89, 116. burnt in a watch, 88. burnt per day, 88. , bulk of, 52. , composition of, 51. consumed by locomotives, 89. -consumption per train-mile, 89. , evaporative-power of, 106, 107. -heating, power of, 52, 58. , practical analysis of, 54, 55. , quantity left at the end of a voyage, 88, 89. , rate of evaporation of various, III. , space required to contain, 54. , specific gravity of, 51* S3- , weight of, 50 52. Coal-ashes, covering for steam-pipes, 99. Coal-bunkers, 53. Coal-dust and saw-dust, evaporative-power of a mixture of, 107. , evaporative-power of, 79> 107. -fuel, burning, 78, 80. Coal-gas, composition of, 59, 62, 83. , heating power of, 59, 83. Coil for heating water, 209. Coke-heating, power of, 58. , patent, 52. , weight of, 52. Cold-blast cast-iron, strength of, 440. feed-water, effect of in boilers, 206, 207. -rolling, effects of on iron, 440. surfaces, steam condensed by, 262, 263. water poured into a hot-boiler, effect of, 236. Collapse of furnace- tubes from over-heating, 2 37- Collapsing-pressure of furnace-tubes, 144, 145- Column of air, 8. of mercury, 7, 8. of water, 7, 8. , pressure of, 10, 15. Colza-oil, composition of, and heat evolved by the combustion of, 83. Combustibles, chemical composition of, 57. , heat developed by, 57 59. , heat evolved by, 65, 66. Combustion, 56, 81. , air required for, 82. , forced, 112129. , force developed by, 92. , influence of air-pressure on, 112. in steam-boilers, rate of, 91. of various coals, rate of, 92. , products of, 82, 83. Combustion-chamber, stays for, 146, 154, 156. -chamber for burning of liquid-fuel, 6973- Communication of heat, 96. Comparative trials of a locomotive burn- ing petroleum, anthracite, bituminous coal and wood, 91. Compensating-rings for manholes and other openings in boilers, 150. Components of the salts of sea- water, 16. Composition, heating-power and evapora- tive-power of crude petroleum-oil, 90. of condenser-tubes, 265. of coal-dust fuel, 79. of coal-gas, 59, 62. of sea-water, 16. of steel-wire, 437. of water-gas, 62. and weight of coal, 51. Compound-engines, conversion of, to triple expansion engines, 418. INDEX. 461 Compound-engines, diameter of cylinders cf, 386. , economy of, 385. , non-condensing, 410, 412 414. , rules for nominal horse-power of, 371373. Compound surface-condensing screw- engines, 415. Compressed-steel-shafting, rules for, 332. Compression of air, 4 6. Compressive strength of cast-iron, 440. strength of ice, 14. strength of timber, 444 447. stress on tube-plates of iron, 147, 148, 159: of steel, 154, 155, 160. Condensation of steam, 253, 255. of steam in condensers, 257 271. loss from in engine cylinders, 424. Condensed steam, water from, 209, 379. Condenser, capacity of, 260. , ejector, the, 261. jet, 259, 260, 268. , power obtained by using a, 257. , temperature of water in, 258. tubes, 264, 265. tubes, packings for, 265, 266. , vacuum in, 257. Condensers, surface, air-pump capacity, cooling surface and quantity of water provided for in marine engines, 271. , surface, 115, 261 268. , water for, 258. Condensing-engines, efficiency of steam in, 257- , air-valve for, 260, 261. , method of testing, 273 277. , nominal horse-power of, 367, 368. Condensing-water, heat carried off in, 272, 276. Conduction of heat, 97. Connecting-rods, 315320. , diameter of, 317. for locomotive engines, 319, 320. for marine-engines, 315 317. for stationary-engines, 316, 318. Connecting-rod-bolts, 317. Constantsforflat-surfacesof iron-plates, 147 : of steel-plates, 154. Construction of feed -water heaters, 209. of steam-boilers, 213 224 Consumption of coal by locomotives, 89. of coal in triple and quadruple ex- pansion engines, 93, 1 16. of coal in a voyage, 87, 116. of coal per indicated horse-power, 88, 116. of coal per indicated horse-power by stationary, portable, locomotive and marine engines, 92. of coal per nominal horse-power, 92. of coal per train-mile, 89. of coal, speed of steamship due to a given, 87. Consumption of coal, variation of, in marine boilers, 87. of fuel by hot-air engines, 63. of fuel in steam - boiler furnaces, 81. of gas by gas-engines, 61. of petroleum-refuse fuel, 90. Contents of tanks, 282. Contraction of boiler-plates, from cold-feed water, 208. of wrought-iron in cooling, 49. Convection of heat, 100. Conversion of compound engines to triple- expansion and quadruple-expansion engines, 418, 420. Cooling, contraction of iron in, 49. surface of surface-condensers, 115, 262, 264, 271. -water, velocity of, through surface- condensers, 264. -water for surface-condensers, 262, 264, 271. Copper, strength of, 442, 443. -wire, strength of, 444. Cork-coverings for steam-pipes, 99. Corliss-engine, 408, 409. cylinder, 409. Corliss-valves, 301, 409. valve-gear, 301, 302. Cornish-boilers, causes of explosion of, 230. , construction of, 215. , evaporative performance of, 107, 108, in. , setting, 216. Corrosion of boilers, 232 235. of boilers, use of zinc for preventing, 234- Corrugated furnace-tubes, L., 168, 169. , strength of, 167 169. , thickness of, 174. Corrugated furnaces of iron-plates, 152, 160 : of steel-plates, 154, 160. Cotton and cotton-seed coverings for steam- pipes, 99. Counterbalanced-levers of safety-valves, 185. Couplings for crank-shafts, 325, 326. and bolts for screw-propeller shafting, 33 2 - Coupling-rods of locomotive engines, 319 321. Coverings, non-conducting, for steam- pipes, 98, 99. Crank and eccentric, 285. , counter-balance weight for, 3 2 7' , proportions of, 326. Cranks and eccentrics of a locomotiye- engine, 285. , bent, 330. of triple-expansion engines, arrange- ment of, 387. , three-throw, for pumps, 330. 462 INDEX. Crank-axles, locomotive, 328, 329. and crank-shafts, analysis of steel for, 330. axles and crank-shafts, failure of, 329. Crank-pin, strain on a, 326, 327. shaft-couplings, 325, 326. -shaft -journals, 325, 326. Crank-shafts, causes of straining, 329, 330. , diameter of, 324, 325. of marine-engines, 322 327. of marine-engines, built up, 322. of triple-expansion marine-engines built up on Mr. J. P. Hall's system, proportions and weight of, 322 324. Crank-webs, to proportion, 325, 326. Creosote-oil as liquid fuel, 59, 73, 74. , evaporative power of, 106, 107. Crossheads, locomotive-engine, 403. , marine -engine, 405, 406. , stationary-engine, 404. , strength of cotter of, and cross-head- pin, 403. Cross-tube boilers, vertical, 217. Crucible-steel, strength of, 436. Crude-petroleum-oil, evaporative power of, 90, 107. , heating-power of, 90. Cubic foot of air, weight of, 4. foot of ice, weight of, 14. foot of sea- water, weight of, 15. foot of snow, weight of, 14. foot of water, weight of, 14. yard of sea-water, weight of, 15. Cushioning, 286. Cut-off by a slide-valve, point of, 288. Cylinder, expansion of steam in a, 377 384- , mean-pressure of steam in a, diagram of, 380. , mean-pressure of steam in a, rules and table for, 381384. of a Corliss engine, 409. of gas-engine, 61. of a steam-engine, to find the diameter of a, 384, 385. Cylinder-area per nominal horse-power, 372. covers, bolts for, 395. escape-valves, 395. metal, test for, 393. Cylinders, metal for liners for, 389. of compound engines, ratio of, 385. of compound marine-engines, pro- portions of, 392. of horizontal and vertical stationary engines, proportions of, 392. of locomotive-engines, thickness of and metal for, 390. of marine-engines, metal for, 393. of marine-engines, thickness of, 389. i of quadruple-expansion-engines, ratio of, 388, 389. , condensation of steam in, 424. Cylinders of stationary-engines, metal for, 391- of triple-expansion-engines, ratio of, 115, 386, 387, 393, 394. of triple-expansion-engines, velocity of steam through, 393. thickness of liners for, 389. Cylindrical-boiler shells, L., 161, 162. shells, strength of, 142. "P)EAD-WEIGHTED safety-valves, 197, *"^ 198. Deep bore-holes, temperature of, 39. mines, temperature of, 40. sea-water, temperature of, 38, 39. Defective workmanship and materials of steam-boilers, 239, 240. Defects in the design of steam-boilers, 239. Deficient lead of slide-valve, 286. Degrees, Fahrenheit, centigrade and Reau- mur, 37. Delineation of a screw-propeller, 339 34i- Density of coal, 52. of sea-water, 17. of sea-water in boilers using it, 22. of steam, 244, 246. Derbyshire coal, composition of, 51. , evaporative power of, 106. Diagram of an expansion slide-valve, 293. of the mean-pressure of steam in a cylinder, 380. of the motion of a slide-valve, 292. of a turbine, 28. showing lap of slide-valve, 292. : weight of steam shown by a, 424. Diameter and stroke of pumps, 279. of a boiler-shell, to find the, 142. of connecting-rods, 317. of connecting-rod-bolts, 317. of crank-shafts, 324, 325. of cylinder of compound -engines, 385, 386. of cylinder of condensing-engines, 384. of cylinder of a steam-engine, to find the, 384. of cylinder of non-condensing-steam- engines, 384. of cylinder per indicated horse-power, 385. of feathering paddle-wheel, 360. of the nozzle of an injector, 201. of piston, 396. of piston-rings, 399- of piston-rod, 400, 401. of rivet, 131 134, 150. of rivet-holes in soft steel-plates, 139. of screw-propeller, 345. of screw-propeller-shafting, 331. of screwed stays for boilers, 158. of a shaft for a given strain, 334. of swelled portion of a stay, 159. INDEX. 463 Disc-area of blade of screw-propeller, 345. Disc-constants for screw-propeller, 352. Discharge of feed-water in boilers, 207. Dished or flanged plates, 161. Dished-ends of boilers, 150. Displacement of ships, 353, 354. , piston, 396. Double-beat valves, 301. ended marine boiler, 221, 222. expansion engines, nominal horse- power of, 371373- -ported slide-valve, 289. Dowson's water-gas. 62. Draught, induced, 128, 129. in chimney, 85, 86. , natural, air required for combustion with, 82, 121. , natural and forced, trials of boilers with, 112, 113, 116, 120128. Drier, steam, 253. Driving-power of flowing water, 25. , temperature of the, 39. - 1 ' Easing- vaive, 196. Eccentric, angle of advance of, 285. , diagram showing position of an, 292. , radius of, 285. Eccentrics 'and eccentric-straps of locomo- tive-engines, 306, 307. and eccentric-straps of marine-engines, 308. and eccentric-straps of stationary- engines, 302, 307. Economical piston-speed, 396. Economy effected by heating feed-water, 208. , maximum of steam, 379. of compound engines, 385. of high-pressure steam, 244. of triple-expansion engines, 387. Effect of carbonic acid gas, 3. of heat on coal, 56. of heat on water, 100. Effective mean-pressure of steam on the piston, 381384. mean-pressure of steam on the piston, table of, 383. power of hot-air engine, 65. Efficiency, evaporative, 103. of an engine, 256. of the heating-surface of a boiler, 119. of pumps, 277. of steam in an engine, 256. of steam-boilers, 104, 108, 177, 178. Efficiency, loss of, in the steam-engine, 424. Egg-ended boilers, 95. , causes of explosions of, 230. , evaporative performance of, 1 08, 1 1 1. Ejector-condenser, the, 261. Elasticity, modulus of, 428. Elastic limit of iron and steel, 429. Electrogen, the, 235. 2nd-thrust on screw-propeller-shafting, 335- Engine, efficiency of an, 256. test, mode of carrying out an, 275 277. Equilibrating-ring for slide-valves, 294, 295. Equivalent weight of water evaporated to steam, 104, 105, 179, 180. Escape-valves for cylinders, 395. Estimation of carbon and hydrogen in coal, of water in coal, 54. Eucalyptus leaves, for preventing scale in steam-boilers, 212. Evaporation, equivalent, 104, 105,179, 180. from the surface of water in lakes, canals, and rivers, 15. of water in steam-boilers, 103. per square foot of total heating sur- face, rate of, in, 178. , rate of, per square foot of fire-grate surface, in, 114. , rate of, with various coals, III. Evaporative-efficiency, 103, 108, 177, 178. Evaporative-performance of steam-boilers, 108113, 177, 178, 240. Evaporative-power of breeze, 79, 80. power of breeze and slack, 79, 106. -power of coal, 106 107. power of coal-dust fuel, 79- power of coke, 106. -power of fuel, 105 107. -power of lignite, 106. -power of patent-fuels, 106. -power of peat, 106. power of petroleum, 106, 107. power of crude petroleum-oil, 90. power of straw, 106. -power of tan-refuse, 106, 107. power of wood, 106. tests of modified locomotive type of boilers for torpedo-boat catchers, 113. Excessive lead of slide-valve, 286. Exhaust-lap of slide-valves, 287. steam, heat carried off in, 272. steam, heating water by, 204, 206, 209, -steam, quantity of, used by an ex- haust-steam injector, 206. steam, velocity of in triple expan- sion-engines, 393. -steam injector, 202 207. -steam injector, quantity of water de- livered by an, 207. Expanded-area of screw-propeller-blade, Expansion and contraction of boiler-plates, unequal, due to cold feed-water, to cal- culate the strain caused by, 207, 208. Expansion-gear of non-condensing com- pound engine, 414. Expansion-hoop for furnace-tubes, 215. links, 303305- of air by heat, 7. 464 INDEX. Expansion of metals by heat, 46 49. of steam, 243. of steam in a cylinder, 377 384. of steam, ratio of the, 288, 384. of superheated steam, 251, 252. of water by heat, 15. of water in freezing, 14. -slide-valve, diagram of an, 293. -valve, gridiron, 289. valve, separate, 290 293. -valve, with fixed cut-off, 291. -worked valve on drain-pipe, 47. Experiments on boilers with natural draught and with forced draught, 121 128. Explosion of gaseous mixtures, pressure produced by the, 62, 63. Explosions of steam-boilers, 230240. External corrosion of steam-boilers, 232. TRACTOR of evaporation, 105. of safety of materials, 429. Factory-chimneys, rules for, 229 231. Fahrenheit, degrees, 37. thermometer, 36. Failure of crank-shafts, causes of, 329, 33- Feathering paddle-wheels, 358, 361. screw-propellers, 356. Feed-back-pressure valve, 200. discharge, position of, in boilers, 207. -pumps for boilers, 199, 200. water-consumption in steam-boilers, 178, 199. -water, delivery of, 207. -water, effect of cold, 207, 208. water heaters, 208 211. -water heaters, proportions of, 210. water heating, economy of, 208. -water heating by exhaust steam, 204, 206, 209. -water-pipes from injectors, 205. water, quantity derived from, in the exhaust- steam injector, 205. water, temperature in injectors, 200. -water, saltness of, when using sea- water, 20. water, scale-forming substances, 21 1. -water, to purify, 212. Feeding boilers with injectors, 200 207. with injectors, evaporative effect of, no. Felt-coverings for steam-pipes, 97, 99. Ferrule for screw of spring-balance, 185. Ferrules, wood, for surface-condenser- tubes, 265. Final temperature of steam in a cylinder or condenser, 256. Fire-box, collapse of, from corrosion and over-pressure, 231. , heating surface of, in locomotive- boilers, 117. Fire-box of boilers using vegetable-refuse fuel, size of, 77. Fire-box plates, steel for, 430. roof stay- bolts, 171. roof stays, 146, 154, 156. roof stays, cast-steel, 172. roof stays of locomotives, 171, 172. side-stays, 146, 154, 156, 222. Fire-boxes, arrangement of, for burning liquid-fuel, 70 73. Fire-grate surface and heating-surface, 1 1 4 1 20. and heating-surface, relation of, 118. , water evaporated per square foot of, in. Flame, action of, in furnace-tubes, 93. , action of, in boiler tubes, 94. Flaming coal, 50. Flanged seams for furnace-tubes, 214, 215. Flat-faced safety-valves, 183, 192. Flat plates supported by stays, strength of, L., 163. Flat surfaces of boilers, staying the, 146, H7, 154- of boilers, thickness of plate for the, I73. Floats of paddle-wheels, 361. Flowing water, measurement of, 23 25, 274, 275. Flow of steam through safety-valves, 180, 181, 194. through an orifice, 250. Flue-tubes, or furnace-tubes, collapsing pressure of, 144, 145. , working-pressure of, 144. Foaming in steam-boilers, 1 14. Force developed by combustion, 92. , expansive, of water in freezing, 14. of wind, 10, ii. Forced combustion, 112 129. draught, advantages of, 120. draught, tests of boilers with, 112, 113, Il6, I2O, 122 129. draught, with warm air, 126, 128. Fossil-meal covering for steam- pipes, 98. Fractured boiler-plates, causes of, 238, 239- furnace-plates from over-heating, 237. Fresh water, pressure of a column of, 15. , volume of, 14. , weight of, 14. Friction of slide-valves, 294. of steam-engines, 377. Frontispiece, description of engines shown in, 415418. Fronde's formulae for screw - propellers, 350352. Fuel, 50. , Barker's. 52. , evaporative-power of, 105 107. , Holland's, 52. , liquid, 58, 6774. , Livingstone's, 53. INDEX. 465 Fuel, lots of, by blowing-off, 21. , loss of, due to a high temperature in a funnel, 86. Mezaline's, 52. patent, 52. Penrose & Richard's, 52. specific gravity of. 41, 53. Warlich's, 52, 53. Wylam's, 52, 53. Fuels, radiant power of, 94. Fuliginous coal, 50. Funnel, flame issuing from, 86. , loss of fuel due to a high tempera- ture in, 86. , temperature of smoke in, 86. Furnace for burning coal-dust, 78. -plates fractured from over-heating, 237- plates, thickness of, 173, 174. -tubes, collapsing-pressure of, 143, 144. tubes, flanged seams of, 215. tubes of boilers, strengthening-rings for, 215. tubes, plain and corrugated, L., 168. tubes, working-pressure of, 151, 152. Furnaces, corrugated, of iron-plates, 152. of steel-plates, 154. Furrowing, corrosive, 235. Fusible-plugs, 224, 225. (~*ALE, pressure of a, 11. ^ J Gallon of pure water, 14. Gallon of sea-water, 17. Galloway-boiler, 216, 217. , evaporative performance of, 108, in. Gas, ammoniacal, weight and volume of, 85- , carbonic acid, 3, 84. , carbonic acid, weight and volume of, 85- , carbonic oxide, weight and volume of. 84. coal, composition of, 59, 83. coal, heat evolved by the combustion of, 59, 83. -coal, heating-power of, 59. coal, weight and volume of, 85. from oil, 60. , hydrogen, weight and volume of, 84. , Keith, 60. , nitrogen, weight and volume of, 84. , olefiant, weight and volume of, 85. , oxygen, weight and volume of, 84. , Pintsch, 60. , quantity of, obtained from coal, 59. Gas-engine, highest temperature in, 63. -engines, 60, 61. Gases and vapours, specific gravity of, 451. and vapours, weight of, 84, 85. , escaping from funnel, temperature of, Gases, specific heat of, 41. weight and volume of, 3, 84, 85. Gaseous coal, 50, 52. mixtures, pressure produced by the explosion of, 62, 63. products of combustion, temperature of the, 95, 96. products of combustion, volume of, 85- steam, weight of, 85. Getting-up steam, 225. Girard-turbines, 31 33. , axial, 32. , radial, 32. Girder-stays, L., 163. Girders for flat-surfaces of boilers, 146, 156. Gold, specific gravity of, 449. , strength of, 443. Goods-engines, consumption of coal by, 89. Governors for marine-engines, 423, 424. for a stationary engine, 408, 409, 414. Grate-surface and heating-surface, 114 1 20. , evaporation per square foot of, III. -, per Ib. of fuel, 114. , power developed hy a given, 1 14 116. Gravity, specific, 447 452. Gridiron expansion-valve, 289. Grooving, corrosive, 235. Guide-ports of turbines, 28. -vanes of turbines, 27, 34. Gun-metal bearings, 326. screw-propellers, metal for, 339. , strength of, 442, 443. Gunpowder, bulk of, 53. Gypsum- waters, to purify, 212. ~LT AIR-FELT for steam-pipes, 97, 99. Hardening steel, effect of, 440. Hard steel-plates, strength of, 436. -water, to soften, 212. Heat and fuel, 36. , capacity for, 42. carried off in condensing-water from condensing-engines, 272, 270. , communication of, 96. , conduction of, 97. developed by combustibles, 57 59. developed by fuels in burning, 56. developed by hydrogen, 57, 105. , distribution of, by convection, ico. , effect of, on water, 100. , effect of, on coal, 56. equivalent of horse-power, 366. evolved by combustibles, 65, 66, 83. evolved by the combustion of coal, coal-gas, tallow, stearine, wax, sperm, paraffin, colza-oil, solar-oil, and petro- leum, 83. in the air, greatest, 6. , latent, 43, 44, 103. 466 INDEX. Heat, loss of, in boiler-furnaces, 107. , loss of, by radiation, 98. lost by blowing-off, 20. , non-conductors of, 97. of the earth, internal, 40. , quantity of, expended in creating natural draught in a chimney, 1 22. , required to evaporate water, 105. , in mixture of water and steam, 43, 204, 254. , radiation of, 94, 97. , radiation of, from steam-pipes, 98, 99. , sensible, 103. , specific, 40 42. , the source of power of steam, 366. , total, of saturated steam, 103, 104. , transmission of, through plates, 118. , unit of, 40. Heaters for feed-water, 208 211. Heating feed-water, 206, 208. -power of carbon and hydrogen, 55. power of coal, 58. -power of coal-gas, 59. power of coke, 58. -power of combustibles, 65, 66. -power of crude petroleum-oil, 90. power of liquid fuel, 58, 59, 90. power of peat, 58. -power of sawdust, 58. -surface and fire-grate surface, 118. -surface, efficiency of, 119, 120. -surface, evaporation per square foot of total, ill. surface of boiler-tubes, 175. 176. surface of a number of marine- boilers, 115. surface of tubes and fire-box, relative value of, 1 1 7. -surface of tubes, ratio of to that of the fire-box, 117. surface, power developed by, 1 14, 1 1 7. surface, standard proportions of loco- motive-engine boilers on railways, 117. surface, total, in proportion to the fire-grate surface, 114. surface total of locomotives, 117. water by steam, 43, 204, 209. 254. -surface, water evaporated per square foot of, in different boilers, in. Highest temperature in gas-engines, 63. High-falls, motors for, 33, 34, 36. High temperatures, to ascertain, 37. Holland's fuel, 52. Hollow-shafting of Whit worth's compressed steel, rules for, 332. Hoop-iron, strength of, 430. -steel, strength of, 430, 436. Hoops, contraction of, in cooling. 49. Horizontal jet-condensers, 259. stationary-engine, 407, 408. Hornbeam, 446, 448. Horse-power of locomotive engines, 117. -power of steam-engines, 366 376. Horse-power, actual or indicated, 375, 376. , due to the complete combustion of I Ib. of coal, 92. , nominal, 366 374. of the " Pantanemone. " 13, 14. of pumps, 282. of steam-boilers, 178180. of windmills, 13, 14. Horseshoe-rings of thrust-bearings, 338. Hot-air, quantity evolved by combustion, 84. -air engines, 63, 64, 65. -blast cast iron, strength of, 441. boiler, effect of pouring cold water into a, 236. mines, temperature of, 39, 40. well, contents of, when sea-water is used for injection, 260. well, temperature of, 259. Howden's system of forced draught with warm air, 126 128. Hurricane, pressure of a, n. Hydraulic-propulsion, 361, 362. -riveted joints, 130. Hydrogen, 55, 56. -gas, weight and volume of, 84, 85, Hydrometer, 18. Hyperbolic logarithms, 382. T CE, compressive strength of, 14. L Ice, specific heat of, 14. , temperature resulting from mixing ice with hot water, 45. , weight of, 14. , weight of, required to be added to water to lower its temperature, 45. Illustrations of the Board of Trade Rules for steam-boilers, 156 160. of Lloyd's Rules for boilers, 165 167. Improper setting of steam-boilers, 233. Impulse-turbines, 31. Incrustation in steam-boilers, 211, 212. Indiarubber-valves for air-pumps, 264, 272. Indicated horse-power developed by marine-engines from a given area of fire- grate-surface and heating-surface with natural draught, 116. horse-power required for a given thrust with a screw-propeller, 347. horse-power of steam-engines, 375. thrust of a screw-propeller, 347. Induced draught, combustion with, 128. Initial condensation of steam, 424 Injection-heaters for feed-water, 209. of steam into water, to prevent noise of, 209. pipe, size of, 260. -water for condensing engines, 258. Injector, automatic exhaust-sUam, 202 207. , automatic re-starting, 201, 202. , evaporative efficiency of a locomotive- engine boiler when fed with an. 1 10. INDEX. 467 Injector, exhaust-steam, method of fixing the, 203. for liquid fuel, 68, 69. nozzles, 201. Injectors for feeding boilers, 200 207. , quantity of water carried by, 201. , rise of temperature of water in, 200. Internal corrosion of steam-boilers, 233 235- Inward-flow turbines, 29. Iron, cast, strength of, 440, 441. , contraction of, in cooling, 49. , expansion of, by heat, 48. , modulus of elasticity of, 428. , specific heat of, 41. , wrought, strength of, 439, 440. wire, strength of, 437, 438, 443, 444. T ACKET, steam, 379 : water, 209. J Jet-condensers, 259, 260, 268, 271. Jet-condensers, air-pump for, 270. condensers, capacity of air-pump, 270. condensers, vacuum in, 257. propellers, 361, 362. Jet water-wheels, 34 36. Joints, riveted, 130. , riveted, proportions of, 131. Jonval-turbine, diagram of buckets of a, 28, 30. Journals of crank-shafts, 325, 326. Joy's valve-gear, 308 310. T^AURI-WOOD, 446. v Keith oil-gas, 60. Keys for screw-propellers, 345 Knots, speed in, data for, 355. Knowles' supplementary governor, 408, 409. Kunstadter's screw-steering-propeller, 358. T AKES, evaporation from the surface of water in, 15. temperature of, 38, 39. Lancashire boilers, cause of explosions of, 230. boilers, construction of, 213, 214. boilers, evaporative performance of, 108, in. boiler, setting, 216. coal, evaporative power of, 107. steam coal, composition of, 51. Lap of a slide-valve, 286288. of slide-valve, diagram of, 292. , lead and travel of locomotive slide- valves, 287. Latent heat, 43, 44. heat of steam, 103. Laws of expansion of metals by heat, 46. Lead, cast, sheet, pipe, strength of, 442. Lead of slide-valves, 285. , deficient and excessive, 286. Lever for working air-pump, 270. -safety-valves, 182 185. Lift of safety-valves, 192. Lignite, evaporative power of, 106. Lignum-vitas, 446, 448. Lime, to purify feed-water containing, 212. Limit, elastic, of metals, 429. Liners for cylinders, metal for, 389. for cylinders, thickness of, 389. Linking-up, 305. Link-motion, 302305. motion of locomotive engines, 303 305- motion of marine engines, 305. motion of a stationary engine, 303. Liquid fuel, heating power of, 58, 59. fuel injector, 68, 69. fuel, methods of burning, 68 74. Liquids, specific gravity of, 451. , specific heat of, 41. Lloyd's proportions for riveted-joints, 132. regulations for safety-valves, 190. rules for boilers, 160 169. Locomotive boiler, modified type of, 223. cranks and eccentrics, 285. engine boilers, 218, 219. engine boilers, causes of explosions of, 230, 235, 236. -engine boiler, evaporative efficiency of, when fed with a pump and with an injector, no. -engine boilers, evaporative perform- ance of, 1 08 in. engine boilers, standard proportions of the heating surface of, on various railways, 117. engine crank-axles, 328, 329. engine cylinders, 390. -engine cylinders, metal for, 391. -engine crosshead, 403. -engine eccentrics and eccentric-straps, 306, 307. slide-valves, lap, lead, and travel of, 287. Locomotives burning liquid fuel, 70, 72. , consumption of coal by, on differeat railways, 89. , horse-power of, 1 1 7. Logarithms, hyperbolic, 382. Loss of efficiency of the steam-engine, 424. of heat in boiler- furnaces, 107. of heat by blowing-off, 21. of heat by radiation from steam-pipes, 98, 99- of vacuum, 257. MANHOLE-OPENINGS of boilers, 150. , strengthening -rings for, 215. Marine-boilers, causes of explosion of, 230. 468 INDEX. Marine-boilers, construction of, 220 224. -boilers, evaporative-performance of, 108, in 113. boilers, consumption of coal in, 87. boilers, proportions of, 115. -engine crossheads, 405, 406. engine crank-shafts, 322327. -engine cylinders, proportions of, 385 389, 392. engine-governors, 423, 424. -engine pistons and piston-rods, 399 402. -engines, 414424. engines, compound, 415, 417. engines, oscillating, 421 423. engines, power developed by, from a given area of fire-grate and heating-sur- face, 115, 1 1 6. engines, quadruple expansion, 374, 388, 419, 420, 422. -engines, triple-expansion, 115, 374 ed-draught, 128, 386, 387, 392395- 415 4i8. Martin's system of indue 129. Materials, radiating-power of, 98. , strength of, 430 446. specific gravity and weight of, 447 456. Mean-pressure of the atmosphere, 7. -pressure of steam in a cylinder, dia- gram of, 380. -pressure of steam on the piston, rules and table, 381 384. pressure of steam required for a given nominal horse-power, 370. temperature of a place, 38. Measurement of flowing-water, 23 25, 274, 275. Measures of water, 14. Mechanical stoker, 81, 82. Mercury, pressure of steam measured in inches of, 104. , specific heat of, 41. , temperature resulting from mixing with hot water, 46. , vapour of, weight and volume of, 85. Metallic-packing for glands, 402. valves for air-pumps, 272. Metal, antifriction, 326, 402, 406. for cylinder-liners, 389. for locomotive-engine cylinders, 391. for marine-engine cylinders, mixture of, 393- for marine-engine cylinders, thickness of, 389. for stationary- engine cylinders, 391. , mixture of, for cranks for pumps, 330. , mixtures of, for gun-metal and cast- iron screw-propellers, 339. Metals, definitions of strains on, 427 429. , expansion of, by heat, 46 49. . , radiating-power of, 98. , specific heat of, 41. Metals, strength of, 430 444. , weight of a cubic foot of various, 452. Mezaline's fuel, 52. Mild-steel, expansion of, 48. plates, bars, axles, and hoops, strength of, 430, 433436. Mill-engines, 406 413. Mineral substances, weight of a cubic foot of, 453- Minerals, expansion of, by heat, 48. , specific heat of, 41. Mines, deep, temperature of, 40. , hot, temperature of, 39, 40. Model of a ship, resistance of, to propul- sion, 349, 350. Models for slide-valves, 284. Modified locomotive-type of marine-boiler, 223, 224. Modulus of elasticity, 428. of pumps, 277. Motion of an expansion slide-valve, diagram of the, 293. of a slide-valve, diagram of, 292. : of a slide-valve, principal points in the, 291. Motors, wind, 12 14. , water, 26 36. Mouth-piece for manhole, 215. Muntz-metal, strength of, 442. TSJATURAL-DRAUGHT, air required * for combustion with, 82. draught, evaporation in steam-boilers with, 108, ill, 121, 122. draught, experiments on boilers with, 121 123, 125, 127. draught and forced-draught, trials of steamships with, 123 128. -draught, power developed from a given area of fire-grate with, 115, 116. Negative exhaust-lap of slide-valves, 288. Newcastle-coal, 50, 51, 106, 107. -coal, evaporation of, 106, 107. Nitrogen, 3. -gas, weight and volume of, 84. Nominal horse-power of compound engines, 371, 373- horse-power of condensing engines, 367, 368. horse - power of non - condensing engines, 368 370. horse-power of quadruple-expansion engines, 374, 375. horse - power of triple - expansion engines, 373, 374. Non-condensing compound engine, 410, 412414. simple engine, 407. engines, nominal horse -power of, 368 370. Non-conducting coverings for steam-pipes, 98, 99- INDEX. 469 Non-conductors of heat, 97. North British Railway, evaporative-per- formance of a locomotive-engine boiler on the, no. Notable temperatures, 38. Notched -board, measurement of flowing- water by a, 2325, 274, 275. Nozzle-boiler, evaporation in, 108, in. QAK, 428, 446, 448. v - y bark, tan-refuse, evaporative power of, 107. Oceans, specific gravity of the water of, 1 6. Oil, crude petroleum, heating-power and evaporative-power of, 90, 107. gas, 60. of turpentine, weight of, 85. engines, 74 76. Oils, specific gravity of, 450, 451. Olefiant gas, weight and volume of, 85. Openings, of safety-valves, 195, 196. for manholes, strengthening rings for, Orifice, flow of steam through an, 180, 181, 194, 250. , measurement of flowing water by discharge through an, 25. Oscillating marine- engines, 421 423. Outward flow turbines, 29. Over-heating in steam-boilers, 235, 236. -pressure in steam-boilers, 238. Oxygen, 3. -gas, weight and volume of, 84. PACKING for glands, metallic, 402. L rings for pistons, 399, 400. Paddle-steamer, rules for speed of, 361. wheels feathering, 358361. wheels, radial, 358. Pantanemone, the, 13, 14. , horse-power of, 13. Paraffin, composition of, and heat evolved by the combustion of, 83. oil, heating power of, 58. Parallel-flow turbine, 30. Patent fuels, 52, 53, 106. fuels, evaporative-power of, 106. Peat, bulk of, 52. , heating power of, 58. Pelton's water-wheel, 34 36. Penrose and Richards' patent coke, 5 2 - Percentage of strength of riveted -joints, 131. Perforating and annealing steel-plates, 154. Perforations in internal steam -pipes of boilers, 176. Performance of steam-ships with natural draught and forced draught, 123 127. Ferret's furnace for burning coal-dust, 78. Petroleum-engines, 74 76. oil, composition of, 58, 83. -oil, evaporative -power of, 90, 107. Petro!eum-oil, heating-power of, 58, 90. refuse, cost of working locomotives with, 91. refuse, specific gravity of, 67. refuse, weight of, 67. refuse fuel, bulk of, 53. Philip's method of applying zinc in boilers, 234- Phosphor-bronze, strength of, 442. bronze-wire, strength of, 443, 444. Pianoforte-wire, steel, strength of, 437. Pine, 428, 446, 448. Pintsch oil-gas, 60. Piston, diameter of a, 396. displacement, 396. , position of, when steam is cut off, 288. , pressure on a, 396. rings, 399, 400. rod, strain on a, 401, 40?. -rods, cone on, and nut on, 401. rods, diameter of, 400, 401. speed, 368, 395, 396. valves, 299. valves, Thorn's, 299, 300. Pistons for locomotive-engines, 397. for marine-engines, 399, 400. for stationary-engines, 398, 400. Pitch of rivets, 131 134, 138 141. of screwed stays for Hat surfaces of boilers, 157. of screw-propellers, rules for the, 342 344- of surface-condenser-tubes, 265. Pitchometer for screw-propellers, 357. Pitted-plates, remedy for, 235. Plain furnaces, strength of, L., 164. Plate and rivet section, 155. Plates and bars of steel and wrought-iron, strength of, 430 440. for boilers, 129, 130. , transmission of heat through, 118. Point of, cut-off by slide-valve, 288. of saturation of steam, 243. Portable engine-boilers, causes of explo- sions of, 230. Ports of turbines, 28, 30, 32. Power applied at the thrust-block of a screw-propeller, 347, 348. developed by marine engines from a given area of fire-grate and heating sur- face with natural draught, 1 1 6. , driving, of flowing water, 25. , evaporative, of fuel, 105 107. , evaporative, of steam-boilers, 103. , of heating surface of locomotives, 117. , heat-conducting, of materials, 97. lost in propelling a ship, 349. of steam, 366. obtained by using a condenser, 257. of wind, 10, II. of windmills, 12, 13. relative to speed of a ship, 355. required to compress air, 5. 470 INDEX. Power required to propel a ship, 353. required to work pumps, 282. Preservation of steam-boilers when not in use, 239. Pressure and velocity of wind, 10, II. Pressure, bursting of cylindrical boilers, 143- , collapsing of furnace-tubes, 144, 145. of the atmosphere, 7, 9. of a column of pure water, 10,11, 15. of steam, 243, 250, 251. of steam at opening of exhaust-port, 38o. of steam, average throughout the stroke, 378. of steam on the internal surface of a boiler, 143. of steam required to expel brine, 20. on a piston, 396. on a safety-valve due to compression of spring, 194. produced by the explosion of gaseous mixtures, 62, 63. required to lift a safety-valve, 192. -turbines, 28, 29. , working, method of determining the, on each part of a boiler, 165. , working, of boiler-shells, 142. , working, of furnace-tubes, 144, 159. , working, on roof-stays of combustion- chamber or fire-box, 146. , working, on screwed stays for flat surfaces, 158. Prevention of corrosion in boilers, 234. of scale in steam-boilers, 211, 212. of smoke, 83. Priming in steam-boilers, 1 14. Proctor's mechanical stoker, 81, 82. Products of combustion from I Ib. of coal, coal-gas, tallow, stearine, wax, sperm, paraffin, colza-oil, solar-oil, and petro- leum, 83. of combustion, temperature of, 94. of combustion, volume of, 85. Projected area of blade of screw-propeller, 345. 352- Propeller, screw, delineation of a, 339 341 : diameter and pitch of, 115. , screw, rules and data for, 342358. , screw-steering, 358. shafting, 331335- Propellers, jet, 361, 362. Properties of steam, 246. Proportions of marine boilers, 115. Proportions and weight of crank-shafts for triple-expansion engines, 323, 324. of cranks, 325, 326. of the cylinders of compound engines, 373. 385. 386, 392. of the cylinders of quadruple-expan- sion engines, 388, 389. of the cylinders of triple-expansion engines, 306, 387, 394. Proportions of the cylinders of triple-ex- pansion engines in a number of steamers, 394- of feed-water heaters, 210. of riveted-joints, 131. of riveted-joints, Board of Trade, 133, 134- of riveted-joints, Lloyd's, 132, 133. of turbines, 33, 34. Propulsion, by screw - propellers and paddle-wheels, 338361. , hydraulic, 361, 362. Pumps, air, 264 272. , circulating, 264, 265. for feeding boilers, 199. 200. for water, 277 282. , horse-power required for, 282. , three-throw cranks for, 330. Punching rivet-holes, effect of, 132. Pure water, weight of, 14. Purification of feed-water, 212. QUADRUPLE-EXPANSION engines, x description of, 419, 420, 422. -expansion engines, nominal horse- power of. 374, 375. -expansion engines, proportions of cylinders of, 388, 389. Quantity of coal contained by bunkers, 53. of coal left at the end of a voyage, 88. of cooling- water for surface-con- densers, 264, 271. of exhaust-steam used by an exhaust- steam injector, 206. of feed-water required when blowing- off is practised, 19. of feed-water, used in boilers, 178, 199. of gas obtained from coal, 59. of heat required to evaporate water, 105. of heat transmitted per hour per square foot of heating-surface by different types of boilers, 1 78. of injection-water in tons, 258. of salt in sea- water, 16. of steam used by an engine. 177, 424. of water blown-off, 19. of water carried by injectors, 201. of water contained in tanks, 282. of water delivered by an exhaust- steam injector, 207. of water delivered by pumps, 278. of water derived from condensed steam, 209, 379. of water evaporated, 19. of water evaporated in a steam- boiler to steam per hour, 177. of water required for condensation in condensing-engines, 258. of water required to condense steam, 254- 255. INDEX. 471 Quantity of water to pump into a boiler to raise the water-level, 280. of water to be pumped out of a ship when leaking, 282. "D ADIAL Girard-turbine, 32. 1X paddle-wheels, 358. Radiant power of fuels, 94. Radiating-power of materials, 98. Radiation of heat, 97. Railways, consumption of coal on, 89. Rastrick-boilers, causes of explosions of, 230. Rate of combustion in steam-boilers, 91. of combustion of various coals, 92. of evaporation of various coals, in. Ratio of the expansion of steam, 288, 384. of the cylinders of compound engines, 385, 386. To calculate the, 372. of the cylinders of quadruple-expan- sion engines, 388, 389. of the cylinders of triple-expansion engines, 386, 387, 394. To calculate, 372. Re-action turbine, 26. Reduction of weight on dead-weighted safety valves, 198. Refuse-fuel, 6774, 7680. Regulation of turbines, 29. Relation of fire-grate-surface to heating surface of boilers, 118. Relief-frames of slide-valves, 295, 296. Resistance, atmospheric, 8. of a ship to propulsion by a screw- propeller, 346, 349, 350. of a ship's model to propulsion, 349, 350. Re-startmg injector, 201. Resulting temperatures, 44 46. Reversing-plate for portable-engines, 302. Revolutions, number of screw-propeller, 356- of shafts, number of, 355. Ribbed furnace-tubes, 169, 170. Rice-chaff covering for steam-pipes, 99. Rider's hot-air engine, 64, 65. Rise of temperature of feed-water in injectors, 201. River Thames, temperature of the, 38. Rivers, evaporation from the surface of water in, 15. Riveted-joints, 130. -joints, Board of Trade proportions for, 133, 134. joints in soft-steel-plates, Professor Kennedy's rules for, 135 '4 1 - joints. Lloyd's proportions for, 132, !33- joints, percentage of strength of, 131. -joints, proportions of, 131. -joints, strength of, 130. Rivet blown out of a boiler, 225. holes, effect of punching, 132. Rivet-holes in soft steel-plates, diameter of, 139- holes of steel-plates, 130, 135141. iron, strength of, 430 433, 438. steel, strength of, 430, 434. Rivets, diameter of, 131 134, 150. , pitch of, 131134, 138141- Rolled-joists, tensile strength of, 430, 432. Rudder-screw, 358. C ADLER'S system of burning liquid fuel, Safety-valve, easing- valve, 196. openings, 195, 196. springs, Board of Trade Rules for, 188190. springs, method of drawing, 186. Safety-valves, Board of Trade Rules for. 186, 187. , dead-weighted, 197, 198. , flow of steam through, 180, 181. for locomotive-boilers, 191, 192, 193. for marine-boilers, 191. for steam-boilers, 180 198. , illustrations of the Board of Trade Rules for, 188-190. , increased pressure due to com- pressing of spring, in bio wing-off, 194. , lift of, 192. , Lloyd's regulations for, 190. , loaded with lever and weight, 182 185. , marine, silent blow-off for, 197. with flat-faces, 183, 192. Sail-surface of the " Pantanemone, " 14. of windmills, 12. Salinometers, 1 8, 19. Salt of sea-water, 16, 17, Salted boiler, 18. Saltness of feed-water, 20. of water in a boiler, 20. Saturated brine, 17. Saturation, point of, 17. Saving effected by working steam ex- pansively, 378. Sawdust, heating power of, 58. Scale-forming substances in feed-water, 211. in boilers, prevention of, 211, 212. Screwed-bolts, loss of strength in screwing, 440. -stays for boilers, pitch of, 157. stays for boilers, diameter of, 158. Screw-propeller, angle of a, 344. , delineation of a, 339 341. , expanded area of blade, 345, 352. , horse-power lost by slip of a, 349. , indicated thrust of a, 347. , life of a, 350. , resistance of a ship to propulsion by a, 346. , projected area of blade. 345, 352. 4/2 INDEX. Screw-propeller shafting, 331 336. shafting, couplings for, 332. shafting of Whitworth's compressed steel, 332. shafting, strain due to weight of pro- peller, 333. -shafting, thrust-bearings for, 337, 338. -shafting, torsional and bending strains on, 333- 334- shafts, 331. shafts, diameter of wrought-iron, 331. , surface of blade of, 346. , speed of ship due to a given pitch and speed of, 350. , thrust of a, 348. Screw-propellers, 338358. , disc-area constants, 352. , feathering, 356. , Froude's formulae for, 350 -352. , keys for, 345. , mixtures of metal for cast-iron and gun-metal, 339- , pitch of, rules for the, 34.2 344. , pitchometer for, 357. , propordons of, 115. , slip of, 343, 344, 349. , Thorn's formulae for, 352, 353. , twin, 356. , velocities at different points of blades of, 341, 342. Screw-steering propeller, 358. Scum-cocks, 18. Seams, riveted, 130 141. , riveted, in soft steel-plates, 135 141. , riveted, longitudinal, percentage of strength of, 131. Seas, temperature of, 38. -, temperature at various depths, 38. Sea- water, boiling-points of, i"j. , components of the salts of, 16. , composition of, 16. , density of, in boilers, 22. , ice of, 1 6. , quantity of salt in, 16. , specific gravity of, 16. , weight of a gallon of. 17. , working, density of, 18. Sediment. from steam-boilers, 211, 234. Sensible heat, 103. Separators, 252, 253. Setting, improper, of boilers, 233. of egg-ended boilers, 95. steam boilers, 216, 217. Shafting, couplings and bolts for, 332. , end thrust, on screw-propeller, 335. for screw-propellers, Plummer- blocks for, 337. for screw-propellers, thrust-bearings for, 337, 338. of Whitworth's compressed-steel rules for, 335. , propeller, Board of Trade Rules for, 335- Shafting, rules for, 331 335. , wrought-iron, 331. Shear of rivet-steel-pins. 137. steel, strength of, 435. Shell of boilers, 142, 143. plates of boilers, thickness of, 172. Ship-plates, strength of, 430, 433, 419. Ship's model, resistance of, to propulsion, 349, 35- Ships, speed of, 353355- Shoes of crossheads, 406. Shortness of water in a boiler, 224. of water in boilers, causes of, 237. Side-rods of locomotive-engines, 319 321. Side-stays of fire-box, 146, 154, 156, 222. Siemens-Martin mild steel-plates, and bars, strength of, 430, 431, 434, 435, 437. steel-wire, strength of, /\/\/\. Silent blow-off for marine-safety-valves, 197. Silicated coverings for steam-pipes, 99. Silicum-bronze-wire, strength of, 444. Single-ended marine-boiler, 220, 221. Slack and breeze, evaporative power of a mixture of, 106, 107. , evaporative power of, 107. Slide-valve, area of opening given by a, 289. , diagram of the motion of a, 292. , double-ported, 289. , gridiron expansion, 289. , point of cut-off, 288. , relief-frames, 295 , 296. , separate expansion, 290 293. , travel of, 287, 289. , trick, 289. Slide-valves, 284298. , balanced, 295 298. , friction of, 294. , lap of, 286288. , lead of, 285. , models for, 298. Slip of riveted-joints, 136. of screw-propellers, 343, 344, 349. Smoke, 83, 86. , temperature of, in a funnel, 86. Snow, weight of, 14. Soft-steel, strength of, 430, 433 436. Solar-oil, composition of, and heat evolved by the combustion of, 83. Solids, specific heat of. 41, 42. Soundness of boiler-plates, 130. Specific gravity of cast-iron, wrought-iron, and other metals and alloys, 449. gravity of coals, 41, 51, 53. gravity of gases and vapours, 451. gravity of ice, 14. gravity of petroleum-refuse, 67. gravity of snow, 14. gravity of timber, 447, 448. gravity of various materials and liquids, 450, 451. gravity of the water of oceans, 16. gravity, rules for, 451, 452. INDEX. 473 Specific heat of ice, 14. heat of metals, minerals, liquids and gases, 41. Speed of engine required for a given horse- power, 371. of modern steam-ships, 354, 355. of paddle-steamers, rules for the, 361. of piston, 368, 395, 396. of steam-ship due to a given con- sumption of coal, 87. of steam-ship due to a given pitch and speed of propeller, 350. of steamships, rules for, 353, 355. Sperm, composition of, and heat evolved by the combustion of, 83. Spirally corrugated tubes, 164. Springs for safety-valves, Board of Trade Rules for, 188 190. for safety-valves, to draw, 186. , warm, temperature of, 49. Spring-steel, strength of, 436. Standard measures of water, 14. temperatures of water, 37. Stationary-engine crossheads, 404. engine cylinders, 391. -engines, 406 414. Stay-bolts for fire-box roofs of locomotives, Stays, boiler, 146, 158. [l7l for flat surfaces, L., 162, 163. Steam, average pressure of, throughout the stroke, 378. and water, heat of mixture, 43, 204, 209, 254. blast, effect of, in a chimney, 108. coal, 5052, 106, 107. coal, evaporation of, 106, 107. , compression of, or cushioning, 286. , condensation of, 253 255. condensed in steam-jackets, 379. , condensed, quantity of water from, 209. condensed by cold surfaces, 262 263. condensed by exhaust steam-injec- tors, 205. , cutting off by slide-valves, 288. -, diagram of mean-pressure of, 380. drier, 253. , efficiency of, in an engine, 256. , equivalent weight of water evapo- rated from, 104, 105. , expansion of, 243, 288, 377, 384. , expansion of steam in a cylinder, 377- , final temperature of, in a cylinder or condenser, 256. , flow of, through an orifice, 1 80, 181, 194, 250. , flow of, through safety-valves, 180. , gain by using high-pressures, 244. , gaseous, weight of, 85. jacket, 379. , maximum economy of, 379. , mean-pressure required for a given nominal horse-power, 370. Steam, ratio of expansion of, 288, 384. , point of saturation of, 243. , pressure of, 243, 250, 251. , pressure of, at opening of exhaust- port, 380. , pressure of, measured in inches of mercury, 104. , quantity used by an engine, 177, 424. separators, 252, 253. space of marine-boilers, 1 76. , superheated, 244, 251, 252. , temperature of, 244. , total heat of, 103. , velocity of, through cylinders of triple-expansion-engines, 393. , volume of, 104, 243. , weight and volume of, 246 250. , weight of a cubic foot of, 104. Steam-boiler explosions, 230 240. Steam-boilers, construction of, 213 224. , chimneys for, 228230. . corrosion of, 232 235. , efficiency of, 104, 108. . evaporative-performance of, 108 113, 121, 122, 12^, 129, 178, 240. , feed-pumps and injectors for, 199207. , feed-waterheatersfor,2o8 211. , fire-grate surfaces of, 114120 , heating surface of, 114 120. , horse-power of, 116, 178 180. , marine, proportions of, 115. , method of testing, 240. , safety-valves for, 180 198. , scale in, 211. Steam-pipe, internal perforated, 176. Steamers, indicated horse-power developed by marine-engines from a given area of " fire-grate and heating-surface, with na- tural draught, 115, 116. Steam-ships, proportions of the cylinder? of triple-expansion engines in, 594. , trials of, with natural and with forced-draught in the boiler-furnaces. 123128. Stearine, composition of, and heat evolved by the combustion of, 83. Steel, average tests of, by noted makers of, 432434. , Bessemer, strength of, 435- boiler-plates, 130. boilers, Board of Trade Rules for, I 53 "55- boilers, Lloyd's rules for, 160. , cast, roof-stays of fire-box, 172. , cast, strength of, 435 437' castings, strength of, 430, 435. crank-shafts, 325. crank-shafts and crank-axles, strength of, 433, 434, 436. crucible, strength of, 436. , expansion of, by heat, 48. -furnaces, plain and corrugated, 154. I I 474 INDEX. Steel-hoop, strength of, 436. liners for cylinders, 389. , mild, strength of, 43*0, 434, 435. -plates and bars, strength of, 430, 440. -plates for fire-boxes, 430. -plates, rivet-holes of, 130, 139. , puddled, strength of, 436. -rivet, rods for, 430, 434. rivets, L., 160. , Siemens-Martin, strength of, 430, 434, 435. 437- , specific heat of, 41. , strength of, L., 160. tires, strength of, 434, 436. wire, strength of, 437, 443. Stern-shaft and stern-tube, 336, 337. Sterro-metal, strength of, 442. Stokeholds, closed, 112, 123 125. Stone and mineral substances, weight of, 453- 454- Stores, stowage capacity of, 53. Storm, pressure of, II. Stowage capacity of fuels and stores, 53. Strain on a crank-pin, to find the, 326, 327. on metals and materials, definitions of, 427429. on a piston-rod, 401, 402. on shafting of screw-propellers due to the weight of a propeller, 332. on stays for flat surfaces of boilers, 158. on a valve-spindle, 298. produced by cold feed-water in boilers, to calculate the, 207, 208. shearing, on bolts of screw-propeller shafting, 332. , torsional, on shafting, 333, 334. Straw-burning, 77. and strawboard-coverings for steam- pipes, 97, 99. Streams, measurement of, 23 25. Strength of alloys, 442, 443. of aluminium-bronze, 442. of boiler-plates, 129, 130, 430439. of brass and gun-metal, 442, 443. of cast-iron, 440, 441. of copper, 442, 443. of copper-bolts, 443. of corrugated furnace-tubes, 167 169. of cylindrical boiler-shells, 142. of fire-box roof-stays, 171, 172. of lead, zinc, and tin, 442. of materials, 427. of Muntz-metal, 442. of phosphor bronze, 442. of phosphor bronze-wire, 443) 444- of plates and bars of wrought-iron and steel, 430440. of ribbed furnace-tubes, 1 70. of riveted-joints, 130, 150. of shafting, 333, 334. of silicium bronze-wire, 444. of steel-castings, 430, 435. Strength of steel-plates and bars, 430, 433 -437- of sterro-metal. 442. of wire of various metals, 443) 4'H- of wrought-iron plates and bars, 430 434, 437440. Strengthening-ring for furnace-tubes, 215. ring for manhole, 215. rings for manholes and other openings in boilers, 150. Stress on stays of iron, 146 ; of steel, 154. Structures, pressure of wind on. 10, II. Superheated steam. 244, 251, 252. Superheaters, 152, 251. Surface-condenser, test of a, 263. condenser tubes, 265. condenser tubes, packings for, 265, 266. -condensers, 261 268. condensers, cooling surface of, 115, 262, 264, 271. -condensers, cooling surface, air- pump capacity and quantity of circulat- ing water provided for, in marine- engines, 271. Surface of a blade of a screw-propeller, 346. Swelled portion of a stay, diameter of, 159. ""TALLOW, composition of, and heat evolved by the combustion of, 83. Tandem mill-engine, vertical. 410, 411. Tank, time required to fill a, 283. Tanks, rules for the size of. 282, 283. , water contained in, 282. Tan-refuse, evaporative-power of, 106, 107. Taper of cone on piston-rod. 401. Tar-refuse, evaporative-power of, 106, 107. , or creosote-oil, 59, 106. 107. Testing condensing-engines, 273 277. Teak, 428, 447, 448. Telegraph-wire, strength of, 443, 444. Telephone-wire, strength of. 444. Temperature and volume of steam, 244 246. and volume of water, 15. due to compression of air, 5. final in a cylinder or condenser, 256. highest in a gas-engine, 63. limit of superheated steam, 251. mean, of a place, 38. mixing ice with water, 45. of air on the surface of the earth, 6. of the atmosphere, 6. of hot mines, 39. of hot well, 259. of hot well, loss of vacuum due to a high, 257. of the products of combustion in various boilers, 94. of the products of combustion at dif- ferent stages between the fire and the chimney of steam-boilers, 94 96. INDEX. 475 Temperature of seas and lakes, 38. of smoke in a funnel, 86. of springs, 39. of the river Thames, 38. of water from condensed steam, 254, 255- of water, standard. 37. of water mixed with steam, 43, 204, 209, 254. resulting from a mixture of water of different temperatures, 44, 45. resulting from mixing mercury with hot water, 45, 46. Temperatures, high, to ascertain, 37. , notable, 38. , underground, 39. Tempest, pressure of a, n. Tensile and bending tests of steel boiler- plates, 153, 154. strength of cast-iron, 440, 441. strength of timber, 444 447. strength of wrought-iron and steel boiler-plates, 129, 130, 430439. strength of wrought-iron and steel- plates and bars, 430 439. strength of various metals and alloys, 442, 443- strength of various wires, 437, 443, 444. Terminal-pressure, 250. Test-bars, of cast-iron, breaking-strength of, 441. , of gun-metal, strength of, 443. Test of a Cornish boiler, 107. of a Lancashire boiler, 240. of a corrugated furnace-tube, 167, 168. of the evaporative efficiency of a loco- motive-engine boiler when fed with an injector and with a feed-pump, 1 10. of the evaporative performance of a locomotive-engine boiler, 109. of furnace for burning coal-dust, 79. of hot-air-engine, 65. of jet-propeller, 361, 362. of locomotive-engine boiler burning petroleum, coal, and wood, 91. of Pelton's water-wheel, 35. of power required to haul a train, 89. of non-conducting coverings for steam-pipes, 98, 99. of ribbed furnace-tubes, 169, 170. of the effect of steam-blast in chim- neys, 1 08. of a surface-condenser, 263. for cylinder-metal, 393. for gun-metal, 443. strips, 153. strips of wrought-iron and steel, 429. Testing boilers, 161 ; method of, 240. Testing condensing-engines, 275- Testing the soundness of iron-plates, 130. Tests of wrought-iron and steel bars and plates, by noted makers of, 431 434. of boilers, calorimeter used in, 42. Tests of boilers with natural draught and forced draught, 120 129. of boilers of modified locomotive- type for torpedo-boat-chasers, 113. of the evaporative-performance of steam-boilers, 108, in. of an exhaust-steam injector, 206. of iron, Lloyd's, 164. of a non-condensing compound- engine, 412. of rivets, 153. of steel-plates for boilers, 153. of torpedo-boat boilers of the locomo- tive-type, 112. of water-tube boilers, 227. of wire of various metals, 443, 444. Thames, river, temperature of the, 38. Theoretical evaporative-power of coal and other fuels, 106. Thermometer, centigrade, 36. , Fahrenheit, 36, 37. , Reaumur, 37. Thermometers, 36, 37. Thickness of boiler-plates, to find the, 143. of furnace-tubes, 173, 174. of liners for cylinders, 389. - of metal of locomotive-engine cylin- ders, 390. of metal of marine-engine-cylinders 389, 390. of plate for boiler-shells, 172. of plate for flat surfaces of boilers, 173- of tube-plates, 173, 174. of wrought-iron girder-stays, or fire- box roof-stays, 172. Thorn's formulas for screw-propellers, 352, 353- Thread of screw-propeller, 345. Thrust-bearings for screw-propeller-shaft- ing, 337, 338. block, power applied of a, 347, 348. of a screw-propeller, 348. on screw-propeller-shafting, 335. Timber, modulus of elasticity of, 428. , specific gravity of, 447, 448. , strength of, 444447. , weight of, 454456. Time required to fill a tank, 283. required to pump water, 280. Tin, strength of, 442. Tool-steel, strength of, 436, 437. Tornado, pressure of a, n. Torpedo-boat boilers, evaporative perform- ance of, 108, 111113. , trials of, 112, 113. Torsional-strain on shafting, 333, 334. Total heat of steam, 104. Train-mile, consumption of coal per, on different railways, 89. Transmission of heat through boiler-plates, 118. Travel of slide-valves, 287, 289. 4/6 INDEX. Trick slide-valve, 289. Triple-expansion engines, consumption of coal by, 93, 116. , description of those shown in the frontispiece, 415 418. , economy of, 387. , nominal horse-power of, 373, 374. . proportions and weight of crank- shafts for, 322324. , proportions of cylinders of, 386, 387, 394- , proportions of the cylinders of, in a number of steamers, 115, 394. ratio of cylinders, to calculate, 372. , velocity of steam through the cylin- ders of, 393. Tube-plates of boilers, thickness of, 174. Tubes, boiler, 174176. of feed- water heaters, 210. of locomotive boilers, heating surface of, 117. of surface-condensers, 263. Tubular-boilers, vertical. 217. Turbine, Jonval, 28, 30. , parallel flow, 30. , Whitelaw's re-action, 26. Turbines, 2634. causes of loss of efficiency of, 27. classes of, 26. for medium and high falls, 33. impulse, 31. inward-flow, 29. measurement of water for, 23 25. outward-flow, 29. pressure, 28, 29. proportions of, 33, 34. regulation of, 29. water-paths -and velocities of, 27, 28. Twin screw-propellers, 356. UNDERGROUND temperatures, 39. ^ Unit of heat, 40. Universal windmill, 13. Uranium, specific heat of, 41. Urquhart's system of burning liquid-fuel, 6873- A7ACUUM in a condenser, 257. v Valuation of the heating power of coal, 55. Valve, worked by the expansion of metal, 47. Valve-gear, Bremme's, 311, 312. , Corliss, 301, 409. . Jy' s 308310. spindle, strain on a, 298. Valves, back-pressure, 200. , Corliss, 301, 409. , double-beat, 301. , metallic for air-pumps, 272. of air-pumps, 264, 271, 272. , piston, 299 300. Valves, safety, 180198. , slide, 284-298. Vanes of turbines, 27, 34. Vapours and gases, weight of, 84, 85. Vegetable- fibre coverings for steam-pipes, 99- Velocities of blades of screw-propellers at different points of, 341, 342. of turbines, 27. of cooling- water in surface-condensers, 264. of steam through the cylinders of triple-expansion engines, 393. of water in a pump, 281. of water in air-pumps, 271. of wind, 10, n. Vertical boilers, 217. boilers, evaporative-performance of, 108. boilers, explosions of, 230, 231. jet-condensers, 259, 260. pump, 278, 280. tandem mill-engine, 410, 411. Vinegar, specific heat of, 41. Vitiation of the air by the products of combustion, 83. Volume, increase of, in air due to eleva- tion of temperature, 7. of air, 4. of gases, 3. of saturated steam, 244 250. of steam, 104, 245 250. - of the products of combustion, 85. of water, 14, 15. Voyage, consumption of coal in a, 87, 89. Vulcanized fibre-valves, 272. WALNUT, 428, 447, 448. Warlich's patent fuel, 52. Watch, quantity of coal burnt in a, 88. Water, 14. blown through a rivet-hole, 225. effect of heat on, 100. - evaporation of, 103. expansion of, in freezing, 14. expansive-force of, in freezing, 14. -feed, quantity required, 178, 199. flowing over weirs, 23, 274, 275. for injection, 258. for injectors, 201, 203. from condensed steam, temperature of, 43, 204, 209, 254, 255. from condensing-engines, measure- ment of, 273. gas, 62. -heater, exhaust steam as a, 206. -heaters, 208 210. , measurement of flowing, 23 25, 274, 275- motors, 26 36. motors, measurement of water for, 2325- INDEX. 477 Water-paths of turbines, 27, 28. , pressure exerted by a column of, IO, "> 15- pumps and tanks, 277 283. , quantity delivered by an exhaust- steam injector, 207. , quantity delivered by pumps, 278 280. , heat of, when mixed with steam, 43, 204, 209, 254. , quantity derived from condensed steam, 209, 379. , heat required to evaporate, 105. , quantity raised by windmills, 13. required for condensation in condens- ing-engines, 258. required to condense steam, 254. , scale forming substances in, 211. , standard measures of, 14. tanks, 282, 283. , time required to pump, 280. , to purify, 212. tube boilers, 226228. -tube boilers, cause of explosion of, 230. tube boilers, evaporative performance of, 108, in. , volume of, 14. , weight of, 14. wheel, Pelton's, 34 36. Wax, composition of, and heat evolved by the combustion of, 83. Weak boiler-shelL 238. furnace-tubes, 237. Wear-and-tear of steam-boilers, 238. Weather-barometer, 8. 9. Webs of cranks, proportions of, 325, 326. Weight and bulk of stone, 454. and volume of gases, 3. and volume of steam, 246 250. of air, 4. of built up crank-shafts for triple- expansion engines, 324. of circulating-water, 262. of coal, 5052. of a cubic foot of metals, 452, 453. of a cubic foot of steam, 104. of a cubic foot of stone and mineral substances, 453. of a cubic foot of timber, 454 456. of fresh-water compared with sea- water, 16. of gases and vapours, 84, 85. of ice, 14. of injection-water, 258. of liquids, 456. of sea- water, 1 5. of snow, 14. of steam condensed in surface-con- densers, 263. of steam through an orifice, 250. of steam used by an engine, 424. of steam engines, 414, 415. Weight of water contained by tanks, 282. of water flowing over a bay or weir, 275- of water of various temperatures, 14. Weights for safety-valves, 182, 184, 197, 198. Weirs, measurement of water flowing over, 23-25, 274, 275. , weight of water flowing over, 275. Welded-joints, loss of strength in, 440. steel-plates, 155. Welsh coal, composition of, 51. , evaporative power of, 106, 107. Whip of windmill, 12. Whitelaw's turbine, 26. White-metal, mixture for, 326, 402. Whitworth's compressed - steel - shafting, rules for, 332. Wind, force of, 10. Wind pressure and velocity of, 10, u. Windmill, universal, 13. Windmills, 12, 13. , efficiency of, 13. , horse-power of, 12, 13. , sail-surface of, 12. Wind-motors, 12 14. Wire, brass, strength of, 443. , copper, strength of, 443. , iron, strength of, 437, 438, 443, 444. , phosphor-bronze, strength of, 443, 444. , silicium-bronze, strength of, 444. , steel, composition of, 437. , steel, for pianofortes, strength of, 437- , steel, strength of, 437, 443. , telegraph, strength of, 444. , telephone, strength of, 444. Wood burnt in locomotives, cost of, 91. ferrules for condenser-tubes, 265. for fuel, bulk of, 53. - Woods, modulus of elasticity of, 428. , specific gravity of various, 447, 448. , specific heat of, 41. , strength of various, 444 447. Working-pressure of boilers, 145. of boiler-shells, 142, 145, 159. of furnace-tubes, 144, 151, 152. on roof-stays of combustion-chamber or fire-box, 146. of screwed-stays for the flat surfaces of boilers, 158. on each part of a boiler, method of determining, 165 167. Worm-heater, 209. Wrought-iron crank-shafts, 324. plates and bars, average tests of, by noted makers of, 431 433. plates and bars, strength of, 129, 439 440. K K 478 INDEX. Wrought-iron cylindrical furnace-tubes, col- lapsing-pressure of, 144, 145. shell-plates of boilers, 142, 143, 150, 159, 161. fire-box roof-stays, 146, 154, 156, 172. plates, proportions of riveted-joints in, I3I133- , specific heat of, 41. , modulus of elasticity of, 428. bars, contraction of, 49 bars, expansion of, 47. plates, effect of punching, 132. tubes, collapsing pressure of, 145. plates, contractile strain in cooling, 208. shafting, rule for diameter for pro- peller, 331. Wrought-iron shafting, torsional strain on 333, 334- test-strips of, 429. plates, to test the soundness of, 130. Wylam's patent fuel, 52. YORKSHIRE coal, evaporative power 1 of, 106. , composition, weight and bulk of, 51. 7IGZ-AG riveting, strength through the plate, diagonally between the rivet- holes, 150. Zinc, method of using for the prevention of internal corrosion in steam-boilers, 234. , strength of, 442. THE END. BKADBURY, AGNEW, & CO. La, PRINTERS, WHITEFRIARS. 7, STATIONERS' HALL COURT, LONDON, E.G. October, 1895. CATALOGUE* OF BOOKS INCLUDING NEW AND STANDARD WORKS IN ENGINEERING: CIVIL, MECHANICAL AND MARINE; ELECTRICITY AND ELECTRICAL ENGINEERING; MINING, METALLURGY; ARCHITECTURE, BUILDING, INDUSTRIAL AND DECORATIVE ARTS; SCIENCE, TRADE AND MANUFACTURES; AGRICULTURE, FARMING, GARDENING; AUCTIONEERING, VALUING AND ESTATE AGENCY LAW AND MISCELLANEOUS. PUBLISHED BY CROSBY LOCKWOOD & SON. MECHANICAL ENGINEERING, etc. D. K. Clark's Pocket-Book for Mechanical Engineers. THE MECHANICAL ENGINEER'S POCKET-BOOK OF TABLES, FORMULAE, RULES, AND DATA : A Handy Book of Reference for Daily Use in Engineering Practice. By D. KINNEAR CLARK, M. Inst. C.E., Author of " Railway Machinery," "Tramways," &c. Second Edition, Revised and Enlarged, Small 8vo, 700 pages, gs. bound in flexible leather covers, with rounded corners and gilt edges. SUMMARY OF CONTENTS. MATHBMATICAL TABLES. MEASUREMENT OF SURFACES AND SOLIDS. ENGLISH WEIGHTS AND MEASURES. FRENCH METRIC WEIGHTS AND MEASURES. FOREIGN WEIGHTS AND MEASURES. MONEYS. SPECIFIC GRAVITY, WEIGHT AND VOLUME. MANUFACTURED METALS. STEEL PIPES. BOLTS AND NUTS. SUNDRY ARTICLES IN WROUGHT AND CAST IRON, COPPER, BRASS, LEAD, TIN, ZINC. STRENGTH OF MATERIALS. STRENGTH OF TIMBER. STRENGTH OF CAST IRON. STRENGTH OF WROUGHT IRON. STRENGTH OF STEEL. TENSILE STRENGTH OF COPPER, LEAD, ETC. RESIST- ANCE OF STONES AND OTHER BUILDING MATERIALS. RIVETED JOINTS IN BOILER PLATES. BOILER SHELLS. WIRE ROPES AND HEMP ROPES. CHAINS AND CHAIN CABLES. FRAMING. HARDNESS OF METALS, ALLOYS AND STONES. LABOUR OF ANIMALS. MECHANICAL PRINCIPLES. GRAVITY AND FALL OF BODIES. ACCELERATING AND RETARDING FORCES. MILL GEARING, SHAFTING, &c. TRANSMISSION OF MOTIVE POWER. HEAT. COMBUSTION: FUELS. WARMING, VENTILATION, COOKING STOVES. STEAM. STEAM ENGINES AND BOILERS. RAILWAYS. TRAMWAYS. STEAM SHIPS. PUMPING STEAM ENGINES AND PUMPS. COAL GAS, GAS ENGINES, &c. AIR IN MOTION. COMPRESSED AIR. HOT AIR ENGINES. WATER POWER. SPEED OF CUTTING TOOLS. COLOURS. ELECTRICAL ENGINEERING. %* OPINIONS OF THE PRESS. " Mr. Clark manifests what is an innate perception of what is likely to be useful in a pocket- book, and he is really unrivalled in the art of condensation. Very frequently we find the information on a given subject is supplied by giving a summary description of an experiment, and a statement of the results obtained. There is a very excellent steam table, occupying five-and-a-half pages; and there are rules given for several calculations, which rules cannot be found in other pocket-books, as, for example, that on page 497, for getting at the quantity of water in the shape of priming in any known weight of steam. It is very difficult to hit upon any mechanical engineering subject concerning which this work supplies no information, and the excellent index at the end adds to its utility. In one word, it is an exceedingly handy and efficient tool, possessed of which the engineer will be saved many a wearisome calculation, or yet more wearisome hunt through various text-books and treatises, and, as such, we can heartily recommend it to our readers, who must not run away with the idea that Mr. Clark's Pocket-book is only Molesworth in another form. On the contrary, each contains what is not to be found in the other; and Mr. Clark takes more room and deais at more length with many subjects than Molesworth possibly could." The Engineer. " It would be found difficult to compress more matter within a similar compass, or produce a book of 650 pages which should be more compact or convenient for pocket reference. . . . Will be appre- ciated by mechanical engineers of all classes." Practical Engineer. " Just the kind of work that practical men require to have near to them." English Mechanic. CROSBY LOCKWOOD & SON'S CATALOGUE, MR. BUTTON'S PRACTICAL HANDBOOKS. Handbook for Works' Managers. THE WORKS' MANAGER'S HANDBOOK OF MODERN RULES, TABLES, AND DATA. For Engineers, Millwrights, and Boiler Makers ; Tool Makers, Machinists, and Metal Workers ; Iron and Brass Founders, &c. By W. S. HUTTON, Civil and Mechanical Engineer, Author of "The Practical En- gineer's Handbook." Fifth Edition, carefully Revised, with Additions. In One handsome Volume, medium 8vo, price 15.?. strongly bound. C*aj* The Author having compiled Riiles and Data for his own use in a great variety of modern engineering work, and having found his notes extremely useful, decided to publish them re-vised to date believing that a practical -work, suited to the DAILY RE- QUIREMENTS OF MODERN ENGINEERS, wotild be favourably received. %* OPINIONS OF THE PRESS. "Of this edition we may repeat the appreciative remarks we made upon the first and third. Since the appearance of the latter very considerable modifications have been made, although the total number of pages remains almost the same. It is a very useful collection of rules, tables, and workshop and drawing office data." The Engineer, May 10, 1895. "The author treats every subject from the point of view of one who has collected workshop notes for application in workshop practice, rather than from the theoretical or literary aspect. The volume contains a great deal of that kind of information which is gained only by practical experience, and is seldom written in books." The Engineer, June 5, 1885. " The volume is an exceedingly useful one, brimful with engineers' notes, memoranda, and rules, and well worthy of being on every mechanical engineer's bookshelf." Mechanical World. "The information is precisely that likely to be required in practice. . . . The work forms a de- sirable addition to the library not only of the works' manager, but of anyone connected with general engineering." Mining Journal. " A formidable mass of facts and figures, readily accessible through an elaborate index. . . . Such a volume will be found absolutely necessary as a book of reference in all sorts of ' works 'connected with the metal trades." Ry land's Iron Trades Circular. " Brimful of useful information, stated in a concise form, Mr. Hutton's books have met a pressing want among engineers. The book must prove extremely useful to every practical man possessing a copy." Practical Engineer. New Manual for Practical Engineers. THE PRACTICAL ENGINEER'S HANDBOOK, Comprising a Treatise on Modem Engines and Boilers, Marine, Locomonive, and Stationary. And containing a large collection of Rules and Practical Data relating to recent Practice in Designing and Constructing all kinds of Engines, Boilers, and other Engineering work. The whole constituting a comprehensive Key to the Board of Trade and other Examinations for Certificates of Competency in Modern Mechanical Engineering. By WALTER S. HUTTON, Civil and Mechanical Engineer, Author of "The Works' Manager's Handbook for Engineers," &c. With upwards of 370 Illustrations. Fourth Edition, Revised, with Additions. Medium 8vo, nearly 500 pp., price iSs. strongly bound. f&* This work is designtd as a companion to the Author's " WORKS' MANAGER'S HANDBOOK." It possesses many new ana original features, and contains, like its prede- cessor, a quantity of matter not originally intended for publication, but collected by the Author for his own use in the construction of a great variety of MODERN ENGINEERING WORK. The information is given in a condensed and concise form, and is illustrated by up- wards of 370 Wuodctits; and comprises a quantity of tabulated matter of great value to all engaged in designing, constructing, or estimating for ENGINES, BOILERS, and OTHER ENGINEERING WORK. \* OPINIONS OF THE PRESS. " We have kept it at hand tor several weeks, referring to it as occasion arose, and we have not on a single occasion consulted its pages without finding the information of which we were in quest.' 1 Athenceum. " A thoroughly good practical handbook, which no engineer can go through without learning some- thing that will be of service to him." Marine Engineer. " An excellent book of reference for engineers, and a valuable text-book for students ot engineer- ing." Scotsman, " This valuable manual embodies the results and experience of the leading authorities on mechanical engineering." Building Neivs. "The author has collected together a surprising quantity of rules and practical data, and has shown much judgment in the selections he has made. . . . There is no doubt that this book is one of the most useful of it> kind published, and will be a very popular compendium." Engineer. " A mass of information, set down in simple language, and in such a form that it can be easily referred to at any time. The matter is uniformly good and well chosen, and is greatly elucidated by the illustrations. The book will find its way on to most engineers' shelves, where it will rank as one of the most useful books of reference." Practical Engineer. " Kull of useful information, and should be found on the office shelf of all practical engineers." English Mechanic. MECHANICAL ENGINEERING, &c. MR. BUTTON'S PRACTICAL HANDBOOKS continued. Practical Treatise on Modern Steam-Boilers. STEAM BOILER CONSTRUCTION. A Practical Handbook for Engineers, Boiler-Makers, and Steam Users. Containing a large Collection of Rules and Data relating to Recent Practice in the Design, Construction, and Work- ing of all Kinds of Stationary, Locomotive, and Marine Steam-Boilers. By WALTER S. HUTTON, Civil and Mechanical Engineer, Author of " The Works' Manager's Handbook," "The Practical Engineer's Handbook," &c. With upwards of 300 Illustrations. Second Edition, medium 8vo, i8j. cloth. (85F THIS WORK is issued in continuation of the Series of Handbooks written by the Author, viz: " THE WORKS' MANAGER'S HANDBOOK" and "THE PRACTICAL ENGINEER'S HANDBOOK," which are so highly appreciated by Engineers for the practical nature of their information ; and is consequently written in the same style as those works. The Author believes that the concentration, in a convenient form for easy reference, of such a large amount of thoroughly practical information on Steam-Boilers, will be of considerable service to those for whom it is intended, and he trusts the book may be deemed worthy of as favourable a reception as has been accorded to its predecessors. %* OPINIONS OF THE PRESS. "Every detail, both in boiler design and management, is clearly laid before the reader. The volume shows that boiler construction has been reduced to the condition of one of the most exact sciences ; and such a book is of the utmost value to the fin de siecle Engineer and Works' Manager." Marine Engineer. " There has long been room for a modern handbook on steam boilers; there is not that room now, because Mr. Hutton has filled it. It is a thoroughly practical book for those who are occupied in the construction, design, selection, or use of boilers." Engineer. " The book is of so important and comprehensive a character that it must find its way into the libraries of every one interested in boiler using or boiler manufacture if they wish to be thoroughly in- formed. We strongly recommend the book for the intrinsic value of its contents." Machinery Market. "The value of this book can hardly be over-estimated. The author's rules, formulae, &c., are all very fresh, and it is impossible to turn to the work and not find what you want. No practical engineer should be without it." Colliery Guardian. Mutton's "Modernised Templeton." THE PRACTICAL MECHANICS' WORKSHOP COMPANION. Com- prising a great variety of the most useful Rules and Formulae in Mechanical Science, with numerous Tables of Practical Data and Calculated Results for Facilitating Mechanical Operations. By WILLIAM TEMPLETON, Author of "The Engineer's Practical Assistant," &c. &c. Seventeenth Edition, Revised, Modernised, and considerably Enlarged by WALTER S. HUTTON, C.E., Author of "The Works' Manager's Handbook," "The Practical Engineer's Handbook," &c. Fcap. 8vo, nearly 500 pp., with 8 Plates and upwards of 250 Illustrative Diagrams, 6s. strongly bound for workshop or pocket wear and tear. %* OPINIONS OF THE PRESS. "In its modernised form Mutton's ' Templeton ' should have a wide sale, for it contains much valuable information which the mechanic will often find of use, and not a few tables and notes which he might look for in vain in other works. This modernised edition will be appreciated by all who have learned to value the original editions of 'Templeton.' " English Mechanic. "It has met with great success in the engineering workshop, as we can testify; and there are great many men who, in a great measure, owe their rise in life to this little book." Building News. " This familiar text-book well known to all mechanics and engineers is of essential service to the every-d ay requirements of engineers, millwrights, and the various trades connected with engineering and building. The new modernised edition is worth its weight in gold." Building News. (Second " This well-known and largely-used book contains information, brought up to date, of the sort so useful to the foreman and draughtsman. So much fresh information has been introduced as to consti- tute it pi actically a new book. It will be largely used in the office and workshop." Mechanical World. " The publishers wisely entrusted the task of revision of this popular, valuable, and useful book to Mr. Hutton than whom a more competent man they could not have found." Iron. Templeton's Engineer's and Machinist's Assistant. THE ENGINEER'S, MILLWRIGHT'S, AND MACHINIST'S PRAC- TICAL ASSISTANT. A collection of Useful Tables, Rules, and Data. By WILLIAM TEMPLETON. Seventh Edition, with Additions. i8mo, 2s. 6d. cloth. ** OPINIONS OF THE PRESS. " Occupies a foremost place among books of this kind. A more suitable present to an apprentice to any of the mechanical trades could not possibly be m&At." Building News. "A deservedly popular work. It should be in the ' drawer ' of every mechanic." English Mechanic CROSBY LOCKWOOD & SON'S CATALOGUE. Foley's Office Reference Book for Mechanical Engineers, THE MECHANICAL ENGINEER'S REFERENCE BOOK, for Machine and Boiler Construction. In Two Parts. Part I. GENERAL ENGINEERING DATA. Part II. BOILER CONSTRUCTION. With 51 Plates and numerous Illus- trations. By NELSON FOLEY. M.I.N.A. Second Edition, Revised throughout and much Enlarged. Folio, .3 $s. net, half-bound. \Just published. SUMMARY OF CONTENTS. PART 1. MEASURES. CIRCUMFERENCES AND AREAS, &c., SQUARES, CUBES, FOURTH POWERS. SQUARE AND CUBE ROOTS. SURFACE OF TUBES. RECIPROCALS. LOGARITHMS. MENSURATION. SPECIFIC GRAVITIES AND WEIGHTS. WORK AND POWER. HEAT. COMBUSTION. EXPANSION AND CONTRACTION. EXPANSION OF GASES. STEAM. STATIC FORCES. GRAVITATION AND ATTRACTION. MOTION AND COMPUTATION OF RESULTING FORCES. ACCUMULATED WORK. | WITH DIAGRAMS FOR VALVE-GEAR, BELTING SCREW PROPELLERS, AND COPPER PIPES. CENTRE AND RADIUS OF GYRATION, MOMENT OF INERTIA. CENTRE OF OSCILLATION. ELECTRICITY. STRENGTH OF MATERIALS. ELASTICITY. TEST SHEETS OF MF.TALS. FRICTION. TRANSMISSION OF POWER. FLOW OF LIQUIDS. FLOW OF GASES. AIR PUMPS, SURFACE CONDENSERS, &c. SPEED OF STEAMSHIPS. PROPELLERS. CUTTING TOOLS. FLANGES. COPPER SHEETS AND TUBES. SCREWS, NUTS, BOLT HEADS, &c. VARIOUS RECIPES AND MISCELLANEOUS MATTER. AND ROPES, DISCHARGE AND SUCTION PIPES, TREATING OF, POWER OF BOILERS. USEFUL RATIOS. NOTES ON CONSTRUCTION. CYLINDRICAL BOILER SHELLS. CIRCULAR FURNACES. FLAT PLATES. STAYS. GIRDERS. i SCREWS. HYDRAULIC TESTS. RIVETING. BOILER SETTING, CHIMNEYS, AND MOUNTINGS. FUELS, &c. EXAMPLES OF BOILERS AND SPEEDS OF STEAM- SHIPS. NOMINAL AND NORMAL HORSE POWER. WITH DIAGRAMS FOR ALL BOILER CALCULATIONS AND DRAWINGS OF MANY VARIETIES OF BOILERS. %* OPINIONS OF THE PRESS. echanical engineer may, with advantage to himself, add to his " The book is one which every library." Industries. *' Mr. Foley is well fitted to compile such a work. . . . Regarding the whole work, it may be ve volume which will undoubtedly fulfil the desire of the aut engineers." Marine Engineer. " We have carefully examined this work, and pronounce it a most excellent reference book for the use of marine engineers." Journal of American Society of Naval Engineers " A veritable monument of industry on the part of Mr. Foley, who has succ is simply invaluable to the engineering profession." Steamship rk. . . . The diagrams are a great feature of the be very fairly stated that Mr. Foley has produced a thor and become indispensable to all mechanical succeeded in producing what Coal and Speed Tables. A POCKET BOOK OF COAL AND SPEED TABLES, for Engineers and Steam-users. By NELSON FOLEY, Author of "The Mechanical Engineer's Reference Book." Pocket-size, 3.?. (>d. cloth. " These tables are designed to meet the requirements of every-day use ; they are of sufficient scope for most practical purposes, and may be commended to engineers and users of steam." Iron. " This pocket-book well merits the attention of the practical engineer. Mr. Foley has compiled a very useful set of tables, the information contained in which is frequently required by engineers, coal consumers, and users of steam." Iron and Coal Trades Review. Steam Engine. TEXT-BOOK ON THE STEAM ENGINE, with a Supplement on GAS ENGINES, and PART II. ON HEAT ENGINES. By T. M. GOODEVE, M.A., Barrister-at-Law, Professor of Mechanics at the Royal College of Science, London ; Author of "The Principles of Mechanics," "The Elements of Mechanism," &c. Twelfth Edition, Enlarged. Crown 8vo, 65. cloth. "Professor Goodeve has given us a treatise on the steam engine, which will bear comparison with anything written by Huxley or Maxwell, and we can award it no higher praise." Engineer. " Mr. Goodeve's text-book is a work of which every young engineer should possess himself." Mining Journal. MECHANICAL ENGINEERING, &c. Gas Engines. ON GAS ENGINES. With Appendix describing a Recent Engine with Tube Igniter. By T. M. GOODEVE, M.A. Crown Svo, 2s. 6d. cloth. " Like all Mr. Goodeve's writings, the present is no exception in point of general excellence. It is a valuable little volume." Mechanical World. Steam Engine Design. A HANDBOOK ON THE STEAM ENGINE, with especial Reference to Small and Medium-sized Engines. For the Use of Engine Makers, Mechanical Draughtsmen, Engineering Students, and Users of Steam Power. By HERMAN HAEDER, C.E. English Edition, Re-edited by the Author from the Second German Edition, and Translated, with considerable Additions and Alterations, by H. H. P. POWLES, A.M.I.C.E., M.I.M.E. With nearly 1,100 Illustrations. Crown Svo, gs. cloth. "A perfect encyclopaedia of the steam engine and its details, and one which must take a permanent place in English drawing-offices and workshops." A Foreman Pattern-maker. " This is an excellent book, and should be in the hands of all who are interested in the construction and design of medium-sized stationary engines. ... A careful study of its contents and the arrange- ment of the sections leads to the conclusion that there is probably no other book like it in this country. The volume aims at showing the results of practical experience, and it certainly may claim a complete achievement of this idea." Nature. " There can be no question as to its value. We cordially commend it to all concerned in the design and construction of the steam engine." Mechanical World. Steam Boilers. A TREATISE ON STEAM BOILERS: Their Strength, Construction, and Economical Working. By R. WILSON, C.E. Fifth Edition. I2mo, 6s. cloth. "The best treatise that has ever been published on steam boilers." Engineer. "The author shows himself perfect master of his subject, and we heartily recommend all employing steam power to possess themselves of the work." Ryland's Iron Trade Circular. Boiler Chimneys. BOILER AND FACTORY CHIMNEYS : Their Draught-Power and Stability. With a Chapter on Lightning Conductors. By ROBERT WILSON, A.I.C.E. , Author of "A Treatise on Steam Boilers," &c. Second Edition. Crown Svc, 3^. 6d. cloth. " A valuable contribution to the literature of scientific building.'' The Builder. Boiler Making. THE BOILER-MAKER'S READY RECKONER AND ASSISTANT. With Examples of Practical Geometry and Templating, for the Use of Platers, Smiths, and Riveters. By JOHN COURTNEY, Edited by D. K. CLARK, M.I. C.E. Third Edition, 480 pp., with 140 Illustrations. Fcap. Svo, 7_r. half-bound. " No workman or apprentice should be without this book." Iron Trade Circular. Locomotive Engine Development. THE LOCOMOTIVE ENGINE AND ITS DEVELOPMENT. A Popular Treatise on the Gradual Improvements made in Railway Engines between 1803 and 1894. By CLEMENT E. STRETTON, C.E., Author of "Safe Railway Working," &c. Third Edition, Revised and Enlarged. With 95 Illustrations. Crown Svo, as. 6d. cloth. [Just published. "Students of railway history and all who are interested in the evolution of the modern locomotive will find much to attract and entertain in this volume." - The Times. "The author of this work is well known to the railway world, and no one, probably, has a better knowledge of the history and development of the locomotive. The volume before us should be of value to all connected with the railway system of this country." Nature. Estimating for Engineering Work, &c. ENGINEERING ESTIMATES, COSTS, AND ACCOUNTS : A Guide to Commercial Engineering. With numerous Examples of Estimates and Costs of Millwright Work, Miscellaneous Productions, Steam Engines and Steam Boilers ; and a Section on the Preparation of Costs Accounts. By A GENERAL MANAGER. Demy Svo, 12s. cloth. " This is an excellent and very useful book, covering subject-matter in constant requisition in every factory and workshop The book is invaluable, not only to the young engineer, but also to the estimate department of every works." Builder. " We accord the work unqualified praise. The information is given in a plain, straightforward manner, and bears throughout evidence of the intimate practical acquaintance of the author with every phrase of commercial engineering." Mechanical World. CROSBY LOCKWOOD & SON'S CATALOGUE. Boiler Making. PLATING AND BOILER MAKING: A Practical Handbook for Workshop Operations. By JOSEPH G. HORNER, A.M.I.M.E. ("A Foreman Pattern Maker " ), Author of " Pattern Making," &c. 380 pages, with 338 Illus- trations. Crown 8vo, "]i. 6d. cloth. [Just published. " A thoroughly practical, plainly-written treatise. The volume merits commendation. The author's long experience enables him to write with full knowledge of his subject." Glasgow Herald. Engineering Construction. PATTERN-MAKING : A Practical Treatise, embracing the Main Types of Engineering Construction and including Gearing, both Hand and Machine-made, Engine Work, Sheaves and Pulleys, Pipes and Columns, Screws, Machine Parts, Pumps and Cocks, the Moulding of Patterns in Loam and Greensand, &c.; together with the methods of Estimating the weight of Castings ; to which is added an Appen- dix of Tables for Workshop Reference. By JOSEPH G. HORNER, A.M.I.M.E. ("Foreman Pattern Maker"), Author of "Plating and Boiler Making," &c. Second Edition, thoroughly Revised and much Enlarged. With upwards of 450 Illustrations. Crown 8vo, "js. 6d. cloth. " A well-written technical guide, evidently written by a man who understands and has practised what he has written about We cordially recommend it to engineering students, young journeymen, and others desirous of being initiated into the mysteries of pattern-making." Builder. " More than 370 illustrations help to explain the text, which is, however, always clear and explicit, thus rendering the work an excellent vade mecnm for the apprentice who desires to become master of his trade." English Mechanic. Dictionary of Mechanical Engineering Terms. LocKWOOD's DICTIONARY OF TERMS USED IN THE PRACTICE OF MECHANICAL ENGINEERING, embracing those current in the Drawing Office, Pattern Shop, Foundry, Fitting, Turning, Smiths', and Boiler Shops, &c. &c. Comprising upwards of 6,000 Definitions. Edited by JOSEPH G. HORNER, A.M.I.M.K. ( "Foreman Pattern Maker"), Author of "Pattern Making," &c. Second Edition, Revised, with Additions. Crown 8vo, 7-r. 6d. cloth. " Just the sort of handy dictionary required by the various trades engaged in mechanical engineer- ing. The practical engineering pupil will find the book of great value in his studies, and every foreman engineer and mechanic should have a copy." Building News. " One of the most useful books which can be presented to a mechanic or student." English Mechanic. " Not merely a dictionary, but, to a certain extent, also a most valuable guide. It strikes us as a happy idea to combine with a definition of the phrase useful information on the subject of which it treats." Machinery Market. Mill Gearing. TOOTHED GEARING : A Practical Handbook for Offices and Work- shops. By JOSEPH HORNER, A.M.I.M.E. ( "Foreman Pattern Maker"), Author of "Pattern Making," &c. With 184 Illustrations. Crown 8vo, 6s. cloth. SUMMARY OF CONTENTS. CHAP. I. PRINCIPLES. II. FORMATION OF ; WHEELS. XI. SKEW BEVELS. XII. VARIABLE TOOTH PROFILES. III. PROPORTIONS OF TEETH. ! AND OTHER GEARS. XIII. DIAMETRICAL PITCH. IV. METHODS OF MAKING TOOTH FORMS. XIV. THE ODONTOGRAPH. XV. PATTERN V. INVOLUTE TEETH VI. SOME SPECIAL TOOTH i GEARS. XVI. MACHINE MOULDING GEARS. FORMS. VII. BEVEL WHEELS. VIII. SCREW i XVII. MACHINE CUT GEARS. XVIII. PROPOR- GEARS. IX. WORM GEARS. X. HELICAL TION OF WHEELS. "We must give the book our unqualified praise for its thoroughness of treatment and we can heartily recommei d it to all interested as the most practical book on the subject yet written." Mechanical World. Fire Engineering. FIRES, FIRE-ENGINES, AND FIRE-BRIGADES, with a History of Fire- Engines, their Construction, Use, and Management ; Remarks on Fire- Proof Buildings, and the Preservation of Life from Fire ; Statistics of the Fire Appliances in English Towns ; Foreign Fire Systems ; Hints on Fire-Brigades, &c. &c. By CHARLES F. T. YOUNG, C.E. With numerous Illustrations, 544 pp., demy 8vo, .1 4-r. cloth. " To such of our readers as are interested in the subject of fires and fire apparatus, we can most heartily commend this book. It is really the only English work we now have upon the subject." Engineering. " It displays much evidence of careful research, and Mr. Young has put his facts neatly together. His acquaintance with the practical details of the construction of steam fire engines, old and new, and the conditions with which it is necessary they should comply, is accurate and full." Engineer. MECHANICAL ENGINEERING, &<:. Stone-working Machinery. STONE-WORKING MACHINERY, and the Rapid and Economical Conversion of Stone. With Hints on the Arrangement and Management of Stone Works. By M. Powis BALE, M.I.M.E. With Illustrations. Crown 8vo, gs. "The book should be in the hands of every mason or student of stonework." Colliery Guardian. " A capital handbook for all who manipulate stone for building or ornamental purposes " Machinery Market. Pump Construction and Management. PUMPS AND PUMPING : A Handbook for Pump Users. Being Notes on Selection, Construction, and Management. By M. Powis BALE, M.I.M.E., Author of "Woodworking Machinery," "Saw Mills," &c. Second Edition, Revised. Crown 8vo, 2s. 6d. cloth. "The matter is set forth as concisely as possible. In fact, condensation rather than diffuseness has been the author's aim throughout ; yet he does not seem to have omitted anything likely to be of use." Journal of Gas Lighting. " Thoroughly practical and simply and clearly written." Glasgow Herald. Milling Machinery, &c. MILLING MACHINES AND PROCESSES : A Practical Treatise on Shaping Metals by Rotary Cutters. Including Information on Making and Grinding the Cutters. By PAUL N. HASLUCK, Author of " Lathe- Work," " Handybooks for Handicrafts," &c. With upwards of 300 Engravings, including numerous Drawings by the Author. Large crown 8vo, 352 pages, 125. 6d. cloth. "A new departure in engineering literature. . . . We can recommend this work to all interested in milling machines ; it is what it professes to be a practical treatise." Engineer. "A capital and reliable book which will no doubt be of considerable service both to those who are already acquainted with the process as well as to those who contemplate its adoption. " Industries. Turning. LATHE-WORK : A Practical Treatise on the Tools, Appliances, and Processes employed in the Art of Turning. By PAUL N. HASLUCK. Fifth Edition. Crown 8vo, $s. cloth. " Written by a man who knows not only how work ought to be done, but who also knows how to do it, and how to convey his knowledge to others. To all turners this book would be valuable." Engineering, " We can safely recommend the work to young engineers. To the amateur it will simply be invalu- able. To the student it will convey a great deal of useful information." Engineer. Screw-Cutting. SCREW THREADS : And Methods of Producing Them. With numerous Tables and complete Directions for using Screw-Cutting Lathes. By PAUL N. HASLUCK, Author of "Lathe- Work," &c. With Seventy-four Illustra- tions. Third Edition, Revised and Enlarged. Waistcoat-pocket size, is. 6d. cloth. " Full of useful information, hints and practical criticism. Taps, dies, and screwing tools generally are illustrated and their action described." Mechanical World. " It is a complete compendium of all the details of the screw-cutting lathe ; in fact a multum-in- parvo on all the subjects it treats upon." Carpenter and Builder. Smith's Tables for Mechanics, &c. TABLES, MEMORANDA, AND CALCULATED RESULTS, FOR ME- CHANICS, ENGINEERS, ARCHITECTS, BUILDERS, &c. Selected and Arranged by FRANCIS SMITH. Fifth Edition, thoroughly Revised and Enlarged, with a New Section of ELECTRICAL TABLES, FORMULA, & MEMORANDA. Waistcoat-pocket size, is. 6J. limp leather. " It would, perhaps, be as difficult to make a small pocket-book selection of notes and formulae to suit ALL engineers as it would be to make a universal medicine ; but Mr. Smith's waistcoat-pocket col- lection may be looked upon as a successful attempt." Engineer. "The best example we have ever seen of 270 pages of useful matter packed into the dimensions of a card-case." Building News. " A veritable pocket treasury of knowledge." Iron. French-English Glossary for Engineers, &c. A POCKET GLOSSARY OF TECHNICAL TERMS : ENGLISH- FRENCH, FRENCH-ENGLISH ; with Tables suitable for the Architectural, Engineer- ing, Manufacturing, and Nautical Professions. By JOHN JAMES FLETCHER, Engineer and Surveyor. Second Edition, Revised and' Enlarged, 200 pp. Waistcoat-poeket size, is. 6J. limp leather. " It is a very great advantage for readers and correspondents in France and England to have so large a number of the words relating to engineering and manufacturers collected in a hliputian volume. The little book will be useful both to students and travellers." Architect. " The glossary of terms is very complete, and many of the Tables are new and well arranged We cordially commend the book." Mechanical World. CROSBY LOCKWOOD & SON'S CATALOGUE. fear-Booh of Engineering Formulas, &c. THE ENGINEER'S YEAR-BOOK FOR 1895. Comprising Formulae Rules, Tables, Data and Memoranda in Civil, Mechanical, Electrical, Marine and Mine Engineering. By H. R. KEMPE, A.M.Inst.C.E., M.I.E.E., Technical Officer of the Engineer-in- Chief s Office, General Post Office, London, Author of "A Handbook of Electrical Testing." "The Electrical Engineer's Pocket-Book, " &c. With 750 Illustrations, specially Engraved for the work. Crown 8vo, 650 pages, 8s. leather. [Just published. "Represents an enormous quantity of work, and forms a desirable book of reference." The Engineer. "The volume is distinctly in advance of most similar publications in this country." Engineering. "This valuable and well-designed book of reference meets the demands of all descriptions of engi- neers." Saturday Review. "Teems with up-to-date information in every branch of engineering and construction." Building News. " The needs of the engineering profession could hardly be supplied in a more admirable, complete and convenient form. To say that it more than sustains all comparisons is praise of the highest sort, and that may justly be said of it." Mining Journal. "There is certainly room for the new comer, which supplies explanations and directions, as well as formula: and tables. It deserves to become one of the most successful of the technical annuals." Architect. " Brings together with great skill all the technical information which an engineer has to use day by day. It is in even' way admirably equipped, and is sure to prove successful." Scotsman. "The up-to-dateness of Mr. Kempe's compilation is a quality that will not be lost on the busy people for whom the work is intended." Glasgow Herald. Portable Engines. THE PORTABLE ENGINE : ITS CONSTRUCTION AND MANAGE- MENT: A Practical Manual for Owners and Users of Steam Engines generally. By WILLIAM DYSON WANSBROUGH. With 90 Illustrations. Crown 8vo, 3-r. 6d. cloth. "This is a work of value to those who use steam machinery. . . . Should be read by every one who has a steam engine, on a farm or elsewhere." Mark Lane Express. " We cordially commend this work to buyers and owners of steam engines, and to those who have to do with their construction or use." Timber Trades Journal. "Such a general knowledge of the steam-engine as Mr. Wansbrough furnishes to the reader should be acquired by all intelligent owners and others who use the steam engine." Building News. _ " An excellent text-book of this useful form of engine. The ' Hints to Purchasers ' contain a good deal of common-sense and practical wisdom." English Mechanic. Iron and Steel. "IRON AND STEEL" : A Work for the Forge, Foundry, Factory, and Office. Containing ready, useful, and trustworthy Information for Ironmasters and their Stock-takers ; Managers of Bar, Rail, Plate, and Sheet Rolling Mills ; Iron and Metal Founders ; Iron Ship and Bridge Builders ; Mechanical, Mining, and Consulting Engineers ; Architects, Contractors, Builders, and Professional Draughtsmen. By CHARLES HOARE, Author of "The Slide Rule," &c. Eighth Edition, Revised throughout and considerably Enlarged. 321110, 6s. leather. " For comprehensiveness the book has not its equal." Iron. " One of the best of the pocket books." English Mechanic. " We cordially recommend this book to those engaged in considering the details of all kinds of iron and steel works." Naval Science. Elementary Mechanics. CONDENSED MECHANICS. A Selection of Formulae, Rules, Tables, and Data for the Use of Engineering Students, Science Classes, &c. In accord- ance with the Requirements of the Science and Art Department. By W. G. CRAWFORD HUGHES, A.M.I.C.E. Crown 8vo, 2s. 6d, cloth. " The book is well fitted for those who are either confronted with practical problems in their work, or are preparing for examination and wish to refresh their knowledge by going through their formulae again." Marine Engineer. " It is well arranged, and meets the wants of those for whom it is intended." Railway News. Steam. THE SAFE USE OF STEAM. Containing Rules for Unprofessional Steam-users. By an ENGINEER. Sixth Edition. Sewed, 6d. " If steam-users would but learn this little book by heart, boiler explosions would become sensations by their rarity." English Mechanic. Warming. HEATING BY HOT WATER ; with Information and Suggestions on (he best Methods of Heating Public, Private and Horticultural Buildings. By WALTER JONES. Second Edition. With 96 Illustrations, crown 8vo, 2s. 6d. net. " We confidently recommend all interested in healing by hot water to secure a copy of this valuable little treatise." The Plumber and Decorator. CIVIL ENGINEERING, SURVEYING, <&*. CIVIL ENGINEERING, SURVEYING, etc. Water Supply and Water-Worhs. THE WATER SUPPLY OF TOWNS AND THE CONSTRUCTION OF WATER-WORKS; A Practical Treatise for the Use of Engineers and Students of Engineering. By W. K. BURTON, A.M.Inst.C.E., Professor of Sanitary Engineering in the Imperial University, Tokyo, Japan, and Consulting Engineer to the Tokyo Water- Works. With an Appendix on THE EFFECTS OF EARTHQUAKES ON WATER-WORKS, by Professor JOHN MILNE, F.R.S. With numerous Plates and Illustrations. Super-royal 8vo, 2$s. buckram. {.Just Published. CONTENTS. CHAP. I. INTRODUCTORY. II. DIFFERENT QUALITIES OF WATER. III. QUANTITY OF WATER TO BE PROVIDED. IV. ON ASCERTAINING WHETHER A PRO- POSED SOURCE OF SUPPLY is SUFFI- CIENT. V. ON ESTIMATING THE STORAGE CAPA- CITY REQUIRED TO BB PROVIDED. VI. CLASSIFICATION OF WATERWORKS. VII. IMPOUNDING RESERVOIRS. VIII EARTHWORK DAMS. IX. MASONRY DAMS. X. THE PURIFICATION OF WATER. XI. SETTLING RESERVOIRS. XII. SAND FILTRATION. XIII. PURIFICATION dp WATER BY ACTION OF IRON SOFTENING OF WATER BY ACTION OF LIME NATURAL FILTRA- TION. CHAP. XIV. SERVICE OR CLEAN WATER RESER- VOIRS WATER TOWERS STAND PIPES. XV THE CONNECTION OF SETTLING RESER- VOIRS, FILTER BEDS AND SERVICE RESERVOIRS. XVI. PUMPING MACHINERY. XVH. FLOW OF WATER IN CONDUITS PIPES AND OPEN CHANNELS. XVIII. DISTRIBUTION SYSTEMS. XIX. SPECIAL PROVISIONS FOR THE EX- TINCTION OF FIRE. XX. PIPES FOR WATERWORKS. XX I. -PREVENTION OF WASTE OF WATER. XXII. VARIOUS APPLICATIONS USED IN CON- NECTION WITH WATERWORKS. APPENDIX. By PROF. JOHN MILNE, F.R.S. CONSIDERATIONS CONCERNING THE PROB- ABLE EFFECTS OF EARTHQUAKES ON WATER- WORKS, AND THE SPECIAL PRECAUTIONS TO BE TAKEN IN EARTHQUAKE COUNTRIES. " The chapter upon filtration of water is very complete, and the details of construction well illus- trated. . . . The work should be specially valuable to civil engineers engaged in work in Japan, jut the interest is by no means confined to that locality." Engineer. " It is with great pleasure that we chronicle an addition to the literature of this important branch of engineering, and of this portant branch upon the practical common sense shown in the prepara- tion of this work. . . . The plates and diagrams have evidently been prepared with great care and cannot fail to be of great assistance to the student." Builder. " The whole art of waterworks construction is dealt with in a clear and comprehensive fashion in this handsome volume. . . . Mr. Burton's practical treatise shows in all its sections the fruit of independent study and individual experience. It is largely based upon his own practice in the branch of engineering of which it treats." Saturday Review The Water-Supply of Cities and Towns. A COMPREHENSIVE TREATISE ON THE WATER-SUPPLY OF CITIES AND TOWNS. By WILLIAM HUMBER, A.-M. Inst. C.E., and M. Inst. M.E., Author of "Cast and Wrought Iron Bridge Construction," &c. &c. Illustrated with 50 Double Plates, I Single Plate, Coloured Frontispiece, and upwards of 250 Woodcuts, and containing 400 pages of Text. Imp. 410, 6 6s. elegantly and substantially half-bound in morocco. LIST OF CONTENTS. I. HISTORICAL SKETCH OF SOME OF THE MEANS THAT HAVE BEEN ADOPTED FOR THE SUPPLY OF WATER TO CITIES AND TOWNS. II. WATER AND THE FOREIGN MATTER USUALLY ASSOCIATED WITH IT.--III. RAINFALL AND EVAPORATION. .'IV. SPRINGS AND THE WATER-BEARING FORMA- TIONS OF VARIOUS DISTRICTS. V. MEASUREMENT .AND ESTIMATION OF THE FLOW OF WATER. VI. ON THE SELECTION OF THE SOURCE OF -SUPPLY. VII. WELLS. VIII. RESERVOIRS. IX. THE PURIFICATION OF WATER. X. PUMPS. XI. PUMPING MACHINERY. XII. CONDUITS. "The most systematic and valuable work upon water supply hitherto produced in English, or In any other language. . . . Mr. Humber's work is characterised almost throughout by an exhaustiveness much more distinctive of French and German than of English technical treatises." Engineer. " We can congratulate Mr. Humber on having been able to give so large an amount of information on a subject so important as the water supply of cities and towns. The plates, fifty in number, are mostly drawings of executed works, and alone would have commanded the attention of every engineer whose -practice may lie in this branch of the profession." Builder. XIII. DISTRIBUTION OF WATER. XIV. METERS SERVICE PIPES, AND HOUSE FITTINGS. -XV. THE LAW AND ECONOMY OF WATER WORKS. XVI. CONSTANT AND INTERMITTENT SUPPLY. XVII. DESCRIPTION OF PLATES. APPENDICES, GIVING TABLES OF RATES OF SUPPLY, VELO- CITIES, &C. &C., TOGETHER WITH SPECIFICA- TIONS OF SEVERAL WORKS ILLUSTRATED, AMONG WHICH WILL BE FOUND: ABERDEEN, BlDEFORD, CANTERBURY, DUNDEE, HALIFAX, LAMBETH, ROTHERHAM, DUBLIN, AND OTHERS. 10 CROSBY LOCKWOOD &> SON'S CATALOGUE. Water Supply. RURAL WATER SUPPLY. A Practical Handbook on the Supply of Water and Construction of Waterworks for Small Conntry Districts. By ALLAN GREENWELL, A.M.I. C.E., and W. T. CURRY, A.M.I.C.E., F.G.S. With Illus- trations. Crown 8vo, 5-r. cloth. \Jrnt ready* Hydraulic Tables. HYDRAULIC TABLES, CO-EFFICIENTS, AND FORMULA for Finding the Discharge of Water from Orifices, Notches, Weirs, Pipes, and Rivers. With New Formulae, Tables, and General Information on Rain-fall, Catchment-Basins, Drainage, Sewerage, Water Supply for Towns and Mill Power. By JOHN NEVILLE,. Civil Engineer, M.R.I.A. Third Edition, carefully revised, with considerable Additions. Numerous Illustrations. Crown 8vo, 14?. cloth. "Alike valuable to students and engineers in practice; its study will prevent the annoyance of avoidable failures, and assist them to select the readiest means of successfully carrying out any given work connected with hydraulic engineering. " Mining Journal. "It is, of all English books on the subject, the one nearest to completeness .... From the good arrangement of the matter, the clear explanations and abundance of formulae, the carefully calculated tables, and, above all, the thorough acquaintance with both theory and construction, which is displayed from first to last, the book will be found to be an acquisition." Architect. Hydraulics. HYDRAULIC MANUAL. Consisting of Working Tables and Explana- tory Text. Intended as a Guide in Hydraulic Calculations and Field Operations. By Lowis D'A. JACKSON, Author of "Aid to Survey Practice," "Modern. Metrology," &c. Fourth Edition, Enlarged. Large crown 8vo, l6s. cloth. " The author has had a wide experience in hydraulic engineering and has been a careful observer of the facts which have come under his notice, and from the great mass of material at his command he has constructed a manual which may be accepted as a trustworthy guide to this branch of the engineer's pro- fession. We can heartily recommend this volume to all who desire to be acquainted with the latest development of this important subject.*' Engineering. "The standard work in this department of mechanics." Scotsman. "The most useful feature of this work is its freedom from what is superannuated, and its thorough adoption of recent experiments ; the text is in fact in great part a short account of the great modern experiments." Nature. Water Storage, Conueyance, and Utilisation. WATER ENGINEERING : A Practical Treatise on the Measure- ment, Storage, Conveyance, and Utilisation of Water for the Supply of Towns, for Mill Power, and for other Purposes. By CHARLES SLAGG, A.-M.Inst.C.E., Author of "Sanitary Work in the Smaller Towns, and in Villages," &c. Second Edition, with numerous Illustrations. Crown 8vo, 7-r. 6J. cloth. "As a small practical treatise on the water supply of towns, and on some applications of water- power, the work is in many respects excellent." Engineering. "The author has collated the results deduced from the experiments of the most eminent authorities, and has presented them in a compact and practical form, accompanied by very clear and detailed explanations. . . . The application of water as a motive power is treated very carefully and exhaustively." Builder. "For anyone who desires to begin the study of hydraulics with a consideration of the practical applications of the science there is no better guide." A rchitect. Drainage. ON THE DRAINAGE OF LANDS, TOWNS, AND BUILDINGS. By G. D. DEMPSEY, C.E., Author of "The Practical Railway Engineer," &c. Revised, with large Additions on RECENT PRACTICE IN DRAINAGE ENGINEERING, by D. KINNEAR CLARK, M.Inst. C.E., Author of "Tramways: their Construc- tion and Working," " A Manual of Rules, Tables, and Data for Mechanical Engineers," &c. Second Edition, Corrected. Fcap. 8vo, $s. cloth. " The new matter added to Mr. Dempsey's excellent work is characterised by the comprehensive grasp and accuracy of detail for which the name of Mr. D. K. Clark is a sufficient voucher." Athenieum. " As a work on recent practice in drainage engineering, the book is to be commended to all who are making that branch of engineering science their special study." Iron. " A comprehensive manual on drainage engineering, and a useful introduction to the student." - Building News. Riuer Engineering. RIVER BARS : The Causes of their Formation, and their Treatment by " Induced Tidal Scour ; " with a Description of the Successful Reduction by this Method of the Bar at Dublin. By I. J. MANN, Assist. Eng. to the Dublin- Port and Docks Board. Royal 8vo, Js. 6d. cloth. " We recommend all interested in harbour works and, indeed, those concerned in the improvements- of rivers generally to read Mr. Mann's interesting work on the treatment of river bars."nineer. CIVIL ENGINEERING, SURVEYING, &c. Tramways and their Working. TRAMWAYS : THEIR CONSTRUCTION AND WORKING. Em- bracing a Comprehensive History of the System ; with an exhaustive Analysis of the Various Modes of Traction, including Horse Power, Steam, Cable Traction, Electric Traction, &c. ; a Description of the Varieties of Rolling Stock ; and ample Details of Cost and Working Expenses. New Edition, Thoroughly Revised, and Including the Progress recently made in Tramway Construction, &c. &c. By D. KINNEAR CLARK, M.Inst. C.E. With 400 Illustrations. 8vo, 780 pages. Price 28j., buckram. [Just published. "Although described as a new edition, this book is really a new one, a large part of it, which covers historical ground, having been re-written and amplified; while the parts which relate to all that has been done since 1882 appear in this edition only. It is sixteen years since the first edition appeared, and twelve years since the supplementary volume to the first book was published. After a lapse, thenj of twelve years, it is obvious that the author has at his disposal a vast quantity of descriptive and statis- tical information, with which he may, and has, produced a volume of great' value to all interested in tramway construction and working. The new volume is one which will rank, among tramway engineers and those interested in tramway working, with his world-famed book on railway machinery." 7 he Engineer, March 8, 1895. "An exhaustive and practical work on tramways, in which the history of this kind of locomotion, and a description and cost of the various modes of laying tramways, are to be found." Building News. " The best form of rails, the best mode of construction, and the best mechanical appliances, are so fairly indicated in the work under review that any engineer about to construct a tramway will be enabled at once to obtain the practical information which will be of most service to him." Athenaum. " Of this work we spoke in terms of deservedly high praise on its first appearance. . . . The work is a standard one, and constitutes really all that an engineer about to construct a tramway would need. Mr. Clark has the very highest reputation, both for soundness and for his tact in imparting instruction. Of this work it is impossible to speak too highly." Colliery Guardian, Student's Text-Booh on Surveying. PRACTICAL SURVEYING: A Text-Book for Students preparing for Examinations or for Survey-work in the Colonies. By GEORGE W. UsiLL, A. M.I. C.E. , Author of "The Statistics of the Water Supply of Great Britain." With 4 Lithographic Plates and upwards of 330 Illustrations. Third Edition, Revised and Enlarged. Including Tables of Natural Sines, Tangents, Secants, &c. Crown 8vo, "js. 6d. cloth ; or, on THIN PAPER, bound in limp leather, gilt edges, rounded corners, for pocket use, price izs. 6d. "The best forms of instruments are described as to their construction, uses and modes of employment, and there are innumerable hints on work and equipment such as the author, in his experience as surveyor, draughtsman and teacher, has found necessary, and which the student in his inexperience will find most serviceable." Engineer. "The latest treatise in the English language on surveying, and we have no hesitation in saying that the student will find it a better guide than any of its predecessors. . . . Deserves to be recog- nised as the first book which should be put in the hands of a pupil of Civil Engineering, and every gentleman of education who sets out for the Colonies would find it well to have a copy." Architect. Survey Practice. AID TO SURVEY PRACTICE : for Reference in Surveying, Level- ling, and Setting-out ; and in Route Surveys of Travellers by Land and Sea. With Tables, Illustrations, and Records. By Lowis D'A. JACKSON, A.M.I.C.E., Author of "Hydraulic Manual," "Modern Metrology," &c. Second Edition, Enlarged. Large crown 8vo, 12s. 6d. cloth. "Mr. Jackson has produced a valuable vade-mecum for the surveyor. We can recommend this book as containing an admirable supplement to the teaching of the accomplished surveyor." Athenaum. "As a text-book we should advise all surveyors to place it in their libraries, and study well the matured instructions afforded in its pages. 1 * Colliery Guardian. " The author brings to his work a fortunate union of theory and practical experience which, aided by a clear and lucid style of writing, renders the book a very useful one." Builder. Field-Booh for Engineers. THE ENGINEER'S, MINING SURVEYOR'S, AND CONTRACTOR'S FlELD-Book. Consisting of a Series of Tables, with Rules, Explanations of Systems, and use of Theodolite for Traverse Surveying and Plotting the Work with minute accuracy by means of Straight Edge and Set Square only ; Levelling with the Theodolite, Casting-out and Reducing Levels to Datum, and Plotting Sections in the ordinary manner : Setting-out Curves with the Theodolite by Tangential Angles and Multiples with Right and Left-hand Readings of the Instrument ; Setting, out Curves without Theodolite on the System of Tangential Angles by Sets of Tan- gents and Offsets; and Earthwork Tables to 80 feet deep, calculated for every 6 inches in depth. By W. DAVIS HASKOLL, C.E. With numerous Woodcuts. Fourth Edition, Enlarged. Crown 8vo, 12s. cloth. "The book is very handy ; the separate tables of sines and tangents to every minute will make i useful for many other purposes, the genuine traverse tables existing all the same." Athenautn. " Every person engaged in engineering field operations will estimate the importance of such a work and the amount of valuable time which will be saved by reference to a set of reliable tables prepared with the accuracy and fulness of those given in this volume." Railway News. CROSBY LOCKWOOD &> SON'S CATALOGUE. Surveying, Land and Marine. LAND AND MARINE SURVEYING, in Reference to the Preparation of Plans for Roads and Railways ; Canals, Rivers, Towns' Water Supplies ; Docks and Harbours. With Description and Use of Surveying Instruments. By W. DAVIS HASKOLL, C.E., Author of "Bridge and Viaduct Construction," &c. Second Edition, Revised, with Additions. Large crown 8vo, 9.?. cloth. " This book must prove of great value to the student. We have no hesitation in recommending it, feeling assured that it will more than repay a careful study." Mechanical World. "A most useful and well arranged book for the aid of a student. We can strongly recommend it as a carefully -wrtten and valuable text-book. It enjoys a well-deserved repute among surveyors." Builder. "This volume cannot fail to prove of the utmost practical utility. It may be safely recommended to all students who aspire to become clean and expert surveyors." Mining Journal. Leuel/ing. A TREATISE ON THE PRINCIPLES AND PRACTICE OF LEVELLING. Showing its Application to purposes of Railway and Civil Engineering in the Con- struction of Roads ; with Mr. TELFORD'S Rules for the same. By FREDERICK W. SIMMS, F.G.S., M. Inst. C.E. Seventh Edition, with the addition of LAW'S Practical Examples for Setting-out Railway Curves, and TRAUTWINE'S Field Practice of Laying-out Circular Curves. With 7 Plates and numerous Woodcuts, 8vo, Ss. 6d. cloth. %* TRAUTWINE on CURVES may be had separate, 5*. " The text-book on levelling in most of our engineering schools and colleges." Engineer. " The publishers have rendered a substantial service to the profession, especially to the younger members, by bringing out the present edition of Mr. Simms's useful work." Engineering. Trigonometrical Surveying. AN OUTLINE OF THE METHOD OF CONDUCTING A TRIGONO- METRICAL SURVEY, for the Formation of Geographical and Typographical Maps and Plans, Military Reconnaissance, LEVELLING, &c., with Useful Problems, Formulae, and Tables. By Lieut. -General FROME, R.E. Fourth Edition, Revised and partly Re-written by Major-General Sir CHARLES WARREN, G.C.M.G., R.E. With 19 Plates and 115 Woodcuts, royal 8vo, i6j. cloth. " No words of praise from us can strengthen the position so well and so steadily maintained by this work. Sir Charles Warren has revised the entire work, and made such additions as were necessary to bring every portion of the contents up to the present date." Broad Arrow. Curves, Tables for Setting-out. TABLES OF TANGENTIAL ANGLES AND MULTIPLES FOR SETTING-OUT CURVES from 5 to 200 Radius. By A. BEAZELEY, M. Inst. C.E. 4th Edition. Printed on 48 Cards, and sold in a cloth box, waistcoat-pocket size, $s. 6d, " Each table is printed on a small card, which, being placed on the theodolite, leaves the hands free to manipulate the instrument no small advantage as regards the rapidity of work." Engineer. " Very handy : a man may know that all his day's work must fall on two of these cards, which he puts into his own card-case, and leaves the rest behind." Athemeum. Earthwork. EARTHWORK TABLES. Showing the Contents in Cubic Yards of Embankments, Cuttings, &c., of Heights or Depths up to an average of 80 feet. By JOSEPH BROADBENT, C.E., and FRANCIS CAMPIN, C.E. Crown Svo, 5^. cloth. " The way in which accuracy is attained, by a simple division of each cross section into three elements, two in which are constant and one variable, is ingenious." A thetuzum. Earthwork, Measurement of. A MANUAL ON EARTHWORK. By ALEX. J. S. GRAHAM, C.E. With numerous Diagrams. Second Edition. i8mo, 2s. 6d. cloth. Tunnelling. PRACTICAL TUNNELLING. Explaining in detail the Setting-out of the Works, Shaft-sinking, and Heading-driving, Ranging the Lines and Levelling under Ground, Sub-Excavating, Timbering, and the Construction of the Brickwork of Tunnels, with the amount of Labour required for, and the Cost of, the various portions of the work. By F. W. SIMMS, M. Inst. C.E. Third Edition, Revised by D. K. CLARK, M.Inst.C.E. Imp. Svo, 30.?. cloth. "The estimation in which Mr. Simms's book on tunnelling has been held for over thirty years cannot be more truly expressed than in the words of the late Professor Rankine : 'The best source of informa- tion on the subject of tunnels is Mr. F. W. Simms's work on Practical Tunnelling."' Architect. " It has been regarded from the first as a text book of the subject . . . Mr. Clark has added immensely lo the value of the book." Engineer. CIVIL ENGINEERING, SURVEYING, &c. 13 Tunnel Shafts. THE CONSTRUCTION OF LARGE TUNNEL SHAFTS : A Prac- tical and Theoretical Essay. By J. H. WATSON BUCK, M. Inst.C.E., Resident Engineer, London and North- Western Railway. Illustrated with Folding Plates, royal 8vo, 12s. cloth. " Many of the methods given are of extreme practical value to the mason, and the observations on the form of arch, the rules for ordering the stone, and the construction of the templates, will be found of considerable use. We commend the book to the engineering profession." Building News. " Will be regarded by civil engineers as of the utmost value, and calculated to save much time and obviate many mistakes." Collierv Guardian. Cast and Wrought Iron Bridge Construction. A COMPLETE AND PRACTICAL TREATISE ON CAST AND WROUGHT IRON BRIDGE CONSTRUCTION, including Iron Foundations. In Three Parts Theoretical, Practical, and Descriptive. By WILLIAM HUMBER, A.-M. Inst. C.E., and M. Inst. M.E. Third Edition, revised and much improved, with 115 Double Plates (aoof which now first appear in this edition), and numerous Additions to the Text. In 2 vols., imp. 410, 6 i6s. 6d. half-bound in morocco. " A very valuable contribution to the standard literature of civil engineering. In addition to elevations, plans, and sections, large scale details are given, which very much enhance the instructive worth of those illustrations." Civil Engineer and Architect's Journal. "Mr. Humber's stately volumes, lately issued in which the most important bridges erected during the last five years, under the direction of the late Mr. Brunei, Sir W. Cubitt, Mr. Hawkshaw, Mr. Page, Mr. Fowler. Mr. Hemans, and others among our most eminent engineers, are drawn and specified in great detail." Engineer. Oblique Bridges, A PRACTICAL AND THEORETICAL ESSAY ON OBLIQUE BRIDGES. With 13 large Plates. By the late GEORGE WATSON BUCK, M.I.C.E. Fourth Edition, revised by his Son, J. H. WATSON BUCK, M.I.C.E. ; and with the addition of Description to Diagrams for Facilitating the Construction of Oblique Bridges, by W. H. BARLOW, M.I.C.E. Royal 8vo, izs. cloth. "The standard text-book for all engineers regarding skew arches is Mr. Buck's treatise, and it would be impossible to consult a better." Engineer. " Mr. Buck's treatise is recognised as a standard text-book, and his treatment has divested the subject of many of the intricacies supposed to belong to it. As a guide to the engineer and architect, on a confessedly difficult subject, Mr. Buck's work is unsurpassed." Builaing News. Oblique Arches. A PRACTICAL TREATISE ON THE CONSTRUCTION OF OBLIQUE ARCHES. By JOHN HART. Third Edition, with Plates. Imperial 8vo, 8j. cloth. Statics, Graphic and Analytic. GRAPHIC AND ANALYTIC STATICS, in their Practical Application to the Treatment of Stresses in Roofs, Solid Girders, Lattice, Bowstring, and Suspension Bridges, Braced Iron Arches and Piers, and other Frameworks. By R. HUDSON GRAHAM, C.E. Containing Diagrams and Plates to Scale. With numerous Examples, many taken from existing Structures. Specially arranged for Class-work in Colleges and Universities. Second Edition, Revised and En- larged. 8vo, i6j. cloth. " Mr. Graham's book will find a place wherever graphic and analytic statics are used or studied." Engineer. " The work is excellent from a practical point of view, and has evidently been prepared wilh much care. The directions for working are ample, and are illustrated by an abundance of well-selected examples. It is an excellent text-book for the practical draughtsman." Athenaum. Girders, Strength of. GRAPHIC TABLE for Facilitating the Computation of the Weights of Wrought Iron and Steel Girders, &c., for Parliamentary and other Estimates. By T. H. WATSON BUCK, M. last. C.E. On a Sheet, 2s. 6d. Strains, Calculation of. A HANDY BOOK FOR THE CALCULATION OF STRAINS IN GIRDERS AND SIMILAR STRUCTURES AND THEIR STRENGTH. Consisting of Formulas and Corresponding Diagrams, with numerous details for Practical Application, &c. By WILLIAM HUMBER, A.-M. Inst. C.E..&C. Fifth Edition. Crown 8vo, with nearly 100 Woodcuts and 3 Plates, 7^. 6d. cloth. "The formula are neatly expressed, and the diagrams %ood."AtAena>um. "We heartily commend this really handy book to our engineer and architect readers." English Mechanic. 14 CROSBY LOCKWOOD S- SON'S CATALOGUE. Trusses. TRUSSES OF WOOD AND IRON. Practical Applications of Science in Determining the Stresses, Breaking Weights, Sa r e Loads, Scantlings, and Details of Construction. With Complete Working Drawings. By WILLIAM GRIFFITHS, Surveyor, Assistant Master, Tranmere School of Science and Art. Oblong 8vo, 4-r. (xt. cloth. ' ' This handy little book enters so minutely into every detail connected with the construction of roof trusses that no student need he ignorant of these matters." Practical Engineer, Strains in Ironwork. THE STRAINS ON STRUCTURES OF IRONWORK ; with Prac- tical Remarks on Iron Construction. By F. W. SHEILDS, M.I.C.E. 8vo, $s. cloth Barlow's Strength of Materials, Enlarged by Humber. A TREATISE ON THE STRENGTH OF MATERIALS ; with Rules for application in Architecture, the Construction of Suspension Bridges, Railways, &c. By PETER BARLOW, F.R.S. A New Edition, revised by his Sons, P. W. BARLOW, F.R.S. , and W. H. BARLOW, F.R S. ; to which are added, Experiments by HODGKINSON, FAIRBAIRN, and KIRKAI.DY ; and Formulas for Calculating Girders, &c. Arranged and Edited by WM. HUMBER, A.-M. Inst. C.E. Demy 8vo, 400 pp., with 19 large Plates and numerous Woodcuts, l8s. cloth. "Valuable alike to the student, tyro, and the experienced practitioner, it will always rank in future, as it has hitherto done, as the standard treatise on that particular subject." Engineer. " There is no greater authority than Barlow." Building News. "As a scientific work of the first class, it deserves a foremost place on the bookshelves of every civil engineer and practical mechanic." English Mechanic. Cast Iron and other Metals, Strength of. A PRACTICAL ESSAY ON THE STRENGTH OF CAST IRON and other Metals. By THOMAS TREDGOLD, C.E. Fifth Edition, including HODGKIN- SON'S Experimental Researches. 8vo, I2s. cloth. Practical Mathematics. MATHEMATICS FOR PRACTICAL MEN : Being a Common-place Book of Pure and Mixed Mathematics. Designed chiefly For the Use of Civil Engineers, Architects and Surveyors. By OLINTHUS GREGORY, LL.D., F.R.A.S., Enlarged by HENRY LAW, C.E. Fourth- Ed., carefully revised by J. R. YOUNG, formerly Professor of Mathematics, Belfast College. With 13 Plates, 8vo, i is. cloth. "The engineer or architect will here find ready to his hand rules for solving nearly e*ery mathematical difficulty that may arise in his practice. The rules are in all cases explained by means of examples, in which every step of the process is clearly worked out." Builder. " One of the most serviceable books for practical mechanics. . . . It is an instructive book for the student, and a Text-book for him who, having once mastered the subjects it treats of, needs occasionally to refresh his memory upon them." Building News. Railway Working. SAFE RAILWAY WORKING : A Treatise on Railway Accidents, their Cause and Prevention ; with a Description of Modern Appliances and Systems. By CLEMENT E. STRETTON, C.E., Vice-President and Consulting Engineer, Amalgamated Society of Railway Servants. With Illustrations and Coloured Plates. Third Edition, Enlarged. Crown 8vo, y. 6d. cloth. " A book for the engineer, the directors, the managers ; and, in short, all who wish for information on railway matters will find a perfect encyclopedia in ' Safe Railway Working.' " Railway Review. "We commend the remarks on railway signalling to all railway managers, especially where a uniforn. code and practice is advocated." HerepatWs Railway Journal. " The author may be congratulated on having collected, in a very convenient form, much valuable information on the principal questions affecting the safe working of railways." Railway Engineer. Heat, Expansion by. EXPANSION OF STRUCTURES BY HEAT. By JOHN KEILY, C.E., late of the Indian Public Works Department. Crown 8vo, 3^. 6d. cloth. "The aim the author has set before him, viz., to show the effects of heat upon metallic and other structures, is a laudable one, for this is a branch of physics upon which the engineer or architect can find but little reliable and comprehensive data in books. 1 ' Builder. Field Fortification. A TREATISE ON FIELD FORTIFICATION, The Attack of Fortresses, Military Mining, and Reconnoitring. By Professor Colonel I. S. MACAULAY. Sixth Edition, crown 8vo, with separate Atlas of 12 Plates, I2s. cloth. CIVIL ENGINEERING, SURVEYING, S-v. 15 MR. H UMBER'S GREAT WORK ON MODERN ENGINEERING. Complete in Four Volumes, imperial 410, price 12 12s. half-morocco. Each volume sold separately as follows : A RECORD OF THE PROGRESS OF MODERN ENGINEERING. FIRST SERIES. Comprising Civil, Mechanical, Marine, Hydraulic, Railway, Bridge, and other Engineering Works, &c. By WILLIAM HUMBER, A.-M. Inst. C.E., &c. Imp. 410, with 36 Double Plates, drawn to a large scale, Photographic Portrait of John Hawkshaw, C.E., F.R.S., &c., and copious descriptive Letterpress, Specifica- tions, &c., 3 3?. half-morocco. LIST OF THE PLATES AND DIAGRAMS. VICTORIA STATION AND ROOF, L. B. & S. C. R. i BRIDGE OVER THE THAMES, WEST LONDON Ex- <8 PLATES): SOUTHPORT PIER (2 PLATES); Vic- TENSION RAILWAY (5 PLATES) ; ARMOUR PLATES: TORIA STATION AND ROOF, L. C. & D. AND ! SUSPENSION BRIDGE, THAMES (4 PLATES) ; THE G. W. R. (6 PLATES) ; ROOF OF CREMORNE Music ALLEN ENGINE; SUSPENSION BRIDGE, AVON HALL; BRIDGE OVER G. N. RAILWAY; ROOF OF (3 PLATES) ; UNDERGROUND RAILWAY (3 PLATES). " Handsomely lithographed and printed. It will find favour with many who desire to preserve in a permanent form copies of the plans and specifications prepared for the guidance of the contractors for many important engineering works." Engineer. NUMBER'S PROGRESS OF MODERN ENGINEERING. SECOND SERIES. Imp. 4to, with 3 Double Plates, Photographic Portrait of Robert Stephenson, C.E., M.P., F.R.S., &c., and copious descriptive Letterpress, Specifications, &c., 3 3^-. half-morocco. LIST OF THE PLATES AND DIAGRAMS. BlRKENHEAD DOCKS, LOW WATER BASIN (ij I MERTHYR, TREDEGAR, AND ABERGAVENNY RAIL- TES) ; CHARING CROSS STATION ROOF, C. C. | WAY ; COLLEGE WOOD VIADUCT, CORNWALL RAILWAY (3 PLATES) ; DIGSWELLVIAOUCT, GREAT NORTHERN RAILWAY; ROBBERY WOOD VIADUCT, GREAT NORTHERN RAILWAY ; IRON PERMA WAY; CLYDACH VIADUCT ; MERTHYR,TREDEGAF RAILWAY ; DUBLIN WINTER PALACE ROOF (3 PLATES) ; BRIDGE OVER THE THAMES, L. C. and D. RAILWAY (6 PLATES) ; ALBERT HARBOUR, GREENOCK (4 PLATES). AND ABERGAVENNY RAILWAY; EBBW VIADUCT, I ' Mr. Humber has done the profession good and true service, by the fine collection of examples he has here brought before the profession and the public." Practical Mechanic's Journal. NUMBER'S PROGRESS OF MODERN ENGINEERING. THIRD SERIES. Imp. 4to, with 40 Double Plates, Photographic Portrait of J. R. M 'Clean, -late Pres. Inst. C.E., and copious descriptive Letterpress, Specifications, &c., 3 y. half-morocco. LIST OF THE PLATES AND DIAGRAMS. MAIN DRAINAGE, METROPOLIS. North Side. PLATES) ; OUTFALL SEWER, RESERVOIR AND MAP SHOWING INTERCEPTION OF SEWERS; ! OUTLET (4 PLATES); OUTFALL SEWER, FILTH MIDDLE LEVEL SEWER (2 PLATES); OUTFALL i HOIST; SECTIONS OF SEWERS (NORTH AND SEWER, BRIDGE OVER RIVER LEA (3 PLATES); [ SOUTH SIDES). OUTFALL SEWER, BRIDGE OVS,R MARSH LANE, > THAMES EMBANKMENT. SECTION OF RIVER NORTH WOOLWICH RAILWAY, AND Bow AND j WALL; STEAMBOAT PIER, WESTMINSTER (2 BARKING RAILWAY JUNCTION ; OUTFALL SEWER, ' PLATES) ; LANDING STAIRS BETWEEN CHARING BRIDGE OVER Bow AND BARKING RAILWAY CROSS AND WATERLOO BRIDGES; YORK GATE (3 PLATES) ; OUTFALL SEWER, BRIDGE OVER (2 PLATES) ; OVERFLOW AND OUTLET AT SAVOY EAST LONDON WATERWORKS' FEEDER (2 PLATES); STREET SEWER (3 PLATES); STEAMBOAT PIER, OUTFALL SEWER RESERVOIR (apLATEsi: OUT- WATKRLOO BRIDGE (3 PLATES): JUNCTION OF FALL SEWER, TUMBLING BAY AND OUTLET; i SEWERS, PLANS AND SECTIONS; GULLIES, OUTFALL SEWER, PENSTOCKS. South Side. PLANS, AND SECTIONS; ROLLING STOCK; OUTFALL SEWER, BERMONDSEY BRANCH (2 I GRANITE AND IRON FORTS. " The drawings have a constantly increasing value, and whoever desires to possess clear representa- tions of the two great works carried out by our Metropolitan Board will obtain Mr. Humber's volume." Engineer. HUMBER'S PROGRESS OF MODERN ENGINEERING. FOURTH SERIES. Imp. 4to, with 36 Double Plates, Photographic Portrait of John Fowler, late Pres. Inst. C.E., and copious descriptive Letterpress, Specifications, &c., 3 y. half- morocco. LIST OF THE PLATES AND DIAGRAMS. ABBEY MILLS PUMPING STATION, MAIN DRAIN- j VIADUCT OVER THE RIVER WYE, MIDLAND RAIL- AGE, METROPOLIS (4 PLATES) ; BARROW DOCKS WAY (3 PLATES) ; ST. GERMANS VIADUCT, CORN- (5 PLATES); MANQUIS VIADUCT, SANTIAGO AND , WALL RAILWAY (2 PLATES); WROUGHT-IRON VALPARAISO RAILWAY (2 PLATES) ; ADAM'S LO- COMOTIVE, ST. HELEN'S CANAL RAILWAY (2 PLATES); CANNON STREET STATION ROOF, CHARING CROSS RAILWAY (3 PLATES); ROAD CYLINDER FOR DIVING BELL; MILLWALL DOCKS (6 PLATES); MILROY'S PATENT EXCAVATOR; METROPOLITAN DISTRICT RAILWAY (6 PLATES) ; HARBOURS, PORTS, AND BREAKWATERS (3 BRIDGE OVER THE RIVER MOKA (2 PLATES); PLATES). TELEGRAPHIC APPARATUS FOR MESOPOTAMIA; "We gladly welcome another year's issue of this valuable publication from the able pen of Mr. Hum- ber. The accuracy and general excellence of this work are well known, while its usefulness in giving the measurements and details of some of the latest examples of engineering, as carried out by the most eminent men in the profession, cannot be too highly prized." Artizan. 16 CROSBY LOCKWOOD & SON'S CATALOGUE. THE POPULAR WORKS OF MICHAEL REYNOLDS ("THE ENGINE DRIVER'S FRIEND"). Locomotive-Engine Driving. LOCOMOTIVE-ENGINE DRIVING: A Practical Manual for Engineers in Charge of Locomotive Engines. By MICHAEL REYNOLDS, Member of the Society of Engineers, formerly Locomotive Inspector, L. B. and S. C. R. Ninth Edition. Including a KEY TO THE LOCOMOTIVE ENGINE. With Illustrations and Portrait of Author. Crown 8vo, 4^. 6d. cloth. " Mr. Reynolds has supplied a want, and has supplied it well. We can confidently recommend the book not only to the practical driver, but to everyone who takes an interest in the performance of loco- motive engines." The Engineer. "Mr. Reynolds has opened a new chapter in the literature of the day. This admirable practical treatise, of the practical utility of which we have to speak in terms of warm commendation." Athentzum. " Evidently the work of one who knows his subject thoroughly." Railway Service Gazette. "Were the cautions and rules given in the book to become part of the every-day working of our engine-drivers, we might have fewer distressing accidents to deplore." Scotsman. Stationary Engine Driving. STATIONARY ENGINE DRIVING: A Practical Manual for Engineers in Charge of Stationary Engines. By MICHAEL REYNOLDS. Fifth Edition, Enlarged. With Plates and Woodcuts. Crown 8vo, 45-. 6d. cloth. "The author is thoroughly acquainted with his subjects, and his advice on the various points treated is clear and practical He has produced a manual which is an exceedingly useful one for the class for whom it is specially intended." Engineering. " Our author leaves no stone unturned. He is determined that his readers shall not only know something about the stationary engine, but all about it." Engineer. "An engineman who has mastered the contents of Mr. Reynolds's book will require but little actual experience with boilers and engines befo e he can be trusted to look after them." English Mechanic. The Engineer, Fireman, and Engine-Boy. THE MODEL LOCOMOTIVE ENGINEER, FIREMAN, AND ENGINE- BOY. Comprising a Historical Notice of the Pioneer Locomotive Engines and their Inventors. By MICHAEL REYNOLDS. Second Edition, with Revised Appendix. With numerous Illustrations, and Portrait of George Stephenson. Crown 8vo, 4-r. 6d. cloth. . [Just published " From the technical knowledge of the author, it will appeal to the railway man of to-day more forcibly than anything written by Dr. Smiles The volume contains information of a technical kind, and facts that every driver should be familiar with." English Mechanic. "We should be glad to see this book in the possession of everyone in the kingdom who has ever laid, or is to lay, hands on a locomotive engine.'' Iron. Continuous Railwau Brakes. CONTINUOUS RAILWAY BRAKES : A Practical Treatise on the several Systems in Use in the United Kingdom : their Construction and Perform- ance. With copious Illustrations and numerous Tables. By MICHAEL REYNOLDS. Large crown 8vo, QJ. cloth. "A popular explanation of the different brakes. It will be of great assistance in forming public opinion, and will be studied with benefit by those who take an interest in the brake." English Mechanic. " Written with sufficient technical detail to enable the principal and relative connection of the various pans of each particular brake to be readily grasped." Mechanical World. Engine-Driving Life. ENGINE-DRIVING LIFE : Stirring Adventures and Incidents in the Lives of Locomotive Engine-Drivers. By MICHAEL REYNOLDS. Third and Cheaper Edition. Crown 8vo, is. 6d. cloth. " From first to last perfectly fascinating. Wilkie Collins's most thrilling conceptions are thrown into the shade by true incidents, endless in their variety, related in every page." North British Mail. "Anyone who wishes to get a real insight into railway life cannot do better than read ' Engine- Driving Life' for himself, and if he once takes it up he will find that the author's enthusiasm and real love of the engine-driving profession will carry him on till he has read every page." Saturday Review. Pocket Companion for Enginemen. THE ENGINEMAN'S POCKET COMPANION and Practical Educator for Enginemen, Boiler Attendants, and Mechanics. By MICHAEL REYNOLDS. With Forty-five Illustrations and numerous Diagrams. Third Edition, Revised. Royal l8mo, 3.?. 6d. strongly bound for pocket wear. " This admirabte work is well suited to accomplish its object, being the honest workmanship of a competent engineer." Glasgow Herald. "A most meritorious work, giving in a succinct and practical form all the information an engine- minder desirous of mastering the scientific princ pies of his daily calling would require." The Miller. "A boon to those who are striving to become efficient mechanics." Daily ChronMe. MARINE ENGINEERING, NAVIGATION, &c. 17 MARINE ENGINEERING, SHIPBUILDING, NAVIGA- TION, etc. Pocket-Book for Naual Architects and Shipbuilders. THE NAVAL ARCHITECT'S AND SHIPBUILDER'S POCKET-BOOK OF FORMUL/E, KULES, AND TABLES, AND MARINE ENGINEER'S AND SURVEYOR'S HANDY BOOK OF REFERENCE. By CLEMENT MACKROW, Member of the Institu- tion of Naval Architects, Naval Draughtsman. Fifth Edition, Revised and En- larged to 700 pages, with upwards of 300 Illustrations. Fcap., 12*. dd. strongly bound in leather. SUMMARY OF CONTENTS. SIGNS AND SYMBOLS, DECIMAL FRACTIONS. RULES FOR BOILERS. LLOYD'S WEIGHT OF TRIGONOMETRY. PRACTICALGEOMETRY. MEN- CHAINS. LLOYD'S SCANTLINGS FOR SHIPS. SURATION. CENTRES AND MOMENTS OF FIGURES. DATA OF ENGINES AND VESSELS. SHIPS' FIT- MOMENTS OF INERTIA AND RADII OF GYRATION. TINGS AND TESTS. SEASONING PRESERVING ALGEBRAICAL EXPRESSIONS FOR SIMPSON'S TIMBER MEASUREMENT OF TIMBER. ALLOYS, RULES. MECHANICAL PRINCIPLES. CENTRE PAINTS, VARNISHES. DATA FOR STOWAGE. OF GRAVITY, LAWS OF MOTION. DISPLACE- ADMIRALTY TRANSPORT REGULATIONS. RULES MENT, CENTRE OF BUOYANCY. CENTRE OF FOR HORSE-POWER, SCREW PROPELLERS, ETC. GRAVITY OF SHIP'S HULL. STABILITY CURVES PERCENTAGES FOR BUTT STRAPS, ETC, PARTI AND METACENTRES. SEA AND SHALLOW-WATER CULARS OF YACHTS. MASTING AND RIGGING WAVES. ROLLING OF SHIPS. PROPULSION AND VESSELS. DISTANCES OF FOREIGN PORTS. RESISTANCE OF VESSELS. SPEED TRIALS. TONNAGE TABLES VOCABULARY OF FRENCH SAILING, CENTRE OF EFFORT. DISTANCES AND ENGLISH TERMS. ENGLISH WEIGHTS ANJ DOWN RIVERS, COAST LINES. STEERING AND MEASURES. FOREIGN WEIGHTS AND MEASURES. RUDDERS OF VESSELS. LAUNCHING CALCULA- DECIMAL EQUIVALENTS. FOREIGN MONEY. TIONS AND VELOCITIES. WEIGHT OF MATERIAL DISCOUNT AND WAGE TABLES. USEFUL NUM- AND GEAR. GUN PARTICULARS AND WEIGHT. BERS AND READY RECKONERS. TABLES OF STANDARD GAUGES. RIVETED JOINTS AND CIRCULAR MEASURES. -TABLES OF AREAS OF RIVETING. STRENGTH AND TESTS OF MATE- AND CIRCUMFERENCES OF CIRCLES. TABLES OF RIALS. BINDING AND SHEARING STRESSES, ETC. AREAS OF SEGMENTS OF CIRCLES. TABLES OF STRENGTH OF SHAFTING, PILLARS, WHEELS, SQUARES AND CUBES AND ROOTS OF NUMBERS. ETC. HYDRAULIC DATA, ETC. CONIC SEC- TABLES OF LOGARITHMS OF NUMBERS. TIONS, CATENARIAN CURVES. MECHANICAL TABLES OF HYPERBOLIC LOGARITHMS. TABLES POWERS, WORK. BOARD OF TRADE REGULA- OF NATURAL SINES, TANGENTS, ETC. TABLES TIONS FOR BOILERS AND ENGINES. BOARD OF OF LOGARITHMIC SINES, TANGENTS, ETC. TRADE REGULATIONS FOR SHIPS. LLOYD'S " In these days of advanced knowledge a work like this is of the greatest value. It contains a vast amount of information. We unhesitatingly say that it is the most valuable ompilation for its specific purpose that has ever been printed. No naval architect, engineer, su ood or iron shipbuilder, can afford to be without this work." Nautical Mag " The first edition of this book appeared in 1879, and its blue and yellow cov familiar object in most shipyard drawing offices. We have now before us the fifth veyor, or seaman, rs have become a dition revised and enlarged, and we notice that it appeals to a wider circle of readers than its predecessors, since it claims to contain information valuable to marine engineers, as well as to naval architects and ship- builders. We may say at once that both author and publishers are to be congratulated upon the production of a very useful, compendious and elegant book, well printed and well bound. The re- vision appears to have been done with care, and nearly all the errors in the earlier editions have been expunged ..... The book is one of exceptional merit." Engineer, Nov. 4, 1892. " Should be used by all who are engaged in the construction or design of vessels. . . . Will be found to contain the most useful tables and formulae required by shipbuilders, carefully collected - from the best authorities, and put together in a popular and simple form." Engineer, Nov. 7, 1879. " The professional shipbuilder has now, in a convenient and accessible form, reliable data for solving many of the numerous problems that present themselves in the course of his work." Iron. " There is no doubt that a pocket-book of this description must be a necessity in the shipbuilding trade. . . . The volume contains a mass of useful information clearly expressed and presented in a handy form." Marine Engineer. Marine Engineering. MARINE ENGINES AND STEAM VESSELS .- A Treatise on. By ROBERT MURRAY, C.E. Eighth Edition, thoroughly Revised, with considerable Additions by the Author and by GEORGE CARLISLE, C.E., Senior Surveyor to the Board of Trade at Liverpool. I2mo, 5^. cloth boards. " Well adapted to give the young steamship engineer or marine engine and boiler maker a general introduction into his practical work." Mechanical World. " We feel sure that this thoroughly revised edition will continue to be as popular in the future as it has been in the past, as, for its size, it contains more useful information than any similar treatise.'' Industries. "The information given is both sound and sensible, and well qualified to direct young sea-goirg hands on the straight road to the extra chief 's certificate. . . . Most useful to surveyors, inspectors, draughtsmen, and all young engineers who take an interest in their profession." Glasgow Herald. English-French Dictionary of Sea Terms. TECHNICAL DICTIONARY OF SEA TERMS, PHRASES AND WORDS USED IN THE ENGLISH AND FRENCH LANGUAGES. For the Use of Seamen, Engineers, Pilots, Ship-builders, Ship-owners and Ship-brokers. Com- piled by W. PIRRIE, late of the African Steamship Company. Fcap. 8vo, $s. cloth limp. [Just published. i8 CROSBY LOCKWOOD &> SON'S CATALOGUE. Electric Lighting of Ships. ELECTRIC SHIP LIGHTING : A Handbook on the Practical Fitting and Running of Ship's Electrical Plant, for the Use of Shipowners and Builders, Marine Electricians and Sea-going Engineers in Charge. By J. W. URQUHART, Author of " Electric Light," " Dynamo Construction," &c. With numerous Illus- trations. Crown 8vo, 7-r. 6d cloth. Docket-Book for Marine Engineers. A POCKET-BOOK OF USEFUL TABLES AND FORMUL/E FOR MARINE ENGINEERS. By FRANK PROCTOR, A.I.N.A. Third Edition. Royal 32mo, leather, gilt edges, with strap, 4^. " We recommend it to our readers as going far to supply a long-felt want. " Naval Science. " A most useful companion to all marine engineers." United Service Gazette. Introduction to Marine Engineering. ELEMENTARY ENGINEERING : A Manual for Young Marine Engineers and Apprentices. In the Form of Questions and Answers on Metals, Alloys, Strength of Materials, Construction and Management of Marine Engines and Boilers, Geometry, &c. &c. With an Appendix of Useful Tables. By JOHN SHERREN BREWER, Government Marine Surveyor, Hongkong. Second Edition, Revised, small crown 8vo, 2s. cloth. " Contains much valuable information for the class for whom it is intended, especially in the chapters on the management of boilers and engines." Nautical Magazine. "A useful introduction to the more elaborate text books. 1 ' Scotsman. " To a student who has the requisite desire and resolve to attain a thorough knowledge, Mr. Brewer offers decidedly useful he\p."Athenceum. Navigation . PRACTICAL NAVIGATION. Consisting of THE SAILOR'S SEA-BOOK, by JAMES GREENWOOD and W. H. ROSSER; together with the requisite Mathe- matical and Nautical Tables for the Working of the Problems, by HENRY LAW, C.E., and Professor J. R. YOUNG. Illustrated. I2mo, 7^. strongly half-bound. Drawing for Marine Engineers. LOCKIE'S MARINE ENGINEER'S DRAWING-BOOK. Adapted to the Requirements of the Board of Trade Examinations. By JOHN LOCKIE, C.E. With 22 Plates, Drawn to Scale. Royal 8vo, y. 6d. cloth. "The student who learns from these drawings will have nothing to unlearn." Engineer. ''The examples chosen are essentially practical, and are such as should prove of service to engineers generally, while admirably fulfilling their specific purpose." Mechanical World. Sailmaking. THE ART AND SCIENCE OF SAILMAKING. By SAMUEL B. SADLER, Practical Sailmaker, late in the employment of Messrs. Ratsey and Lapthorne, ol Cowes and Gosport. With Plates and other Illustrations. Small 4to, I2s. 6d. cloth. "This extremely practical work gives a complete education in all the branches of the manufacture, cutting out, roping, seaming, and goring. It is copiously illustrated, and will form a first-rate text-book and guide." Portsmouth Times. "The author of this work has rendered a distinct service to all interested in the art of sailmaking. The subject of which he treats is a congenial one. Mr. Sadler is a practical sailmaker, and has devoted years of careful observation and study to the subject ; and the results of the experience thus gained he has set forth in the volume before us." Steamship. Chain Cables. CHAIN CABLES AND CHAINS. Comprising Sizes and Curves of Links, Studs, &c., Iron for Cables and Chains, Chain Cable and Chain Making, Forming and Welding Links, Strength of Cables and Chains, Certificates for Cables, Marking Cables, Prices of Chain Cables and Chains, Historical Notes, Acts of Parliament, Statutory Tests, Charges for Testing, List of Manufacturers of Cables, &c. &c. By THOMAS W. TRAILL, F.E.R.N., M.Inst.C.E., Engineer- Surveyor-in-Chief, Board of Trade, Inspector of Chain Cable and Anchor Proving Establishments, and General Superintendent, Lloyd's Committee on Proving Establishments. With numerous Tables, Illustrations, and Lithographic Drawings. Folio, 2 2s. cloth, bevelled boards. ' It contains a vast amount of valuable information. Nothing seems to be wanting to make it a com- plete and standard work of reference on the subject." Nautica! Magazine. MINING AND METALLURGY. 19 MINING AND METALLURGY. Mining Machinery. MACHINERY FOR METALLIFEROUS MINES : A Practical Treatise for Mining Engineers, Metallurgists and Managers of Mines. By E. HENRY DAVIES, M.E., F.G.S. Crown 8vo, 580 pp., with upwards of 300 Illustrations. I2s. 6d. cloth. [Just published. " Mr. Davies, in this handsome volume, has done the advanced student and the manager of mines good service. Almost every kind of machinery in actual use is carefully described, and the woodcuts and plates are good." Athenaum. '' From cover to cover the work exhibits all the same characteristics which excite the confidence and attract the attention of the student as he peruses the first page. The work may safely be recom- mended. By its publication the literature connected with the industry will be enriched, and the reputation of its author enhanced." Mining Journal. " Mr. Davies has endeavoured to bring before his readers the best of everything in modern mining appliances. His work carries internal evidence of the author's impartiality, and this constitutes one of the great merits of the book. Throughout his work the criticisms are based on his own or other reliable experience." Iron and Steel Trades' Journal. " The work deals with nearly every class of machinery or apparatus likely to be met with or required in connection with metalliferous mining, and is one which we have every confidence in recom- mending." Practical Engineer. "Invaluable to mining engineers, metallurgists, and mine managers. 1 ' The Mining Review Denver, Colorado, U.S.A. Metalliferous Minerals and Mining. A TREATISE ON METALLIFEROUS MINERALS AND MINING. By D. C. DAVIES, F.G.S., Mining Engineer, &c., Author of " A Treatise on Slate and Slate Quarrying." P'ifth Edition, thoroughly Revised and much Enlarged by his Son, E. HENRY DAVIES, M.E., F.G.S. With about 150 Illustrations. Crown 8vo, 12s. 6d cloth. " Neither the practical miner nor the general reader, interested in mines, can have a better book for his companion and his guide." Mining Journal. " We are doing our readers a service in calling theirattention to this valuable work." Mining World. " A book that will not only be useful to the geologist, the practical miner, and the metallurgist ; but also very interesting to the general public." Iron. " As a history of the present state of mining throughout the world this book has a real value, and it supplies an actual want." Athenautn. Earthy Minerals and Mining. A TREATISE ON EARTHY AND OTHER MINERALS AND MINING. By D. C. DAVIES, F.G.S., Author of "Metalliferous Minerals," &c. Third Edition, Revised and Enlarged, by his Son, E. HENRY DAVIES, M.E., F.G.S. With about 100 Illusts. Crown 8vo, I2s. 6d. cloth. " We do not remember to have met with any English work on mining matters that contains the same amount of information packed in equally convenient form." Academy. " We should be inclined to rank it as among the very best of the handy technical and trades manuals which have recently appeared." British Quarterly Review. Metalliferous Mining in the United Kingdom. BRITISH MINING : A Treatise on the History, Discovery, Practical Development, and Future Prospects of Metalliferous Mines in the United Kingdom. By ROBERT HUNT, F.R.S., Keeper of Mining Records ; Editor of " Ure's Dic- tionary of Arts, Manufactures, and Mines," &c. Upwards of 950 pp., with 230 Illustrations. Second Edition, Revised. Super-royal 8vo, 2 2s. cloth. " One of the most valuable works of reference of modern times. Mr. Hunt, as Keeper of Mining Records of the United Kingdom, has had opportunities for such a task not enjoyed by anyone else, and has evidently made the most of them. . . . The language and style adopted are good, and the treat- ment of the various subjects laborious, conscientious, and scientific." Engineering. " The book is, in fact, a treasure-house of statistical information on mining subjects, and we know of no other work embodying so great a mass of matter of this kind. Were this the only merit of Mr. Hunt's volume it would be sufficient to render it indispensable in the library of everyone interested in the development of the mining and metallurgical industries of this country." Athemzum. " A mass of information not elsewhere available, and of the greatest value to those who may be in- terested in our great mineral industries." Engineer. Underground Pumping Machinery. MINE DRAINAGE : Being a Complete and Practical Treatise on Direct-Acting Underground Steam Pumping Machinery, with a Description of a large number of the best known Engines, their General Utility and the Special Sphere of their Action, the Mode of their Application, and their merits compared with other forms of Pumping Machinery. By STEPHEN MICHELL. 8vo, 15 s. cloth. " Will be highly esteemed by colliery owners and lessees, mining engineers, and students generally who require to be acquainted with the best means of securing the drainage of mines. It is a most valu- able work, and stands almost alone in the literature of steam pumping machinery." Colliery Guardian. " Much valuable information is given, so that the book is thoroughly worthy of an extensive cir- lation amongst practical men and purchasers of machinery." Mining Journal. 20 CROSBY LOCKWOOD &> SON'S CATALOGUE. Prospecting for Gold and other Metals. THE PROSPECTOR'S HANDBOOK : A Guide for the Prospector and Traveller in Search of Metal-Bearing or other Valuable Minerals. By J. W. ANDERSON, M.A. (Camb.), F R.G.S., Author of "Fiji and New Caledonia." Sixth Edition, thoroughly Revised and much Enlarged. Small crown 8vo, 3*. 6d. cloth ; or, 4.?. 6d. leather, pocket-book form, with tuck. [Just published. " Will supply a much felt want, especially among Colonists, in whose way are so often thrown many mineral ogical specimens the value of which it is difficult to determine." Engineer. " How to find commercial minerals, and how to identify them when they are found, are the leading points to which attention is directed. The author has managed to pack as much practical detail into his pages as would supply material for a book three times its size." Mining Journal. Mining Notes and Formulae. NOTES AND FORMUL/E FOR MINING STUDENTS. By JOHN HERMAN M.ERIVALE, M.A., Certificated Colliery Manager, Professor of Mining in the Durham College of Science, Newcastle-upon-Tyne. Third Edition, Revised and Enlarged. Small crown Svo, 2s. (>d. cloth. " Invaluable to anyone who is working up for an examination on mining subjects." Iron and Coal Trades' Review. " The author has done his work in an exceedingly creditable manner, and has produced a book that will be of service to students, and those who are practically engaged in mining operations." Engineer. Handybook for Miners. THE MINER'S HANDBOOK: A Handy Book of Reference on the subjects of Mineral Deposits, Mining Operations, Ore Dressing, &c. For the Use of Students and others interested in Mining matters. Compiled by JOHN MILNE, F.R.S., Professor of Mining in the Imperial University of Japan. Revised Edition. Fcap. Svo, TS. 6d. leather. \Just published. " Professor Milne's handbook is sure to be received with favour by all connected with mining, and will be extremely popular among students. " A thenocum. Miners' and Metallurgists' Pochet-Booh. A POCKET-BOOK FOR MINERS AND METALLURGISTS. Com- prising Rules, Formula;, Tables, and Notes, for Use in Field and Office Work. By F. DANVERS POWER, F.G.S., M.E. Fcap. Svo, gs. leather. "This excellent book is an admirable example of its kind, and ought to find a large sale amongst English-speaking prospectors and mining engineers." Engineering. " Miners and metallurgists will find in this work a useful vaae-mecum containing a mass of rules, formulae, tables, and various other information, the necessity for reference to which occurs in their daily duties." Iron. Mineral Surveying and Valuing. THE MINERAL SURVEYOR AND VALUER'S COMPLETE GUIDE. Comprising a Treatise on Improved Mining Surveying and the Valuation of Mining Properties, with New Traverse 1 ables. By WM. LINTERN. Third Edition, Enlarged. I2mo, 4-r. cloth. " Mr. Lintern's book forms a valuable and thoroughly trustworthy guide." Iron and Coal Trades' Review. Asbestos and its Uses. ASBESTOS : Its Properties, Occurrence, and Uses. With some Account of the Mines of Italy and Canada. By ROBERT H. JONES. With Eight Collotype Plates and other Illustrations. Crown Svo, I2s. 6d. cloth. " An interesting and invaluable work." Colliery Guardian. Explosiues. A HANDBOOK ON MODERN EXPLOSIVES. Being a Practical Treatise on the Manufacture and Application of Dynamite, Gun-Cotton, Nitro- Glycerine and other Explosive Compounds. Including the Manufacture of Collodion-Cotton. By M. EISSLER, Mining Engineer and Metallurgical Chemist, Author of "The Metallurgy of Gold," "The Metallurgy of Silver," &c. With about 100 Illustrations. Crown Svo, IDS. 6d. cloth. " Useful not only to the miner, but also to officers of both services to whom blasting and the nse of explosives generally may at any time become a necessary auxiliary." Nature. " A vetitable mine cf information on the subject of explosives employed for military, mining and blasting purposes." A rmy and Navy Gazette. MINING AND METALLURGY. Colliery Management. THE COLLIERY MANAGER'S HANDBOOK : A Comprehensive Treatise on the Laying-out and Working of Collieries, Designed as a Book of Reference for Colliery Managers, and for the Use of Coal-Mining Students pre- paring for First-class Certificates. By CALEB PAMELY, Mining Engineer and Surveyor ; Member of the North of England Institute of Mining and Mechanical Engineers; and Member of the South Wales Institute of Mining Engineers. With nearly 500 Plans, Diagrams, and other Illustrations. Second Edition, Revised, with Additions, medium 8vo, about 700 pp. Price l $s. strongly bound. SUMMARY OF CONTENTS. GEOLOGY. SEARCH FOR COAL. MINERAL LEASES AND OTHER HOLDINGS. SHAFT SINKING. FITTING UP THE SHAFT AND SURFACE AR- ON THE FRICTION OF AIR IN MINES. THE PRIESTMAN OIL ENGINE; PETROLEUM AND NATURAL GAS. Sui SAFETY LAMPS AND FIRE-DAMP DETECTORS. SUNDRY AND INCIDENTAL OPERATIONS AND AP- COLLIERY EXPLOSIONS. MISCELLANEOUS QUESTIONS AND ANSWERS. Appendix: SUMMARY OF REPORT OF H.M. COM- MISSIONERS ON ACCIDENTS IN MINES. RANGEMENTS. STEAM BOILERS AND THEIR FITTINGS. TIMBERING AND WALLING. NARROW WORK AND METHODS OF WORKING. UNDERGROUND CONVEYANCE. DRAINAGE. THE GASES MET WITH IN MINES ; VENTILATION. %* OPINIONS OF THE PRESS. "Mr. Pamely has not only given us a comprehensive reference book of a very, high order. suitable to the requirements of mining engineers and colliery managers, but at the same time has provided mining students with a class-book that is as interesting as it is instructive." Colliery Manager. " Mr. Pamely's work is eminently suited to the purpose for which it is intended being clear, inter- esting, exhaustive, rich in detail, and up to date, giving descriptions of the very latest machines in every department. ... A mining engineer could scarcely go wrong who followed this work." Colliery Guardian. s s te most compete a-round' wor on coa-mnng pushe n te Engls language. . . . No library of coal-mining books is complete without it." Colliery Engineer (Scranton, Pa., U.S.A.). _ " Mr. Pamely's work is in all respects worthy of our admiration. No person in any responsible position connected with mines should be without a copy.' 1 - Westminster Review. Goal and Iron. THE COAL AND IRON INDUSTRIES OF THE UNITED KINGDOM. Comprising a Description of the Coal Fields, and of the Principal Seams of Coal, with Returns of their Produce and its Distribution, and Analyses of Special Varie- ties. Also, an Account of the occurrence of Iron Ores in Veins or Seams ; Analyses of each Variety ; and a History of the Rise and Progress of Pig Iron Manufacture. By RICHARD MEADE, Assistant Keeper of Mining Records. With Maps 8vo, 1 8j. cloth. " The book is one which must find a place on the shelves of all interested in coal and iron production, and in the iron, steel, and other metallurgical industries." Engineer. " Of this book we may unreservedly say that it is the best of its class which we have ever met. . . . A book of reference which no one engaged in the hon or coal trades should omit from his library." Iron and Coal Trades' Review. Goal Mining. COAL AND COAL MINING, A Rudimentary Treatise on. By the late Sir WARINGTON W. SMYTH, M.A., F.R.S., &c., Chief Inspector of the Mines of the Crown. Seventh Edition, Revised and Enlarged. With numerous Illus- trations, I2mo, 4s. cloth boards. " As an outline is given of every known coal-field in this and other countries, as well as of the principal methods of working, the book will doubtless interest a very large number of readers." Mining Journal. Subterraneous Surueying. SUBTERRANEOUS SURVEYING, Elementary and Practical Treatise on ; with and without the Magnetic Needle. By THOMAS FENWICK, Surveyor of Mines, and THOMAS BAKER, C.E. Illustrated. I2mo, 3*. cloth boards. Granite Quarrying. GRANITES AND OUR GRANITE INDUSTRIES. By GEORGE F. HARRIS, F.G.S., Membre de la Societe Beige de Geologic, Lecturer on Economic Geology at the Birkbeck Institution, &c. With Illustrations. Crown 8vo, 2s. 6d. cloth. " A clearly and well-written manual for persons engaged or interested in the granite industry. ' Scotsman. " An interesting work, which will be deservedly esteemed." Colliery Guardian. " An exceedingly interesting and valuable monograph on a subject which has hitherto received unaccountably little attention in the shape of systematic literary treatment." Scottish Leader. CROSBY LOCKWOOD & SON'S CATALOGUE. Gold, Metnllurgy of. THE METALLURGY OF GOLD: A Practical Treatise on the Metallurgical Treatment of Gold-bearing Ores. Including the Processes of Concen- tration and Chlorination, and the Assaying, Melting, and Refining of Gold. By M. EISSLER, Mining Engineer and Metallurgical Chemist, formerly Assistant Assayer of the U.S. Mint, San Francisco. Third Edition, Revised and greatly Enlarged. With 187 Illustrations. Crown 8vo, i2s. 6d. cloth. " This book thoroughly deserves its title of a ' Practical Treatise.' The whole process of gold milling, from the breaking of the quartz to the as ay of the bullion, is described in clear and orderly narrative and with much, but not too much, fulness of detail." Saturday Review. "The work is a storehouse of information and valuable data, and we strongly recommend it to all professional men engaged in the gold-mining industry." Mining Journal. Gold Extraction. THE CYANIDE PROCESS OF GOLD EXTRACTION; and Us Prac- tical Application on the Witwatersrand Gold Fields in South Africa. By M. EISSLER, M.E., Mem. Inst. Mining and Metallurgy, Author of "The Metallurgy of Gold," &c. With Diagrams and Working Drawings. Large crown 8vo, Js. 6d. cloth. \Jttst published. " This book is just what was needed to acquaint mining men with the actual working of a process which is not only the most popular, but is, as a general rule, the most successful for the extraction of gold from tailings." Mining Journal. "The work will prove invaluable to all interested in gold mining, whether metallurgists or as investors." Chemical Nevis. Siluer, Metallurgy of. THE METALLURGY OF SILVER : A Practical Treatise on the Amalgamation, Roasting, and Lixiviation of Silver Ores. Including the Assaying, Melting, and Refining of Silver Bullion. By M. EISSLER, Author of " The Metal- lurgy of Gold," &c. Second Edition, Enlarged. Crown 8vo, icxr. 6d. cloth. "A practical treatise, and a technical work which we are convinced will supply a long lelt want amongst practical men, and at the same time be of value to students and others indirectly connected with the industries." Mining Journal. "From first to last the book is thoroughly sound and reliable." Colliery Guardian. "For chemists, piactical miners, assayers, and investors alike, we do not know ot any work on the subject so handy and yet so comprehensive." Glasgow Herald. Lead, Metallurgy of. THE METALLURGY OF ARGENTIFEROUS LEAD : A Practical Treatise on the Smelting of Silver-Lead Ores and the Refining of Lead Bullion. Including Reports on various Smelting Establishments and Descriptions of Modern Smelting Furnaces and Plants in Europe and America. By M. EISSLER, M.E., Author of " The Metallurgy of Gold," &c. Crown 8vo, 400 pp., with 183 Illus- trations, 12s. 6d. cloth. " The numerous metallurgical processes, which are fully and extensively treated of, embrace all the stages experienced in the passage of the lead from the various natural states to its issue from the refinery as an article of commerce." - Practical Engineer. " The pn sent volume fully maintains ^he reputation of the author. Those who wish to obtain a thorough insight into the present state of this industry cannot do better than read this volume, and all mining engineers canno f fail to find many useful hints and suggestions in it." Industries. "This is the work of an expert for experts, by whom it will be prized as an inc'ispensable text- book." Brutal Mercutv. Iron, Metallurgy of. METALLURGY OF IRON. Containing History of Iron Manufacture, Methods of Assay, and Analyses of Iron Ores, Processes of Manufacture of Iron and Steel, &c. By H. BAUERMAN, F.G.S., A.R.S.M. With numerous Illus- trations. Sixth Edition, Revised and Enlarged. lamo, $s. 6d. cloth. Iron Mining. THE IRON ORES OF GREAT BRITAIN AND IRELAND: Their Mode of Occurrence, Age and Origin, and the Methods of Searching for and Working Them. With a Notice of some of the Iron Ores of Spain. By J. D. KENDALL, F.G.S., Mining Engineer. Crown 8vo, i6s. cloth. " The author has a thorough practical knowledge of his subject, and has supplemented a careful study of the available literature by unpublished information derived from his own observations The result is a very useful volume which cannot fail to be of value to all interested in the iron in- " Mr. Kendall is a great authority on this subject and writes from personal observation." Colliery Guardian. ELECTRICITY, ELECTRICAL ENGINEERING, &c. 23 ELECTRICITY, ELECTRICAL ENGINEERING, ETC. Dynamo Management. THE MANAGEMENT OF DYNAMOS : A Handybook of Theory and Practice for the Use of Mechanics, Engineers, Students and others in Charge of Dynamos. By G. W. LUMMIS PATERSON. With numerous Illustrations. Crown 8vo, $s. 6J. cloth. \Just published. Electrical Engineering. THE ELECTRICAL ENGINEER'S POCKET-BOOK OF MODERN RULES, FORMUL/E, TABLES, AND DATA. By H. R. KEMPE, M. Inst. E.E., A. M. Inst. C.E., Technical Officer, Postal Telegraphs, Author of " A Handbook of Electrical Testing," &c. Second Edition, Thoroughly Revised, with Additions. With numerous Illustrations. Royal 32010, oblong, 5.?. leather. " There is very little in the shape of formulae or data which the electrician is likely to want in a hurry which cannot be found in its pages." Practical Engineer. ' A very useful book of reference for daily use in practical electrical engineering and its various applications to the industries of the present day." Iron. " It is the best book of its kind." Electrical Engineer. "The Electrical Engineer's Pocket-Book is a good one." Electrician. " Strongly recommended to those engaged in the electrical industries." Electrical Review. Electric Lighting. ELECTRIC LIGHT FITTING : A Handbook for Working Electrical Engineers, embodying Practical Notes on Installation Management. By J. W. URQUHART, Electrician, Author of " Electric Light, " &c. With numerous Illusts. Second Edition, Revised, with Additional Chapters. Crown 8vo, 5*. cloth. "This volume deals with what may be termed the mechanics of electric lighting, and is addressed to men who are already engaged in the work, or are training for it. The work traverses a great deal of ground, and may be read as a sequel to the same author's useful work on ' Electric Light.' "Electrician. "This is an attempt to state in the simplest language the precautions which should be adopted in installing the electric light, and to give information for the guidance of those who have to run the plant when installed. The book is well worth the perusal of the workman, for whom it is written." Electrical Review. " Eminently practical and useful Ought to be in the hands of everyone in charge of an electric light plant." Electrical Engineer. " Mr. Urquhart has succeeded in producing a really capital book, which we have no hesitation in recommending to working electricians and electrical engineers." Mechanical World. Electric Light ELECTRIC LIGHT : Its Production and Use, Embodying Plain Directions for the Treatment of Dynamo-Electric Machines, Batteries, Accumulators, and Electiic Lamps. By J. W. URQUHART, C.E., Author of " Electric Light Fitting," "Electroplating," c. Fifth Edition, carefully Revised, with Large Additions and 145 Illustrations. Crown 8vo, Js. 6d. cloth. " The whole ground of electric lighting is more or less covered and explained in a very clear and concise manner." Electrical Review. "Contains a good deal of very interesting information, especially in the parts where the author gives dimensions and working costs." Electrical Engineer. . M . . " A vade-mecum of the .-alient facts connecced with the science of electric lighting. titectru "You cannot for your purpose have a better book than ' Electric Light, 1 by Urquhart.' -Engineer. "The book is by far the best that we have yet met with on the subject." Athenaum. Construction of Dynamos. DYNAMO CONSTRUCTION : A Practical Handbook for the Use of Engineer Constructors and Electricians-in-Charge. Embracing Framework Build- ing, Field Magnet and Armature Winding and Grouping, Compounding, &c. With Examples of leading English, American, and Continental Dynamos and Motors. By J. W. URQUHART, Author of "Electric Light," &c. Second Edition, Enlarged. With 114 Illustrations. Crown 8vo, 7s. 6d. cloth. " Mr. Urquhart's book s the first one which deals with these matters in sucn a way that the engineer- ing student can understand them. The book is very readable, and the author leads his readers up to difficult subjects by reasonably simple tests." Engineering Review. "The author deals with his subject in a style so popular as to make his volume a handbook of great practical value to engineer contractors and electricians in charge of lighting installations. -Scotsman. " ' Dynamo Construction ' more than sustains the high character of the author's previous publica- tions. It is sure to be widely read by the large and rapidly-increasing number of practical electricians. - Glasgow Herald. " A book for which a demand has long existed." Mechanical World. 24 CROSBY LOCKWOOD & SON'S CATALOGUE. A New Dictionary of Electricity. THE STANDARD ELECTRICAL DICTIONARY. A Popular Dic- tionary of Words and Terms Used in the Practice of Electrical Engineering. Con- taining upwards of 3,000 Defir.itions. By T. O'CONNOR SLOANE, A.M.. Ph.D., Author of "The Arithmetic of Electricity," &c. &c. Crown 8vo, 630 pp., 350 Illustrations, 75. dd. cloth. [Just published. " The work has many attrac f ive features in it, and is, beyond doubt, a well put together and use- ful publication. The amount of ground covered may be gathered from the fact that in the index about 5,000 references will be found. The inclusion of such comparatively modern words as ' im- pedence; 1 'reluctance,' &c., shows that the author has desired to be up to date, and iadeed there are other indications of carefulness of compilation. The work is one which does the author great credit and it should prove of great value, especially to students." Electrical Review. " Very complete and contains a large amount of useful information." industries. " An encyclopaedia of electrical science in the compass of a dictionary. The information given is sound and clear. The book is well printed, well illustrated, and well up to date, and may be confidently recommended." Builder. " The volume is excellently printed and illustrated, and should form part of the library of every one who is directly or indirectly connected with electrical matters." Hardware Trade Journal. Electric Lighting of Ships. ELECTRIC SHIP-LIGHTING : A Handbook on the Practical Fitting and Running of Ship's Electrical Plant. For the Use of Shipowners and Builders, Marine Electricians, and Sea-going Engineers in Charge. By J. W. URQUHART, C.E , Author of " PJlectric Light," &c. With 88 Illusts., crown 8vo, Js. 6d. cloth. "The subject of ship electric lighting is one of vast importance, and Mr. Urquhart is to be highly complimented for placing such a valuable wojk at the service of marine electricians." The Steamship. " Distinctly a book which of its kind stands almost alone, and for which there should be a demand." Electrical Review. Country House Electric Lighting. ELECTRIC LIGHT FOR COUNTRY HOUSES: A Practical Hand- .book on the Erection and Running of Small Installations, with Particulars of the Cost of Plant and Working. By J. H. KNIGHT. Crown 8vo, is. wrapper. [Just published. "The book contains excellent advice and many practical hints for the help of those who wish to light their own houses." Building News. Electric Lighting. THE E'LEMENTARY PRINCIPLES OF ELECTRIC LIGHTING. By ALAN A. CAMPBELL SWINTON, Associate I.E.E. Third Edition, Enlarged and Revised. With Sixteen Illustrations. Crown 8vo, is. 6d. cloth. " Anyone who desires a short and thoroughly clear exposition of the elementary principles of electric-lighting cannot do better than read this little work." Bradford Observer. Dynamic Electricity. THE ELEMENTS OF DYNAMIC ELECTRICITY AND MAGNETISM. By PHILIP ATKINSON, A.M., Ph.D., Author of " Elements of Static Electricity," &c. Crown 8vo, 417 pp., with 120 Illustrations, los. 6al. cloth. Electric Motors, &c. THE ELECTRIC TRANSFORMATION OF POWER and its Applica- tion by the Electric Motor, including Electric Railway Construction. By P. ATKINSON, A.M., Ph.D. With 96 Illustrations. Crown 8vo, 7-r. 6d. cloth. Dynamo Construction. HOW TO MAKE A DYNAMO: A Practical Treatise for Amateurs. Containing numerous Illustrations and Detailed Instructions for Constructing a Small Dynamo to Produce the Electric Light. By ALFRED CROFTS. Fourth Edition, Revised and Enlarged. Crown 8vo, 2s. cloth. "The instructions given in this unpretentious little book are sufficiently clear and explicit to enable any amateur mechanic possessed of average skill and the usual tools to be found in an amateur's workshop, to build a practical dynamo machine." Electrician. Text-Booh of Electricity. THE STUDENT'S TEXT-BOOK OF ELECTRICITY. By H. M. NOAD, F.R.S. Cheaper Edition. 650 pp., with 470 Illustrations. Crown 8vo, gs. cloth. ARCHITECTURE, BUILDING, &\ t 25 ARCHITECTURE, BUILDING, etc. Building Construction. PRACTICAL BUILDING CONSTRUCTION : A Handbook for Students Preparing for Examinations, and a Book of Reference for Persons En- gaged in Building. By JOHN PARNELL ALLEN, Surveyor, Lecturer on Building Construction at the Durham College of Science, Newcastle-on-Tyne. Medium 8vo, 450 pages, with 1,000 Illustrations. 12s. 6d. cloth. [Just published. "The most complete exposition of building construction we have seen. It contains all that is necessary to prepare students for the various examinations in building construction." Building News. 'The author depends nearly as much on his diagrams as on his type. The pages suggest the hand of a man of experience in building operations and the volume must be a blessing to many teachers as well as to students." The Architect. "The work is sure to prove a formidable rival to great and small competitors alike, and bids fair to take a permanent place as a favourite students' text-book. The large number of illustrations deserve particular mention for the great merit they possess for purposes of reference, in exactly corresponding to convenient scales. " Jour. Inst. Brit. Archts. The New London Building Act, 1894. THE LONDON BUILDING ACT, 1894. With the By-Laws and Regulations of the London County Council, and Introduction, Notes, Cases and Index. By ALEX. J. DAVID, B.A., LL.M., of the Inner Temple, Barrister-at- Law. Crown 8vo, 3.?. dd. cloth. \just published. " To all architects and district surveyors and builders, Mr. David's manual will be welcome." Building News. "The volume will doubtless be eagerly consulted by the buildin? fraternity." Illustrated Carpenter and Builder. Concrete. CONCRETE: ITS NATURE AND USES. A Book for Architects, Builders, Contractors, and Clerks of Works. By GEORGE L. SUTCLIFFE, A.R.I.B.A. 350 pages, with numerous Illustrations. Crown 8vo, 7*. 6d. cloth. " The author treats a difficult subject in a lucid manner. The manual fills a long felt gap. It is careful and exhaustive ; equally useful as a student's guide and an architect's book of reference." Journal of Royal Institution of British Architects. " There is room for this new book, which will probably be for some time the standard work on the subject for a builder's purpose." Glasgow Herald. Mechanics for Architects, THE MECHANICS OF ARCHITECTURE : A Treatise on Applied Mechanics, especially Adapted to the Use of Architects. By E. W. TARN, M. A., Author of "The Science of Building," &c. Second Edition, Enlarged. Illus- trated with 125 Diagrams. Crown 8vo, 7-f. 6d. cloth. " The book is a very useful and helpful manual of architectural mechanics, and really contains sufficient to enable a careful and painstaking student to grasp the principles bearing upon the ma- jority of building problems. ... Mr. Tarn has added, by this volume, to the debt of gratitude which is owing to him by architectural students tor the many valuable works which he has pro- duced for their use." The Builder. " The mechanics in the volume are really mechanics, and are harmoniously wrought in with the distinctive professional matter proper to the subject. The diagrams and type are commendably clear." The Schoolmaster. The New Builder's Price Booh, 1896. LOCKWOOD'S BUILDER'S PRICE BOOK FOR 1896. A Com- prehensive Handbook of the Latest Prices and Data for Builders, Architects, Engineers, and Contractors. Re-constructed, Re-written, and Greatly Enlarged. By FRANCIS T. W. MILLER. 800 closely-printed pages, crown 8vo, 4-r. cloth. " This book is a very useful one, and should find a place in every English office connected with the building and engineering professions." Industries. " An excellent book of reference." Architect. " In its new and revised form this Price Book is what a work of this kind should be compre- hensive, reliable, well arranged, legible, and well bound." British Architect. Designing Buildings. THE DESIGN OF BUILDINGS: Being Elementary Notes on the Planning, Sanitation and Ornamentive Formation of Structures, based on Modern Practice. Illustrated with Nine Folding Plates. By W. WOODLEV. 8vo, 6s. cloth. Sir William Chambers's Treatise on Ciuil Architecture. THE DECORATIVE PART OF CIVIL ARCHITECTURE. By sir WILLIAM CHAMBERS, F.R.S. With Portrait, Illustrations, Notes, and an EXAMINATION OF GRECIAN ARCHITECTURE, by JOSEPH GWILT, F.S.A. Re- vised and Edited by W. H. LEEDS. 66 Plates, 410, 2U. cloth. CROSBY LOCKWOOD 6- SON'S CATALOGUE. Villa Architecture. A HANDY BOOK OF VILLA ARCHITECTURE : Being a Series of Designs for Villa Residences in various Styles. With Outline Specifications and Estimates. By C. WICKES, Architect, Author of "The Spires and Towers of England," c. 6l Plates, 410, i us. 6d. half-morocco, gilt edges. "The whole of the designs bear evidence of their being the work of an artistic architect, and they will prove very valuable and suggestive." Building: News. Text- Booh for Architects. THE ARCHITECT'S GUIDE : Being a Text-book of Useful Infor- mation for Architects, Engineers, Surveyors, Contractors, Clerks of Works, &c. &c. By FREDERICK ROGERS, Architect. Third Edition. Cr. 8vo, 3-r. 6d. cloth. " As a text-book of useful information for architects, engineers, surveyors, &c., it would be hard to find a handier or more complete little volume." Standard. Taylor and Gresy's Rome. THE ARCHITECTURAL ANTIQUITIES OF ROME. By the late G. L. TAYLOR, Esq., F.R.I.B.A., and EDWARD CRESY, Esq. New Edition,, thoroughly Revised by the Rev. ALEXANDER TAYLOR, M.A. (son of the late G. L Taylor, Esq.), Fellow of Queen's College, Oxford, and Chaplain of Gray's Inn. Large folio, with 130 Plates, ^"3 $s. half-bound. "Taylor and Cresy's work has from its first publication been ranked among those professional books which cannot be bettered." Architect. Linear Perspective. ARCHITECTURAL PERSPECTIVE. The whole Course and Opera- tions of the Draughtsman in Drawing a Large House in Linear Perspective. Illustrated by 43 Folding Plates. By F. O. FERGUSON. Second Edition, En- larged. 8vo, 3.5-. 6d. boards. [Just published. "It is the most intelligible ( the treatises on this ill-treated subject that I have met with." E. INGRESS BELL, ESQ., in the R.I.B.A. Journal. Architectural Drawing. PRACTICAL RULES ON DRAWING, for the Operative Builder and Young Student in Architecture. By GEORGE PYNE. With 14 Plates, 410,. js. 6d. boards. Vitruuius' Architecture. THE ARCHITECTURE OF MARCUS VITRUVIUS POLLIO. Trans- lated by JOSEPH GWILT, F.S.A., F.R.A.S. New Edition, Revised by the Translator. With 23 Plates, fcap. 8vo, 5-r. cloth. Designing, Measuring, and Valuing. THE STUDENT'S GUIDE TO THE PRACTICE OF MEASURING AND VALUING ARTIFICERS' WORK. Containing Directions for taking Dimen- sions, Abstracting the same, and bringing the Quantities into Bill, with Tables of Constants for Valuation of Labour, and for the Calculation of Areas and Solidities. Originally edited by EDWARD DOBSON, Architect. With Additions by E. WYND- HAM TARN, M.A. Sixth Edition. With 8 Plates and 63 Woodcuts. Crown 8vo, js. 6d. cloth. " This edition will be found the most complete treatise on the principles of measuring and valuing artificers' work that has yet been published." Building News. Pocket Estimator and Technical Guide. THE POCKET TECHNICAL GUIDE, MEASURER, AND ESTIMATOR FOR BUILDERS AND SURVEYORS. Containing Technical Directions for Measuring Work in all the Building Trades, Complete Specifications for Houses, Roads, an5 Drains, and an Easy Method of Estimating the parts of a Building collectively. By A. C. BEATON. Seventh Edition. Waistcoat-pocket size, is. (>d. gilt edges. " No builder, architect, surveyor, or valuer should be without his ' Beaton.' " Building News. Donaldson on Specifications. THE HANDBOOK OF SPECIFICATIONS; or, Practical Guide to- the Architect, Engineer, Surveyor, and Builder, in drawing up Specifications and Contracts for Works and Constructions. Illustrated by Precedents of Buildings actually executed by eminent Architects and Engineers. By Professor T. L. DONALDSON, P.R.I.B.A., &c. New Edition, in One large Vol., 8vo, with upwards- of 1,000 pages of Text, and 33 Plates, l us. 6d. cloth. " . . . Valuable as a record, and more valuable still as a book of precedents. . . . Suffice it to say. that Donaldson's ' Handbook of Specifications' must be bought by all architects." Builder. ARCHITECTURE, BUILDING, &*c. Bartholomew and Rogers' Specifications. SPECIFICATIONS FOR PRACTICAL ARCHITECTURE. A Guide to the Architect, Engineer, Surveyor, and Builder. With an Essay on the Structure and Science of Modern Buildings. Upon the Basis of the Work by ALFRED BARTHOLOMEW, thoroughly Revised, Corrected, and greatly added to by FREDERICK ROGERS, Architect. Third Edition, Revised, with Additions. 8vo, 15*. cloth. " The collection of specifications prepared by Mr. Rogers on the basis of Bartholomew's work is too well known to need any recommendation from us. It is one of the books with which every young archi- Construction. THE SCIENCE OF BUILDING: An Elementary Treatise on. the Principles of Construction. By E. WYNDHAM TARN, M.A., Architect. Third Edition, Revised and Enlarged, with 59 Engravings. Fcap. 8vo, 4J. cloth. "A very valuable book, which we strongly recommend to all students." Builaer. House Building and Repairing. THE HOUSE-OWNER'S ESTIMATOR; or, What will it Cost to Build, Alter, or Repair ? A Price Book for Unprofessional People, as well as the Architectural Surveyor and Builder. By J. D. SIMON. Edited by F. T. W MILLER, A.R.I.B.A. Fourth Edition. Crown 8vo, $s. 6d. cloth. " In two years it will repay its cost a hundred times over." Field. Cottages and Villas. COUNTRY AND SUBURBAN COTTAGES AND VILLAS : How to Plan and Build Them. Containing 33 Plates, with Introduction, General Explanations, and Description of each Plate. By JAMES W. BOGUE, Architect, Author of "Domestic Architecture," &c. 410, los. 6d. cloth. Building ; Ciuil and Ecclesiastical. A BOOK ON BUILDING, Civil and Ecclesiastical, including Church Restoration ; with the Theory of Domes and the Great Pyramid, &c. By Sir EDMUND BECKETT, Bart., LL.D., F.R.A.S. Second Edition. Fcap. 8vo, 5*. cloth. "A book which is always amusing and nearly always instructive," The Times. Sanitary Houses, etc. THE SANITARY ARRANGEMENT OF DWELLING-HOUSES : A Handbook for Householders and Owners of Houses. By A. J. WALLIS-TAYLER, A. M. Inst. C. E. With numerous Illustrations. Crown 8vo, 2s. 6d. cloth. [Just published. "This book will be largely read; it will be of considerable service to the public. It is well arranged, easily read, and for the most part devoid of technical terms." Lancet. Ventilation of Buildings. VENTILATION. A Text-Book to the Practice of the Art of Venti- lating Buildings. By W. P. BUCHAN, R.P. I2mo, 4.? cloth-. " Contains a great amount of useful practical information, as thoroughly interesting as it is techni- cally reliable.'" - British Architect. The Art of Plumbing. PLUMBING. A Text-Book to the Practice of the Art or Craft of the Plumber. By W. P. BUCHAN, R.P. Sixth Edition, Enlarged. I2mo, 45. cloth. " A test book which may be safely put in the hands of every young plumber." Builder. Geometry for the Architect, Engineer, &c. PRACTICAL GEOMETRY, for the Architect, Engineer, and Mechanic. Giving Rules for the Delineation and Application of various Geometrical Lines, Figures, and Curves. By E. W. TARN, M.A., Architect. 8vo, gs. cloth. " No book with the same objects in view has ever been published in which the clearness of the rules laid down and the illustrative diagrams have been so satisfactory." Scotsman. The Science of Geometry. THE GEOMETRY OF COMPASSES; or, Problems Resolved by the mere Description of Circles, and the use of Coloured Diagrams and Symbols. By OLIVER BYRNE. Coloured Plates. Crown 8vo, y. 6d. cloth. 28 CROSBY LOCKWOOD & SON'S CATALOGUE. CARPENTRY, TIMBER, ^tc. Iredgold's Carpentry, Reuised and Enlarged by Tarn. THE ELEMENTARY PRINCIPLES OF CARPENTRY : A Treatise on the Pressure and Equilibrium of Timber Framing, the Resistance of Timber, and the Construction of Floors, Arches, Bridges, Roofs, Uniting Iron and Stone with Timber, &c. To which is added an Essay on the Nature and Pro- perties of Timber, &c., with Descriptions of the kinds of Wood used in Building; also numerous Tables of the Scantlings of Timber for different purposes, the Specific Gravities of Materials, &c. By THOMAS TREDGOLD, C.E. With an Appendix of Specimens of Various Roofs of Iron and Stone, Illustrated. Seventh Edition, thoroughly Revised and considerably Enlarged by E. WYNDHAM TARN, M.A., Author of " The Science of Building," &c. With 61 Plates, Portrait of the Author, and several Woodcuts. In One large Vol., 4to, 2$s. cloth. "Ought to be in every architect's and every builder's library." Builder. "A work whose monumental excellence must commend it wherever skilful carpentry is concerned. The author's principles are rather confirmed than impaired by time. The additional plates are of great intrinsic value." Building News. Woodworking Machinery. WOODWORKING MACHINERY: Its Rise, Progress, and Con- struction. With Hints on the Management of Saw Mills and the Economical Con- version of Timber. Illustrated with Examples of Recent Designs by leading English, French, and American Engineers. ByM. Powis BALE, A.M.Inst.C.E., M.I.M.E. Second Edition, Revised, with large Additions, large crown 8vo, 440 pages, gs. cloth. [Just published. " Mr. Bale is evidently an expert on the subject, and he has collected so much information that his book is all-sufficient for builders and others engaged in the conversion of timber." Architect. " The most comprehensive compendium of wood-working machinery we have seen. The author is a thorough master of his subject." Building 'News. Saw Mills. SAW MILLS : Their Arrangement and Management, and the Economical Conversion of Timber. (A Companion Volume to "Woodworking Machinery.") By M. Powis BALE. Crown 8vo, los. 6d. cloth. "The administration of a large sawing establishment is discussed, and the subject examined from a financial standpoint. Hence the size, shape, order, and disposition of saw-mijls 2nd the like are gone into in detail, and the course of the timber is traced from its reception to its delivery in its converted state. We could not desire a more complete or practical treatise." Builder. Nicholson's Carpentry. THE CARPENTER'S NEW GUIDE ; or, Book of Lines for Car- penters ; comprising all the Elementary Principles essential for acquiring a knowledge of Carpentry. , Founded on the late PETER NICHOLSON'S standard work. A New Edition, Revised by ARTHUR ASHPITEL, F.S.A. Together with Practical Rules on Drawing, by GEORGE PYNE. With 74 Plates, 410, .1 u. cloth. Handrailing and Stairbuilding. A PRACTICAL TREATISE ON HANDRAILING: Showing New and Simple Methods for Finding the Pitch of the Plank, Drawing the Moulds, Bevelling, Tointing-up, and Squaring the Wreath. By GEORGE COLLINGS. Second Edition, Revised and Enlarged, to which is added A TREATISE ON STAIR- BUILDING. With Plates and Diagrams. I2mo, 2s. 6d. cloth limp. " Will be found of practical utility in the execution of this difficult branch of joinery." Builder. " Almost every difficult phase oi this somewhat intricate branch of joinery is elucidated by the aid of plates and explanatory letterpress." Furniture Gazette. Circular Work. CIRCULAR WORK IN CARPENTRY AND JOINERY : A Prac- tical Treatise on Circular Work of Single and Double Curvature. By GEORGE COLLINGS. With Diagrams. Second Edition, I2mo, 2s. 6d. cloth limp. " An excellent example of what a book of this kind should be. Cheap In price, clear in definition, and practical in the examples selected." - Builder. Handrailing. HANDRAILING COMPLETE IN EIGHT LESSONS. On the Square- cut System. By J. S. GOLDTHORP, Teacher of Geometry and Building Construc- tion at the Halifax Mechanic's Institute. With Eight Plates and over 150 Practical Exercises. 410, 3.?. 6d. cloth. " Likely to be of considerable value to joiners and others who take a pride in good work. The arrangement of the book is excellent. We heartUy commend it to teachers and students." Timber Trades Journal. CARPENTRY, TIMBER, & c . 29 Timber Merchant's Companion. THE TIMBER MERCHANT'S AND BUILDER'S COMPANION. Con- taining New and Copious Tables of the Reduced Weight and Measurement of Deals and Battens, of all sizes, from One to a Thousand Pieces, and the relative Price that each size bears per Lineal Foot to any given Price per Petersburgh Stan- dard Hundred ; the Price per Cube Foot of Square Timber to any given Price per Load of 50 Feet ; the proportionate Value of Deals and Battens by the Standard, to Square Timber by the Load of 50 Feet ; the readiest mode of ascertaining the Price of Scantling per Lineal Foot of any size, to any given Figure per Cube Foot, &c. &c. By WILLIAM DOWSING. Fourth Edition, Revised and Corrected. Cr. 8vo, 3*. cloth. " Everything is as concise and clear as it can possibly be made. There can be no doubt that every timber merchant and builder ought to possess it. 1 ' Hull Advertiser. " We are glad to see a fourth edition of these admirable tables, which for correctness and simplicity of arrangement leave nothing to be desired." Timber Trades' Journal. Practical Timber Merchant. THE PRACTICAL TIMBER MERCHANT : Being a Guide for the use of Building Contractors, Surveyors, Builders, &c. , comprising useful Tables for all purposes connected with the Timber Trade, Marks of Wood, Essay on the Strength of Timber, Remarks on the Growth of Timber, &c. By W. RICHARDSON. Second Edition. Fcap. 8vo, y. 6d. cloth. [Jiist pitblished. "This handy manual contains much valuable information for the use of timber merchants, builders, foresters, and all others connected with thegrowth, sale, and manufacture of timber. 11 Journal of Forestry . Packing-Case Makers, Tables for. PACKING-CASE TABLES ; showing the number of Superficial Feet in Boxes or Packing-Cases, from six inches square and upwards. By W. RICHARD- SON, Timber Broker. Third Edition. Oblong 410, 3-r. 6d. cloth. " Invaluable labour-saving tables." Ironmonger. " Will save much labour and calculation." Grocer. Superficial Measurement. THE TRADESMAN'S GUIDE TO SUPERFICIAL MEASUREMENT. Tables calculated from I to 200 inches in length, by I to 108 inches in breadth. For the use of Architects, Surveyors, Engineers, Timber Merchants, Builders, &c. By JAMES HAWKINGS. Fourth Edition. Fcap., 3-r. 6d. cloth. " A useful collection of tables to facilitate rapid calculation of surfaces. The exact area of any surface of which the limits have been ascertained can be instantly determined. The book will be found of the greatest utility to all engaged in building operations." Scotsman. " These tables will be found of great assistance to all who require to make calculations in superficial measurement." English Mechanic. Forestry. THE ELEMENTS OF FORESTRY. Designed to afford Information concerning the Planting and Care of Forest Trees for Ornament or Profit, with suggestions upon the Creation and Care of Woodlands. By F. B. HOUGH. Large crown 8vo, icw. cloth. Timber Importer's Guide. THE TIMBER IMPORTER'S, TIMBER MERCHANT'S, AND BUILDER'S STANDARD GUIDE. By RICHARD E. GRANDY. Comprising: An Analysis of Deal Standards, Home and Foreign, with Comparative Values and Tabular Arrangements for fixing Net Landed Cost on Baltic and North American Deals, including all intermediate Expenses, Freight, Insurance, &c. &c. ; together with copious Information for the Retailer and Builder. Third Edition, Revised. I2mo, 2s. cloth limp. " Everything it pretends to be : built up gradually, it leads one from a forest to a treenail, and throws in, as a makeweight, a host of material concerning bricks, columns, cisterns, &c. English Mechanic. 30 CROSBY LOCKWOOD & SON'S CATALOGLE. DECORATIVE ARTS, etc. Woods and Marbles, Imitation of. SCHOOL OF PAINTING FOR THE IMITATION OF WOODS AND MARBLES, as Taught and Practised by A. R. VAN DER BURG and P. VAN DER BURG, Directors of the Rotterdam Painting Institution. Royal folio, i8J by iaj in., Illustrated with 24 full-size Coloured Plates ; also 12 plain Plates, comprising 154 Figures. Second and Cheaper Edition. Price jl us. 6d. LIST OF PLATES. i. VARIOUS TOOLS REQUIRED FOR WOOD LIMINARY STAGES OF PROCESS AND FINISHED PAINTING. 2, 3. WALNUT; PRELIMINARY STAGES 1 SPECIMEN. 19. MAHOGANY; SPECIMENS OF VARI- OF GRAINING AND FINISHED SPECIMEN. i. TOOLS ous GRAINS AND METHODS OF MANIPULATION. USED FOR MARBLE PAINTING AND METHOD OF j 20, 21. MAHOGANY ; EARLIER STAGES AND MANIPULATION. 5, 6. ST. KEMI MARBLE; FINISHED SPECIMEN. 22,23 24. SIENNA MARBLE; EARLIER OPERATIONS AND FINISHED SPECIMEN. VARIETIES OF GRAIN, PRELIMINARY STAGES AND 7. METHODS OF SKETCHING DIFFERENT GRAINS, FINISHED SPECIMEN. 25, 26,27. JUNIPER WOOD; KNOTS, &c. 8, 9, ASH: PRELIMINARY STAGES i METHODS OF PRODUCING GRAIN, &c. ; PRELIMI- AND FINISHED SPECIMEN. 10. METHODS OF j NARY STAGES AND FINISHED SPECIMEN. 28, 29 SKETCHING MARBLE GRAINS. n, 12. BRECHE i 30. VERT DE MER MARBLE; VARIETIES OF MARBLE; PRELIMINARY STAGES OF WORKING ! GRAIN AND METHODS OF WORKING, UNFINISHED AND FINISHED SPECIMEN. 13. MAPLE; ME- | AND FINISHED SPECIMENS. 31, 32, 33. OAK; THODS OF PRODUCING THE DIFFERENT GRAINS, i VARIETIES OF GRAIN, TOOLS EMPLOYED AND 14, 15. BIRD'S-EYE MAPLE; PRELIMINARY METHODS OF MANIPULATION, PRELIMINARY STAGES AND FINISHED SPECIMEN. if. METHODS j STAGES AND FINISHED SPECIMEN. 34, 35, 36, OF SKETCHING THE DIFFERENT SPECIES OF , WAULSORT MARBLE; VARIETIES OF GRAIN, WHITE MARBLE. 17, 18. WHITE MARBLE ; PRE- ' UNFINISHED AND FINISHED SPECIMENS. " Those who desire to attain skill in the art of painting woods and marbles will find advantage in consulting this book. . . . Some of the Working Men's Clubs should give their young men the opportunity to study it." Builder. " A comprehensive guide to the art. The explanations of the processes, the manipulation and manage- ment of the colours, and the beautifully executed plates will not be the least valuable to the student who aims at making his work a faithful transcript of nature." Building Nevus. " Students and novices are fortunate who are able to become the possessors of so noble a work." The Architect. House Decoration. ELEMENTARY DECORATION : A Guide to the Simpler Forms of Everyday Art. Together with PRACTICAL HOUSE DECORATION. By JAMES W. FACEY. With numerous Illustrations. In One Vol., 5^. strongly half-bound. House-Painting, Graining, etc. HOUSE-PAINTING, GRAINING, MARBLING, AND SIGN WRITING, A Practical Manual of. By ELLIS A. DAVIDSON. Sixth Edition. With Coloured Plates and Wood Engravings. I2mo, 6s. cloth boards. " A mass of information, of use to the amateur and of value to the practical man." English Mechanic. Decorators, Receipts for. THE DECORATOR'S ASSISTANT : A Modern Guide to Decora- tive Artists and Amateurs, Painters, Writers, Gilders, &c. Containing upwards of 600 Receipts, Rules and Instructions ; with a variety of Information for General Work connected with every Class of Interior and Exterior Decorations, &c., Sixth Edition. 152 pp., crown 8vo, is. in wrapper. " Full of receipts of value to decorators, painters, gilders, &c. The book contains the gist of larger treatises on colour and technical processes. It would be difficult to meet with a work so full of varied information on the painter's art." Building News. Moyr Smith on Interior Decoration. ORNAMENTAL INTERIORS, ANCIENT AND MODERN. By j. MOYR SMITH. Super-royal 8vo, with Thirty-two full-page Plates and numerous smaller Illustrations, handsomely bound in cloth, gilt top, iSs. " The book is well illustrated and handsomely got up, and contains some true criticism and a good many good examples of decorative treatment." The Builder. DECORATIVE ARTS, British and Foreign Marbles. MARBLE DECORATION and the Terminology of British and Foreign Marbles. A Handbook for Students. By GEORGE H. BLAGROVE, Author of " Shoring and its Application," &c. With 28 Illustrations. Cr. 8vo, y. 6d. cloth. "This most useful and much wanted handbook should be in the hands of every architect and builder." Building World. " A carefully and usefully written treatise ; the work is essentially practical." Scotsman. Marble Working, etc. MARBLE AND MARBLE WORKERS : A Handbook for Architects, Artists, Masons, and Students. By ARTHUR LEE, Author of "A Visit to Carrara," "The Working of Marble," &c. Small crown 8vo, 2s. cloth. " A really valuable addition to the technical literature of architects and masons." Building News. DELAMOTTE'S WORKS ON ILLUMINATION AND ALPHABETS. A PRIMER OF THE ART OF ILLUMINATION, for the Use of Beginners; with a Rudimentary Treatise on the Art, Practical Directions for its Exercise, and Examples taken from Illuminated MSS., printed in Gold and Colours. By F. DELAMOTTE. New and Cheaper Edition. Small 410, 6s. ornamental boards. "The examples of ancient MSS. recommended to the student, which, with much good sense, the author chooses from collections accessible to all, are selected with judgment and knowledge, as well as taste." Athenaum. ORNAMENTAL ALPHABETS, Ancient and Mediaeval, from the Eighth Century, with Numerals ; including Gothic, Church-Text, large and small, German, Italian, Arabesque, Initials for Illumination, Monograms, Crosses, &c. &c., for the use of Architectural and Engineering Draughtsmen, Missal Painters, Masons, Decorative Painters, Lithographers, Engravers, Carvers, &c. &c. Collected and Engraved by F. DELAMOTTE, and printed in Colours. New and Cheaper Edition. Royal 8vo, oblong, 2s. 6d. ornamental boards. " For those who insert enamelled sentences round gilded chalices, who blazon shop legends over shop- doors, who letter church walls with pithy sentences from the Decalogue, tnis book will be useful." Atlienaum. EXAMPLES OF MODERN ALPHABETS, Plain and Ornamental, including German, Old English, Saxon, Italic, Perspective, Greek, Hebrew, Court Hand, Engrossing, Tuscan, Riband, Gothic, Rustic, and Arabesque ; with several Original Designs, and an Analysis of the Roman and Old English Alphabets, large and small, and Numerals, for the use of Draughtsmen, Surveyors, Masons, Decora- tive Painters, Lithographers, Engravers, Carvers, &c. Collected and Engraved by F. DELAMOTTE, and printed in Colours. New and Cheaper Edition. Royal 8vo, oblong, 2s. dd. ornamental boards. ' ' There is comprised in it every possible shape into which the letters of the alphabet and numerals can be formed, and the talent which has been expended in the conception of the various plain and ornamental letters is wonderful." Standard. MEDI/EVAL ALPHABETS AND INITIALS FOR ILLUMINATORS. By F. G. DELAMOTTE. Containing 21 Plates and Illuminated Title, printed in Gold and Colours. With an Introduction by J. WILLIS BROOKS. Fourth and Cheaper Edition. Small 4to, 4^. ornamental boards. "A volume in which the letters of the alphabet come forth glorified in gilding and all the colours of the prism interwoven and intertwined and intermingled." Sun, THE EMBROIDERER'S BOOK OF DESIGN. Containing Initials, Emblems, Cyphers, Monograms, Ornamental Borders, Ecclesiastical Devices, Mediaeval and Modern Alphabets, and National Emblems. Collected by F. DELA- MOTTE, and printed in Colours. Oblong royal 8vo, is. 6d. ornamental wrapper. " The book will be of great assistance to ladies and young children who are endowed with the art of plying the needle in this most ornamental and useful pretty work." East Anglian Times. Wood Caruing. INSTRUCTIONS IN WOOD-CARVING FOR AMATEURS; with Hints on Design. By A LADY. With Ten Plates. New and Cheaper Edition. Crown 8vo, 2s. in emblematic wrapper. " The handicraft of the wood-carver, so well as a book can impart it, may be learnt from ' A Lady's publication." A thenieum. 32 CROSBY LOCKWOOD er> SON'S CATALOGUE. NATURAL SCIENCE, etc. The Heavens and their Origin. THE VISIBLE UNIVERSE : Chapters on the Origin and Construc- tion of the Heavens. By J. E. GORE, F.R.A.S., Author of "Star Groups," &c. Illustrated by 6 Stellar Photographs and 12 Plates. Demy 8vo, 1 6s. cloth. " A valuable and lucid summary of recent astronomical theory, rendered more valuable and attractive by a series of stellar photographs and other illustrations.." The Times. "In presenting a clear and concise account of the' present state of our knowledge, Mr. Gore has made a valuable addition to the literature of the subject." .Xature. " Mr. Gore's ' Visible Universe ' is one of the fii.est works on astronomical science that has recently appeared in our language. In spirit and in method it is scientific from cover to cover, but the style is so clear and attractive that it mil be as acceptable and as readable to those who make no scientific preten- sions as to those who devote themselves specially to matters astronomical." Leeds Mercury. " As interesting as a novel, and instructive withal ; the text being made still more luminous by stellar photographs and other illustrations. . . . A most valuable book." Manchester Examiner. The Constellations. STAR GROUPS : A Student's Guide to the Constellations. By J. ELLARD GORE, F.R.A.S., M.R.I. A., &c., Author of "The Visible Universe," "The Scenery of the Heavens." With 30 Maps. Small 410, 5.?. cloth, silvered. " A knowledge of the principal constellations visible in our latitudes may be easily acquired from the thirty maps and accompanying text contained in this work." Nature. "The volume contains thirty maps showing stars of the sixth magnitude the usual naked-eye limit and each is accompanied by a brief commentary, adapted to facilitate recognition and bring to notice objects of special interest. For the purpose of a preliminary survey of the ' midnight pomp ' of Ae heavens, nothing could be better than a set of delineations averaging scarcely twenty square inches in area, and including nothirg that cannot at once be identified. 1 ' Saturday Review. *' A very compact and handy guide to the constellations." Athetueum. Astronomical Terms. AN ASTRONOMICAL GLOSSARY ; or, Dictionary of Terms used in Astronomy. With Tables of Data and Lists of Remarkable and Interesting Celestial Objects. By J. ELLARD GORE, F.R.A.S., Author of "The Visible Universe," &c. Small crown 8vo, 2s. dd. cloth. "A very useful little work for beginners in astronomy, and not to be despised by more advanced students." The Times. "A very handy book . . . the utility of which is much increased by its valuable tables of astro- nomical data." The Athenaum. " Astronomers of all kinds will be glad to have it for reference." Guardian. The Microscope, THE MICROSCOPE : Its Construction and Management. Including Technique, Photo-micrography, and the Past and Future of the Microscope. By Dr. HENRI VAN HEURCK. Re-Edited and Augmented frcm the Fourth French Edition, and Translated by WYNNE E. BAXTER, F.G.S. 400 pages, with upwards of 250 Woodcuts, imp. 8vo, 18*., cloth. "A translation of a well-known work, at once popular and comprehensive." Times. " The translation is as felicitous as it is accurate." Nature. The Microscope. PHOTO-MICROGRAPHY. By Dr. H. VAN HEURCK. Extracted from the above Work. Royal 8vo, with Illustrations, is. sewed. Astronomy. ASTRONOMY. By the late Rev. ROBERT MAIN, M.A., F.R.S. Third Edition, Revised by WILLIAM THYNNE LYNN, B.A., F.R.A.S., formerly of the Royal Observatory, Greenwich. lamo, 2s. cloth limp. "A sound and simple treatise, very carefully edited, and a capital book for beginners." Knowledge. " Accurately brought down to the requirements of the present time by Mr.Lynn." Educational Times. Recent and Fossil Shells, A MANUAL OF THE MOLLUSCA : Being a Treatise on Recent and Fossil Shells. By S. P. WOODWARD, A.L.S., F.G.S. With an Appendix on RECENT AND FOSSIL CONCHOLOGICAL DISCOVERIES by RALPH TATE, A.L.S., F.G.S. With 23 Plates and upwards of 300 Woodcuts. Reprint of Fourth Edition (1880). Crown 8vo, ^s. 6d. cloth. " A most valuable storehouse of conchological and geological information." Science Gossif. Geology and Genesis. THE TWIN RECORDS OF CREATION ; or Geology and Genesis, their Perfect Harmony and \Vonderful Concord. By G. W. V. LE VAUX. 8vo, 5*. cl. " A valuable contribution to the evidences of Revelation, and disposes very conclusively of the argu- ments of those who would set God's Works against God's Word. No real difficulty is shirked, and no sophistry is left unexposed." The Rock. NATURAL SCIENCE, &c. 33 DR. LARDNER'S COURSE OF NATURAL PHILOSOPHY. THE HANDBOOK OF MECHANICS. Enlarged and almost re-written by BENJAMIN LOEWY, F.R.A.S. With 378 Illustrations. Post 8vo, 6s. cloth. "The perspicuity of the original has been retained, and chapters which had become obsolete have been replaced by others of more modern character. The explanations throughout are studiously popular, and care has been taken to show the application of the various branches of physics to the industrial arts, and to the practical business of life." Mining Journal. " Mr. Loewy has carefully revised the book, and brought it up to modern requirements." Nature. " Natural philosophy has had few exponents more able or better skilled in the art of popularising the subject than Dr. Lardner : and Mr. Loewy is doing good service in fitting this treatise, and the others of the series, for use at the present time." Scotsman. THE HANDBOOK OF HYDROSTATICS AND PNEUMATICS. New Edition, Revised and Enlarged by BENJAMIN LOEWY, F.R.A.S. With 236 Illustrations. Post 8vo, $s. cloth. " For those ' who desire to attain an accurate knowledge of physical science without the profound methods of mathematical investigation,' this work is not merely intended, but well adapted." Chemical News. "The volume before us has been carefully edited, augmented to nearly twice the bulk of the former edition, and all the most recent matter has been added. . . . It is a valuable text-book." Nature. " Candidates for pass examinations will find it, we think, specially suited to their requirements." English Mechanic. THE HANDBOOK OF HEAT. Edited and almost entirely re-written by BENJAMIN LOEWY, F.R.A.S., &c. 117 Illustrations. Post 8vo, 6s. cloth. "The style is always clear and precise, and conveys instruction without leaving any cloudiness or lurking doubts behind." Engineering. "A most exhaustive book on the subject on which it treats, and is so arranged thai it can be under- stood by all who desire to attain an accurate knowledge of physical science. . . . Mr. Loewy has included all the latest discoveries in the varied laws and effects of heat." Standard. " A complete and handy text-book for the use of students and general readers." English Mechanic. THE HANDBOOK OF OPTICS. By DIONYSIUS LARDNER, D.C.L., formerly Professor of Natural Philosophy and Astronomy in University College, London. New Edition. Edited by T. OLVER HARDING, B. A, Lond., of University College, London. With 298 Illustrations. Small 8vo, 448 pages, 5-r. cloth. "Written by one of the ablest English scientific writers, beautifully and elaborately illustrated.'' Mechanic's Magazine. THE HANDBOOK OF ELECTRICITY, MAGNETISM, AND ACOUSTICS. By Dr. LARDNER. Ninth Thousand. Edited by GEO. CAREY FOSTER, B.A., F.C.S. With 400 Illustrations. Small 8vo, $s. cloth. "The book could not have been entrusted to anyone better calculated to preserve the terse and lucid style of Lardner. while correcting his errors and bringing up his work to the present state of scientific knowledge." Popular Science Review. THE HANDBOOK OF ASTRONOMY. Forming a Companion to the "Handbook of Natural Philosophy." By DIONYSIUS LARDNER, D.C.L., formerly Professor of Natural Philosophy and Astronomy in University College, London. Fourth Edition. Revised and Edited by EDWIN DUNKIN, F.R.A.S., Royal Observatory, Greenwich. With 38 Plates and upwards of loo Woodcuts. In One Vol., small 8vo, 550 pages, gs. 6d. cloth. " Probably no other book contains the same amount of information in so compendious and well- arranged a form-certainly none at the price at which this is offered to the public." A tlunaum. " We can do no other than pronounce this work a most valuable manual of astronomy, and we strongly recommend it to all who wish to acquire a general but at the same time correct acquaintance with this sublime science." Quarterly Journal of Science. " One of the most deservedly popular books on the subject . . . We would recommend the student of the elementary principles of the science, but him who aim* at mastering the higher and mathematical branches of astronomy, not to be without this work beside him. Practical Magazine. Geology. RUDIMENTARY TREATISE ON GEOLOGY, PHYSICAL AND HISTORICAL. Consisting of " PHYSICAL GEOLOGY," which sets forth the Leading Principles of the Science ; and " HISTORICAL GEOLOGY," which treats of the Mineral and Organic Conditions of the Earth at each successive epoch, especial reference being made to the British Series of Rocks. By RALPH TATE, A.L.S., F.G.S., c. &c. With 250 Illustrations. I2mo, 5-f. cloth boards. The fulness of the matter has elevated the book into a manual. Its information is exhaustive and well arranged." School Boat d Chronicle. 34 CROSBY LOCKWOOD & SON'S CATALOGUE. DR. LARDNER'S MUSEUM OF SCIENCE AND ART. THE MUSEUM OF SCIENCE AND ART. Edited by DIONYSIUS LARDNER, D.C.L., formerly Professor of Natural Philosophy and Astronomy in University College, London. With upwards of 1,200 Engravings on Wood. In 6 double volumes, i is., in a new and elegant cloth binding; or handsomely bound in half morocco, 31 s. 6d. %* OPINIONS OF THE PRESS. " This series, besides affording popular but sound instruction on scientific subjects, with which the humblest man in the country ought to be acquainted, also undertakes that teaching of ' Common Things ' which every well wisher of his kind is anxious to promote. Many thousand copies of this serviceable publication have been printed, in the belief and hope that the desire for instruction and improvement widely prevails ; and we have no fear that such enlightened faith wil meet with disappointment." The Times. " A cheap and interesting publication, alike informing and attractive. The papers combine subjects of importance and great scientific knowledge, considerable inductive powers, and a popular style of treatment. " Spectator. " The ' Museum of Science and Art ' is the most valuable contribution that has ever been made to the scientific instruction of every class of society." Sir DAVID BREVVSTER, in the North British Review. '' Whether we consider the liberality and beauty of the illustrations, the charm of the writing, or the durable interest of the matter, we must express our belief that there is hardly to be found among the new books one that would be welcomed by people of so many ages and classes as a valuable present." Examiner, * V Separate books formed from the above, suitable for Workmen s Libraries, Science Classes, &c. Common Things Explained. Containing Air, Earth, Fire, Water, Time, Man, the Eye, Locomotion, Colour, Clocks and Watches, &c. 233 Illustrations, cloth gilt, 5.?. The Microscope. Containing Optical Images, Magnifying Glasses, Origin and Description of the Microscope, Microscopic Objects, the Solar Microscope, Micro- scopic Drawing and Engraving, &c. 147 Illustrations, cloth gilt, 2s. Popular Geology. Containing Earthquakes and Volcanoes, the Crust of the Earth, &c. 201 Illustrations, cloth gilt,'2.r. 6d. Popular Physics. Containing Magnitude and Minuteness, the Atmosphere, Meteoric Stones, Popular Fallacies, Weather Prognostics, the Thermometer, the Barometer, Sound, &c. 85 Illustrations, cloth gilt, 2s. 6d. Steam and its Uses. Including the Steam Engine, the Locomotive, and Steam Navigation. 89 Illustrations, cloth gilt, 2s. Popular Astronomy. Containing How to observe the Heavens. The Earth, Sun, Moon, Planets. Light, Comets, Eclipses, Astronomical Influences, &c. 182 Illus- trations, cloth gilt, 45 1 . ftd. The Bee and White Ants : Their Manners and Habits. \Vith Illustrations of Animal Instinct and Intelligence. 135 Illustrations, cloth gilt, 2s. The Electric Telegraph Popularized. To render intelligible to all who can Read, irrespective of any previous Scientific Acquirements, the various forms of Telegraphy in Actual Operation. 100 Illustrations, cloth gilt, Is, dd. Dr. Lardner's School Handbooks. NATURAL PHILOSOPHY FOR SCHOOLS. By Dr. LARDNER. 328 Illustrations. Sixth Edition. One Vol., 3.?. 6d. cloth. "A very convenient class-book for junior students in private schools. It is intended to convey, in clear and precise terms, general notions of all the principal divisions of Physical Science." British Quarterly Review. ANIMAL PHYSIOLOGY FOR SCHOOLS. By Dr. LARDNER. With 190 Illustrations. Second Edition. One' Vol., 3^. 6d. cloth. "Clearly written, well arranged, and excellently illustrated." Gardener's Chronicle. Lardner and Bright on the Electric Telegraph. THE ELECTRIC TELEGRAPH. By Dr. LARDNER. Revised and Re-written by E. B. BRIGHT, F.R.A.S. 140 Illustrations. Small 8vo, 2s. 6d. cloth. " One of the most readable books extant on the ElectricTelegraph." English Mechanic. CHEMICAL MANUFACTURES, CHEMISTRY, &>c. 35 CHEMICAL MANUFACTURES, CHEMISTRY, etc. Chemistry for Engineers, etc. ENGINEERING CHEMISTRY : A Practical Treatise for the Use of Analytical Chemists, Engineers, Iron Masters, Iron Founders, Students and others. Comprising Methods of Analysis and Valuation of the Principal Materials used in Engineering Work, with numerous Analyses, Examples and Suggestions. By H. JOSHUA PHILLIPS, F.I.C., F.C.S., Formerly Analytical and Consulting Chemist to the Great Eastern Railway. Second Edition, Revised and Enlarged. Crown 8vo, 400 pp., with Illustrations, IQJ. 6a. cloth. \Just published. " In this work the author has rendered m small service to a numerous body of practical men. . . The analytical methods may bs pronounced most satisfactory, being as accurate as the despatch required of engineering chemists permits." Cltemical News. "Those in search of a handy treatise on the subject of analytical chemistry as applied to the every-day requirements of workshop practice will find this volume of great assistance." Iron. "The book will be very useful to those who require a handy and concise resume of approved methods of analysing and valuing metals, oils, fuels, &c. It is, in fact, a work for chemists, a guide to the routine of the engineering laboratory. . . . The book is full of good things. As a handbook ot technical analysis, it is very welcome." Builder. " The analytical methods given are, as a whole, such as are likely to give rapid and trustworthy results in experienced hands. . . . There is much excellent descriptive matter in the work, the chapter on ' Oils and Lubrication ' being specially noticeable in this respect." Engineer. Explosiues and Dangerous Goods. DANGEROUS GOODS: Their Sources and Properties, Modes of Storage and Transport. With Notes and Comments on Accidents arising there- from, together with the Government and Railway Classifications, Acts of Parlia- ment, &c. A Guide for the Use of Government and Railway Officials, Steamship Owners, Insurance Companies and Manufacturers and Users of Explosives and Dangerous Goods. By H. JOSHUA PHILLIPS, F.I.C., F.C.S., Author of "En- gineering, Chemistry," &c. Crown 8vo, 350 pages, 9.?. cloth. \Just ready. The Alkali Trade, Manufacture of Sulphuric Acid, &c. A MANUAL OF THE ALKALI TRADE, including the Manufacture of Sulphuric Acid, Sulphate of Soda, and Bleaching Powder. By JOHN LOMAS, Alkali Manufacturer, Newcastle-upon-Tyne and London. With 232 Illustrations and Working Drawings, and containing 390 pages of Text. Second Edition, with Additions. Super-royal 8vo, i los. cloth. " This book is written by a manufacturer for manufacturers. The working details of the most ap- proved forms of apparatus are given, and these are accompanied by no less than 232 wood engravings, all of which may be used for the purposes of construction. Every step in the manufacture is very fully described in this manual, and each improvement explained." Atkenieutn. " We rind not merely a sound and luminous explanation of the chemical principles of the trade, but a notice of numerous matters which have a most important bearing on the successful conduct of alkali works, but which are generally overlooked by even experienced technological authors." Chemical Review. The Blowpipe. THE BLOWPIPE IN CHEMISTRY, MINERALOGY, AND GEOLOGY. Containing all known Methods of Anhydrous Analysis, many Working Examples, and Instructions for Making Apparatus. By Lieut. -Colonel W. A. Ross, R.A., F.G.S. With 120 Illustrations. Second Edition, Enlarged. Crown 8vo, 5-r. cloth. " The student who goes conscientiously through the course of experimentation here laid down will gain a better insight into inorganic chemistry and mineralogy than if he had ' got up ' any of the best text-books of the day, and passed any number of examinations in their contents." Cticmical News . Commercial Chemical Analysis. THE COMMERCIAL HANDBOOK OF CHEMICAL ANALYSIS; or, Practical Instructions for the determination of the Intrinsic or Commercial Value of Substances used in Manufactures, in Trades, and in the Arts. By A. NORMANDY, New Edition by H. M. NOAD, Ph.D., F.R.S. Crown 8vo, I2s. 6d. cloth. "We strongly recommend this book to our readers as a guide, alike indispensable to the housewife as to the pharmaceutical practitioner."' Medical Times. Due-Wares and Colours. THE MANUAL OF COLOURS AND DYE-WARES : Their Pro- perties, Applications, Valuations, Impurities, and Sophistications. For the use of Dyers, Printers, Drysalters, Brokers, &c. By J. W. SLATER. Second Edition, Revised and greatly Enlarged, crown 8vo, "js. 6d. cloth. " A complete encyclopa/dia of the materia. tinctoria. The information given respecting each article is full and precise, and the methods of determining the value of articles such as.these so liable to sophis- tication are given with clearness, and are practical as well as valuable. Chemist aiui Druggist. "There is no other work which covers precisely the same ground To students prepanng for examinations in dyeing and printing it will prove exceedingly useful. LHemicai news. 36 CROSBY LOCKWOOD & SON'S CATALOGUE. Modern Brewing and Malting. A HANDYBOOK FOR BREWERS: Being a Practical Guide to the Art of Brewing and Malting. Embracing the Conclusions of Modem Research which bear upon the Practice of Brewing. By HERBERT EDWARDS WRIGHT. M.A. Crown 8vo, 530 pp., 12s. 6d. cloth. " May be consulted with advantage by the student who is preparing himself for examinational tests, while the scientific brewer will find in it a rtsume of all the most important discoveries ot modern times. The work is written throughout in a clear and concise manner, and the author takes great care to discriminate between vague theories and well-established facts." Brewers' Journal. " We have great pleasure in recommending this handybook, and have no hesitation in saying that it is one of the best if not the best which has yet been written on the subject of beer-brewing in this country, it should have a place on the shelves of every brewer's library." Brewer's Guardian. "Although the requirements of the student are primarily considered, an acquaintance of half-an- hour's duration cannot fail to impress the practical brewer with the sense of having found a trustworthy Ruide and practical counsellor in brewery matters."- Chemical Trade Journal. Analysis and Valuation of Fuels. FUELS : SOLID, LIQUID, AND GASEOUS : Their Analysis and Valuation. For the Use of Chemists and Engineers. By H. J. PHILLIPS, F.C.S., Formerly Analytical and Consulting Chemist to the Great Eastern Railway. Second Edition, Revised and Enlarged. Crown 8vo, 5j. cloth. " Ought to have its place in the laboratory of every metallurgical establishment, and wherever fuel is used on a large scale." Chemical News. Pigments. THE ARTISTS' MANUAL OF PIGMENTS. Showing their Com- position, Conditions of Permanency, Non- Permanency, and Adulterations ; Effects in Combination with Each Other and with Vehicles ; and the most Reliable Tests of Purity. By H. C. STANDAGE. Second Edition, crown 8vo, 2s. 6d. cloth. " This work is indeed multum-in-parvo , and we can, with good conscience, recommend it to all w ho come in contact with pigments, whether as makers, dealers, or users." Chemical Review, Gauging. Tables and Rules for Revenue Officers, Brewers, &c. A POCKET BOOK OF MENSURATION AND GAUGING : Containing Tables, Rules, and Memoranda for Revenue Officers, Brewers, Spirit Merchants, &c. ByJ. B. MANT (Inland Revenue). Second Edition, Revised. i8mo, 4*. leather. " This handy and useful book is adapted to the requirements of the Inland Revenue Department, and will be a favourite book of reference. The range of subjects is comprehensive, and the arrangement simple and clear." Civilian. " Should be in the hands of every practical brewer." Brewers' Journal. INDUSTRIAL ARTS, TRADES AND MANUFACTURES. Cotton Spinning. COTTON MANUFACTURE: A Manual of Practical Instruction in the Processes of Opening, Carding, Combing, Drawing, Doubling and Spinning of Cotton, the Methods of Dyeing &c. For the Use of Operatives, Overlookers and Manufacturers. By JOHN LISTER, Technical Instructor, Pendleton. 8vo, 7-r. 6d. cloth. [Just published. "This invaluable volume is a distinct advance in the literature of cotton manufacture." Machinery. " It is thoroughly reliable, fulfilling nearly all the requirements desired.'' Glasgow Herald. Flour Manufacture, Milling, etc. FLOUR MANUFACTURE: A Treatise on Milling Science and Prac- tice. By FRIEDRICH KICK, Imperial Regierungsrath, Professor of Mechanical Technology in the Imperial German Polytechnic Institute, Prague. Translated from the Second Enlarged and Revised Edition with Supplement. By H. H. P. POWLES, Assoc. Memb. Institution of Civil Engineers. Nearly 400 pp. Illustrated with 28 Folding Plates, and 167 Woodcuts. Roy. 8vo, 25^. cloth. " This valuable work is, and will remain, the standard authority on the science of milling. . . . The miller who has read and digested this work will have laid the foundation, so to speak, of a successful career ; he will have acquired a number of general principles which he can proceed to apply. In this handsome volume we at last have the accepted text-book of modern milling in good, sound English, which has little, if any, tiace of the German idiom." The Miller. " The appearance of this celebrated work in English is very opportune, and British millers will, we are sure, not be slow in availing themselves of its pages." Millers' Gazette. INDUSTRIAL AND USEFUL ARTS. 37 Agglutinants. CEMENTS, PASTES, GLUES AND GUMS : A Practical Guide to the Manufacture and Application of the various Agglutinints required in the Building, Metal- Working, Wood-Working, and Leather-Working Trades, and for Workshop, Laboratory or Office Use. With upwards of 900 Recipes and Formula:. By H. C. STANDAGE, Chemist. Crown 8vo, 2s. 6d. cloth. "We have pleasure in speaking favourably of this volume. So far as we have had experience which is not inconsiderable, this manual is trustworthy.'' Athenccum. "As a revelation of what are considered trade secrets, this book will arouse an amouut of curiosity among the large number of industries it touches." Daily Chronicle. In this goodly collection of recipes it would be strange if a cement for any purpose cannot be found." Oil and Cornerman's Journal. Soap-making. THE ART OF SOAP-MAKING : A Practical Handbook of the Manufacture of Hard and Soft Soaps, Toilet Soaps, &c. Including many New Processes, and a Chapter on the Recovery of Glycerine from Waste Leys. By ALEXANDER WATT. Fifth Edition, Revised, with an Appendix on Modern Candlemaking. Crown 8vo, 'js. 6d. cloth. [Just published. " The work will prove very useful, not merely to the technological student, but to the practical soap- boiler who wishes to understand the theory of his Art." Chemical News. " A thoroughly practical treatise on an art which has almost no literature in our language. We con- gratulate the author on the success of his endeavour to fill a void in English technical literature." Nature. Paper Making. PRACTICAL PAPER-MAKING: A Manual for Paper-makers and Owners and Managers of Paper-Mills. With Tables, Calculations, &c. By G. CLAPPERTOX, Paper-maker With Illustrations of Fibres from Micro-photographs. Crown 8vo, 5-r. cloth. \Just published. "The author caters for the requirements of responsible mill hands, apprentices, &c., whilst his manual will be found of great service to students of technology, as well as to veteran paper-makers and mill owners. .The illustrations form an excellent feature." The World's Paper Trade Review. " We recommend everybody interested in the trade to get a copy of this thoroughly practical book." Paper Making. Paper Making THE ART OF PAPER MAKING : A Piactical Handbook of the Manufacture of Paper from Rags, Esparto, Straw, and other Fibrous Materials. Including the Manufacture of Pulp from Wood Fibre, with a Description of the Machinery and Appliances used. To which are added Details of Processes for Recovering Soda from Waste Liquors. By ALEXANDER WATT, Author of "The Art of Soap-Making." With Illustrations. Crown 8vo, "js. 6d. cloth. " It may be regarded as the standard work on the subject. The book is full of valuable informa- tion. The ' Art or Paper-making,' is in every respect a model or a text-book, either for a technical class, or for the private student." Paper and Printing Trades Journal. Leather Manufacture. THE ART OF LEATHER MANUFACTURE : Being a Practical Handbook, in which the Operations of Tanning, Currying, and Leather Dressing are fully Described, and the Principles of Tanning Explained, and many Recent Processes Introduced ; as also Methods for the Estimation of Tannin, and a Description of the Arts of Glue Boiling, Gut Dressing, &c. By ALEXANDER WATT, Author of "Soap-Making," &c. Second Edition. Crown 8vo, gj. cloth. "A sound, comprehensive treatise on tanning and its accessories. The book is an eminently valuable production, which redounds to the credit of both author and publishers." Chemical Review. Boot and Shoe Making. THE ART OF BOOT AND SHOE-MAKING : A Practical Hand- book, including Measurement, Last-Fitting, Cutting-Out, Closing and Making, with a Description of the most approved Machinery Employed. By JOHN B. LEND, late Editor of St. Crispin, and The Boot and Shoe-Maker. I2mo, 2s. cloth. " This excellent treatise is by far the best work ever written. The chapter on clicking, which shows how waste may be prevented, will save fifty times the price of the book." Scottish Leather Tradtr. Dentistry Construction. MECHANICAL DENTISTRY: A Practical Treatise on the Construc- tion of the various kinds of Artificial Dentures. Comprising also Useful Formula?, Tables, and Receipts for Gold Plate, Clasps, Solders, &c. &c. By C. HUNTER. Third Edition. With 100 \Vood Engravings. Crown 8vo, 3-f. 6d. cloth. "We can strongly recommend Mr. Hui.ter's treatise to all students preparing for the profession of dentistry, as well as to every mechanical dentist." Dublin Journal SON'S CATALOGUE. HANDYBOOKS FOR HANDICRAFTS. BY PAUL N. HASLUCK, Editor of " Work ' (New Series), Author of " Lathe Work," "Milling Machines," &c. Crown 8vo, 144 pages, cloth, price is. each. t^" These HANDYBOOK.S have been written to supply information for WORKMEN, STUDENTS, and AMATEURS in the several Handicrafts, on the actual PRACTICE of the WORKSHOP, and are intended to convey in plain language TECHNICAL KNOWLEDGE of the several CRAFTS. In describing the processes employed, and the manipulation of material, workshop terms are used ; workshop practice is fully explained ; and the text is freely illustrated with drawings of modern tools, appliances, and processes. THE METAL TURNER'S HANDYBOOK. A Practical Manual for Workers at the Foot- Lathe. With over loo Illustrations. Price is. " The book will be of service alike to the amateur and the artisan turner. It displays thorough knowledge of the sub' xt." Scotsman. THE WOOD TURNER'S HANDYBOOK. A Practical Manual for Workers at the Lathe. With over 100 Illustrations. Price is. "We recommend the book to youn? turners and amateurs. A multitude of workmen have hitherto sought in vain for a manual of this special industry." Mechanical World. THE WATCH JOBBER'S HANDYBOOK. A Practical Manual on Cleaning, Repairing, and Adjusting. With upwards of 100 Illustrations. Price is. " We strongly advise all young persons connected with the watch trade to acquire and study this inexpensive work." Clerkenwell Chronicle. THE PATTERN MAKER'S HANDYBOOK. A Practical Manual on the Construction of Patterns for Founders. With upwards of 100 Illustrations, u. " A most valuable, if not indispensable, manual for the pattern maker." Knowledge. THE MECHANIC'S WORKSHOP HANDYBOOK. A Practical Manua on Mechanical Manipulation, embracing Information on various Handicraft Processes. With Useful Notes and Miscellaneous Memoranda. Comprising about 200 Subjects. Price is. "A very clever and useful book, which should be found in every workshop ; and it should cer- tainly find a place in all technical schools." Saturday Review. THE MODEL ENGINEER'S HANDYBOOK. A Practical Manual on the Construction of Model Steam Engines. With upwards of 100 Illustrations. is. " Mr. Hasluck has produced a very good little book." Builder. THE CLOCK JOBBER'S HANDYBOOK. A Practical Manual on Cleaning. Repairing, and Adjusting. With upwards of 100 Illustrations. Price is. It is of nestimable service to those commencing the trade." Coventry Standard. THE CABINET WpRKER's HANDYBOOK. A Practical Manual on the Tools, Materials, Appliances, and Processes employed in Cabinet Work. With upwards of 100 Illustrations. Price is. " Mr. Hasluck's thoroughgoing little Handybopk is amongst the most practical guides we have seen for beginners in cabinet-work." Saturday Review. THE WOODWORKER'S HANDYBOOK OF MANUAL INSTRUCTION. Kmbracing Information on the Tools, Materials, Appliances and Processes Em- ployed in Woodworking. With 104 Illustrations. Price is. [Just published. THE METALWORKER'S HANDYBOOK. With upwards of 100 Illus- trations. [/ preparation. OPINIONS OK THE PRESS. " Written by a man who knows, not only how work ought to be done, but how to do it, and how to convey his knowledge to others." Engineering. " Mr. Hasluck writes admirably, and gives complete instructions." Engineer. " Mr. Hasluck combines the experience of a practical teacher with the manipulative skill and scientific knowledge of processes of the trained mechanician, and the manuals are marvels of what can be produced at a popular price." Schoolmaster. " Helpful to workmen of all ages and degrees of experience." Daily Chronicle. " Practical, sensible, and remarkably cheap." Journal of Education. "Concise, clear, and practical." Sattirday Review. COMMERCE, COUNTING-HOUSE WORK, TABLES, &c. 41 COMMERCE, COUNTING-HOUSE WORK, TABLES, etc. Commercial Education. LESSONS IN COMMERCE. By Professor R. GAMBARO, of the Royal High Commercial School at Genoa. Edited and Revised by JAMES GAULT, Professor of Commerce and Commercial Law in King's College, London. Crown 8vo, 3-r. 6d. cloth. " The publishers of this work have rendered considerable service to the cause of commercial educa- tion by the opportune production of this volume. . . . The work-is peculiarly acceptable to English readers and an admirable addition to existing class books. In a phrase, we think the work attains its object in furnishing a brief account of those laws and customs of British trade with which the commer- cial man interested therein should be familiar." Chamber of Commerce Journal. " An invaluable guide in the hands of those who are preparing for a commercial career, and, in fact the information it contains on matters of business should be impressed on every one." Counting House. Foreign Commercial Correspondence. THE FOREIGN COMMERCIAL CORRESPONDENT: Being Aids to Commercial Correspondence in Five Languages English, French, German, Italian, and Spanish. By CONRAD E. BAKER. Second Edition. Cr. 8vo, 3-r. 6d. cl. "Whoever wishes to correspond in all the languages mentioned by Mr. Baker cannot do better than study this work, the materials of which are excellent and conveniently arranged. They consist not of entire specimen letters, but what are far more useful short passages, sentences, or phrases expressing the same general idea in various forms." Athenteum. "A careful examination rus convinced us that it is unusually complete, well arranged and reliable. The book is a thoroughly good one." Schoolmaster. Commercial French. A NEW BOOK OF COMMERCIAL FRENCH: Grammar Voca- bulary Correspondence Commercial Documents Geography Arithmetic Lexicon. By P. CARROUE, Professor in the City High. School J. B. Say (Paris). Crown 8vo, 4*. 6d. cloth. [Just published. Accounts for Manufacturers. FACTORY ACCOUNTS : Their Principles and Practice. A Handbook for Accountants and Manufacturers, with Appendices on the Nomenclature of Machine Details ; the Income Tax Acts ; the Rating of Factories ; Fire and Boiler Insurance; the Factory and Workshop Acts, &c., including also a Glossary of Terms and a large number ol Specimen Rulings. By EMILE GARCKE andj. M. FELLS. Fourth Edition, Revised and Enlarged. Demy 8vo, 250 pages. 6s. strongly bound. "A very interesting description of the requirements of Factory Accounts. . . . The principle of assimilating the Factory Accounts to the general commercial books is one which we thoroughly agree V " " Characte'riseYby extTe^ie thoroughness. There are few owners of factories who would not Derive great benefit from the perusal of this most admirable work." Local Government Chronicle. Modern Metrical Units and Systems. MODERN METROLOGY : A Manual of the Metrical Units and Systems of the present Century. With an Appendix containing a proposed English System. By Lowis D'A. JACKSON, A.-M. Inst. C.E., Author of " Aid to burvey Practice," &c. Large crown 8vo, 12s. 6d. cloth. " We recommend the work to all interested in the practical reform of our weights and m ' The Metric System and the British Standards. A SERIES OF METRIC TABLES, in which the British Standard Measures and Weights are compared with those of the Metric System at present in Use on the Continent. By C. H. DoWLlNG, C.E. 8vo, los. 6d. leather. House Property. HANDBOOK OF HOUSE PROPERTY: A Popular and Practical Guide to the Purchase, Mortgage, Tenancy, and Compulsory Sale of Houses and Land, including the Law of Dilapidations and Fixtures : with Examples of all kinds of Valuations, Useful Information on Building and Suggestive Elucidations of Fine Art. By E. L. TARBUCK, Architect and Surveyor. Fifth Edition Enlarged. I2mo, 5^. cloth. "The advice is thoroughly practical." Law 'Journal. " For all who have dealings with house propertyi, this is an indispensable guide " Decoration ' Carefully brought up to date, and much improved by the addition of a divisiou on Fine Art. . . . A well-written and thoughtful work." Land Agent's Record. LAW AND^ MISCELLANEOUS. Journalism. MODERN JOURNALISM: A Handbook of Instruction and Counsel for the Young Journalist. By JOHN B. MACKIE, Fellow of the Institute of Journalists. Crown 8vo, 2s. cloth. \Just published. " This invaluable guide to journalism is a work which all aspirants to a journalistic career will read with advantage." Journalist. Private Bill Legislation and Provisional Orders. HANDBOOK FOR THE USE OF SOLICITORS AND ENGINEERS Engaged in Promoting Private Acts of Parliament and Provisional Orders, for the authorization of Railways, Tramways, Gas and Water Works, &c. By L. LIVING- STON MACASSEY, of the Middle Temple, Barrister-at-Law, M. Inst. C.E. 8vo, 25$. cloth. Law of Patents. PATENTS FOR INVENTIONS, AND How TO PROCURE THEM Compiled for the Use of Inventors, Patentees and others. By G. G. M. HARDING- HAM, Assoc. Mem. Inst. C. E., &c. Demy 8vo, is. 6d. cloth. Labour Disputes. CONCILIATION AND ARBITRATION IN LABOUR DISPUTES: A Historical Sketch and Brief Statement of the Present Position of the Question at Home and Abroad. ByJ. S. JEANS, Author of "England's Supremacy,"&c. Crown 8vo, 200 pp., 2s. 6d. cloth. [Just published. " Mr. Jeans is wall qualified to write on this subject, both by his previous books and by his practical experience as an arbitrator." The Times. Pocket-Booh for Sanitary Officials. THE HEALTH OFFICER'S POCKET-BOOK : A Guide to Sani- tary Practice and Law. For Medical Officers of Health, Sanitary Inspectors, Members of Sanitary Authorities, &c. By EDWARD F. WILLOUGHBY, M.D. (Lond.), &c. Fcap. 8vo, 7-r. 6d., cloth. [Just published. " A mine of condensed information of a pertinent and useful kind on the various subjects of which it treats. The matter seems to have bsen carefully compiled and arranged for facility of reference and it is well illustrated by diagrams and woodcuts. The different subjects are succinctly but fully and scientifically dealt with." The Lancet. " Ought to be welcome to those for whose use it is designed, since it practically boils down a reference library into a pocket volume. ... It combines, witn an uncommon decree of efficiency, the qualities of accuracy, conciseness and comprehensiveness." Scotsman. " An excellent publication, dealing with the scientific, technical and legal matters connected with the duties of medical officers of health and sanitary inspectors." Local Government Journal. 48 CROSBY LOCI: WOOD & SOWS CATALOGUE. A Complete Epitome of the Laws of this Country. EVERY MAN'S OWN LAWYER : A Handy-Book of the Principles of Law and Equity. With a Concise Dictionary of Legal Terms. By A BAR- RISTER. Thirty-second Edition, carefully Revised, and including New Acts of Parliament of 1894. Comprising tlie Local Government Act, 1894 (establishing District and Parish Councils) ; finance Act, 1894 (imposing the New Death Duties) ; Merchant Shipping Act, 1894 ; Prevention of Cruelty to Children Act. 1894 ; Building Societies Act, 1894 ; Notice of Accidents Act, 1894 ; Sale of Goods Act, 1893 J Voluntary Conveyances Act, 1893 ; Married Women's Property Act, 1893 ; Trttstee Act, 1893 '> Feitiliser and Feeding Stuffs Act, 1893 ; Betting and Loans (infants) Act, 1892 ; Shop Hours Act, 1892 ; Small Holdings Act, 1892 ; and many other important new Acts. Crown 8vo, 750 pp., price 6s. ?>d. (saved at every consultation ! ), strcntjly hound in cloth. [Just published. ** The Book will be found-to comprise (amongst other matter) THE RIGHTS AND WRONGS OF INDIVIDUALS LANDLORD AND TENANT VENDORS AND PURCHASERS LEASES AND MORTGAGES PRINCIPAL AND AGENT PARTNERSHIP AND COMPANIES MASTERS, SERVANTS AND WORK- MEN CONTRACTS AND AGREEMENTS BORROWERS, LENDERS AND SURETIES SALE AND PURCHASE OF GOODS CHEQUES, BILLS AND NOTES BILLS OF SALE BANKRUPTCY RAILWAY AND SHIPPING LAW LIFE, FIRE, AND MARINE INSURANCE ACCIDENT AND FIDELITY INSURANCE CRIMINAL LAW PARLIAMENTARY ELECTIONS COUNTY COUNCILS DISTRICT COUNCILS PARISH COUNCILS MUNICIPAL CORPORATIONS LIBEL AND SLANDER PUBLIC HEALTH AND NUISANCES COPYRIGHT, PATENTS, TRADE MARKS HUSBAND AND WIFE DIVORCE INFANCY CUSTODY OF CHILDREN TRUSTEES AND EXECUTORS CLERGY, CHURCHWARDENS, ETC. GAME LAWS AND SPORTING INNKEEPERS HORSES AND DOGS TAXES AND DEATH DUTIES FORMS OF AGREEMENTS, WILLS, CODWJILS, NOTICES, ETC. 13* The object of this work is to enable those who consult it to help themselves to the law ; and thereby to dispense, as far as possible, with professional assistance and advice. There are many wrongs and grievances 'which persons submit to from time to time through not knowing how or where to apply for redress ; anal many persons have as great a dread of a lawyer's office as of a lion' s den. With this book at hand it is believed that many a SlX-AND-ElGHTPENCE may be saved; many a wron^.redressed ; many a right reclaimed ; many a law suit avoided; and mmy an evil abated. The work has established itself as the standard legal adviser of all classes, and has also made a reputa- tion for itself as a useful book of reference for lawyers residing at a distance from law libraries, who are glad to have at hand a work embodying recent decisions and enactments. ** OPINIONS OF THE PRESS. " It is a complete code of English LAW written in plain language, which all can understand. . . Should be in the hands of every business man, and all who wish to abolish lawyers' bills." Weekly Times " A useful and concise epitome of the law, compiled with considerable care." Laiv Magazine. " A complete digest of the most useful facts which constitute English law." Globe. " This excellent handbook. . . . Admirably done, admirably arranged, and admirably cheap.'' Leeds Mercury. " A concise, cheap, and complete epitome of the English law. So plainly written that he who runs may read, and he who reads may understand. ' ' Figaro. "A dictionary of legal *ac :ogether. The book is a very useful one." Spectator. " A work which has long been wanted, which is thoroughly well done, and which we most cordially recommend." Sunday Times. "The latest edition of this popular book ought to be in every business establishment, and on every library table." Sheffield Post. " A complete epitome of the law; thoroughly intelligible to non-professional readers." Bell's Legal Guide for Pawnbrokers. THE PAWNBROKERS', FACTORS' AND MERCHANTS' GUIDE TO THE LAW OF LOANS AND PLEDGES. With the Statutes and a Digest of .Cases, t-y H. C. FOLKARD, Esq., Barrister-at-Law. Fcap. 8vo, 3^. 6d. sewed. Scale's ittOumentarg Aeries, 5 onion, 1862, THE PRIZE MEDAL Was awarded to the Publishers of "WE ALE'S SERIES." A NEW LIST OF WEALE'S SERIES OF RUDIMENTARY SCIENTIFIC WORKS. ar " WEALE'S SERIES includes Text-Books on almost every branch of Science and Industry, comprising such subjects as Agriculture, Architecture and Building, Civil Engineering, Fine Arts, Mechanics and Mechanical Engineering, Physical and Chemical Science, and many miscellaneous Treatises. The whole are constantly undergoing revi- sion, and new editions, brought up to the latest discoveries in scientific research, are constantly issued. The prices at which they are sold are as low as their excellence is assured." American Literary Gazette. " Amongst the literature of technical education, WEALE'S SERIES has ever enjoyed a high reputation, and the additions being made by Messrs. CROSBY LOCKWOOD & SON render the series even more complete, and bring the information upon the several subjects down to the present time." Mining Journal. "Any persons wishing to acquire knowledge cannot do better than look through WEALE'S SERIES and get all the books they require. The Series is indeed an inexhaus- tible mine of literary wealth." The Metropolitan, "WEALE'S SERIES has become a standard as well as an unrivalled collection of treatises in all branches of art and science." Public Opinion. "The excellence of WEALE'S SERIES is now so well appreciated that it would be wasting our space to enlarge upon their general usefulness and value." Builder. "It is not too much to say that no books have ever proved more popular with or more useful to young engineers and others than the excellent treatises comprised m WEALE'S SERIES." Engineer. "The volumes of WEALE'S SERIES form one of the best collections of elementary technical books in any language." Architect. " A collection of technical manuals which is unrivalled." Weekly Dispatch. Philadelphia, 1876, THE PRIZE MEDAL Was awarded to the Publishers for Books : Rudimentary Scientific, "WEALE'S SERIES," &c. CROSBY LOCKWOOD & SON, 7, STATIONERS' HALL COURT, LUDGATE HILL, LONDON, EC. 50 CROSBY LOCKWOOD & SON'S CATALOGUE. WEALE'S RUDIMENTARY SCIENTIFIC SERIES. * # * The volumes of this Series are freely Illustrated with Wood- cuts, or otherwise, where requisite. Throughout the following List it must umen> be understood that the books are bound in limp cloth, unless otherwise Stated ; but the volumes marked with a J may also be had strongly bound in cloth boards for >d. extra. N.B. In ordering from this List it is recommended, as a means of facilitating business and obviating error, to quote the numbers affixed to the volumes, as well as the titles and prices. CIVIL ENGINEERING, etc. 3X . WELLS AND WELL-SINKING. By JOHN GEO. SWINDELL, A.R.I.B.A., and G. R. BURNELL, C.E. Revised Edition. With a New Appendix on the Qualities of Water. Illustrated 2/0 " Solid practical information, written in a concise and lucid style. The work can be recommended as a text-book for all surveyors, architects, &c." Iron and Coal Trades Review. 3S . THE BLASTING AND QUARRYING OF STONE, for Building and other Purposes. With Remarks on the Blowing up of Bridges. By Gen. SirJ. BURGOYNE, K.C.B 1/6 43 . TUBULAR AND OTHER IRON GIRDER BRIDGES, describing the Britannia and Conway Tubular Bridges. With a Sketch of Iron Bridges, &c. By G. DRYSDALE DEMPSEY, C.E. Fourth Edition . 2/0 44 . FOUNDATIONS AND CONCRETE WORKS. With Prac- tical Remarks on Footings, Planking, Sand, Concrete, B^ton, Pile-driving, Caissons, and Cofferdams. By E. DOBSON, M.R.I.B.A. Seventh Edition .1/6 6o . LAND AND ENGINEERING SURVEYING. For Students and Practical Use. By T. BAKER, C.E. Fifteenth Edition, revised and corrected by J. R. YOUNG, formerly Professor of Mathematics, Belfast College. Illustrated with Plates and Diagrams 2/oJ 80*. EMBANKING LANDS FROM THE SEA. With Examples and Particulars of actual Embankments, &c. By JOHN WIGGINS, F.G.S. . 2/0 8l . WATER WORKS, for the Supply of Cities and Towns. With a Description of the Principal Geological Formations of England as influencing Supplies of Water ; and Details of Engines and Pumping Machinery for raising Water. By SAMUEL HUGHES, F.G.S., C.E. Enlarged Edition . . 4/oJ " Every one who is debating how his village, town, or city shall be plentifully supplied with pure water should read this book." Newcastle Coitrant. 117 . SUBTERRANEOUS SURVEYING. By THOMAS FEN- WICK. Also the Method of Conducting Subterraneous Surveys without the use of the Magnetic Needle, and other modern Improvements. By T. BAKER, C.E. 2/6J 118 . CIVIL ENGINEERING IN NORTH AMERICA, A Sketch of. By DAVID STEVENSON, F.R.S.E., &c. Plates and Diagrams. .3/0 l67 A TREATISE ON THE APPLICATION OF IRON TO THE CONSTRUCTION OF BRIDGES, ROOFS, AND OTHER WORKS By FRANCIS CAMPIN, C.E. Fourth Edition .... 2/6 J "For numbers 01 young engineers the book is just the cheap, handy, first guide they want." Middlesbrough Weekly News. " Remarkably accurate and well written." Artizan. I97 . ROADS AND STREETS (THE CONSTRUCTION OF\ in Two Parts : I. THE ART OF CONSTRUCTING COMMON ROADS, by H. LAW, C.E., Revised by D. KINNEAR CLARK, C.E.; II. RPCENT PRACTICE: Including Pavements of Stone, Wood, and Asphalte, By D. K. CLARK, C.E. 4/6J "A book which every borough surveyor and engineer must possess, and which will be of considerable service to architects, builders, and property owners generally."' Building News. ^SANITARY WORK IN THE SMALLER TOWNS AND 7/V VILLAGES. By CHARLES SLAGG, Assoc. M. Inst. C.E. Second Edition, enlarged 3/0* " This is a very useful book. There is a great deal of work required to be done in the smaller towns and villages, and this little volume will help those who are willing to do it." Builder. t&" Tht 1 indicates that these vols. may be had strongly bound at 6d. extra. WE ALE'S RUDIMENTARY SERIES. 5l Civil Engineering, etc., continued. 212. THE CONSTRUCTION OF GAS WORKS, and the Manu- facture and Distribution of Coal Gas. By S. HUGHES, C.E. Re-written by WILLIAM RICHARDS, C.E. Eighth Edition, with important Additions 5/6J "Will be of infinite service alike to manufacturers, distributors, and consumers. ' Foreman Engineer. 213. PIONEER ENGINEERING: A Treatise on the Engineering Operations connected with the Settlement of Waste Lands in New Countries. By EDWARD DOBSON, A.I. C.E. With numerous Plates. Second Edition . 4/6J " Mr. Dobson is familiar with the difficulties which have to be overcome in this class of work, and much of his advice will be valuable to young engineers proceeding to our colonies." Engineering, 216. MATERIALS AND CONSTRUCTION: A Theoretical and Practical Treatise on the Strains, Designing, and Erection of Works of Construction. By FRANCIS CAMPIN, C.E. Second Edition, carefully revised. 3/0$ " No better exposition of the practical application of the principles of construction has yet beep published to our knowledge in such a cheap comprehensive form." Building News. 219. CIVIL ENGINEERING. By HENRY LAW, M. Inst. C.E. Including a Treatise on HYDRAULIC ENGINEERING by G. R. BURNELL, M.I. C.E. Seventh Edition, revised, WITH LARGE ADDITIONS ON RECENT PRACTICE by D. KINNEAR CLARK, M. Inst. C.E. 6s. 6d. t cloth boards . 7/6 " An admirable volume, which we warmly recommend to young engineers. 1 ' Builder. 260. IRON BRIDGES OF MODERATE SPAN: Their Con- struction and Erection. By HAMILTON WELDON PENDRED, late Inspector of Ironwork to the Salford Corporation. With 40 Illustrations .... 2/0 " Students and engineers should obtain this book for constant and practical use." Colliery Guardian 268. THE DRAINAGE OF LANDS, TOWNS, AND BUILD- INGS. By G. D. DEMPSEY, C.E. Revised, with large Additions on Recent Practice in Drainage Engineering, by D. KINNEAR CLARK, M.I.C.E. Second Edition, corrected 4/6J MECHANICAL ENGINEERING, etc. 33 . CRANES, the Construction of, and other Machinery for Raising Heavy Bodies for the Erection of Buildings, &c. By JOSEPH GLYNN, F.R.S. 1/6 34 . THE STEAM ENGINE. By Dr. LARDNER. Illustrated . 1/5 59 . STEAM BOILERS: Their Construction and Management. By R. ARMSTRONG, C.E. Illustrated 1/6 " A mass of information suitable lor beginners." Design and Work. 82. THE POWER OF WATER, as applied to drive Flour Mills, and to give motion to Turbines and other Hydrostatic Engines. By JOSEPH GLYNN, F.R.S., &c. New Edition, Illustrated 2/0 Q 8 PR A CTI CAL MECHANISM, and Machine Tools. By T. BAKER, C.E. With Remarks on Tools and Machinery, by J. NASMYTH, C.E. 2/6 r , g THE STEAM ENGINE, a Treatise on the Mathematical Theory of, with Rules and Examples for Practical Men. By T. BAKER, C.E. 1/6 "Teems with scientific information in reference to the steam-engine. Design and Work. I6 , MODERN WORKSHOP PR A CTICE, as applied to Marine, Land, and Locomotive Engines, Floating Docks, Dredging Machines, Bridges, Ship-building, &c. By T. G. WINTON. Fourth Edition, Illustrated . . 3/6, "Whether for the apprentice determined to master his profession, or for the artisan bent upon himself to a higher position, this clearly written and practical treatise will be a great help. -Scots, T 6 C IRON AND HEAT, exhibiting the Principles concerned in the Construction of Iron Beams, Pillars, and Girders. By J. ARMOUR, C.E. . 2/6 "A very useful and thoroughly practical little volume." Mining Journal. fifi POWER IN MOTION: Horse-power Motion, Toothed-Wheel Gearing, Long and Short Driving Bands, Angular Forces, &c. By JAMES ARMOUR, C.E. With 73 Diagrams. Third Edition . . a/t "The value of the knowledge imparted cannot well be over-estimated."- Newcastle Weekly THE WORKMAN'S MANUAL OF ENGINEERING DRA WING. By JOHN MAXTON, Instructor in Engineering Drawing. Royal Naval College, Greenwich. Seventh Edition. 300 Plates and Diagrams 3 6J " A copy of it should be kept for reference in every drawing office. -Enginet KM- The Vindicates that these wb. may be had strongly bound at 6d. extra. 52 CROSBY LOCKWOOD 6- SON'S CATALOGUE. Mechanical Engineering, etc., continued. i 9 o. STEAM AND THE STEAM ENGINE, Stationary and Port- able, An Elementary Treatise on. Being an Extension of the Treatise on the Steam Engine of Mr. J. SEWELL. By D. K. CLARK, C.E. Third Edition 3/6$ "Every essential part of the subject is treated of competently, and in a popular style." Iron. 200. FUEL, ITS COMBUSTION AND ECONOMY. Con- sisting of an Abridgment of " A Treatise on the Combustion of Coal and the Prevention of Smoke." By C. W. WILLIAMS, A. I. C.E. With extensive Additions by D. KINNEAR CLARK, M. Inst. C.E. Third Edition, corrected 3/6J " Students should buy the book and read it, as one of the most complete and satisfactory treatises on the combustion and economy of fuel to be had." Engineer. 202. LOCOMOTIVE ENGINES, A Rudimentary Treatise on. By G. D. DEMPSEY, C.E. With large Additions treating of the Modern Locomotive, by D. K. CLARK, M. Inst. C.E. With numerous Illustrations . 3/oJ " A model of what an elementary technical book should be." Academy. 211. THE BOILERMAKER'S ASSISTANT in Drawing, Tern- plating, and Calculating Boiler Work, &c. By J . COURTNEY, Practical Boiler- maker. Edited by D. K. CLARK, C.E. Third Edition, revised . . 2/0 " With very great care we have gone through the ' Boilermaker's Assistant,' and have to say that it has our unqualified approval. Scarcely a point has been omitted." Foreman Engineer. 217. SEWING MACHINERY: Its Construction, History, &c. With full Technical Directions for Adjusting, &c. By J. W. URQUHART, C.E. 2/0 "A full description of the principles and construction of the leading machines, and minute instruc- tions as to their management." Scotsman. 223 MECHANICAL ENGINEERING. Comprising Metallurgy, Moulding.Casting. Forging.Tools, Workshop Machinery, Mechanical Manipula- tion, Manufacture of the Steam Engine, &c. By FRANCIS CAMPIN, C.E. Third Edition, Re-written and Enlarged . . . . \Just published. 2/6 J "A sound and serviceable text-book, quite up to date." Building News. 23 6. DETAILS OF MACHINERY. Comprising Instructions for the Execution of various Works in Iron in the Fitting-Shop, Foundry, and Boiler- Yard. By FRANCIS CAMPIN, C.E ........ 3/oJ " A sound and practical handbook for all engaged in the engineering trades." Building World, 2 37 . THE SMITHY AND FORGE, including the Farrier's Art and Coach Smithing. By W. J. E. CRANE. Second Edition, revised . . 2/6 J " The first modern English book on the subject. Great pains have been bestowed by the author upon the book ; shoeing smiths will find it both useful and interesting." Builder. 83 3. THE SHEET-METAL WORKER'S G UIDE : A Practical Handbook for Tinsmiths, Coppersmiths, Zincworkers, &c., with 46 Diagrams and Working Patterns. By W. J. E. CRANE. Second Edition, revised. .1/6 " The author has acquitted himself with considerable tact in choosing his examples, and with no ess ability in treating them." Plumber. 251 STEAM AND MACHINERY MANAGEMENT: A Guide to the Arrangement and Economical Management of Machinery, with Hints on Construction and Selection. By M. Powis BALE, M.Inst.M.E. . . 2/6{ i Of high practical value. "Colliery Guardian. "Gives the results of wide experience." Lloyd's Newspaper. Z54 . THE BOILER-MAKER'S READY RECKONER, with Examples of Practical Geometry and Templating far the Use of Platers, Smiths, and Riveters. By JOHN COURTNEY. Edited by D. K. CLARK, M.I.C.E. Second Edition, revised, with Additions ........ 4/0 %* Nos. 211 and 254 in One Vol., half -bound, entitled "THE BOILERMAKER'S READY- RECKONER AND ASSISTANT." By J. COURTNEY and D. K. CLARK. Price 75. " A most useful work. No workman or apprentice should be without it." Iron Trade Circular. , S5 . L O CO MO TIVE ENGINE-DRIVING. A Practical Manual for Engineers in charge of Locomotive Engines. By MICHAEL REYNOLDS, M.S.E. Eighth Edition. 3.?. 6d. limp ; cloth boards ..... 4/6 " We can confidently recommend the book, not only to the practical driver, but to everyone who takes an interest in the perfotmance of locomotive engines.- The Enginter. 256. STA TIONAR Y ENGINE-DRIVING. A Practical Manual for Engineers in charge of Stationary Engines. By MICHAEL REYNOLDS, M.S.E. Fourth Edition. 3.5. 6d. limp ; cloth boards ..... 4/6 "The author is thoroughly acquainted with his subjects, and has produced a manual which is exceedingly useful one for the class for whom it is specially intended." Engineering. The + indicates that these vols. may be had strongly bound at 6d. extra. WE ALE'S RUDIMENTARY SERIES. MINING, METALLURGY, etc. 4 . MINERALOGY, Rudiments of. By A. RAMSAY F.G.S. Third Edition, revised and enlarged. Woodcuts and Plates ' r 6t la^SES^ *-' <^'ty I n 7 . SUBTERRANEOUS SURVEYING, with and without the Magnetic Needle. By T. FEN WICK and T. BAKER, C.E. Illustrated. . 2 /6T i 3S . ELECTRO-METALLURGY, Practically Treated. By ALEX- ANDER WATT. Ninth Edition, enlarged and revised. With Additional Illustrations, and including the most Recent Processes .... o/6J " From this book both amateur and artisan may learn everything necessary '' Iron 172. MINING TOOLS, Manual of. By WILLIAM MORGANS, Lecturer on Practical Mining at the Bristol School of Mines . . . .2/6 V&.MINING TOOLS, ATLAS of Engravings to Illustrate the above, containing 235 Illustrations of Mining Tools, drawn to Scale. 410. . 4/6 ", Stu dents, Overmen Captains Managers, and Viewers may gain practical knowledge and useful hints by the study of Mr. Morgans' Manual." Colliery Guardian. I7 6. METALLURGY Of IRON. Containing History of Iron Manufacture, Methods of Assay, and Analyses of Iron Ores, Processes of Manu- facture of Iron and Steel, &c. By H. BAUERMAN, F.G.S., A.R.S.M. With numerous Illustrations. Sixth Edition, revised and enlarged .... 5/oJ "Carefully written, it has the merit of brevity and conciseness, as to less important points ; while all material matters are very fully and thoroughly entered into." Standard. I8o . COAL AND COAL MINING, A Rudimentary Treatise on. By the late Sir WARINGTON W. SMYTH, M.A., F.R.S., &c., Chief Inspector of the Mines of the Crown. Seventh Edition, revised and enlarged . . 3/6J "Every portion of the volume appears to have been prepared with much care, and as an outline is given of every known coal-field in this and other countries, as well as of the two principal methods of working, the book will doubtless interest a very large number of readers." Mining Journal. i 9S . THE MINERAL SURVEYOR AND VALUER'S COM- PLETE GUIDE. Comprising a Treatise on Improved Mining Surveying and the Valuation of Mining Properties, with New Traverse Tables. By W. LINTERN, Mining and Civil Engineer. Third Edition, with an Appendix on Magnetic and Angular Surveying, with Records of the Peculiarities of Needle Disturbances. With Four Plates of Diagrams, Plans, &c. .... 3/6J " Contains much valuable information, and is thoroughly trustworthy " Iron &> Coal Trades Review. ai4 . SLATE AND SLATE QUARRYING, Scientific, Practical, and Commercial. By D. C. DAVIES, F.G.S., Mining Engineer, &c. With numerous Illustrations and Folding Plates. Third Edition .... 3/oJ "One of the best and best-balanced treatises on a special subject that we have met with." E ll A FIRST BOOK OF MINING AND QUARRYING, with the Sciences connected therewith, for Primary Schools and Self Instruction. By T. H. COLLINS, F.G.S. , Lecturer to the Miners' Association of Cornwall and Devon. Second Edition, with additions r/6 " For those concerned in schools in the mining districts, this work is the very thing that should be in the hands of their schoolmasters." Iron. ARCHITECTURE, BUILDING, etc. X 6. ARCHITECTURE ORDERS The Orders and their ^Esthetic Principles. By W. H. LEEDS. Illustrated 1/6 X7 . ARCHITECTURE STYLES The History and Descrip- tion of the Styles of Architecture of Various Countries, from the Earliest to the Present Period. By T. TALBOT BURY, F.R.I. B.A., &c. Illustrated . .2/0 %* ORDERS AND STYLES OF ARCHITECTURE, in One Vol., y. 6d. I8 . ARCHITECTURE DESIGN The Principles of Design in Architecture, as deducible from Nature and exemplified in the Works of the Greek and Gothic Architects. By EDW. LACY GARBETT, Architect. Illustrated 2/6 " We know no work that we would sooner recommend to an attentive reader desirous to obtain clear views of the nature of architectural art. The book is a valuable one." Builder. * * The three preceding Works in One handsome Vol., half bound, entitled " MODERN ARCHITECTURE,"//-*'** 6s. tS" The J indicates that these vols. may be had strongly bound at 6d. extra. 54^ CROSS Y LOCK WOOD 6- SON'S CATALOGUE. Architecture, Building, etc., continued. ea . THE ART OF BUILDING, Rudiments of. General Prin- ciples of Construction, Strength and Use of Materials, Working Drawings, Specifications, &c. By EDWARD DOBSON, M.R.I. B.A., &c 2/oJ " A good book for practical knowledge, and about the best to be obtained." Building News. as . MASONRY AND STONE CUTTING : The Principles of Masonic Projection and their application to Construction. By E. DOBSON, M.R.I. B.A 2/6J 42. COTTAGE BUILDING. By C. BRUCE ALLEN. Eleventh Ed.,with Chapter on Economic Cottages for Allotments, by E. E. ALLEN, C.E. 2/0 45 . LIMES, CEMENTS, MORTARS, CONCRETES, MAS- TICS, PLASTERING, &*c. By G. R. BURNELL, C.E. Thirteenth Edition 1/6 S7 . WARMING AND VENTILATION of Domestic and Public Buildings, Mines, Lighthouses, Ships, &c. By CHARLES TOMLINSON, F.R.S. 3/0 in. ARCHES, PIERS, BUTTRESSES, &c.: Experimental Essays on the Principles of Construction in. By WILLIAM BLAND . . 1/6 n6. ACOUSTICS IN RELATION TO ARCHITECTURE AND BUILDING : The Laws of Sound as applied to the Arrangement of Buildings. By Professor T. ROGER SMITH. F.R.I. B.A. New Edition, Revised. With numerous Illustrations .... [Just published. 1/6 127. ARCHITECTURAL MODELLING IN PAPER, The Art of. By T. A. RICHARDSON. With Illustrations, engraved by O. JEWITT . 1/6 "A valuable aid to the practice of architectural modelling." Builder's Weekly Reporter. 128. VITRUVIUSTHE ARCHITECTURE OF MARCUS VITRUVIUS POLLO. In Ten Books. Translated from the Latin by JOSEPH GWILT, F.S.A., F.R.A.S. With 23 Plates 5/0 N.B. This is the only Edition of VITRUVIUS procurable at a moderate price. 130. GRECIAN ARCHITECTURE, An Inquiry into the Prin- ciples of Beauty in ; with an Historical View of the Rise and Progress of the Art in Greece. By the EARL OF ABERDEEN i/o %* The two preceding Works in One handsome Vol., half bound, entitled "ANCIENT ARCHITECTURE, "price 6s. 132. DWELLING-HOUSES, The Erection of, Illustrated by a Perspective View, Plans, Elevations, and Sections of a Pair of Villas, with the Specification, Quantities, and Estimates. By S. H. BROOKS, Architect . 2/6J 156. QUANTITIES AND MEASUREMENTS, in Bricklayers', Masons', Plasterers', Plumbers', Painters', Paperhangers", Gilders', Smiths', Carpenters' and Joiners' Work. By A. C. BEATON, Surveyor . . . 1/6 " This book is indispensable to builders and their quantity clerks." English Mechanic. i 7S . LOCKWOOD'S BUILDER'S PRICE BOOK FOR 1896. A Comprehensive Handbook of the Latest Prices and Data for Builders, Architects, Engineers, and Contractors, Re-constructed, Re-written, and greatly Enlarged. By FRANCIS T. W. MILLER, A. R.I.B.A. 700 pages. .4/0 182 CARPENTRY AND JOINERY THE ELEMENTARY PRIN- CIPLES OF CARPENTRY. Chiefly composed from the Standard Work of THOMAS TREDGOLD, C.E. With Additions, and a TREATISE ON JOINERY by E. W. TARN, M.A. Fifth Edition, Revised and Extended . 3/6J 182*. CARPENTRY AND JOINERY. ATLAS of 35 Plates to accompany and illustrate the foregoing book. With Descriptive Letterpress. 4to 6/0 " These two volumes form a complete treasury of carpentry and joinery, and should be in the hands of every carpenter and joiner in the empire." Iron. x8 S . THE COMPLETE MEASURER; setting forth the Measure- ment of Boards, Glass, Timber and Stone. By R. HORTON. Fifth Edition . 4/0 ** The above, strongly bound in leather, price 5-J. 187. HINTS TO YOUNG ARCHITECTS. By GEORGE WIGHT- WICK, Architect, Author of "The Palace of Architecture," &c., &c. Fifth Edition, revised and enlarged by G. HUSKISSON GUILLAUME, Architect. 3/6J " A copy ought to be considered as necessary a purchase as a box of instruments." Architect. f^" The I indicates thai these -vols. may be had strongly bound at 6d. extra. , enlarged, with 380 Illustrations ,/ 6 j A text-book which may be safely put into the hands of every young plumber, and which will also be found useful by architects and medical professors." Builder. WEALE^JWDIMENTAR\ SERIES. 55 Architecture, Building, etc., continued. 188 HOUSE PAINTING, GRAINING, MARBLING AND SIGN WRITING : With a Course of Elementary Drawing, and a CoUection of Useful Receipts. By ELLIS A. DAVIDSON. Sixth Edition Coloured Plat 5/0 %* The above in cloth boards, strongly bound, 6s. " A mass of information of use to the amateur and of value to the practical man."- English Mecfuinic. 189. THE RUDIMENTS OF PRACTICAL BRICKLAYING General Principles of Bricklaying ; Arch Drawing, Cutting, and Settine ' Pointing; Paving, Tiling, &c. By ADAM HAMMOND. With 68 Woodcuts i '6 The young bricklayer will find it infinitely valuable to \um."-Glute*w Herala. 191. PLUMBING: A Text-Book to the Practice of the Art or Craft of the Plumber. With Chapters upon House Drainage and Ventilation By WM. PATON BUCHAN, R.P.,Sanitary Engineer. Sixth Edition, revised and enlarged, with 380 Illustrations >ut int 1 profe 192 . THE TIMBER IMPORTER'S, TIMBER MERCHANT'S, AND BUILDER'S STANDARD GUIDE. By R. E. GRANDY . . 2/0 " Everything it pretends to be : built up gradually, it leads one from a forest to a treenail, and throws in, as a makeweight, a host of material concerning bricks, columns, cisterns, &c." English Mechanic. 206. A BOOK ON BUILDING, Civil and Ecclesiastical. By Sir EDMUND BECKETT, Bart., LL.D., Q.C., F.R.A.S., Author of "Clocks and Watches and Bells," &c. Second Edition, enlarged 4/6} "A book which is always amusing and nearly always instructive." Times. 226. THE JOINTS MADE AND USED BY BUILDERS. By WYVILL J. CHRISTY, Architect. With 160 Woodcuts 3/oJ "The work is deserving of high commendation." Builder. 228. THE CONSTRUCTION OF ROOFS, OF WOOD AND IRON : Deduced chiefly from the Works of Robison, Tredgold, and Humber. By E. WYNDHAM TARN, M. A., Architect. Second Edition, revised . .1/6 " Mr. Tarn is so thoroughly master of his subject, that although the treatise is founded on the works of others, he has given it a distinct value of his own. It will be found valuable by all students." Builder. 229. ELEMENTARY DECORATION: As applied to Dwelling Houses, &c. By JAMES W. FACEY. Illustrated */o " The principles which ought to guide the decoration of dwelling-houses are clearly set forth, and elucidated by examples ; while full instructions are given to the learner." Scotsman. 2 S7 . PRACTICAL HOUSE DECORATION. A Guide to the Art of Ornamental Painting, the Arrangement of Colours in Apartments, and the Principles of Decorative Design. By JAMES W. FACEY .... 2/6 %* Nos. 229 and 257 in One handsome Vol., half-bound, entitled " HOUSE DECORA- TION, ELEMENTARY AND PRACTICAL, "price $s. 23 0. A PRACTICAL TREATISE ON HANDRAILING ; Showing New and Simple Method?. By GEO. COLLINGS. Second Edition. Revised, including a TREATISE ON STAIRBUILDING. With Plates . 2/6 "Will be found of practical utility in the execution of this difficult branch of joinery." Builder. 247. BUILDING ESTATES: A Treatise on the Development, Sale, Purchase, and Management of Building Land. By F. MAITLAND. Second Edition, revised 2/0 "This book should undoubtedly be added to the library of every professional man dealing with building \m&."-Land Agent's Record. 248. PORTLAND CEMENT FOR USERS. By HENRY FAIJA, A.M. Inst. C.E. Third Edition, Corrected a/o "Supplies in a small compass all that is necessary to be known by users of cement." Building News. 252. BRICKWORK : A Practical Treatise, embodying the General and Higher Principles of Bricklaying, Cutting and Setting ; with the Applica- tion of Geometry to Roof Tiling, &c. By F. WALKER 1/6 " Contains all that a young tradesman or student needs to learn from books." Building News. 259. GAS FITTING : A Practical Handbook. By JOHN BLACK. Second Edition, Enlarged. With 130 Illustrations a/6J "Contains all the requisite information for the successful fitting of houses with a gas service, &c. It is written in a simple practical style, and we heartily recommend it. ' Plumber and Decorator. ts- The J indicates that these vols. may be had strongly bound at 6d. extra. 56 CROSBY LOCKWOOD & SON'S CATALOGUE. Architecture, Building, etc., continued. 23. | THE PRACTICAL BRICK AND TILE BOOK. Com- 189.^ prising: BRICK AND TILE MAKING, by E. DOBSON, A.I.C.E.; Practical 252. 1 BRICKLAYING, by A. HAMMOND ; BRICKWORK, by F. WALKER. 550 pp. ' with 270 Illustrations, strongly half-bound ....... 6/0 25 8. CIRCULAR WORK IN CARPENTR Y AND fOINER Y. A Practical Treatise on Circular Work of Single and Double Curvature. By GEORGE COLLINGS. Second Edition 2/6 " Cheap in price, clear in definition, and practical in the examples selected." Builder. 261. SHORING, and Its Application : A Handbook for the Use of Students. By GEORGE H. BLAGROVE. With 31 Illustrations . . .1/6 " We recommend trrs valuable treatise to all students." Building News. 265. THE ART OF PRACTICAL BRICK CUTTING AND SETTING. By ADAM HAMMOND. With 90 Engravings . . . .1/6 267- THE SCIENCE OF BUILDING: An Elementary Trea- tise on the Principles of Construction. By E. WYNDHAM TARN, M.A. Lond. Third Edition, revised and enlarged ....... 3/6J 271. VENTILATION: A Text Book to the Practice of the Art of Ventilatmg Buildings. By W. P. BUCHAN, R. P., Author of " Plumbing," &c. With 170 Illustrations 3/6J 272. ROOF CARPENTRY; Practical Lessons in the Framing of Wood Roofs. For the Use of Working Carpenters. By GEO. COLLINGS, Author of " Handrailing and Stairbuilding," &c. ........ 2/- 2 ,3. THE PRACTICAL PLASTERER: A Compendium of Plain and Ornamental Plaster Work. By WILFRED KEMP 2/- SHIPBUILDING, NAVIGATION, etc. 5I NAVAL ARCHITECTURE: An Exposition of the Elemen- tary Principles. ByjAMES PEAKE, H.M. Dockyard, Portsmouth . . 3/6J S3 .. SHIPS FOR O CEAN AND RIVER SERVICE, Elementary and Practical Principles of the Construction of. By HAKON A. SOMMERFELDT. 1/6 K**.AN ATLAS OF ENGRAVINGS to Illustrate the above. Twelve large folding Plates. Royal 410, cloth . . . . * . . . 7/6 54 . MASTING, MAST-MAKING, AND RIGGING OF SHIPS. Also Tables of Spars, Rigging, Blocks ; Chain, Wire, and Hemp Ropes, &c., relative to every class of vessels. By ROBERT KIPPING, N.A. 2/0 S4 v IRON SHIP-BUILDING. With Practical Examples and Details. By JOHN GRANTHAM. Fifth Edition 4/0 55 . THE SAILOR'S SEA BOOK: A Rudimentary Treatise on Navigation. By JAMES GREENWOOD, B.A. With numerous Woodcuts and Coloured Plates. New and enlarged Edition. By W. H. ROSSER . 2/6J " Is perhaps the best and simplest epitome of navigation ever compiled. Field. 55 PRACTICAL NAVIGATION. Consisting of THE SAILOR'S & SEA-BOOK, by JAMES GREENWOOD and W. H. ROSSER ; together with 204. Mathematical and Nautical Tables for the Working of the Problems, by HENRY LAW, C.E. , and Prof, J. R. YOUNG. Half-bound in leather . . 7/0 " A vast amount of information is contained in this volume, and we fancy in a very short time that it will be seen in the library of almost everv ship or yacht afloat." Hunts Yachting Magazine. 80. MARINE ENGINES AND STEAM VESSELS. By R. MURRAY, C.E. Eighth Edition, thoroughly Revised, with Additions by the Author and by GEORGE CARLISLE, C.E 4/6J "An indispensable manual for the student of marine engineering." Liverpool Mercury. stfis. THE FORMS OF SHIPS AND BOATS. By W. BLAND. Seventh Edition, revised, with numerous Illustrations and Models . . . 1/6 99 . NAVIGATION AND NAUTICAL ASTRONOMY, in Theory and Practice. By Prof. J. R. YOUNG. New Edition. Illustrated . 2/6 " A very complete, thorough, and useful manual for the young navigator " Observatory. ro 6. SHIPS' ANCHORS, a Treatise on. By GEORGE COTSELL. x /6 I49 . SAILS AND SAIL-MAKING. With Draughting, and the Centre of Effort of the Sails. Also, Weights and Sizes of Ropes ; Masting, Rigging, and Sails of Steam Vessels, &c. By ROBERT KIPPING, N.A. . 2/6 J 1SS THE ENGINEER'S GUIDE TO THE ROYAL AND MERCANTILE NA VIES. By a PRACTICAL ENGINEER. Revised by D. F. M'CARTffY, late of the Ordnance Survey Office. Southampton . . 3/0 "^s- The J indicates that these vols. may be had strongly bound at 6d. extra. 4LESS RUDIMENTARY SERIES. 57 AGRICULTURE, GARDENING, etc 6I *' A SMPLETE READY RECKONER FOR THE AD- and extended by C. NORRIS, Surveyor, ValuerT&c." '"' a/o book to all who have land to measure."-;)/^ Lane Express. sons having any connection with land." Irish Farm. MERCHANT'S, AND FARMER'S RECKONER. Second Edition, revised, with a Price List of Modern Flour Mill Machinery, by W. S HUTTON C E 2 / o ng has been ' ' MANURES, AND CROPS. (Vol. I. OUTLINES OF MODERN FARMING.) By R. SCOTT BURN. Woodcuts ..... 2/0 141. FARMING AND FARMING ECONOMY, Historical and Practical. (Vol. II. OUTLINES OF MODERN FARMING.) By R. SCOTT BURN 3/0 treats E r e L n r e e n? 't y h CaI ?Hfi te H d l , enli . ghten th f e agricultural community on the varied subjects of which it treats , hence it should find a place in every farmer s libraiy." City Press. 142. STOCK; CATTLE, SHEEP, AND HORSES. (Vol.111. OUTLINES OF MODERN FARMING.) By R. SCOTT BURN. Woodcuts. 2/6 mendThi^^ ' ' ' Weco - 1 45 . DAIRY, PIGS, AND POULTRY. (Vol. IV. OUTLINES OF MODERN FARMING.) By R. SCOTT BURN. Woodcuts . . . .2/0 best'IuThorfdes" ^'^ ^ r . ness and intelli S ibilit y ofthe m aer, which has been compiled from the 14 6. UTILIZATION OF SEWAGE, IRRIGATION, AND RECLAMATION OF WASTE LAND. (Vol. V. OUTLINES OF MODERN FARMING.) By R. SCOTT BURN. Woodcuts ...... 2/6 " A work containing valuable information, which will recommend itself to all interested in modern farming." Field. A OUTLINES OF MODERN FARMING. By R. SCOTT BURN, Author of "Landed Estates Management," "Farm Management," and Editor of "The Complete Grazier." Consisting of the above Five 146. Volumes in One, 1,250 pp., profusely Illustrated, half-bound . . . .12/0 ".The aim of the author has been to make his work at once comprehensive and trustworthy, and in this aim he has succeeded to a degree which entitles him to much credit." Morning Advertiser. Should find a place in every farmer's library." City Press. No farmer should be without it." Banbury Guardian. i 77 . FRUIT TREES, The Scientific and Profitable Culture of. From the French of M. Du BREUIL. Fourth Edition, carefully Revised by GEORGE GLENNY. With 187 Woodcuts ........ 3/6J "The book teaches how to prune and train fruit trees to perfection." Field. i 9 8. SHEEP: The History, Structure, Economy, and Diseases of. By W. C. SPOONER, M.R.V.C., &c. Fifth Edition, with fine Engravings, including Specimens of New and Improved Breeds. 366 pp ..... 3/6J " The book is decidedly the best of the kind in our language." Scotsman. 2 oi. KITCHEN GARDENING MADE EASY. Showing the best means of Cultivating every known Vegetable and Herb, &c., with direc- tions for management all the year round. ByGEO. M. F. GLENNY. Illustrated i/6J "This book will be found trustworthy and useful." North British Agriculturist. 207. OUTLINES OF FARM MANAGEMENT. Treating of the General Work of the Farm ; Stock ; Contract Work ; Labour, &c. By R. SCOTT BURN, Author of "Outlines of Modern Farming," &c. . . . 2/6J " The book is eminently practical, and may be studied with advantage by beginners in agriculture, while it contains hints which will be useful to old and successful farmers." Scotsman. 2o8 . UTLINES OF LANDED ESTA TES MANA GEMENT: Treating of the Varieties of Lands, Methods of Farming, the Setting-out of Farms, &c. ; Roads, Fences, Gates, Irrigation, Drainage, &c. By R. S. BURN. 2/6J " A complete and comprehensive outline of the duties appertaining to the management of landed estates." ^oumai of Forestry. %* Nos. 207 6 208 in One Vol., handsomely half-bound, entitled " OUTLINES OF LANDED ESTATES AND FARM MANAGEMENT.'" By ROBERT SCOTT BURN. Price 6s. 13*" The 1 indicates that these vols. may be had strongly bound at 6d. extra. 58 CROSBY LOCKWOOD & SON'S CATALOGUE. Agriculture, Gardening, etc., continued. 209. THE TREE PLANTER AND PLANT PROPAGATOR : With numerous Illustrations of Grafting, Layering, Budding, Implements, Houses, Pits, &c. By S. WOOD, Author of "Good Gardening," &c. . . 2/0 "Sound in its teaching and very comprehensive in its aim. It is a good book." Gardeners' Magazine. "The instructions are thoroughly practical and correct." North British Agriculturist. 210 . THE TREE PRUNER: Being a Practical Manual on the Pruning of Fruit Trees, including also their Training and Renovation, also treating of the Pruning of Shrubs. Climbers and Flowering Plants. With numerous Illustrations. By SAMUEL WOOD, Author of " Good Gardening," &c. 1/6 " A useful book, written by one who has had great experience." Mark Lane Express. " We recommend this treatise very highly."- North British Agriculturist. *,* Nos. 209 6* 210 in One Vol., handsomely half-bound, entitled " THE TREE PLANTER, PROPAGATOR AND PRUNER." By SAMUEL WOOD. Price 35. 6d. 2I8 . THE HAY AND STRAW MEASURER: New Tables for the Use of Auctioneers, Valuers, Farmers, Hay and Straw Dealers, &c., forming a complete Calculator and Ready Reckoner. By JOHN STEELE .2/0 "A most useful handbook. It should be in every professional office where agricultural valuations are conducted." Land Agent's Record. 231 . THE ART OF GRAFTING AND BUDDING. By CHARLES BALTET. With Illustrations 2/6J "The one standard work on this subject." Scotsman. 23 2. COTTAGE GARDENING; or, Flowers, Fruits, and Vege- tables for Small Gardens. By E. HOBDAY 1/6 " Definite instructions as to the cultivation of small gardens." Scotsman. "Contains much useful information at a small charge." Glasgow Herald. 2 33 . GARDEN RECEIPTS. Edited by CHARLES W. QUIN. 1/6 "A singularly complete collection of the principal receipts needed by gardeners." Fanner. "A useful and handy book, containing a good deal of valuable information." Athenaeum. 234 . MARKET AND KITCHEN GARDENING. - By C. W. SHAW, late Editor of "Gardening Illustrated" 3/oJ " The most valuable compendium of kitchen and market-garden work published." Farmer. " A most comprehensive volume on market and kitchen-gardening." Mark Lane Express. 239 . DRAINING AND EMBANKING. A Practical Treatise. By JOHN SCOTT, late Professor of Agriculture and Rural Economy at the Royal Agricultural College, Cirencester. With 68 Illustrations . . . . 1/6 "A valuable handbook to the engineer, as well as to the surveyor." Land. "This volume should be perused by all interested in this important branch of estate improvement." Land Agent's Record. 240. IRRIGATION AND WATER SUPPLY : A Practical Trea- tise on Water Meadows, Sewage Irrigation, Warping, &c. ; on the Construc- tion of Wells, Ponds and Reservoirs, &c. By Prof. J. SCOTT. With 34 Illusts. 1/6 "A valuable and indispensable book for the estate manager and owner." Forestry. "Well worth the study of all farmers and landed proprietors.' 1 Building News. 241 . FARM ROADS, FENCES, AND GATES: A Practical Treatise on the Roads, Tramways, and Waterways of the Farm ; the Prin- ciples of Enclosures ; and the different kinds of Fences, Gates, and Stiles. By Professor JOHN SCOTT. With 75 Illustrations 1/6 " Mr. Scott's treatise will be welcomed as a concisely compiled handbook." Building News. "A useful practical work, which should be in the hands of every farmer." Farmer. 242. FARM BUILDINGS. A Practical Treatise on the Buildings necessary for various kinds of Farms, their Arrangement and Construction, with Plans and Estimates. By Prof. JOHN SCOTT. With 105 Illustrations . 2/0 " No one who is called upon to design farm-buildings can afford to be without this work." Builder "This book ought to be in the hands of every landowner and agent." Kelso Chronicle. 243 . BARN IMPLEMENTS AND MACHINES. Treating of the Application of Power to the Operations of Agriculture; and of the various Machines used in the Threshing-barn, in the Stock-yard, Dairy, &c. By Professor JOHN SCOTT. With 123 Illustrations 2/0 1^" The 1 indicates that these vols. may be had strongly bound at 6d. extra. WEALED RUDIMENTARY SERIES. 59 Agriculture, Gardening, etc., continued. 244- FIELD IMPLEMENTS AND MACHINES: With Prin - , * c wSh^^S^ 6 ' their Manage - 2/0 245- AGRICULTURAL SURVEYING: A Treatise on Land Surveymg, Levelling, and Setting-out ; with Directions for Valuing and Re- porting on Farms and Estates. By Prof. J. SCOTT. With 62 Illustrations 1/6 *yj.\FARM ENGINEERING : By Professor JOHN SCOTT. Com- 245- ) HaTfSun^ 150 ^ SeV6n V lumes in One ' * Z 5 P a S es - and over 600 Illustrations. -l ( S l 25& red " p in very library where th<; own " ther ' eof is in any 250. MEAT PRODUCTION: A Manual for Producers, Distribu- ' , . > A compac uc tors> and Consumers of Butchers' Meat. By JOHN EWART mpact and handy volume on the meat question. "Meat and Provisi ;ian Trades' Review. a/6 ny voume on te meat queston. Meat and Provision Trades' Revie 266. BOOK-KEEPING FOR FARMERS AND ESTATE OWNERS. A Practical Treatise, presenting, in Three Plans, a System , , , eS f FarmS< By J' M ' WoODMAN - Charterea Accountant. tion, revised ........... 2/5 %* The above in cloth boards, strongly bound, y. 6d. Will be found of great assistance by those who intend to commence a system of book-keeping, the author s examples being clear and explicit, and his explanations full and accurate." Live Stock Journal. MATHEMATICS, ARITHMETIC, etc. 32. MATHEMATICAL INSTRUMENTS, a Treatise on ; Their Construction, Adjustment, Testing, and Use concisely Explained. By J. F. HEATHER, M.A., of the Royal Military Academy, Woolwich. Fourteenth Edition, Revised, with Additions, by A. f . WALMISLEY. M.I.C.E., Fellow of the Surveyors' Institution. Original Edition, in i vol., Illustrated . . . 2/oJ %* In ordering the above, be careful to say " Original Edition," or give the number in the Series (32), to distinguish it from the Enlarged Edition in 3 vols. fA'os.ibS-g-joJ. 7 6. DESCRIPTIVE GEOMETR Y, an Elementary Treatise on ; with a Theory of Shadows and of Perspective, extracted from the French of G. MONGE. To which is added a Description of the Principles and Practice of Isometrical Projection. By J. F. HEATHER, M. A. With 14 Plates .2/0 78. PRACTICAL PLANE GEOMETRY: giving the Simplest Modes of Constructing Figures contained in one Plane and Geometrical Con- struction of the Ground. By J. F. HEATHER, M.A. With 215 Woodcuts . 2/0 "The author is well-known as an experienced professor, and the volume contains as complete a collection of problems as is likely to be required in ordinary practice." A rchitect. 8 3 . COMMERCIAL BOOK-KEEPING. With Commercial Phrases and Forms in English, French, Italian, and German. By JAMES HADDON, M.A., formerly Mathematical Master, King's College School . 1/6 8 4 . ARITHMETIC, a Rudimentary Treatise on : with full Expla- nations of its Theoretical Principles, and numerous Examples for Practice. For the Use of Schools and for Self-Instruction. By J. R. YOUNG, late Professor of Mathematics in Belfast College. Eleventh Edition . . r/6 zf.A KEY TO THE ABOVE. By J. R. YOUNG . . . r /6 8 5 . EQUATIONAL ARITHMETIC, applied to Questions of Interest, Annuities, Life Assurance, and General Commerce ; with various Tables by which all Calculations may be greatly facilitated. By W. HiPSLEY. 2/0 86. ALGEBRA, the Elements of. By JAMES HADDON, M.A., formerly Mathematical Master of King's College School. With Appendix, containing Miscellaneous Investigations, and a collection of Problems . 2/0 86*. A KEY AND COMPANION TO THE ABOVE. An extensive repository of Solved Examples and Problems in Illustration of the various Expedients necessary in Algebraical Operations. By J. R. YOUNG. 88. EUCLID, THE ELEMENTS OF: with many Additional Proposi- & tions and Explanatory Notes ; to which is prefixed an Introductory Essay on 89. Logic. By HENRY LAW, C.E .......... 2/6 *** Sold also separately, viz. : 88. EUCLID, The First Three Books. By HENRY LAW, C.E. . - .,''' . 1/6 89. EIJCLTD. Books 4. 5, 6, it, 12. By HENRY LAW. C.E. . . . . t/6 IS- The J indicates that these vols. may be had strongly bound a 6d. extra. 60 CROSBY LOCKWOOD 6" SON'S CATALOGUE. Mathematics, Arithmetic, etc., continued. go. ANALYTICAL GEOMETRY AND CONIC SEC- TIONS, a Rudimentary Treatise on. By JAMES HANN. A New Edition, re-written and enlarged by Professor J. R. YOUNG a/oj " The author's style is exceedingly clear and simple, and the book is well adapted for the beginner and those who may be obliged to have recourse to self-tuition.' 1 Engineer. 9 i. PLANE TRIGONOMETRY, the Elements of. By JAMES HANN, formerly Mathematical Master of King's College, London . . 1/6 9a . SPHERICAL TRIGONOMETRY, the Elements of. By JAMES HANN. Revised by CHARLES H. DOWLING, C.E i/o *** Or with " The Elements of Plane Trigonometry," in One Volume, 2s. 6d. 93 . MENSURATION AND MEASURING, for Students and Practical Use. With the Mensuration and Levelling of Land for the purposes of Modern Engineering. By T. BAKEK, C.E. New Ed. by E. NUGENT, C.E. 1/6 ,01. DIFFERENTIAL CALCULUS, Elements of the. ByW.S.B. WOOLHOUSE, F.R.A.S., &C 1/6 I02 . INTEGRAL CALCULUS. By HOMERSHAM Cox, B.A. . i/ X3 6. ARITHMETIC, Rudimentary, for the Use of Schools and Self- instruction. By JAMES HADDON, M.A. Revised by ABRAHAM AKMAN . 1/6 I37 . A KEY TO THE ABOVE. By A. ARMAN . . . .1/5 ,68. DRA WING AND MEASURING INSTRUMENTS. In- eluding I. Instruments employed in Geometrical and Mechanical Drawing, and in the Construction, Copying, and Measurement of Maps and Plans. II. Instruments used for the purposes of Accurate Measurement, and for Arithmetical Computations. By J. F. HEATHER, M.A 1/6 " Valuable and instructive to all whose occupations require exceptional accuracy in measurements." -Jeweller and Metal Worker. l69 . OPTICAL INSTRUMENTS. Including (more especially) Telescopes, Microscopes, and Apparatus for producing copies of Maps and Plans by Photography. By J. F. HEATHER, M.A. Illustrated . . .1/6 " An excellent treatise." British Journal of Photography . , 7 o. SURVEYING & ASTRONOMICAL INSTRUMENTS. Including I. Instruments used for Determining the Geometrical Features of a portion of Ground. II. Instruments employed in Astronomical Observa- tions. By J. F. HEATHER, M.A. Illustrated 1/6 " A good, sensible, useful book." School Board Chronicle. * \* The above three volumes form an enlargement of the Author s original work, ' ' Mathematical Instruments " : price 2s. (See No. 32 in the Series. ) \ MATHEMATICAL INSTRUMENTS: Their Construction, 168. I Adjustment, Testing and Use. Comprising Drawing, Measuring, Optical, 169. V Surveying, and Astronomical Instruments. By J. F. HEATHER, M.A. 170. Enlarged Edition, for the most part entirely re-written. The Three Parts ' as above, in One thick Volume 4/6J " An exhaustive treatise, belonging to the well-known Weale's Series. Mr. Heather's experience well qualifies him for the task he has so ably fulfilled." Engineei ing and Building Times. , S 8. THE SLIDE RULE, AND HOW TO USE IT. Con- taining full, easy, and simple Instructions to perform all Business Calculations with unexampled rapidity and accuracy. By CHARLES HOARE, C.E. With a Slide Rule, in tuck of cover. Fifth Edition 2/6 J 19 6. THEORY OF COMPOUND INTEREST AND ANNUI- TIES ; with Tables of Logarithms for the more Difficult Computations of Interest, Discount, Annuities, &c., in all their Applications and Uses for Mer- cantile and State Purposes. By FEDOR THOMAN, of the Socie"te" Credit Mobilier, Paris. Fourth Edition, carefully revised and corrected . . 4/0 " A very powerful work, and the author has a very remarkable command of his subject." Professor A de MORGAN. " We recommend it to the notice of actuaries and accountants." Atheneeum. The { indicates that these vols. may be had strongly bound at 6d. extra. _J WE ALE'S RUDIMENTARY SERIES. 6l Mathematics, Arithmetic, etc., continued 199. THE COMPENDIOUS CALCULATOR (Intuitive Calcu- *")/ Of. Easy and Concise Methods of Performing the various Arith- metical Operations required in Commercial and Business Transition.* together with Useful Tables. &c. By DANIEL O'GoRMAN. Twenty-seventh Edition, carefully revised by C. NORRIS ..... y sevenl a/fi *** The above strongly half-bound, price y. 6d 204 . MATHEMATICAL TABLES, for Trigonometrical, Astro- nomical and Nautical Calculations ; to which is prefixed a Treatise on Logarithms. By H. LAW, C.E. Together with a Series of Tables for Navi- gation and Nautical Astronomy. By Professor J. R. YOUNG. New Edition 4/0 204.' LOGARITHMS. With Mathematical Tables for Trigonome- trical, Astronomical, and Nautical Calculations. By HENRY LAW, C.E. Revised Edition. (Forming part of the above work.) . ' Q/ O 221. MEASURES, WEIGHTS, AND MONEYS OF ALL NA TIONS, and an Analysis of the Christian, Hebrew, and Mahometan Calendars. By W. S. B. WOOLHOUSE, F.R.A.S., F.S.S. Seventh Edition, a/6J "A work necessary for every mercantile office." Building Trades Journal. 227. A TREATISE ON MATHEMATICS, as applied to the Constructive Arts. By FRANCIS CAMPIN, C.E., &c. Second Edition . . a/o! Should be m the hands of everyone connected with building construction." /7 u M -R- LB - A - Additions by C. TOMLINSON, F.R.S. Illust.' 3 /ot 1 he best handbook on the subject. We can safely recommend it as a good investment." Builder 67. CLOCKS AND WATCHES, AND BELLS, a Rudimentary Treatise on. By Sir EDMUND BECKETT, Bart. Q.C. Seventh Edition. . 4/6 *** The above handsomely bound, cloth boards, $s. 6d. *t. ," Thebes ^ work on Ae subject probably extant. The treatise on bells is undoubtedly the best in the \?*&."-En S ineering. < The only modern treatise on clock-making. "-Horological Journal 8 3 *#. CONSTRUCTION OF DOOR LOCKS. From the Papers of A. C. HOBBS. Edited by CHARLES TOMLINSON, F.R.S. With a Note upon IRON SAFES by ROBERT MALLET. Illustrated ..... 2 /6 162. THE BRASS FOUNDER'S MANUAL: Instructions for Modelling, Pattern Making, Moulding, Turning, &c. By W. GRAHAM. . 2/oJ 205. THE ART OF LETTER PAINTING MADE EASY. By JAMES GREIG BADENOCH. With 12 full-page Engravings of Examples . 1/6 " Any intelligent lad who fails to turn out decent work after studying this system, has mistaken his vocation." English Mechanic. 215. THE GOLDSMITH'S HANDBOOK, containing full In- structions in the Art of Alloying, Melting, Reducing, Colouring, Collecting and Refining. The processes of Manipulation, Recovery of Waste, Chemical and Physical Properties of Gold ; Solders, Enamels and other useful Rules and Recipes, &c. By GEORGE E. GEE. Third Edition, considerably enlarged . 3/0 J "A good, sound, technical educator." Horological Journal. "A standard boo-k, which few will care to be without." Jeweller and Metal-worker. 225. THE SILVERSMITH'S HANDBOOK, on the same plan as the above. By GEORGE E. GEE. Second Edition, Revised . . . 3/0 J "A valuable sequel to the author's ' Practical Goldworker.'" Silversmith's Trade Journal. " As a guide to workmen it will prove a good technical educator." Glasgow Herald. %* The two preceding Works, in One handsome Vol., half-boiind, entitled " THE GOLDSMITH'S AND SILVERSMITH'S COMPLETE HANDBOOK," 75. a49 . THE HALL-MARKING OF JEWELLERY. Compris- ing an account of all the different Assay Towns of the United Kingdom ; with the Stamps at present employed ; also the Laws relating to the Standards and Hall-Marks at the various Assay Offices. By GEORGE E. GEE . . . 3/0 J "Deals thoroughly with its subject from a manufacturer's and dealer's point of \\evi." Jeweller. " A valuable and trustworthy guide." English Mechanic. 224 . COACH-BUILDING: A Practical Treatise, Historical and Descriptive. By JAMES W. BURGESS. With 57 Illustrations . . . 2/6 J is particularl oach-build 2 35 . PRACTICAL ORGAN BUILDING. By W. E. DICKSON, M.A., Precentor of Ely Cathedral. Second Edition, Revised, with Additions. 2/6} "The amateur builder will find in this book all that is necessary to enable him personally to con- struct a perfect organ with his own hands." Academy. "The best work on the subject that has yet appeared in book form." English Mechanic. 262. THE ART OF BOOT AND SHOEMAKING, including Measurement, Last-fitting, Cutting-out, Closing and Making ; with a Descrip- tion of the most Approved Machinery employed. By JOHN BEDFORD LENO, late Editor of" St. Crispin " and " The Boot and Shoemaker." With numerous Illustrations. Third Edition .......... 2/oJ "This excellent treatise is by far the best work ever written on the subject. The chapter on clicking. which shows how waste may be prevented, will save fifty times the price of the book." Scottish Leather. Trader. 2 6 3 . MECHANICAL DENTISTRY: A Practical Treatise on the Construction of the Various Kinds of Artificial Dentures, comprising also Useful Formulas, Tables and Receipts for Gold Plate, Clasps, Solders, &c. By CHARLES HUNTER. Third Edition, revised, with additions . . . 3/oJ "We can strongly recommend Mr. Hunter's treatise to all students preparing for the profession of dentistry, as well as to every mechanical dentist." Dublin Journal of Medical Science. 270. WOOD ENGRA VING : A Practical and Easy Introduction to the Study of the Art. By W. N. BROWN ....... 1/6 K3- The % indicates that these vols. may be had strongly bound at fid. extra. This handbook will supply a long-felt want, not only to manufacturers themselves, but more arly apprentices and others whose occupations may be in any way connected with the trade of coach-building. " European Mail. 64 WE ALE'S RUDIMENTARY SERIES. MISCELLANEOUS VOLUMES. 3 6. A DICTIONARY OF TERMS used in ARCHITECTURE, BUILDING, ENGINEERING, MINING, METALLURGY, ARCHAE- OLOGY, the FINE ARTS, &c. By JOHN WEALE. Sixth Edition. Edited by ROBT. HUNT, F.R.S., Keeper of Mining Records, Editor of " Ure's Dictionary." Numerous Illustrations S/o %* The above, strongly bound in cloth boards, price 6s. "The best small technological dictionary in the language." Architect. "The absolute accuracy of a work of this character can only be judged of after extensive consultation and from our examination it appears very correct and very complete." Mining "Journal. " There is no need now to speak of the excellence of this work ; it received the approval of the com- munity long ago. Edited now by Mr Robert Hunt, and published in a cheap, handy form, it will be of the utmost service as a book of reference scarcely to be exceeded in value." Scotsman. so . THE LAW OF CONTRACTS FOR WORKS AND SERVICES. By DAVID GIBBONS. Fourth Edition, with Appendix of Statutes by T. F. 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A Manual of Home and Personal Hygiene. By the Rev. JAMES BAIRD, B.A i/o "The author gives sound instructions for the preservation of health. " --Athenceum. " It is wonderfully reliable, it is written with excellent taste, and there is instruction crowded into every page." English Mechanic. IS0 . LOGIC, Pure and Applied. By S. H. EMMENS. Third Edition i/e " This admirable work should be a text-book not only for schools, students and philosophers, for all literateurs and men of science, but for those concerned in the practical affairs of life, &c." The News. IS3 . SELECTIONS FROM LOCKE'S ESSAYS ON THE HUMAN UNDERSTANDING. With Notes by S. H. EMMENS . . 1/6 I34 . GENERAL HINTS TO EMIGRANTS. Containing No- tices of the various Fields for Emigration. With Hints on Preparation for Emigrating, Outfits, &c., Useful Recipes, Map of the World, &c. . . 2/0 IS7 . THE EMIGRANT'S GUIDE TO NATAL. By ROBERT JAMES MANN, F.R.A.S., F.M.S. Second Edition, revised. 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THE HOUSE MANAGER. ti2 1 By an OLD HOUSEKEEPER. II. DOMESTIC MEDICINE. By RALPH GOODING, & f M.D. III. MANAGEMENT OF HEALTH. By JAMES BAIRD. In One Vol., 112*. ' strongly half-bound 6/0 The J indicates that these vols. may be had strongly bound at 6d. extra. UNIVERSITY OF CALIFORNIA AT LOS ANGELES THE UNIVERSITY LIBRARY This book is DUE on the last date stamped below JAN Form L-9-20m-8,'37 DC SOUTHERN REGIONAL LIBRARY FAPIl ITV illllllllllllil AA 000482112 o