Class Book diSI COPYRIGHT DEPOSHV > a S3 . o B » |§, tp 2 *-• iS • CO sui 03 — ec S S o Q. c 8 a z 1-H c^ 2 I .2 .S ^ fe Tiij / 6- SJ 3- c 1915 EDITION THE MECHANICS' COMPLETE LIBRARY OF MODERN RULES, FACTS PROCESSES, ETC. j^'acts About Electricity — How to Make and Run Dynamos — All About Batteries, Telephones, Electric Railways and Lighting — Engineering Explained — Rules for the In- struction of Engineers, Firemen, Machinists, Mechan- ics, Artisans and all Craftsmen — Tables of Alloy — Useful Recipes — Information Concerning Glass, Metal, Wood Working, Leather, Arti- ficial Ice-making, Chemical Experiments — Glossary of Technical Terms — Electric, Oxy-acetylene and Russian Welding. FIVE BOOKS IN ONE COMPILED BY Thomas F. Edison, A. IVK^, and Charles J. Westinghouse II Copyright, 1915, by Laird & Lee, Inc. Copyright, 1900, by Wm. H. Lee. Copyright, 1890, 1895, by Laird & Lee. CHICAGO Laird & Lee, Inc., Publishers riechanical Works , \ THAT ARE \; RECOGNIZED AS AUTHORITIES k tevens' Mechanical Catechism. An entirely new and original work for stationary and marine engi- neers, machinists, firemen, and mechanics generally. 250 illustra- tions. Fully describes machinery and tools, construction an# operation of machines, etc.. etc. Substantially bound, Cloth, $1.00% Morocco, marbled edges, $1.50. Kilbarn'g Standard Handbook for Kailroad Men. Illustrated. Questions and Answers on all points referring to R. R Engines, Automatic Air Brakes, Link Motion, Injector Practice Br«akdowns, Signals, etc. Keratol binding, with pocket, $1.00. The Motorman's Guide. By J. W. Gayetty. Illustrated. Everything a motorman should know about the care and running of his car. Flexible cloth, red edges, 50c. E^ng^ineers' Practical Test and Reference Book. For Engineers, Mechanics, Machinists, Firemen, etc. Boilers and Engines and how to make them; Engineer's License, Examination Questions and Answers. Stiff silk cloth, red edges, $1.00. The Mechanical Arts Simplified. 497 pages. Arranged and edited by D. B. Dixon. New improved edition. Illustrated. A thor- ough and original book of reference for Architects, Iron Workers, Boiler Makers, Contractors, Civil and Mechanical Engineers, Fire- men, etc. Silk cloth, $1.50. Flexible leather, $^.50. IThe Machinists' and Engineers' Pocket Manual. An exhaustive treatise on Gear, Valve and Indicator Practice. Vocabu- lary of 2,000 mechanical and electrical words. How to connect Dynamos and Motors; Shafting Drills, Wire Weights and Resistances, Screw Gutting, Properties of Saturated Steam, Fractions, etc., etc. Illustrated with mechanical sketches and diagrams. Leather, stained edges, gold stamped title, pocket, flap ana button clasp, $1.00* The Mechanics* Complete Liibrary. 676 pages. Illustrated. Five books in one. Mechanics in a nutsheNs. Statistics of all kinds. Rules, Processes, Tables, Curious Facts. Greatest buildings described. Glossary of technical terms. How to make Batteries, etc., etc. Stiff silk cloth, red edges, $1.00; Morocco, marbled edges, $1.50. Zivicker's Revised Instructor. For Artisans, Fire, Marine and Locomotive Engineers. The work of a practical mashiniet in the form of questions and answers. Stiff cloth, 75c. Practical Application of Dynamo Electric Machinery. By McFaddkn & jIay. Every Motorman, Lineman, Dynamo Tender and Engineer should have a copy. By far the best and cheapest book of iO? kind. Flexible cloth, red edges, $1.00. For sale by all booksellers and newsdealers, or sent postpaid on receipt of price by LAIRD % LEE, Publishers. CHICAGO, U. S. A. For lul) de£ 'riotions write for our illustrated catalogue. ©CI,A39iB99 FEB 12 1915 CONTENTS Accidents by Shafting, to prevent 130 Prom Running Machinery, prevention of 127-130 to boilers, how to prevent • . 147 Air Brake. Westinghouse Automatic. j9-74 Alloy, a new 284 Alloys and Solders 186 Altitude above the sea level of various places in the United States 424 Aluminum, how to solder 368 Ampere the (electrical measure) 538 Ampere's Rule 487 Analysis of Boiler Incrustations 155 Apprentices, points for 301 Architects, laws affecting 442 Etc., pointers for 420, 421 Armature, the largest 165 Artesian Wells, valuable 344 Ash Sifter, how made 382 Atmosphere; effect on bricks 437 Estimated mean pressure of the 55 Automatic Sprinklers, care of 185 Avoirdupois Weight 356 Babbitt Metal, composition of , 369 Ball, cast iron, weight of 282 How to turn a 209 Bank of England Doors, the 228 Barrels, how made 234 Basswood Moldings 445 Batteries, closed circuit (electrical); electric; galvanic; open circuit (electrical); primary (electrical); voltaic 536 Belt, the largest 216 Belting, camel's hair 289 How to calculate speed of 332 Notes on 80 Rules for Calculating Power Transmitted by 82 Benzine and its Weight 416 Bessemer Process, real inventor of 220 Blowing Off Under Pressure 152 Boiler Circumferences, points on 88 Boilers, Steam 45 Boiler Tubes, cleaning 155 Boiling 145 Bolts, weight per 100 207 Brass Castings, hard and ductile 186 Cleaning 155 Its treatment 323-325 How to lacquer , 219 Weight of sheet 196, 197 Breaking Strains of Metals ( 282 Breathing Apparatus, a new 215 Bricks, made from refuse of slate quarries 337 Number of, to construct building 439 Bronze, bow to make maL.eable 288 Building Blocks Made of Corn Cobs 445 Builders, points for 411-413 Cables, submarine, breaks in 278-282 Calcimine, how to prepare 445 Calking 314 •^ans, fiat top, size and weight 415 Cast Iron Columns 367 Cast Iron Columns, safe load for 349, 350 Cast Iron Columns, safety load 362-364 Cast Iron Columns, weight of 353, 354 Cast Iron Piles, action of sea water 210 Cast Iron Pipes, weight of 410 Cast Iron, weight per lineal foot 205 Cathedrals^ dimensions of 441 Celluloid Sheathing 135 Cement, a new 284 A reliable 446 As used in Paris 344 for Granite Monuments 394 Useful 134 Centigrade and Metric Equivalents 283 Chemical Substances, common names of 238 Chimneys, how to cure smoky 459-461 One that will draw 363 Sweating of ^ 458 Table of sizes of 90 Chinese Cash 414 China, cost of living in 367 Chisels, cold 75- 77 Circles, area of 351 Circumferences of 352 ';:)isterns, cylindrical, capacity of 292 Cylindrical, capacity per foot 365 Clock Movement, self-winding 307-310 Coal, a large lump of 297 How combustion is produced 291 Steam 151 Fields, the world's 174 Coins of Different Countries 172, 173 Colors, suggestions for 441 Combustion, spontaneous 136-139,297 Spontaneous, liable to 291 Compass— Why it varies 227 Conductors (electrical) 535 Copper, deoxidized 217 Production of 170 Tenacity and loss 336 Weight of sheet 196-197 Corliss Engine Valves, how to adjust 27 Counter-boring, Tool for , 311 Crystallized Tin Plates 373 Cubic Measure 355 Oube Roots, tables of , 107-11*" 3 Damper, oval, iow to make, 400 Deafness Caused by Electric Lights 297 Deep Soundings near Friendly Islands 414 Decimal Equivalents 187 Equivalents for inches, feet, ounces, pounds, etc... 442 Dies, metal working , 326-33 1 Dry Rot in Timber ., 429 Dynamo, the; how made and how used.. 478-531 What a Dynamo is; Faraday's Discovery 478 How to make one; the Galvanometer 479 Permanen t Magnets 481 Testing the Galvanometer 482 Experiments with one 483 Experiments with a Magnet 48& The Magnet Poles; Currents produce Magnetism. 486 Ampere's Rule 487 The First Dynamo 488 Clarke's Dynamo 489 Function of the Commutator 490 Hjorth's Dynamo , *. 492 Siemens' Armature 493 Currents not Continuous 494 Magnetism produces Heat 495 Pacinotti's Ring Armature 496 Patterns for a Dynamo .497 Pattern for Armature ..' 498 Drawing for Armature 501 Patterns for Field Magnets ..500-503 Patterns and Drawings for Standard 504 The Castings 505 Assembling the Castings 506 The Bearings 510 The Commutator ...., 513 The Driving Gear 516 Wiring the Dynamo : Wiring the Armature 51 P Wiring the Field Magnets 52'o: Attachment of Wires 52a The Brushes „ 526 Binding Screws and Connections 528 The Complete , 531 Management of the , , 532 Novel 164 Eccentric, How to set a locomotive 89 Economy in f he Use of Injectors 131 Eiffel Tower, the » 437 Elbow, to describe a pattern for a four-piece 383 Elbow Angles, table of height. 380 Electrical Measurements 538 Electricity Developed by Chemical Action 535 Simplified 533 Frictional; negative; positive 534 Voltaic and galvanic 535 Whatisit? , 535 Electric Batteries (see Batteries) 53() Experiments 536 Hand Lantern 242 Heating 20- Electric Light; largest in the world 476 Locomotive 19 Machine 535 Electro-Magnetism 486 Emery Wheels, value of 273 Engines (see Steam Engines) 23 Comparative economy of high and low speed 116 Manipulation of new 167 Triple expansion 168 Engine, Steam, use of Indicator. 30- 44 Engineers, a warning to ... 189 Pointers for 169 Valuable information for.... ..... 161 Experiment, an interesting 319 Explosion of Hot Water Boiler 391-394 Expansion of Substances by Heat 206 Eve Trough, making 379 Feed Water Heaters 84 Ferrules, how to draw 305 Figures, valuable 448 Filter, a cheap 368 Fire Grate Surface, rule for finding 47 Firemen, rules for 140 Fire Proofing Wood Work 440 Flange Joint, how to make a strong 122 Flaring Articles with Round Corners 376-379 Flaring Oval Articles, pattern for 375-376 Flash-Points of various Hydro-Carbons 277 Floor, how to make a 425 Floors, how to wax 338 Painting 430 Painting and varnishing 456 Flower Stand, a wire 385 Foaming in Boilers 144 Forests of the United States 423 French Cubic Measure 355 Square Measure 357 Weights. , 356 Friction of Water in Pipes 55 Fuel, heating powers of 211 Furnaces, facts about 461 Galvanic batteries ; galvanic electricity 536 Galvanometer, the 479-483 Gamboge, how prepared 226 Gauges, steam 146 Gear Teeth, how to prevent breaking 269 Gearing, high speed 290 Geometry, practical, for mechanics 98 Glass Cutting by Electricity 296 Glass, flexible 237 Glass, frosted 448 Glass, how to perforate 289 Glossary of Technical Terms 545 Glue for Damp Places 426 Glue, on the use of, Glue Paint for Kitchen Floors 436 Granite, polishing , 342 Graphite, in steam fitting 141 Grindstone, how to make a small 79 Quarries 344 To find weight of 42:i Gun Barrels, browning them 297 Guns, large ones made 296 Hand-hole Plates 145 Heat, amount of, required to melt wrought-iron 268 Divisions of degrees of 160 Expansion of substances by 206 Produced by Rapid Magnetization 495 -proof Paints 408 What is latent heat? 157 Heating and Ventilation 386-390 Power of Fuel 211 Steam 154 Steam m. hot water 462-464 Surface of Boilers 47 Surface, steam radiators 369 High-speed Gearing 290 Hip Bath in Two Pieces .406, 407 Horse-power, nominal, indicated, effective 142 of Steam Boilers 46^ 47 of Steam Engines 23, 130 Horses, strength of 458 Hot Water Systems 368 How to Cast a Face 284 Hudson Bay Company 344 Ice House, how to build 444 Making, artificial 174 Ice, Strength of 422 Incrustations of Steam Boiler 146 Indicator, Steam Engine 30, 42 Description 30 Method of indicating 31 Driving rigging 32 Diagrams 34 Uses of 35 Tables for 39 Taking diagrams 40 Special instructions 41 Computing horse-power 42 Injectors, economy in the use of 131 How to set up; Suggestions regarding 53 Insulators (electrical) 535 -Iron and Steel, average breaking strain 159 Making in India 275 Iron Brick . . . : 428 Castings, facts about 235 Castings, how to bronze 336 Combustibility of, proved 271 Different colors, caused by heat 305 Flat-rolled, weight by foot 198-203 How it breaks 272 in the Conoco 296 Iron, Russian slieet • . • f ^ J Nevrmef hod of bronzing 47d Painting of *JJ-J Removing rust •■• -^r Weight and areas of , rS?'} R^ Weight of sheet .-. ,...196, 19/ Isinglass, facts about ^^ Ivory Gloss, how to put on wood '^d» Japanese Lacquer for Iron Ships 295 Japanese Water Pipes • • -^-^ Lap on Slide Valves ':^5 Lathe, how to gear for screw cutting ii^ Tools for metals ]^ Lead, ancient use of ^^Y on Roofs and in Sinks ^;^i Pipes, caliber and weight o6^ Leather, making japanned ^1° Lightning Rods, uselessness of ^^f Liquid Air • , Yqq Fuel Burners ^°^ Fuel, precautions to be taken m using 41/ Hydrogen , . • ^l^ Locomotive, an experiment with a J go Eccentric, how to set a ^^ Gas for 165 Long Measure « 2 yS Lubricating without Oil 2^7 Lumber Measurement Tables * / / Machinery, care of 1|^ Magnetic Poles, north and south 4»u Magnetism 5g2 Effect on watches ° 2^2 Faraday's discovery :••••••• • \^":"'-' la- Magnetization or Demagnetization Produces Heat 49o Mahogany, value of ^^^r Malleable Iron, to tin YeV Manilla Rope Transmission ^^^ Manufactures in the United States ••••••; ^^ Mathematics, definitions and useful numbers in 91 Measures of Different Countries i^^ Measurements, electrical ^^^ Mensuration oc^ Metals, melting points of ^%% Value of Metrical and Centigrade'Equivalents 2 83 Mica, uses of ^9? Mineral Wool ikVl^i Mitering, perfect ^*^ ^g^ Miter, to describe a x%i Molders, a valuable point for.... .^ ..;.;. i'A--;-' , Monetary Units and Standard Coins of Different Coun^ (^^^ tries .....••......••.••••••••••••.•••*•*.*** -. QQ Morse Code iSX Mortar Making "Jf ' Mud Drums, pitting of ,. ^^^ '/ Nails, Ten-penny ; what a pound will do , 427 Number of, in a pound 337 Natural Gas, use of, in cupolas 284 Nickel Plating 226 To polish 374 Non-conductors (electrical) 535 Novel Drawing Instrument 403 Nuts, square number in a keg 268 Hexagon, number in keg 26i) Oak Lumber, cars of 339 'Of Course," for engineers., 26 Ohm, the (electrical) 538 Oil and Coal Buying „ 317 Old Tins no Longer Useless 371 Open Circuit Batteries (el ectrical) 53« Oval Damper, how to make 40") Oval of any Length, how to strike 385 with Square and Circle o . . 398 Paint, a durable black 407 A valuable preservative < .. . 180 Heatproof 408 Work 418 Painting Floors 430 Paper Holder, an ornamental , 386 Paper-Makers, valuable points for 417 Patterns for a Dynamo 497-505 How to mend 286 Pattern for Tapering Square Article 404 for a T Joint 402 Making, hints on , 239 Making, notes on - 318 Pavements 447 Pipes, cold water supply 431-434 Cast iron, weight of 410 Lead, caliber and weight 334 Steam, a non-conducting coating for 134 To find amount for heating buildings 434 How to thaw out frozen 126 Testsof steel 310 Plane Iron, how to sharpen a 340 Planing Machine, a novel 221 Plaster, a new wall » 446 for Moldings 457 Plastering, estimating cost of 413 Plating, gold and silver 23 Power, transmitting 136 Animal 122 Pressure, atmospheric mean 55 Primary Batteries (electrical) 536 Principles of Boiler Construction 148 Proposed Great Engineering Feat 435 Proof of the Earths Motioii , 227 Proportions for Steam Boilers 1H6 Pulleys, rule for width and diameter 82 Pumps for Supplying Boilers (see Steam Pump) 54 Pumice Stone, how made 266 8 Pattern Making, notes on 3^ 447 Pavements Pipes, cold water supply 431-434 Pipes, cast iron, weight of ^^° Pipes, lead, calioer and weight 334 Pipes, steam, a non-conducting coating for i34 Pipes, to find amount for heating buildings 434 Pipes, how to thaw out '^ Pipes, steel, tests of ^i Plane Iron, how to sharpen 34^ Planing Machines ^^' Plaster, a new wall ^"^ Plastering, estimating cost of. 4i3 Plaster for Moldings ^^57 Pointers for Success in Business • • 55^) Poles, the magnetic " * " ^° Power, transmitting by vacuum • • ^^ Pressure, atmospheric mean 55 Primary Batteries (electrical) 53 Principles of Boiler Construction ^4 Proportions for Steam Boilers *. ^^^ Proof of the Earth's Motion ^^7 Proposed Engineering Feat "^35 Pulleys, rule for width and diameter 82 Pumps (see Steam Pump) 54 Pumice Stone, how made Rails, steel ^-° Railroads, consumption of coal » 43° Railroads, electric, in Japan 325 Railroad, electric, largest in country 282 Railroad Signals ° ' ^ ^ Railway Gauges of the World ^7° Railway Transit, rapid ' • ^34 Redwood Finish ^ Reservoir, tapering, round-cornered one 4oi Rivets, boiler, number per 100-pound keg 336 _^ . , . 204 Rivets, weight ot Rock, cost of excavating - . . 42 Roof Framing, hip and valley -455 Rope, how to select ^^3 Rope, length per coil, and weight 2»» 9 Rails, steel 350 Railroads, consumption of coal 430 Railway Transit, rapid 134 Red wood Finish 446 Reservoir, tapering, round-cornered 401 Rivets, boiler, number per 100-pound keg 336 Weight of 204 Rock, cost of excavating 428 Roof Framing, hip vallej^ 455 Rope, how to select 293 Length per coil, and weight 288 Rot in Timbers, dry 429 Rule, General, for all classes of boilers 49 To determine lap on steam side slide valve 25 To find Area Steam Piston of Pumps 56 Capacity of water cylinder of pumps 56 Diameter of cylinder for required horse- power 24 Diameter pump cylinder 55 Height for discharging given quantity of water 51 Fire grate surface of boiler 47 Fire grate surface of locomotive boiler 47 Heating surface of boiler 47 Heating surf ace of locomotive boiler 47 Horse-power of boiler 46 Horse-power of locomotive boiler 47 Indicated horse-power of engines 24 Horse-power for eleva ting water 56 Quantity of water to be discharged 56 Quantity of water elevated . 55 Pressure of a column of water 54 Size orifice to discharge given quantities of water 56 Rules for Firemen 140 Rules and Regulations for Properly Wiring and Install- ing Electric Light Plants 539 Moisture danger 539 Earth danger 540 Consulting engineer 540 Conductors • 540 Sectional area 540 Accessibility 540 Insulating 540 Maximum temperature 640 Distance apart 541 Inflammable structures 541 Metallic armor 541 Joints 541 Gas and water pipes 541 Overhead conductors 541 Lightning protectors 541 Insulation resistance 542 Switches; Main switches; Switchboards 542 Construction and action 542 Insulating handles 642 Electrical fitting 642 Cut-outs; Imperative use of 543 Rope Transmission in England 4 Rot ia Timbers ._ 43 Rule to find area steam piston of pumps 56 Rules for Belting: To find length and width 80 To calculate horse-power. 82 To find width of pulley,.., 82 To find diameter of pulley , 82 To find number of revolutions. 82 Rule— To find capacity of water cylinder of pumps 56 Rule— To find diameter of cylinder for required horse-power. 24 Rule — To find diameter pump cylinder 55 Rule— General rule for all classes of boilers 49 Rule— To find height for discharging given quantity of water. "5 1 Rule— To find fire grate surface of boiler 47 Rule— To find fire grate surface of locomotive boiler 47 Rule — To find heating ^lurface boiler 4.7 Rule — To find heating surface of locomotive boiler 47 Rule— To find horse-power of boiler 46 Rule — To find horse-power locomotive boiler 47 Rule — To find indicated horse-power of engines 24 Rule— To determine lap on steam side slide valve 25 Rule — To find horse-power for elevating water 36 Rule— To find quantity of water to be discharged 56 Rule— To find quantity water elevated 55 Rule — To find pressure of a column of water , 54 Rule — To find size orifice to discharge given quantities water 56 Rule for Firemen % 140 jEUiles and Regulations for Properly Wiring and Installing Electric Light Plants 53P Moisture danger •••••••• •-••.. S99 Earth danger -• - S4o Ignorance, etc uo Consulting Kng^eer ^ S4o Conductors • 54o Sectional area 54C> AoT'^'ssibility • 54^ Insularly '>'.«. 540 Maximum teu-'>^rature 540 Distance apart •..*,.«,.• »»jf«54I Inflammable structures 541 II. Metallic armor... o »,..<,.... o.... = co„o,<. » » 541 Joints ...... o , ... o CO... o .., o ..... o . o o , . . . . 541 Gas and water pipes 541 Overhead conductors. . ................. ............ .0 ..... . 541 Lightning protectors ... = ...... 541 Insulation resistance • 542 Switches «... — 542 Construction and action. 542 Insulating handles ........... . — ... 542 Main switches. .......................... ............. 542 Switch boards ....................... ^ -....., . .... 542 Electrical fitting.... .».. ..o. ............................. . 542 Cut outs 543 Inoperative use of. ...... o ...... ^ ................ . ..... 543 Situation. .. o c ..... o c c o o o . o . c . o .. o o o .... o o ........ o . o o ,,,, . 543 Portable fittings. .... .o. <,,«>,.. o .... ....... = .....,,,, 543 Arc lamps .... ,,,0 ..<.<, 0.0 ...o o o .................. ....»,.. . 543 The dynamo .» o o.o, o ..» 00. o o . o = ......, ..... c ........ . . » . . « 544 Batteries. .... oo , .0 o,.,oo ............... ....c ....oo.. ....- 544 Maintenance .......... ...................... .... o,,,. .0, o . 544 General. .......... o.. ......,..» 544 Rust, how to remove from iron ,0=, ... ........ ....... . 222 Rust-Proof Wrapping Paper. ,.,....., .... .... ....... ..o ........ , 406 Rusty Steel, to clean. ...... 00 .....oo.o.cooo.o..ooc.o».,«=,.... 238 Safety Valves .o...,o.......o.oooooo.ooo«oo.o...... .49, 50 Safety Valve, rule for weights ......... o ...» o . .o .o o .. 00, o ....... . ng Saturated Steam, properties of, ..0..... co.,.co o...... .......... . 150 Screw Auger, inventor of .............. ....... oo. ............... . 405 Screw Ctitting, how to gear a lathe for. ....... c ............... o . <,• no Screw Drivers, an Improved ......... o ................ .......... . 229 Screw Heads, how to bury out of sight .......................... 455 Screw Making at Providence .298-300 Screw Threads, table of gears for cutting. .................. .243-264 Sea Water, action of on, cast iron piles,.... . 00 <,..oc..... ........ . 210 Watch, facts about .....000.0000........ 325 Shafting, accidents by ................ ... ... o ... o o o o o .......... . 130 Shafting, an easy way to level . . . ^ ...... o . o «« o o o .,« ....... . ..... 307 Shafting, belting at right angles .„o... .,..000004000.0000. 306 Shafting, things to remember. ....ooooo.oo.ooooeoooo.ooo. 0.0.320 321 Sheathing ce-llulold . ,^.,.o.......ooo.oooo..ooooooo.«oo.o...o.o.. ^35 Shingles, to calculate number oil. ooe.oooo...oe3ooeo»ooo.. 00.000. 44^ 12 Situation 543 Portable fittings 543 Arc lamps 543 The djl^namo 544 Batteries 544 Maintenance 544 Rust, to remove from iron 222 Rust-proof Wrapping Paper 406 Rusty Steel, to clean 238 Safety Valves 49, 51 Safety Valve, rule for weights 119 Saturated Steam, properties of 150 Saw-Mill Operated by Air 185 Screw Cutting, how to gear a lathe for 110 Driver, an improved 229 Heads, how to bury out of sight 455 Making at Providence 298-300 Threads, table of gears for cutting 243-264 Sea Water, action of, on cast iron piles 210 Shafting, accidents by 130 An easy way to level 307 Belting at right angles 306 Things to remember about 320, 321 Sheathing, celluloid 135 Shingles, to calculate number of 447 Shop Kinks, useful 395-398 Signals, railway 183 Sleepers Used by World's Railroads 409 Slide Valves 24 Setting of.. ■.... 87 Smoke, how formed. 156 Soda A.sh in Boilers 438 Solder, cold 370 Soldering 470, 472 Soutii C?.^olina Cotton Industry 13 Specific Gravity, weight and strength of metals 416 Square Measure 357 Square Roots, table of 107-110 Steam as a Cleansing Agent 1^8 An invisible gas — 126 Steam Boilers, analysis of incrustations loC Boiling 145 Blowing off under pressure 152 Care of 45 Calking 124 Cleaning tubes 155 Foaming 144 Hand-hole plates 145 Horse power of 46 How plates are proved , 179 How to prevent accidents ... 147 How to test 162 Important to those operating 147 Incrustations of 146 Kinds of 45 Law of proportions 160 \ \ Steam Boilers, Marine 47 Mistakes in designing 158 Principles of construction 148 Proportions for * 166 Rules for 47, 53 Safe working pressure flues 184 Testing plates 166 The total pressure 152 Treatment of ., 115 Tubular 47 Steam Coal 151 Steam Engine, The 23 Comparative economy high and low speed 116 Corliss valves, how to adjust 27 Expansion by lap , 25 Horse powers— actual, indicated, nominal.. '^3, 142, 143 Indicator 30, 42 Manipulation of new 102 Mean pressure in cylinder 23 Rules 23, 25 Slide valves 24 Slide valves, setting of 87 Theory of the y. . 112 Steam Fitting, use of graphite 141 for Heating 58 Gauges 146 Heating 154 Radiators, heating surface of 369 Pipes, for heating buildings 434 how to thaw out 126 Properties of saturated 150 Pumps, suggestions 54 to find diameter cylinder 55 to find quantity water elevated 55 Super-heated 146 vs. Hot Water Heating 462-464 Steel, chemical or physical tests for 212 How to anneal 223 Notes on working of 267 To clean rusty 238 Pipes, tests of 310 Punches, tempering 208 Rails, used as girders 35G Rules, how they are made 211-212 Sheet Pavements 22 Sleepers, rivetless 184 Square, how to use 372 Suggestions to workers 213 The secret of cast 274 Weight of sheet 196, 197 When hardened 139 Why hard to weld 304 Stone, natural and artificial 365 Crushing strength 365 Storage Battery, how to make one 312 Strainer, rain water 399 Strength of Materials 359-361 Switching from an Engine Cab 183 14 Submarine Cables ....o.. 278 Superheated Steam .,., 146 Surveying Measures 358 Sycamore 439 Tables:— Alloys 186 Chimneys 90 Heating surface per horse-power 48 Cube and square roots 107-110 Density of water 123 Diameters, high and low pressure Cylinders 122 Difference of time from New York 180-182 Friction of water in pipes 55 Horse-Power transmitted by belts 120, 121 Lap according to travel of slide valve 25 Length and number of tacks per pound 182 Proportions cylinder tubular boilers 48 Properties of saturated steam 150 Safe working pressure for iron boilers 153 Safety-valves, capacity of 51 Size and capacity of standard pumps 57 Saving by feed water heater 86 Specific gravity 160 Square and cube roots 107-110 Strength of belting material 83 Tacks, length and number per pound • 182 Tanks, how to calculate capacity of 335 Taps, universal, table for making 265, 266 Telephones 132 Temperature, indicated by color of flame 49 Tempering Steel Punches , 208 Testing Boiler Plates 166 Testing Exterior Stains , 444 Tests for steel, chemical or physical 212 Thermometers, how made 300 Thermometer Scales 302, 304 Thermal Unit, explanation of 155 Theory of Steam Engine 112 Things That Will Never Be Settled 293 Worth Knowing 294 Timber, a colosal stick of 457 dry rot in , 429 in favor of small 343 properties of 366 rot in 438 seasoning 435 specific gravity and strength of 417 Time, difference from New York 180-182 Tin, Modern uses of 466-468 Plate, crystallized 37 3 endless 373 Production of 170 Sizes and weights of 333 Tinning by simple immersion 434 Improved process of 469 Tool for counter-boring 311 Tools in daily use 17b, 215 lb Tools, how to anneal small 187 How to detect iron and steel 173 How to keep '229 Tracing Paper, how to make 208 Traction, influence of roads and weather 74 Trees, the annual ring in 419 Tubes, solid drawn , :224 Tu-ningor Lathe Tools for Metals 77 Underground London 22 Universal Taos 265-266 Useful Cements i;i4 Useful Numbers and Definitions 91, 315-317 Useful Receipts 374 Useful Shop Kinks 395-398 Vacuum, transmitting power by a , 136 Valuable Figures 448 Varnish, to make it adhere to metals 282 Removal of old 441 Varnishing and Painting Floors 456 Ventilation and Heating. 386-390 of Buildings 451-454 Hints on 422 Vibration how to overcome -. 185 Volt, the (electrical) 538 Voltaic Electricity 536 Wages in Two Countries 1 64 Wastes, Kitchen and Table Ill Watch as a Compass 290 Watch and Learn 216 Watches, effect of magnetism upon 230 Watch, facts about 325 Wheels, number of revolutions of 283 Water and Pumps 170 Curtain, a 23 2 Density of 123 Fresh 170 Friction of, in pipes 55 Salt , 170 Simple tests for 294 Useful information about 54 Pipes, Japanese.... 210 Weight, avoird tipois 356 of Animals 165 of Bolts per 100 207 of Copper 196,197 Cast Iron per lineal foot . 205 Cubic loct of substance 340-348 of Fuels 165 of Iron 190-203 of Rivets and Round-Headed Bolts 204 and Specific Gravity of Metals . CC^ of Sheet Brass 196, 197 of Sheet Steel 196, 197 Weights, French 356 of Metals, useful numbers for 418 i6 "Welding, Various Processes • 17, 17a, 370 Wells, artesian 344 Wesiinghouse Automatic Brake— Description 59 Air Pump 61 'I riple valve 63 Westinghouse Automatic Brake-Engineer's brake-valve 65 Pump g:overnor 67 Equalizing valve 65 IiistructioDS 69 How to apply— how to release 71 Brake power 73 Car levers , . 74 Wh^ii a day's work begins 289 Window Glass, how large cylinders are cut 344 Number of lights in a box of 50 feet 270 Wire Manufacture, new process 409 Wood, a polish for 447 A very durable 443 Preservation by lime ' 443 Woods, tensile strength of common 208 weight of 333 Wooden Beams, safe load for 345 Workshop Jottings 322 Wrapping Paper, rust-proof 406 Zinc, as a fire extinguisher 381 How to polish 424 Production of 170 COTTON INDUSTRY IN NORTH CAROLINA. In i886 this state had 8o cotton mills, 4,071 looms and 199,433 spindles. In 1894 this had increased to 156 mills, with 14,908 looms and 700,497 spindles. In 1897 has been witnessed a wonderful increase in cot- ton manufacturing, for there are now in this state 1,010 cotton mills, with 1,410 knitting machines, 24,517 looms and 1,044.835 spindles. The average daily wages paid skilled men (exclusive of machinists, engineers, firemen and superintendents) $1.11; unskilled, 66^ cents; skilled women, 67^ cents; unskilled, 46 cents, and children 34^ cents, or a general average of 65 cents a day. The prospect for a rapid extension of the cotton mill industry is excellent, for within the state are water courses with an aggregate of 3,500,000 horse-power, capable of running 140,000,000 spindles. Here is the cotton grown and its transportation to the northern mills saved by its manufacture here. The mills are in excellent condition, and some are declaring as high as 15 per cent, dividend on the capital invested. MECHANICS' COMPLETE LIBRARY ELECTRIC WELDING. The process of electrical welding consists of pressing the two pieces of metal firmly together and passing through them a heavy current of electricity at a low voltage. The metals almost immediately reach a high temperature at the point of juncture, and weld together. The heat is developed at the point of juncture and not elsewhere, for the reason that by far the largest share of the resistance is found at this point, resulting in the production of heat according to well-known electrical laws. This localization of the heat is one of the great advantages of electrical welding, as it is thus possible to make welds heretofore considered impossible — as for example, the welding of a tungsten tip on a steel spring without destroying its temper. High speed steel to low carbon steel — steel to brass or bronze — malleable iron to steel — vanadium, tungsten, nickel, and nickel-chrome steel — all these can be welded successfully by electricity. One and two throw-crank forgings are welded so as to make three, four, and six throw-crank shafts. The strength of the ordinary electric weld varies from 75 to 95 per cent of the original piece, but can easily be made to run above 1 00 per cent. Standard electric welding machines are now on the market designed for all classes of work. These machines consist primarily of clamps to hold the stock firmly together while hot, and means to provide a large volume of current at a low voltage. The current is almost universally obtained from an alternating current transformer having but one turn on the low side. The electric method of welding effects great saving in manufacturing costs where many welds of the same sort are to be made. For Russian method of welding see page 3J0, 17 I7a OXY-ACETYLENE WELDING. Autogenous welding with the oxy-acetylene flame is the process of causing two parts or pieces of the same or different metals to flow together under extreme heat in a melted state, forming one solid piece when cooled. The temperature of 6,300 degrees Fahrenheit used in this process is generated by the burning of two gases, oxygen and acetylene, in certain definite proportions. The two gases are led through tubes to the welding torch, this torch consisting of a mixing chamber and a suitable nozzle or jet at which the flame appears. Built into the torch are two valves by means of which the operator controls the mixture and, to a certain extent, the heat and action of the flame. The gases are secured from special generating machines or may be drawn from steel cylinders filled with gas under compression. Attached to the generators or cylinders are regulating valves which control the pressure of the oxygen and of the acetylene flowing into the tubes. The oxy-acetylene flame will melt practically any known material, its heat being more than twice that at which the hardest metals melt. The process is used in the manufac- ture of new articles which require seams or joints and in the repair of broken or cracked metal parts. The joint made is so perfect that it cannot be distinguished when smoothed after the weld. To prevent the formation of scale or gases at the joint during welding, materials, known as * 'scaling powders" or "fluxes," are used. Fluxes are made from borax, salt and various chemicals, the flux varying with the material to be welded. Additional metal is added to the joint by melting a sufficient quantity from a rod held by the operator, the rod and the edges to be united being made to flow simultaneously. The pieces to be welded are cleaned at the edges and are usually beveled in such a way that the flame can reach every part of the edge. Heavy parts are held in place by suitable rests or clamps and are placed to allow for the contraction of the metal when cooling. Cast iron and aluminum require that the whole piece be heated before welding, thus uneven contraction and resulting breakage are avoided. Unless especially treated after cooling a welded joint has not the same strength as the original piece. This is overcome by adding metal to the joint, making it slightly thicker than the part itself. 1 7b RULE TO TEMPER TOOLS USED DAILY. Tempering is the process used to make steel cutting tools tough enough to hold their edge after hardening. Tempering steel makes the grain finer and adds greatly to its strength. The steel is first hardened by heating red hot and cooling more or less quickly. The degree of hard- ness depends on the rapidity with which the metal is cooled. Cooling is usually accomplished by dipping in water, although for securing extreme hardness, brine or mercury may be used. Oil used for cooling gives tough- ness without extreme hardness. To temper flat, cape or side chisels, and common flat drills, put the tool to be tempered in the fire and heat slowly to a cherry-red color, about four inches from the point. Then take it out and put it in the water, point first, about three or four inches, then draw it back quick about an inch from the point, and leave it so until the water will barely dry on the chisel, then take it out, polish it with a piece of sand stone, and let the heat that is left in the body of the tool force its way towards the point; it will be noticed immediately in the change of color. The color of temper for chisels to cut cast iron should be dark straw, turning to a blue. The temper of chisels to cut wrought iron or steel should be plunged into water after the dark straw color has disappeared and the blue begins to show itself, and left in the water to cool off. In some cases, where the tool is too cold and the temper will not draw, put the tool in and out of the fire often, until the temper shows itself, then cool immediately. If the temper gets to the point of the tool before it is polished, it will have to be heated over again. The above ru^e answers for lathe, planer and shaper tools as well. Taps, dies, reamers and twist drills should be tempered in oil. After being heated to a cherry red all over equally, drop the tool into a bucket of oil (plumb) and leave it there until cold; then take it out and brighten it with emery cloth; be careful not to drop it, because it is brittle and liable to break. To draw the temper of taps, reamers and twist drills, heat a heavy ring red hot and enter the tool centrally in the ring, so the heat will be equal from all sides. The hole In the ring should be about three times the diameter of the tool. An old pulley hub would be about right. The color for reamers, taps and twist drills lb L- P O B to \ V S % 3 Un =: a m\ 1 : g; W 2 MACHINISTS H SQUARE. TOOLS IN COMMON USE. 19 should be dark straw, turning to a blue near the shank; where the color is changing too fast, drop a little water on it; after the right color is obtained, cool off in water. To draw the temper in dies after being cooled in oil, set them (the threads up) on a piece of red-hot iron and draw tem- per the same color as taps. For tempering a spring, heat it cherry-red and put it in oil; after it is cool, take it out and hold it over the fire until the oil burns off; then put the spring in the oil again, the in the fire; do this three times; after the last time, plunge it into water and cool off. ELECTRIC LOCOMOTIVES. The Baldwin and Westinghouse electric engine has solved the problem of a locomotive running 120 miles an hour. In appearance this new wonder does not betray its qua- lities. The motors are incased, so that hardly any mechan- ism is in sight. The electric headlight and the pilot alone disclose its character as a motor car or locomotive. The locomotive weighs 150,000 lbs. and is 37 feet long over the pilot. The frame is made of lo-inch rolled steel plate over the entire floor, giving enormous strength to resist blows in collisions, etc. This frame is carried on two trucks, with all the modern devices of springs, for swinging motion and free movement. The trucks are built very strong and they are of the swivel- ing type, so they may go around any curve passable for an ordinary freight car. The geared connection between the axles and the elec- tric motors permits of any gear racio desired. The driving wheels may be connected by parallel rods for pulling heavy trains, as such rods would not permit one pair of wheels to slip without the other. The motors are directly beneath the car floor, between the two trucks, and are * ' iron-clad ' ' consequent pole motors. They are entirely encased in thin steel shells, so as to be protected from all injury under normal conditions of service. The armatures are laminated, being made up of thin slotted discs of steel. In the slots the armature wires are placed. The commutators are of the best forged copper with mica insulation. The motors have the highest grade of insulation. Power is furnished by the third-rail system. At both ends is a controller. The path of the current may be divided so as to pass to both motors independently, or it may be sent through one motor to the other. ^'iThe breaking system has some unique features. The compressed air-brake is used. The engineer's valve is of the standard Westinghouse type. When the handle of the brake valve is put at '* emergency" pneumatic action breaks the circuit at the same time as it applies the brakes. A special reversing switch acts on the motors. The auto- matic air pump is driven by electricity, its special motor being directly coiinected and without gear. The interior of this locomotive is that of an observation car, and very handsome. Our I20-miles-an-hour locomotive is ready for us, but we are not quite ready for it. Before we can risk flying across the country at such speed all grade crossings must be abolished and the whole present R. R. signal system must be changed. Signals are now about a mile apart, while the newlocomotive cannot stop within less than one and a half miles of clear way. ELECTRICITY FOR HEATING. To fit heating and cooking utensils for the use of elec- tricity, a thin film of enamel or cement is spread over the outer saucepan, griddle, kettle or heater. Then iron, plati- num or other high resistance wire is laid zigzag over it, with copper wire connections made to the two ends; and more of the cement or enamel is spread over the wires so as to com- pletely embed them. When enamel is used the apparatus is put in a kiln and burnt on similar to the ordinary iron 21 cooking utensils. In both methods the fil..n of enamel oi cement insulating the heating wires is put on so thni and is so good a conductor of heat that the heat generated by the electricity is rapidly conveyed to the utensil to be heated. CUlDDUi. CQEESBcHEAXEB. Electricity can thus be sent through the wires without fear of overheating them. This would not be possible it they were exposed to the air, which does not conduct heat but radiates it. 22 RECEIPTS FOR GOLD AND SILVER PLATING. Ail articles to be plated should be dipped in strong lye or diluted nitric acid, and rinsed ofi: with soft water; then place the article to be plated in the glass that has the solu- tion of either gold or silver, and take a couple of pieces of zinc I inch wide, and double to ^-inch wide, by lo long; let it touch the article to be plated, and you will be sur- prised at the result. This answers for both. Take a tablespoonful cyanide of gold and put it in a glass of water, to do gold plating. Take silver and dissolve in a glass with little nitric acid, when the silver is dissolved then drop hydro- chloric acid in until the white precipitates (silver chloride) ceases to fall; pour off the colored water after it has settled, and add soft water to it, then it is ready for use. STEEL SHEET PAVEMENTS. For certain structural purposes the combination of iron and steel with concrete has in various instances been suc- cessfully resorted to by builders. According to this method, a steel sheet of light guage is slit perpendicularly in short lengths, say three inches, these slits running in a straight line clear down the sheet, each new one beginning about half an inch from the point where the preceding one ended and the lines being about half an inch apart, this method leaving the sheet of steel cut into long strips of half an inch in width, but connected together every three inches or so. The sheet is now grasped by the same machines on two opposite sides and pulled apart or expanded, so that all the openings appear in diamond shape, the sheet really looking like a wire grating when ready for use. On the earth of the street graded into shape and bedded over with sand is placed the sheet of expanded steel, and over the steel is then laid a layer of concrete, this latter being so tamped into the meshes of the metal as to form a perfect bond. Upon this foundation can be laid asphalt, bitumin- ous rock, basalt block, brick or any kind of surface pave- ment desired. UNDERGROUND LONDON. Underground London contains 3,000 miles of sewers, 34,000 miles of telegraph wires, 4,530 miles of water mains, 3,200 miles of gaspipes, all definitely fixed. ^3 THE STEAM-ENGINE. The term " Horse-power " is the standard measure of power as applied to steam-engines. This unit of power has been adopted by all manufacturers of steam-engines in all parts o^ the world. The term originated with Watts, the so-called inventor of the steam-engine. He demonstrated that a horse could work 8 hours a day continuously, traveling at the rate of 2% miles an hour, raising a weight of 150 pounds 100 feet high by means of a block and tackle. Reducing this to equivalent terms, a horse could raise 150 pounds at the rate of 220 feet per minute, or 2% miles an hour, or 33,000 pounds one foot per minute. Thus, a horse-power is the power required to raise 33,000 pounds one foot a minute. There are three kinds of horse-power referred to in connection with engines, ''^ nominal^'''' '■'•indicated'''' and ^^acfz^ a I." The nominal horse-power is found by multiplying the area of the piston in inches by the average pressure, and multiply- ing this product by the number of feet the piston travels in feet per minute, then dividing this last product by 33,000. The quotient will be the nominal horse-power of the engine. The indicated horse-power is found by multiplying together tne mean effective pressure in the cylinder in pounds per square inch, the area of th^ piston in square inches and the speed of the piston in feet per minute, and dividing the prod- uct by 33,000. The actual horse-power i> the 'ndicated horse-power minus the amount expended inovercc mingthe friction. The following is a general rule for calculating the liorse-]:)ower of an engine: Rule. — Multiply the area of the piston in square inches^ the mean pressure of the steam on the piston per square inch^ and the velocity of the piston in feet per minute^ , together^ and divide this product by jj,ooo. The quotient will be the horse-power. The mean pressure in the cylinder, when cutting off at X stroke, equals boiler pressure x .597 M (< X .670 Ks (< X .743 'A a X .847 % (I X .919 % I a X .937 K ( <« ((. X .966 7;. I <» (f ( X .Q92 24 TO FIND THE DIAMETER OF A CYLINDER OF AN ENGINE OF A REQUIRED NOMINAL HORSE-POWER. Divide 5,500 by the velocity of the piston in feet per minute, and multiply the quotient by the required horse-pov^^er. The product will be the area of piston in square inches. From this the diameter can be obtained by referring to table of areas of circles. TO DETERMINE THE EFFECTIVE POWER OF AN ENGINE BY AN INDICATOR. Multiply the area ot the piston m square mches by the average force of the steam in pounds; multiply this product by the velocity of the piston in feet per minute ; divide this last product by 33,000, and {'q of the quotient vi^ill be the eflective power. The travel in feet of a piston is found by multiplying the distance it travels in inches for 07ze stroke by the whole number of strokes per minute. Dividing this product by 12 gives the number of feet the piston travels per minute. THE SLIDE VALVE. How to set a slide valve. — Place the crank at the center, and the eccentric at right angles with the crank; then put the valve in the center of its travel, and the rocker plumb at right angles with both cylinder and crank-pin ; when this is done, adjust the valve-gear to its proper length, the^ move the eccentric forward until the valve has the desired amount of lead; make the eccentric fast in this position, and turn the crank around to the other center, and see if the lead is equal; if so, the engine will run all right. In case the lead is not equal, equalize it by moving the eccentric slightly back and forth. Where the lead is unequal on account of wear, the travel of the valve may be equalized by placing lines of brass or tin behind or in front of the box which connects the valve-rod with the rocker. The " outside lap '' means steam lap ; the " inside lap " means exhaust lap. To compute the stroke of a slide valve, — To twice the lap 3,dd twice the width of a steam port in incheSj and the smri will give the stroke required. Half the throw of the valve should be at least equal to chfc lap on the steam side, added to the breadth of the port. li this breadth does not give the required area of port, the throw of the vaive most be increased until the required area is attained. By referring to the following tatle, the desired lap may be found if the travel of the valve is known: The travel of the p iston where the ' steam is cut off. Travel of the valve 4 -i 3 2 i ti 2 3 4 !S in inches. The required lai • T 3 I 1, b ^ 1. I a 2 8 4 1 6 ,8„ if 2 IG f 3 ;? I 7 I 4 i 1 I 31 I* I,^« i.^ i| '"'> I 7 8 * % 2 iil 1^ ;t I 8 5 2i 2 >fs I ft I ^ I 1 li I 51 2l^« 2,^« 2 III I f a I i ' li 6 2i 2^6 2 1^6 2 lii I? li 1 1^6 To find how much lap imist be given on the steam side of a slide valve to cut off the stea??z at any given part of the stroke of the piston. — From the length of stroke of the piston subtract the length of the stroke that is to be made before the steam is cut off; divide the remainder by the stroke of the piston, and extract the square root of the quotient; multiplv this root by half the throw of the valve; from the product subtract half the lead and the remainder will give the lap required. Expansion by lap^ with a slide valve operated by an eccen- tric alone, cannot be extended beyond one-third of the stroke of a piston without interfering with the efficient operation of a valve; when the lap is increased, the throw of the eccentric should also be increased. The lap on the steam side must always be greater than that on the exhaust side, and this difference must be in- creased the higher the velocity of the piston, for, in fast-run- ning engines, also m locomotives, it is necessary that the ex- haust valve should open before the end of tlie stroke of the piston, so that more time can be allowed for the escape of steam. 26 " OF COURSE " FOR ENGINEERS. Of course you will always start your engine slowly, so that the air and water condensation can be expelled from your cold cylinder; then you will gradually bring it to its regular speed. Of course you will be sure to keep open the drip cock, both in the front and back heads of the cylinder, when the engine is standing still, and never close them until all the water has dripped out. Of course you will never let in any oil or tallow to your cylinder until it is made hot by the steam. Of course you will be careful not to put in too much oil at any time, knowing, as you do, that it will be sent to the feed- water and cause your boiler to prime and foam. Of coiv/se you will always oil up before starting your engine. Of course you will always keep your piston and valve-pack- ing in a bag or clean drawer, so as to keep sand, dirt or other grit from becoming attached to it, and so cut or flute the rods. Ofcottrse you will not use new waste to wipe up the dirty oil from the stub-ends, crank-pins or cross-head guides, and then use the same waste to polish up the bright and finished work. Of course you will exercise great care in adjusting the packing in steam-cylinders. Of course you know that when you generally pack the piston packing, both cylinder and packing are cold, and if they are screwed or wedged in very tight while in this condition that the expansion, when exposed to the heat of the steam, will induce great rigidity. Of course you understand, if this is so, the oil or lubricat- ing substance cannot enter between the surfaces in contact, and that great friction, heating and cutting will be the result. Of course you are aware that when packing loses its elas- ticity it is no good, and should be removed. Of course you know that piston or valve-rod packing should never be screwed up more than sufficient to prevent it from leaking, and that the softer the packing the longer it will last and the better your engine will run. Of course you have tried that little trick of screwing the packing up tight when it is first inserted in the boxes, and then slacking the nut off to allow the packing to swell when exposed to the heat of the ste.m.. Of course you will read pages 53, 88, 90, 95, 97* and 103 in ihis book- HOW TO ADJUST AND SET CORLISS ENGINE VALVES. The original crab-claw valve- gear, as used by the inventor, Geo. H. Corliss, has been gradually superseded by the im- proved half-moon valve-gear, used on the Reynold's engine and other prominent Corliss engine builders. This difference between the old and new style of valve applies only to the steam-valves, as, in both cases, the ex- haust-valves open toward the center of the cylinder. In the Corliss valve-gear (sometimes called " detachable valve-gear ") the action of the steam-valves is positive, the direct action of the working parts of the engine opening them at the proper time, and keeping them open until the connection with the engine is detached or broken, and the hook tripped by the working of the cut-off cams. The steam- valves are closed by vacuum dash-pots (sometimes by springs or weights). The cut-off is automatic and is determined by the lequirements of the load on the engine, so that the cut- off cams do not always trip the hook at the same point, as they are moved by the governor. To those unfamiliar with the Corliss valve-gear, it ap- pears a very complicated affair, yet, in reality it is very simple, and is more easily adjusted than the ordinary slide-valve. To understand the simplicity of the Corliss valve-gear, the four valves (two steam, two exhaust), must be considered as the four parts — or edges — of the common slide-valve, that is, the working edges of the two steam-valves are equivalent to the two steam edges of the slide-valve, and the working edges of the two exhaust-valves as equivalent to the exhaust edges of the shde-valve. The principle is the same in the two styles of valves — Corliss and slide — but the difference comes in the adjustment, for the slide-valve is a solid valve, and any adjustment of one part affects the whole, while with the Corliss valve each part is susceptible of an individual and separate adjustment, which can be made, if necessary, while the engine is work- ing, without shutting down. The eccentric works the valves, and are connected with them on the Corliss gear, by means of the wrist plate, carrier-arm, rocker-arm and reach-roc? Besides imparting motion to 'he valves, the wrist-plate modifies the speed of travel at different parts of the stroke, giving a quick and accelerating speed when opening the steam-valve, and a quick opening and closing of the exhaust- ki6 vaive, both stearr. and exhaust -valves being at their slowest speed when closed. First, remove the back-leads or back-caps of the fo'ir valve- chambers; when thiS is done the engineer will find guide hnes on the ends of the valves, and also on the ends of the valve- chambers. The lines on the steam-valve will coincide with the workmg edges of the valve, and those on the steam-valve chamber with the working edges of the steam-ports. Guide lines will also be found on the exhaust-valves and ports. The wrist-plate is located on the valve-gear side of the cylin- der, in a central position, between the four valve-chambers. On the stand, which is bolted to the cylinder, will be found a deeply scribed line, and on the hub of the wrist-plate, three other lines, which show the center of the wrist-plates, and the limits of its travel or throw. To adjust the valves, the reach-rod which connects the wrist-plates with the rocker-arm, must first be unhooked; next place the wrist-plate in its central position and hold it there. All the connecting-rods between the steam and exhaust valve-arms and the wrist-plate, are made with right and left hand threads on their opposite ends, and furnished with jamb- nuts, so that the rods can be easily lengthened or shortened by merely slacking the jamb-nuts and turning the rods. ■ In this manner, set the steam-valves so that for every lo inch diameter there will be ]^ inch lap, and for every 32 inch diameter ^ inch lap, other intermedi^.te diameters in pro- portion to these distances. Set the exhaust-valves for every 10 inch diameter of cylin- der with -^ inch lap, and for 32 inch diameter ^ inch lap. Double these distances for condensing engines. The lines on the valves which are nearer the center of the cylinder than the "lines on the valve-chambers show the lap on both steam and exhaust valves. After the valves have thus been adjusted, turn the wrist- plate to the extreme limits of its throw, and adjust the rods connecting the steam- valve arms with the dash-pots, so that, when the rod is down as far as it will go, the square steel block on the valve-arms will just clear the shoulder of the hook. The adjustments of these connecting rods must be properly made, for if too long the steam-valve arm will be bent or broken, and if too short the valve will not open, be- cause the hook will not engage. Now hook the engine in, loosen the eccentric on the shaft, and turn it over, adiustin;? tiie eccentric-rod so that the lines 5*9 on the hub of the wrist-plate, which show the limits of its travel and throw, will coincide with the line scribed ou the stand. Place the crank on iis dead-center, and turn the eccentric in the direction which the engine is to run, so that the steam- valve will show an opening of ^-^ to ^ of an inch (depending on the speed at which the engine is to run — the faster the speed the more lead it requires). The Ime on the valve, which is nearer the end of the cylinder than the line on the valve-chamber, shows the opening required, v/hich is the *' lead " or port opening when the engine is on its dead-center. Now secure the eccentric, or the shaft, by tightening the set- screw, and throw the engine over to its other dead-center, carefully noting if the other steam-valve shows the same opening or lead. If it does not, adjust it properly by length- ening or shortening the connecting-rod from the valve-arm to the wrist-plate. The exhaust-valves are adjusted in the same manner. The directions just given are for the half-moon style of valve- gears, which open from the center of the cylinder. In cases of the crab-claw, or any other style which open toivard the center of the cylinder, the method of adjustment is the same as given above; but, with the difference that the lap on the steam-valves will be shown when the line on the steam-valve is nearer the end of the cylinder, and the lead when the line is nearer the center of the cylinder than the line on the valve- chamber. In adjusting the rod connecting the cut-off or tripping cam with the governor, the governor must be at rest, and the wrist-plate at one extreme of its throw or travel. First adjust the rod connecting with the cut-off cam on the opposite steam-valve so that there will be ^^ inch clear- ance between the cam and the steel on the tail of the hook. Throw the wrist-plate to the other extreme of its travel and adjust the cam for the other steam-valve in the same manner. Now block the governor up i^ inch, which will be its average distance when running. Hook the engine in and turn it slowly in its running direction, and mark the distance the cross-head travels from its extreme position of dead- center when the cut-off cam trips the steam-valve. Continue to turn the engine slowly past the oiner dead-center, aiid mark the distance of the cross-head from its extreme of travel when the steam-valve drops. If the distance is the same in both cases, the cut-off is equal and the adjustment is correct. If not, adjust one or the other of the lods until this is so. 3« THE STEAM-ENGINE INDICATOR The steam-engine indicator is now recognized as a higlil> essential device, with which every engineer should be familiar. The three main objects for which the indicator can be em- ployed are: 1. To serve as a guide for setting the valves of an engine. 2. To determine the indicated power developed by an engine. 3. To determine, in connection with feed-water test, showing the actual amount of steam consumed, the economy with which an engine works. Among the various indicators now on the market, the Ta- bor Indicator is recognized as the standard, and has been se- lected to ■"iius-rate this article. All inaicators b?7e one essential plan ot construction: There is a steam-cy Under ana a pape7' dru7?i. The steam-cylinder is designed to connect with the inte- rior of the engine-cylinder and receive steam whenever the engine receives" it. - piston, which is inclosed, communi- cates motion to a pencil arranged to move in a straight line; the amount of movement being limited by the tensior of a spiral spring against which the piston acts. 31 The i)aper dntm is a cylindrical shell moimted on its axis, and is made to turn forward and backward by a motion de- rived from the cross-head of the engine. A sheet of paper, ox' card, as it is named, is stretched upon the drum, and a pencil is brought to bear upon it. In this manner, the instrument traces upon the paper a line termed the indicator diagram, which is the object sought. Since the motion of the card is made to coincide with that of the piston of the engine, and the height to which the pencil rises varies according to variations in the force of the steam, the indicator diagram presents a record of the pressure of the steam in the engine cylinder at every point of the stroke. Sectional View of Standard Instrumcht THE METHOD OF INDICATING A STEAM-ENGINE. There are two things to be done in making arrangements for indicating a steam-engine. First, the indicator must be at- tached to the cylinder; and second, means must be provided for giving motion to the paper drum. To attach the indicator, a hole is drilled at each end of the cylinder, and tapped for the reception of a half-inch steam-pipe(f()r the Tabor indicator) to which to connect the indicator cock. In horizontal engines^ 3^ the barrel of the cylinder should be selected in prc^erenc e to the heads, as m the position thus secured the indicator can be themost easily operated. V/hercver attached, it isimportant that the pipe should communicate freely with the steam in the cylinder. The hole should not be located, for example, in such a position that it is covered by the piston rings at the end of the stroke. The pipes should be short and free from unnecessary bends. If a valve is used beneath the cock, it should be of the straght-way type. It is not best to connect the two ends and use a single indicator applied at the center. Errors are pro- duced by the long connections and increased number of bends that this requires, especially at high speeds. If but one indicator is available, it may be used alternately, first on one end and then on the other; should it be necessary to place the indicator at the center, as convenience in operat- ing generally requires in locomotive work, the errors due to long connections may be reduced by the employment of large pipes and easy bends. For these positions, a three-way cock, to which the indicator cock is attached, is a useful appliance. In drilling and tapping new holes in a cylinder, care should be taken that the chips do not enter it, unless they can after- ward be removed. If no better means can be employed, steam may be admitted while the work is going on, and the chips blown out as fast as formed. Before attaching the indicator, the cock should be opened to the atmosphere, and the pipes cleared of any loose material that may have lodged in them. INDICATOR DRIVING RIGGING. The motion to be given the paper drum is one that coin- cides, on a reduced scale, with the motion of the piston of the engine. It may be obtained in a variety of ways. The active instrument here shown, is the reducing lever, A C, which is a strip of pine board 3 or 4 inches wide, and about I % times as long as the stroke of the engine. It is hung by a screw or small bolt to a wooden frame at- tached overhead. At the lower end a connecting rod, C D, about one-third as long as the stroke, is at one end at- tached to the lever, and at the other end to a stud screwed into the cross-head, or to an iron clamped to the cross-head by one of the nuts that adjusts the gibs, or to any part of the cross-head that may be conveniently used. The lever A C should stand in a vertical position when the piston is in the middle of the stroke. The connecting rod, C D, when 33 at that point, should be about as far below a horizontal posi« tion as it is above it at either end of the stroke. The cords which drive the paper drums may be attached to a screw in- serted in the lever near the point of suspension; but a better plan is to provide a segment, A B, the center of which coin- cides with the point of suspension, and allow the cords to pass around the circular edge. The distance from edge to center should bear the same proportion to the length of the reducing lever as the desired length of diagram bears to the length of the stroke. On an engine having a length of 48 inches the lever should be 72 inches, and the connecting rod 16 inches in length, in which case, to obtain a diagram 4 inches long, the radius of the segment should be 6 inches. It is immaterial what the actual length of the diagram is, but 4 inches is a length that is usually satisfactory. It maybe reduced to advantage to 3 inches at very high speeds. 34 The coj'ds should leave segment in a line pai^allel with the axis of the cylinder. The pulleys over which they pass should mcline from a vertical plane and point to the indj cators wherever they may be placed. If the indicators and reducing lever can be placed so as to be in line with each other, the pulleys may be dispensed with, and the cords carried directly from the segment to the instrument, a longer arc being provided for this purpose. The carrier pulley on each indicator should be adjusted so as to point in the direction in which the cord is received. THE ESSENTIAL FEATURES OF THE INDICATOR DIAGRAM. The shape of the figure traced upon the indicator card depends altogether upon the manner in which the steam pressure acts in the cylinder. If the steam be admitted a^ the beginning, and exhausted at the end, of the stroke, and ad- mission continue from one end to the other, the shape of the diagram is nearly rectapgular. If the admission continue through only a part of tlie stroke, the diagram assumes a shape similar to that of Fig. No. I. These two representative forms have, in matters of detail, numlierless modifications. Fig. No. I has been taken to illustrate the essential features of the indicator diagram, because it exhibits clearly all the operations affected by pressure that commonly take place in the steam engine jylinder. This diagram shows that the a^^.Isslon of steam commences at A and ends at D; the cut-off commences at C and becomes complete at D; expansion recurs from D to E; the release or exhaust begins at ii and continues to the point 11 ; iiiG com- pression of the exhaust steam commences at G and ends at the admission point, A. The Hne A B is called the adinission line ; B C, the steam line; D E, the expansion li7ie; F G, the exhaust or back p7'essure line (or, in the case of condensing engines, the vacuum line); H A, the compression line; and J I, the atmospheric line. The curve which joins two adjacent lines, represents the action of the steam when one operation changes to another and cannot properly be classed with either line. The point of cut-off, D, lies at the end of admission; the point of release, E, at the beginning of the exhaust, the point of compression, H, at the end of the exhaust. The propor- tion of the whole length of the diagram borne by the distance of the point D from the admission end, represents the pro- portion of the stroke completed at the point of cut-off; so also in the case of the point of release, and in that of com- pression for the uncompleted portion of the stroke. The pressures at the points of cut-off, release and compression are the heights of these various points ahove the atmospheric line measured on the scale of the spring. THE USES TO WHICH THE STEAM-ENGINE INDICATOR Ma. BE APPLIED. There are three main objects for the deterrrination of which the indicator diagram may be employed: First. To serve as a guide in setting the valves of an engine. Second. To determine the indicated power developea by an engine. Third, To determine, in connection with a feed-water test showing the actual amount of steam consumed, the econ- omy with which an engine works. First. Figure No. i, shows the general features of a well-formed indicator diagram, the attainment of which should be the aim in setting the valves of an engine. The admission of steam is prompt, making the admission line per- pendicular to the atmospheric ?ine; the initial pressure is fully maintained up to the po^'ii'; where the steam begins to be cut off; the somewhat early release secures a free exhaust and a uniformly low back pressure, and the exhaust valve closes before the return stroke is comi)leted, providing for compression. These are the first requirements to be met in producing an 'Economical engine. 3^ Derangement ot tne valve-gearing is revealed in the dir gram by tardy admission or release, by low initial pressure or high back pressure, or by absence of compression, either one of which causes an increased consumption of steam for per- forming the same amount of work. The angular position of the eccentric controls all the movements of the valves, but improper lengths of the con- necting rods which operate them, or improper proportions ot lap and lead, are liable to produce some of the faults we mention, as will also a wrong position of the eccentric. In regulating the exhaust of an engine, the desirability of employing compression should not be overlooked. In the first place, it serves to overcome the momentum of the recip- rocating parts and to reduce the strain up^u the connections caused by the sudden application of the pressure at admis- sion. In the second place, compression is desirable on the ground of economy in the consumption of steam. It fills the wasteful clearance spaces of the cylinder widi exhaust steam, otherwise requiring the expenditure of live steam from the boiler. Compression produces a loss by the increased back pressure which it occasions, but the loss is more than cov- ered by the gain resulting from the reduction of clearance waste. Hypothetically, the greater the amount of exhaust that is utilized by compression the less the consumption of steam. Practically, it is not advisable to compress above the boiler pressure. In a non-condensing automatic cut-off engine with 3 per cent, clearance working at 75 lbs. boiler pressure, cut off at one-fifth of the stroke, and exhausting under a min- imum back pressure, the gain produced by compressing up to boiler pressure over working under the same conditions with- out compression, should be not less than 6 per cent. Tn a condensing engine, working under similar condition^, the gain should be larger. It should be larger, also, with an earlier cut-off. The valves being in proper adjustment, the indicator dia- gram shows whether the pipe and passages for the admission and exhaust of the steam are of sufficient size. In automatic cut-off engines the admission line should be parallel with the atmospheric line, and the initial pressure should not be more than 3 lbs. less than the boiler pressure. The back pressure should not in any engine exceed i lb. when the ex- haust proceeds directly to the atmosphere. Much can often be learned by applying the indicator to the steam and exhaust pipes, using the same mechanism for driving the paper drum as that used when the indicator is operated at the cylinder. 3/ Before making adjustments upon engines that have been long in tise, the operator should ascertain whether a valve which should travel in a different place has woi'n to a shoul- der upon its seat. If changed under such circu??istances^ loss from leakage may follow, sufficient in amount to neutral' izc the saving that might otherwise result. This is a matter of much importance. Second. The indicator is useful in determining the amount of power developed by an engine. The diagram reveals the force of the steam at every point of the stroke. The power is computed from the average amount of this force, which is independent either of the adjustment of the valves, the form of the diagram or of any condition upon which economy depends. The diagram gives what is termed the indicatec power of an engine, which is the power exerted by the steam. The indicated power consists of the net power deHvered and, in addition, that consumed in propelling the engine itself. In this connection the indicator proves invaluable for measuring the amount of power transmitted to a machine or set of machines, which the engine is employed to drive. The process of measuring power thus used consists in indicating the engine, first with the machinery in operation, and then with the driving belt or shaft thrown off. The difference in the amount oi power developed in the two cases is the desired result. Tenants, and those who Jet power, frequently employ the indicator for this purpose. Third A third use for the indicator is in connection with 3. feed-water test, in determining the number of pounds of steam consumed byxn engine per indicated horse-power pei' hour. This quantity forms a if*reasure of the performance of an *^.ngine, and when compared with the performance of the best of its class, shows the economy with which the engine works. The amount of steam consumed is usually found by weigh- ing the feed-water before it is supplied to the boiler, the steam being employed during the test for no other purpose than driving the engine. This requires the erection of a weighing apparatus, the most satisfactory form of which con- sists of two tanks and platform scales. One tank is placed on the scales, and these are elevated abo\'e the second tank, which is of comparatively large size. The water is firs' drawn into and weighed in the first tank. It is then empticJ into the second tank, which serves as a reservoir, and from this it is pumped into the boiler. A simpler plan may be resorted to, which gives approxi- 3» mate results. The feed-water is brought to a high point on the glass water-gauge and then shut off, and a test made by observing the rate at which the water boils away. A fall of six inches may be allowed in nearly every case without again feeding. The heights at the beginning and the end of the test being carefully observed, the amount of water evapo- rated and supplied to the engine is computed from the cubical contents that it occupied in the boilers. A test made in this manner can be repeated a number of times, and the results averaged to insure greater accuracy. Feed-water tests, made by measuring the water fed to the boiler, are of no value unless leakage of water from the boiler, if any exist, is allowed for. Attention should always be given to this point and the rate of leakage determined by observing the fall of water in the gauge, when no steam is being drawn from the boiler, a constant pressure being main- tained. A portion of the feed- water consumption of an engine may be found without the aid of a feed- water test, by computation from the diagram. Were it not for the losses produced by leakage and cylinder condensation, to which engines are sub- ject the whole amount of feed- water consumed mieht be de- termined in this manner. Leakage of steam often occurs and cylinder condensatioii is mevitable, while the extent to which these losses act is not revealed by any marked effect produced upon the lines of the diagram. The measurement of the consumption of steam by diagram, therefore, cannot be taken to show actual performance without allowing a margin for these losses. Much value, however, often at- taches to these computations. Besides showing the economy of an engine compared with the best of its class, the indicator, by means of the feed-water test, reveals the extent of the losses produced by leakage and cylinder condensation. These losses are represented by that part of the feed-water consumption which remains after de- ducting the steam computed from the diagram, or steam ac- counted for by the indicator^ as it is termed. One of these losses, condensation, is nearly constant for different engines working under similar conditions, and an allowance may be made for its amount. The other, leakage, is variable in dif- ferent cases, depending upon the condition of the wearing surfaces of valves, piston and cylinder. The fact of the pres- ence of the latter may be detected by a trial under boiler pressure with engine at rest, the leakage being revealed Dv escape at the indicator cock or exhaust pipe. The amount of this leakage may be found by computing that part of the loss not covered by condensation. In other words, in the case of leaking engines, when the indicator and feed- water test show that there is more loss than is produced in good practice by condensation, the excess represents the probable amount of loss by leakage. A valuable use for the indicator is thus found in connection with the feed-water test. To make it available in practice, Tables Nos. i, 2. and 3 are appended, showing the percentages of loss that occui from cylinder condensation. The quantities in Table No. I apply to that type of simple engine commonly used, that is, to unjacketed engines having cylinders exceeding twenty inches in diameter; the quantities m Table No. 2 apply to compound engines of the best class having steam jacketed cylinders; and the quan- tities in Table No. 3 apply to triple expansion engines of the best class, also having steam jacketed cylinders, all supplied with dry but not superheated steam. TABLE NO. I. Percentage of loss by cylinder condensattoit taken at cut-ojf in sifnple engines. Percentage of Feed- Percentage of Feed- Percentage of stroke watcr consumption water consumption completed at cut- off. accounted for by the indicator diagram. due to cylinder con- densation. 5 5? 42 10 66 34 15 71 29 20 74 26 30 78 22 40 82 18 50 * 86 14 TABLE NO. 2. Percentage of loss by cyliitder condensation taken at ciit-of^ in the II. P. cylinder in compound engines. Percentage of stroke compJeted at cut-c ff. 10 20 30 40 50 Percentage of Feed- water consumption accounted for »>y the indicator diagram. Percentage of Feed- water consumption due to cylinder con- densation. 74 76 78 82 85 88 26 24 22 18 15 12 4^5 MANNER OF TAKING DIAGRAMS To take a diagram, a blank card is stretched smoothly upon the paper drum, the ends being held by the spring clips. The driving cord is attached and so adjusted that the motion of the drum is central. The cock is opened to admit steam to the indicator till the parts have become heated, which will be after a half-dozen revolutions. On being shut off, the pencil or marking point is brought into conf ict with the paper, the stop screws is adjusted, and a fine clear line traced upon the card. This is the atmospheric line. The cock is then opened, and c.fter two or three revolutions the pencil is again applied and the diagram taken. If it is desired to as- certain the condition of the valve adjustment, the pencil needs to be applied only while the engine is making one rev- olution. But to de«ermixie power, it should be applied a longer time, so as to obtain a number of diagrams superposed on the same card. The fluctuations in the admission of steam, produced by gcvernors which do not regulate closely, ire so common, that ih\% course should always be followed to obtain average results. The diagram having been traced, and the cock shut, the pencil should be applied lightly to the paper to see that the position of the atmospheric line re- mains the same. If a nevi' line is traced, it is evidence of error or derangement, and the operations should be re- peated on a new card. It is well to mark upon evei}' card the date, time of day, and end of the cylinder from which it was taken. In ad- justing the valves, the boiler pressure should be observed, and the changes that are made before taking a diagram noted on the card for reference. If a series of diagrams is being obtained for power, they should be numbered in order, and the number of revolutions per minute noted, either upon every card, or, if the speed is nearly constant, upon every other one. If tests are to be made for power used by machines or tenants, a number of diagrams should be obtained mider each condition and the results averaged. It is well, in these cases, to mark each card of a set by some letter of the alphabet, and on the first of the set specify the machines in operation at the time. SPECIAL INSTRUCTIONS. When accurate work is desired, too much care cannot be exercised in indicating an engine, and a further consideration 4i of some of the points lo be observed will aid the engineei in realizing their importance. Short steaffi connections from the cylinder to the indicator are desirable in all cases, and absolutely necessary with high cpeed engines. Avoid all turns, if possible. Lubrication of the indicator pistoti. — The best cylinder oil only should be used for this purpose. The piston should be removed, and the cylinder and piston cleaned and oiled every half-dozen diagrams. The oil contained in the steam ts not sufficient in any case to iabricate this piston. Alack of lubrication will make a jumping action in the movement of the pencil, showing a series of steps, not waves, on the diagram. Spring to he used. —On slow speed engines the lightest pring that will accommodate the pressure is best, but in high speed engines a heavier spring is necessary for the same pressure, in order to restrict the movement of the pencil bar and connections, and prevent their inertia from distorting the diagram. A waving line is the result of too great a move- ment of these parts. The tension of the spring in paper drui7i should in all cases be just sufficient to keep the cora tight; but this means that a greater tension must be used with high than with low peeds, to prevent the inertia of the drum over-winding itself and distorting the diagram; breakage of the cord also fre- quently results from this cause. (^, ' Keeping the cord leading from engine under tension. . This is of no importance with slow running engines, but when indicatmg high speed engines it is desirable that this cord should always be kept taut, whether the paper drum is running or not. A good plan is to fasten one end of a rubber band to the driving cord four or five nches from the end and attach the other end of the band to he indicator just below the carrier pulley, so that it always keeps a tension on the driving cord; then make a loop m tli': 2nd of this cord for hooking on the indicator, and the loost* 2nd admits of readily connecting and disconnecting without lilowing the driving cord to become slack for an instant. Length of the diagra?ns. — With slow speeds a length of 4 in. to 4^ in. will show well proportioned diagrams, but as the speeds increase the diagrams must be shortened to avoid the effects of the inertia of the paper drum; and at very high speeds an instrument with the small paper drum should be used. Diagrams at very high speeds should not exceed 2 in length, and frenaently 1% in. will give better results. 42 The pressure of the pencil on the paper should be just sufficient to make a legible mark, and no more; a greater pressure only creates friction, and consequent inaccuracy in the diagram. Water in the indicator will make a curious but not a use- ful diagram, and therefore care should be exercised that the indicator is thoroughly heated up before a diagram is taken. Also, if much water is entrained in the steam, it will be nec- essary to leave the cylinder cocks slightly open while taking diagrams, as otherwise a distorted diagram is almost a cer- tainty. When taking diagrams from steam-engines, the height of the barometer or pressure of the atmosphere should always be carefully noted. This is necessary when the economy of the engines are to be considered, and it is desirable in all cases to know how much the exhaust pressure is above zero. Even at the sea level the pressure is constantly changing, and there are many engines working at places far above the sea level where the atmospheric pressure is always less, and in some cases very much less, than 14.7 lbs. per square inch, or 29.9 in. of murcury. Care should therefore be exercised in this respect, as there is a tendency among engineers to ignore this fact. All gauges in ordinary use indicate pressures above the atmos]:)here; if pressure gauges, or if vacuum gauges the amount below atmospheric pressure; but neither kind show the pressure above zero, or total pressure, and to arrive at this, the pressure of the atmosphere must be added to the gauge pressure in the first case, or the amount of vacuum sub- tracted from the atmospheric pressure in the second. THE METHOD OF COMPUTING THE HORSE-POWER OF AN ENGINE FROM THE INDICTOR DIAGRAM. The work done by the steam in the cylinder of an engine is measured by the product of thf. force exerted on the pistoUj mto the distance through T/bich the piston moves, and is usually expressed by the te. ii foot-pounds. If, for example, a force of 33 lbs. per squarv- inch on a piston having an area of 100 square inches is employed to drive the piston 100 times over a stroke of 4 feet, the work done by the steam amounts to 1,320,000 ft. lbs. 7''he umount of horse-power which the steam develops is the fcot-pcands of work done in a 77iinute divided by 33.000. In the ^>xample given, the horse-power developed when 100 strokes are made per minute is 1.320,000 divided by 33,000 or 40 H. P 4j The force exerted upon the piston is given by theindicavC** diagram, but as it varies in amount at different points of the stroke, it is necessary to determine the equivalent force which, acting constantly, vi^ould produce the same result. This is done by compating from the diagram what is termed the mean effective pressure. The product of the meaji effective pressure, expressed in pounds per square inch; the area of the cyHnder, expressed in square inches; the length of the stroke, expressed in feet; and the number of strokes per minute, which is twice the number of revolutions per minute, gives the number of foot-pounds of work performed per Fi^.^^ %, minute. This result, divided by 33,000 gives the amount o* horse-power developed. To compute from the diagram the mean effective pressure, two lines are drawn perpendicular to the atmospheric line, one at each end of the diagram, and the intermediate space divided into 10 equal parts, with a perpen- dicular at each point of division. A ready method of performing the division is to lay upon the diagram a scale of 10 equal parts, the total length of which is a small amount in excess of the length of the diagram. It is so placed in a diagonal position that the extreme points on the scale lie upon the two outside perpen- diculars. The desired points may then be dotted with a sharp pencil opposite the intermediate divisions on the «5cale. The points where the lines of division cross the • 44 diagram should be dotted; and in locating these points they should be so placed that the area of the figure inclosed by straight lines joining them is exactly equal to the area m- closed by the curved line of the diagram. The proper loca- tions can be readily determined by the eye. Figure No. 2 shows the extreme perpendiculars A B and CD, the intermediate lines of division, the points of inter- section, and those points which require special location, as, for example, the one at E, which is so placed that the area inclosed by the straight lines, E F and E G, is equal to that inclosed by the diagram from F to G. The determination of the mean effective pressure consists now of finding the average length of the various perpendicu- lar lines included between the points of intersection, meas- ured on the scale of the spring. This may be done by meas- uring each line with the scale and averaging the results. A better and quicker method is to employ a strip of paper, one of the cards upon which the diagram is traced, if desired, and mark one after another the various distances on its edge, making thereby a mechanical addition, and requiring only a final measurement. The proper course to pursue is to lay the edge of the paper on the first line and mark off the distance, A H , starting from the end of the paper. Transfer the edge of the paper to the last line, and add to the first measurement the distance, I D. Mark off from the end of the paper one-half of the sum of these two distances, and from the middle point continue the addition for the intermediate nine divisions. When all have been marked measure with the scale of the spring, from the end of the paper to the end of the last addition, and divide the result by ten. This gives die mean effective })ressure. It is essential that one -half the sum of the first and last distances be taken, and the sum of this together with the intermediate nine be divided by ten. An erroneous result is obtained by taking the sum of the whole and dividing by eleven. The engineer who is so fortunate as to possess the knowl- edge necessary to operate an Indicator will find that his posi- tion is not only more secure to him, but his employers will be very apt to show their appreciation in a pecuniary manner. The use of the Indicator as a detective, detecting errors, misadjustments, waste and lost motion in an engine makes it a most necessary adjunct to the engine-room. This fact is becoming ^ore patent every day. 45 STEAM-BOILERS. All boilers are dividea into three different parts, viz., fire- surface, water-space and steam-room. Each part or division has a distinct and separate duty to perform. The fire-surface includes the furnace and combustion chamber, flues and tubes; the water-space is that part occupied by the water; and the steam-room is the reservoir which holds and supplies the steam necessary to run the engine. All steam-boilers are either internally or externally fired. Locomotive, marine and portable boilers are internally fired because the fuel is burned in an iron furnace surrounded with a water-jacket or v/ater-leg. Cylinder-flue, double-deck, tub- ulous and sectional boilers are externally fired, because the fuel is burned in a brick furnace lined with fire-brick. A perfect steam-boiler should be made of the best material sanctioned by use, and should be simple in construction. It should have a constant and thorough circulation of water throughout the boiler, so as to maintain all parts at one tem- perature. It should be provided with a mud-drum to receive all im- purities deposited from the water, and the mud-drum should be in a place removed from the action of the fire. It should have a combustion chamber so arranged that the combustion of the gases commenced in the furnace may be completed before the escape to the chimney. All parts should be readily accessible for cleaning and repairs. The boiler should have ample water surface for the dis- engagement of the steam from the water in order to prevent foaming. It should have a large excess of strength over any legitimate strain. It should be proportioned for the work to be done. It should have the very best gauges, safety-valves, fusible plugs, and other fixtures. A zvater-tiibe ^^//^r should have from lo to 12 square feet of heating surface for one horse-power; a tubular boiler 14 to 18 square feet of heating surface for one horse-power; a fliie-boiler% to 12 square feet of heating surface for one horse- power ; a plain cylinder boiler should have from 6 to 10 square feet of heating surface for one horse-power; ^locomotive boiler should have from 12 to 16 square feet of heating surface for one horse-power; a vertical boiler should have from 15 to 20 square feet of heating surface for one horse-j^ower. The following table gives an approximate list of square reet ■Oi heating surface per H. P. in different styles of boilers; the 40 rate of combustion of coal per hour, per square foot of grate surface, required for that rating; the relative , economy, and the rapidity of steaming: Type of Boiler. Sq. ft. for one H. P. Coal for eachsq. ft. Relative Kconomy. Relative rapidity of Steaming. Water tube lO to 12 14 to 18 8to 12 6 to 10 12 to 16 15 to 20 •3 .25 .4 .5 .275 .25 1. 00 .91 '19 .69 .80 1. 00 .25 .20 Tubular Flue Plain cyHnder Locomotive Vertical tubular. , . . . . HOPvSE-POWER. Strictly speaking there is no such thing as " horse-power to a steam boiler; it is a measure applicable only to dynamic effect. But, as boilers are necessary to drive steam-engines, the same measure applied to steam-engines has come to be universally applied to the boiler. The standard, as fixed b> Watt, was one cubic foot of water evaporated per hour from 212° for each horse-power. This was, at that time, the requirement of the best engine in use. Since Watt'j time, however, this requirement has been reduced unti engines requiring but one-half or one-quarter a cubic foot ol water per hour, are in daily use. However, even thougl the Centennial Exposition in Philadelphia adopted as 2 standard for tests oihoilers ^o pounds water per hour^ eva porated at 70 pounds pressure, from 100° for each horse power, the general rule, in estimating horse-power of boilers is based on its evaporating one cubic foot of water per horse power per hour. A cubic foot of water weighs 62^ pounds Estimating horse-poiver of boilers. — One cubic foot, 62>^ pounds, or 6.23 gallons of water evaporated per hour is equivalent to one horse-power. That is, a boiler that wil evaporate ten cubic feet of water, or 625 pounds of water, 62 >^ gallons of water per hour, is a boiler of 10 horse-power An easy approximate rule for estimating the horse-power o a boiler off-hand (if the boiler is a cylinder or flue boiler) i: to multiply the length of the boiler by the diameter, in feet and divide by 6; the quotient will be the nominal horse ^(y\^^x,i% Another r///^.— Multiply the heating surface ii square yards hy \\iQ f re -grate surface in square feet; th square rooioiik^Q product will be the nominal horse-power. 4/ In estimating the heating surface of a boiler, a vertical or ipright surface has only one-half the evaporative value of a lorizontal surface above the flame. That is, the sides of a ocomotive fire-box are only half as effective per square foot IS the flat top of the box. In flues and tubes, the effective iurface, measured on the circumference, is 1^4^ times the iiameter. To find the fire-grate surface of flue boilers. — Square the lominal horse-power, and divide it by the heating surface in quare yards ; the quotient will be the fire-grate surface m )quare feet — or, one square foot of fire-grate surface per lominal horse-power. To find the heating surface of a flue-boiler. — Square the lominal horse-power and divide that by the fire-grate surface n square feet; the quotient will be the heating surface in 'quare ya7'ds. , Capacity of Boiler flue. — One cubic yard of boiler capa- city for each nominal horse-power. Steam room should be ibout eight times the contents of the cylinder of the engine mpplied with steam by the boiler. To find the no7mna.l horse-pozver of a locomotive boiler. — Square the area of the heating surface in square feet, and iivide by the area of the fire grate in square feet; multiply he quotient by .0022; the product will be the nominal horse- )ower. To find the area of the heating surface of a locomotive wiler. — Multiply the nominal horse-power by the area of he grate \n square feet; extract the cube root of the product, ind multiply the root by 21.2, the product is the area of the leating surface in square feet. To find the area of the fire-grate sttrfac^ of a locomotive W/^r. --Square the area of the heating surface in square eet, divide it by the number of nominal horse-power, or the :ubic feet of water evaporated per hour. The quotient tiultiplied by .0022 will be the area of the fire-grate surface in quai^e feet. Or, divide the area of the heating surface in square feet by 5, the quotient will be the area of the fire-grate in square ^eet, nearly. Tubular or mari7te boilers. — Each nominal horse-power equires the evaporation of one cubic foot of water per hour; 2 square feet of heating surface, only three-fourths of the /hole tube-surface being taken as effective; and 30 square iches of fire-grate per nominal horse-power. The sectional rea of the tubes to be about one-sixth of the fire-grate. ^ SI pu u 3unod ui ssanjxij B a^lToq JO iqSpAV LOOOOOOOO^OOOOOO ir^ vo J>. r^C rf - - --• l-l HH M -. hH c^ •spunod I J3|ioq JO }qSpA\ »£>OOQO OOOi>-)QOOOOO cT CO Tf to i-nvcTvo tCocT o" o" •"•" CO rf t^ in •}33j UI 5qSpH iDiqx cc; OD^yxrtlx «|* «!x Mloo cclx n OJc^x H!^H^^-^H^M5^N u •saqoui [ jpqs JO sssu^Diqx ^^-k=..>-.;sc*hS'.!:hs:|s:s:>="»H!S J) (U s o ft •saqoui UI ;qSi3fj O O ^ ThO OOOOOOOvO^O^vO W c^) M M CS CS rocococococ^. rococo •saqoui UI jajauiBiQ M Co">o\hV)vb "vOMD "t^MD >^"K, •SSqOUI UI J313UIBTQ rOcO^^^'^LOU") i-OvO VO "O O O I>» -a9A\od-3SJO}-* -' OJ C^ CO CO 'sf 's^ LOVO x^ r-^io On O m •3ZIS JO -O^ •-< M CO "^ u-jvO t^OO C^ O '-' 04 ro -^ VO 4^ y General rule for all classes of boilers. — Twelve square leet of heating surface and three-fourths square foot of fire-grate per nominal horse-power, are very good proportions. TEMPERATURE INDICATED BY THE COLOR OF THE FIRE. To determine the temperature of a furnace fire from the color of the flame: Faint red 960^^ F. Bright red. . . . > 1,300^ F. Cherry red 1,600^ F. Dull orange 2,000° F. Bright orange 2, 100° F. White heat.. 2,400° F. Brilliant white heat 2,700° F. RULES FOR SAFETY-VALVES. I. — To find the distance fro7n the fulcrtun at zvhich a given weight is to be placed on the lever ^ in order to balance a given pressure in the boiler. — Multiply the steam pressure oh the whole area of the safety-valve by the distance of the center of the valve from the center of the fulcrum. Multiply the dead weight of the lever and the valve by half the length of the lever, subtract this product from the first product, and divide the remainder by the given weight, supposed to be a cast-iron ball The quotient is the required distance of the weight from the fulcrum in inches. It is necessary, in order to find the steam pressure on the valve, to multiply the area of the valve-seat in inches by the pounds pressure per square inch. Suppose that the entire pressure of steam on the valve is 24 pounds, that the center of the valve is 2 inches from the cen- ter of the fulcrum, and that the weight of the ball is 3 pounds — the first product is 24 X 2 = 48 ; the length of the lever is 16 inches, and the united weight of the lever and valve is 4 pounds; then the second product is (16-^2) 8 X 4 = 32. Then 48 — 32 = 16, and 16 -^ 3 = S/4 inches, the required distance of the center of the ball from the center of the fulcrum. 2. 7b find the weight of the ball to hang onto a given length of lever, in order that the steam may blozv off at a given pressure. — Multiply the whole pressure on the valve by its distance from the fulcrum (center to center) ; from this product subtract the product of the weight of the lever and valve, multiplied by one-half of the length of the lever; then divide the remainder by the whole length of the lever. The quotient is the weight of the ball in pounds. For ex..mple — The pressure in the boiler is 60 p -uiuls per square inch on the valve, the center of the valve is 2 inches from the fulcrum, the weight of the valve and lever is 10 pounds, and the length of the lever is 14 inches. Suppose the opening in the boiler to be 2 inches in diame- 'cer, then 2 squared = 4 : and 4 multiplied by .7854 = 3. 1416 square inches, the area of the valve. The whole pressure on the valve is 60 pounds 31416 = 188.496 pounds. The distance of the center of the valve from the fulcrum is 2 inches, and 188.496 multiplied by 2 = 376.992, From this proauct, subtract the product of the weight of the valve and lever (lo pounds) by the half-length of lever, 7 inches (total length of lever 14 inches) or 10 7 = 70. Then 376.992 — 70 = 306.992; and 306.922 divided by the length of the lever, or 14 inches, equals 21.928 pounds, the required length of ball. To find the pressure on the valve. — Multiply the weight of *1>^ ball by the length of the lever; to this product add the ^rocruct of the v/eight of the lever and valve by the half- length of lever, and divide the sum by the distance of the valve from the fulcrum. The quotient is the pressure on the valve in pounds. Divide this quotient by the area of the valve in square inches, and the quotient will give the blow-off pressure. v Suppose the ball weighs 21.928 pounds, the length of the lever 14 inches, the weight of the lever and valve 10 pounds, the distance of the valve from the fulcrum 2 inches, then (21.928 X 14 = 306.992) + 10 X 7 r= 70 = 376.992; and 376.992 7-2= 188.496 pounds, the whole pressure on the valve. This pressure divided by 3. 1416 square inches, the area of the 2" valve =60 pounds, the pressure per square inch on the boiler. SAFETY VALVE CAPACITY. A safety valve should be capable of discharging all the steam that the boiler can make with all other outlets shut. The United States regulations call for one-half square inch valve area for each square foot of grates; but where the lift will give an effective area of one-half that due to the diameter of the valve, one-fourth square inch valve area per square foot of grate will answer. They give the following diame- ters: 51 Area of Grate, Square Feet. D 7 o O 9 lO 12 14 i6 i8 20 22 24 26 28 32 34 a6 Diameter of Valve, Inches. .... Common Valve. Improved Valve. ISX ^ 2 I 2'/$ I 2X i>^ 2^8 i>i 2K iX 2|< iH 3 I'A 3X iH 3^8 iH 3>^ 1% 3^ i^ 3^ 2 4 2 4X 2>^ ■ 4>^8 2% 4^ 2X 4^ 2/8 4I4: 2^ CARE OF BOILERS. 1. Safety Valves. — Great care should be exercised to sec that these valves are ample in size and in working order. (See rules for Safety Valves, page 82.) Overloading or neg- lect frequently lead to the most disastrous results. Safety- valves should be tried at least once a day to see if they will act properly. 2. Pressure Gauge. — The steam-gauge should stand at zero when the pressure is off, and it should show same press- ure as the safety valve when the latter is blowing off. If not, then one is wrong, and the gauge should be tested by one known to be correct. 3. Water Level. — The first duty of an engineer before starting is to see that the water is at the proper height. Do not rely on glass gauges, floats or water alarms, but try the gauge-cocks. 4. Gauge-Cocks and Water-Gauges. — Both must be kept clean. Water-gauges should be blown out frequently, and the glasses and passages to gauge kept clean. 5. Feed- Pump or Injector. — TJ-ese should be kept in per- 52 feet order, and of ample size. No make of pump can be expected t*^ be continuously reliable without regular and care- ful attention. It is always safe to have two ireans of feeding the boiler. Check-valves and self-acting feed-valves should be frequently examined and cleaned. . Satisfy yourself that the valve is acting when the feed-pump is at work. 6. Lozv Water. — In case of low water immediately cover the fire with ashes (wet if possible) or any earth that may t>e at hand. If nothmg else is handy use fresh coal. Draw fires as soon as it can be dene without increasing the heat. Veitker tiii-n on the feed, start or stop engine^ or lift safety- valve until fires are out a7td the boiler cooled down. 7. Blister and Cracks. — These are liable to occur in the best plate iron or steel. When first indications appears, there must be no delay in having it examined and carefully cared for. 8. Fusible Plugs. — When used, must be examined when the boiler is cleaned, and carefully scraped clean on both water and fire sides, or they are liable not to act. 9. Firing. — Charge evenly and regularly, a little at a time. Moderately thick fires are most economical, but thin firing must be used when draught is poor. Take care to keep the grates evenly covered, and allow no air-holes in the fire. Be especially careful to lay the coal along the sides and in the corners. All lumps should be broken into the size of a man's fist. With bituminous coal, a " coking fire-* (that is, hring in front, and then shoving the coal back when it is coked), gives the best result. Do not " clean " fires oftener than necessary. The cleaning of the fire is best done, in ordinary working, by a " rake," or other tool, working on the under side of the grate, and not by a " slice-bar," driven into the mass of fuel above the grates. 10. Cleaning. — All heating surfaces must oe kept clean, outside and in, or there will be serious waste of fuel. The frequency of cleaning will depend on the nature of the fuel and water. As a rule never allow over one-sixteenth inch scales or soot to collect on surfaces between cleanings. Hand holes should be frequently removed and surfaces examined, particularly in case of a new boiler, until proper intervals between cleanings have been established by experience. Examine mud-drums and remove sediment therefrom. 1 1. Hot Water Feed. — Cold water should never be fed into a boiler if it can be avoided, but when necessary, it should be caused to mix with ihe heated water before ceding in con- tact with any portion of the boiler. .S3 12. Foaini7ig. — When fv:)aming occurs in a boiler, check- ing the outflow of the steam will usually stop it. If caused by dirty water, blowing dow^n and pumping up will generally cure it. In cases of violent foaming, check the draught and oover the fires. 13. Air Leaks. — Be sure that all openings for admission of air to boiler or flue, except -through the fire, be carefully stopped. This is often an unsuspected cause of serious waste. 14. BloTving Off. — If feed-water is muddy or salt, blow oft a portion often, according to the condition of the water. Empty the boiler every week or two, and fill up fresh. When surface blow-cocks are used, thev should be often opened for a few minutes at a time. Make sure no water is escaping from the blnw-off cock when it is supposed to be closed. Blow-off cocks an J check-valves should be examined every time the boiler is cleaned. 15. Leaks. — Repair leaks as soon as possible after dis- covered. 16. Emptying Boiler. — Never empty the boiler while the brick- work is hot. 17. Rapid Llring. — Don't indulge in rapid firing. S.tean? should be raised slowly from a cold boiler, 18. Standing Unused. — If a boiler is not required foi some time, empty and dry it thoroughly. If this is imprac- tical, fill it quite full of water, and put in a quantity of common washing soda. 19. Genei'al Cleanliness. — -All things about the boiler- room should be kept clean and in good order.. Negligence tends to waste and decay. INJECTORS, In setting up injectors, be careful that all the supply-pipes, steam, water or delivery, have the same diameter (internal diameter) as the hole, nipple, branch, ping, tee, or reducer to which tljey are attache:!, and that they are as smooth, direct and straight as possible. Place a sirainer over the end of the supply pipe to keep out chips, dirt, etc., but be careful that the meshes or holes of the str?iner will equal in area the area of the sup)")ly-)-)ipe. In piping for steam for the injector, take steam from the highest ])art of the boiler so as to get dry steam. All pipes should l)e air and water tight, otherwise the injectr^r will k'ck back, take air and sjnitter. In ca^e the water is not to be lifted, but is fed witii a heuU 5V from a tank or hydrant, place a stop cock on the pipe to keep the boiler from being flooded. A stop-valve should also be placed in the steam-pipe, be- tween ike steam-room and the boiler and injector, and a check-valve between the water- space and injector. PUMPS FOR SUPPLYING BOILERS. N^ver use smaller diameters of pipes than are called for in tne tables furnished by the manufacturers of the pump, as all makers of pumps know the capacity and work to be done by their pumps and their calculations are correct; however, when long pipes are used it is necessary to increase the diam- eter to allow for increased friction. Observe this suggestion especially in regard to suction-pipes. Use as few elbows, T\^# and valves as possible, and run every pipe in as direct a line as practicable; use full, round bends when convenient; use Y's instead of T's when possible. Bends, returns, T's 5ind elbows increase friction more rapidly than length of pipe. Care should he taken against leaks in the sitction-ptpe, as a very s?nall leak destroys the effectiveness of the suction of a ptwip. See to it that a full head of water is constantly furnished to pump. To prevent the pump from freezing in cold weather, care should be taken to open the drip-plugs and cocks which are provided for the purpose of draining the pump, Water at a high temperature cannot be raised any consid- erabfe distance by suction. For pumping very hot water, .place the supply high enough so that the water will gravitate to the pump. A large suction-chamber placed on the suction-pipe im- mediately by the pump is very advantageous, and for pumps ranning at high speed it is a 7iecessity. Keep the stuffing- boxes nicely packed. Ordinary speed to run a pump is not over ioo feet piston travel per minute. For continuous boiler-feeding service about half that speed is recommended. Take as good care of your piwip as you do of your engine. SOME USEFUL INFORMATION ABOUT WATER. Doubling the diameter of a pipe increases its capacity /(^^/r times. Friction of liquids increases as the square of velocity. To fnd the pressure in square inches of a colu7nn of water, — Multiply the height of the column in feet by .434, approxi- mately, every foot elevation is equal to % pound pressure per square inch ; this allows for ordinary frictioa. 55 FRICTION OF WATER IN PIPES. Friction-loss in Pounds Pressure per square inch, for each loo feet of length in different size clean Iron Pipes discharging given quanti- ties of water per minute. a 2 SIZES OF PIPES— [NSIDE DIAMETER. J2 s K In. t In. iKIn. iMIn. 2 In. 2MIn. 3 In. 4 In. 6 .n. 8 In. 5 lO 3 3 13. 28.7 50 4 78.0 84 3 16 6.98 12 3 19.0 27 5 37 48. 31 1.05 2.38 4.07 6.40 915 12.4 16. 1 20. 2 24.9 56.1 12 0.47 0.97 1.66 2.62 3-75 505 6.52 8.15 10. 22.4 39-0 ' 0.12 15 t 20 0.42 0-91 ' * ' 25 30 35 40 45 50 75 100 0.21 O.IO 1.60 2.44 5-32 9.46 14.9 21.2 28.1 37-5 0.81 1.80 3.20 4.89 7.0 9.46 12.47 19.66 28 06 0-35 0.74 I-3I 3-85 5.02 7.76 II. 2 15-2 29s 25.0 30.8 0.09 0-33 0.05 125 150 175 200 0.69 O.IO 1.22 1.89 2.66 3-65 4-73 6.01 7-43 0.17 0.26 0.37 0.50 0.65 0.81 0.96 2.21 3.88 250 300 350 400 450 500 750 c .... 12 16 0.25 0.53 0.94 1.46 2.09 1250 1500 * The mean pressure of the atmosphere is usually estimated at 14.7 pounds per square inch, so that with a perfect vacu- um, it will sustain a column of mercury 29.9 inches, or a col- umn of water 33.9 feet high. To find the diafneter of a p7imp cylinder to move a given quantity of water per minute (100 feet of piston travel being the standard of speed), divide the number of gallons by 4, then extract tlie square root, and the product will be the diameter in inches of the pump cylinder To find tJie quantity of water ^X^^dX^A in one minute, run- ning at 100 feet of piston speed per minute, square the dianv eter of the water-cylinder in inches and multiply by 4. Ex- ample' Capacity of a 5 -inch cylinder is desired. The square of the diameter (5 inches) is 25, vvhich, multipHed by 4, q^ives 100, the number of gallons per minute, nearlv 56 71 fi^ni {l-:f..e. plier Feet. Feet. Feet. 5 2o2S 18 9-5 40 14.2 2 3.2 20 10. 45 151 4 4.5 22 10.5 50 16. 6 5-44 24 II. 60 17-4 8 6.4 26 11.5 70 18.8 m 7-1 28 12. 80 20.1 jf2 7.8 30 12.3 90 21,3 14 8.4 32 12.7 100 22.5 KO 9- 35 133 To find the size of hole necessary to discharge a given quan- tity of water tinder a given head. — Divide the cubic feet of water discharged by the number corresponding to height, as per tal:>le. The quotient will be the area of orifice required in square inches. 57 O 00 0>4^ ^0 G OO'-^r W *~J <-^- Or 4::^ Ck) Ck) Ui tj 2 cu. rD r 3 4^ M O OC" to 4^-1^ On to to to to O O^4'^"^<-n4^4^O0OJ Gs k-i <-n to h) »H >-< b ^J 4>> On b 4*- b OC OnOJ c1> to »-i b b b o 0<-/i4^ i-t O'^I tOO^vO^-fi>t-n >->i«J to 1-1 C^ O-iC-M-^rO O O O O O to to tOLnO-iO-n-nLn 00<-^000 0<-rn^;-nO OO OO CO ?r OCOi 4i^ to to 1-1 1-1 ^ O0oOC^O-I^O00 ON-f^ 4^ OO i-i NH O OCOOi-i O^J tOC-nVOO tO ^ C^ O ■^ 4^ (^ crq OjOJN)tOpi-HMHI-IHNI-l 4i.4uU)tOtOMI-ll-ll-.WI-*HH 00 On OnUiOt 4^ ^i- 10 tO tO •-1 •-" 00 O On On On^-ti C-n4i.4u^OJ to tOt-i t-i K>tOMKtO-Ni-.i-.i-(»-<»-ihH^ ^^. re — w ^3 0^ n 0) 1— ■ 0) o 3 U' n w c •13 •-t n 5 ^ p Tl v; t3 g ?? 3 CL n> rD n» C HI C/5 3 H-ic o ► o 3^'r; :t. H) re o ^ f rt -I f^ I— ( N M > o n > O > C/5 > > w o w w w o c S8 To find the height 7iecessa7'y to discharge a given quantity through a given orifice. — Divide the cubic feet of water dis- charged by the area of orifice in square inches. The quotient will be the number corresponding to height, as per table. The above rules represent the actual quantities that will be delivered through a hole cut in the pij?te; if a short pipe be attached the quantity "v^'ill be increased, the greatest deUvery with a straight pipe being attained with a length equal to four times the diameter of the hole. If a taper pipe be attached the delivery will be still greater, being \y^ times the delivery through the plain orifice. STEAM FOR HEATING. In estimating for steam-heating, allow one square foot of boiler surface for each ten square feet of radiating surface. Small boilers should be larger proportionately than large boilers. Each horse-power of boiler will supply from 250 to 350 feet of I inch pipe, or 80 to 120 square feet of radiating surface. Under ordinary circumstances, one horse-power will heat about as follows : Brick buildings in blocks 15,000 to 20,000 cubic feet. Brick stores in blocks 10,000 to 15,000 '* *' Brick dwellings, exposed all sides io,coo to 15,000 *' '* Brick mills, shops, etc 7,000 to 10,000 " *' Wooden buildings, exposed 7,000 to 10,000 Foundries and wooden shops. . , .6,000 to 10,000 It is, of course, but g^od workmanship to make ell the ioints steam and water tight, as the slightest leak in a steam- heating system is apt to do considerable damage to furniture, curtains, carpets, etc., if the steam is intended to heat a dwell- ing. Red or white lead is all right as material to make up joints, but graphite is much better (see page 141). For gas- kets there is nothing better than asbestos, and this material is now manufactured into gasket rings cut true to size, mak- ing asbestos gaskets not only the best, but furnished in a convenient form which will be highly appreciated by the steam-fitter. The quality of rubber sheets sold by dealers for gaskets, is sometimes of the poorest order, and rubber in any form, vul- canized or otherwise, is poor stuff to put in contact with steam. Gaskets made of thin lead are good, and first class packing can be made of candle wicking and ordinary resin soap, but asbestos is the best. 59 THE WESTINGHOUSE AUTOMATIC BRAKE. The Westinghouse Automatic Brake consists of the follow- ing essential parts : I St. The stea7Ji engine and piuiip^ which produce the com- pressed air, the supply of steam being regulated by the pump- governor. 2d. The 7?iain reservoir^ in which the compressed air is stored. 3d. The e7tginee'/s drake-valve, which regulates the flow of air from the main reservoir into the brake-pipe for releas- ing the brakes, and from the brake-pipe to the atmosphere for applying the brakes. 4th. The equalizing -valve, which is connected to a small reservoir, and permits the escape of air from the main brake- pipe, until the pressure in that pipe throughout the entire train is reduced to the same pressure as that in the small reservoir, thus preventing the release of the forward brakes by the engineer closing the brake-valve too quickly, before the pressure in the rear part of the pipe has had time to be- come reduced. 5th. The main brake-pipe , which leads from the main reservoir to the engineer's brake-valve, and thence along the train, supplying the apparatus on each vehicle with air. 6th. The auxiliary resej'z'oir, which take^ a supply of air from the main reservoir through the brake-pipe, and stores it for use on its own vehicle. yth. The brake-cylinder, which has its piston-rod attached to the brake-levers in such a manner that, when the piston is forced out by air pressure, the brakes are applied. 8th. The triple valve, which connects the brake- pipe to the auxiliary reservoir, and connects the latter to the brake- cylinder, and is operated by a sudden variation of pressure in the brake-pipe (i) so as to admit air from the auxiliary reser- voir to the brake-cylinder, which applies the brakes, at the same time cutting off the communication from the brake-pipe to the auxiliary reservoir, or (2) to restore the supply from the brake-pipe to the auxiliary reservoir, at the same time letting the air in the brake-cylinder escape, which releases the brake. 9th. The couplings, which are attached to flexible hose and connect the brake-pipe from one veliicle to another. The automatic action of the brake is due to the C(Mistruc- tion of the triple valve, the primary ]\ans of which arc a piston and a slide-valve. A reduction of pressure in tlic br.\ke- pipe causes the excess of pressure in the auxiliary r-sorv -ir 'o force the piston of the triple valve down, moving the slide" valve tiown so as to allow the air in the auxiliary reservoir to pass directly into the brake-cyhnder and apply the brakes. When ihe pressuie in the brake-pipe is again increased above that in the auxiliary reservoir the piston is forced up, moving the slide-valve to its former position, opening communication from the brake-pipe to the auxiliary reservoir and permitting the air in the brake-cylinder to escape, thus releasing the brakes. Thus it will be seen that any reduction of pressure in the brake-pipe applies the drakes^which is the essential feature of the automatic brake. If the engineer wishes to apply the brakes he moves the handle of the engineer's brake- valve to the right, which first closes a valve retaining the pressure in the main reservoir and then permits a portion of the air in the brake-pipe to escape. To release the brakes he turns the handle to its former position, which allows the air in the main reservoir to flow into the brake- pipe, restoring the pressure and releasing the brakes. A valve called the conductor'' s valve is placed in each car, with a cord running the length of the car, and any of the trainmen, by pulling this cord can open the valve, which allows the air to escape from the brake-pipe. In applying the brake in this manner the valve must be held open until the train comes to a stop. Should the train break in two the air in the brake-pipe escapes and the brakes are ap- plied to both sections of the train, and should a hose or pipe burst the brakes are also automatically applied. 77^^ ^^^7/^^ shows the pressure in the main reservoir and brake-pipe when they are connected, and the pressure in the brake-pipe alone when the main reservoir is shut off by the movement of the engineer's brake-valve. A stop cock is placed in each end of the brake-pipe, and is closed before separating the couplings, thus preventing an application of the brakes when cars are uncoupled. The diagram above the engineer's brake-valve shows the various positions of the handle for applying the brakes with any desired degree of force, for releasing the brakes, and the position in which the handle is to be kept after the brakes have been released. Following will be .found detailed views and descriptions of detached portions of the apparatus; also a full series of in- structions for its proper use and maintenance. ,Too much importance cannot be attached to that portion of the instruc- tions stating that engineers should use care and moderation 6i in applying the brakes for ordina 'y stops. By applying them at a lair distance Irom the station, with moderate force, the tram is stopped gently and without inconvenience to the passengers, while if they are thrown on with the utmost force possible, the train is jerked in a manner that is extremely disagreeable to the passengers. AIR PUMP. Referring to cut, it will be seen that the steam from the boiler enters the top cylinder between two pistons forming the main valve. The upper piston being of greater diameter than the lower, the tendency of the pressure is to raise the valve, unless it is held down by the pressure of a third piston of sti)i greater diameter, working in a cylinder directly above the main valve. The pressure on this third piston is regulated by the small slide-valve, working in the central chamber on the top head. This valve receives its motion from a rod extending into the hollow piston which, as shown in the drawing, has a knob at its lower end and a shoulder just below the top head. This valve chamber in the top head, by a suitable steam-port, is constantly in communication with the steam space between the two pistons of the main valve. The steam acting on the third piston and holding the main valve down, admits steam below the main piston; as the main piston approaches the upper head, the reversing-valve rod and its valve are raised until the slide-valve exhausts the steam from the space above the third, or reversing-piston, vi^hen the main valve is raised by the steam pressure on the greater area of its upper piston, which movement of the main valve admits steam to the upper end of the main cylinder. When the main valve i. ^noved up to admit steam to the upper end of the cylinder, it opens an exhaust port at the lower end just below the lower steam-port, which latter is closed by the lower piston of the main valve; and when the main j^iston is on its upward stroke the upper exhaust-port is similarly opened. The air valves of the pump are similar to those used in all pumps. The lift of a discharge valve should not exceed one- sixteenth of an inch, and the lift of receiving valves should not exceed one-eighth of an inch. Care should be taken to have the lift of the discharge valves exactly the same, other- wise the stroke of the pump will b^ quicker in one direction than in the other. 02 TRIPLE VALVE. The arrangement of the auxiliary reservoir, cylinder and triple-valve, with the latter in section, are shown in cut The triple valve has a piston 5, working in the chamber Bj and carrying with it the slide-valve 6. Air entering from the main pipe passes through the four-way cock 13 by ports a^ <:, and the drain-cup A, and chamber B, forcing the piston 5 into its normal position as shown, thence through a small groove past the piston into the valve-chamber above, and into the auxiliary reservoir, while at the same time there is an op'' b4 communication from the brake-cylinder to the atmosphere, through the passage d^ e^ f ana g. Air will continue to flow into the auxiliary reservoir until it contains the same pressure as the main brake-pipe. To apply the brakes with their full force, the pressure in the main brake-pipe is allowed to escape, whereupon the greater pressure in the auxiliary reservoir forces the piston he brake-cylinder, the triple-valve and auxiliary reservoii being cut out, and the apparatus can be worked as a non- automatic brake by admitting air into the main brake-pipe and brake-cylinder, to apply the brakes. When from any cause it is desirable to have the brake inoperative on any particular car, the four-way cock is turned to an intermediate position, which shuts off the brake-cylinder and reservoir, leaving the main brake-pipe uTiobstructed to supply air to the remaining vehicles. The drain cup A collects any moisture that may accumu- late, and is drained by unscrewing the bottom nut. engineer's brakb-valve. The handle i of the engineer's brake-valve terminates in S Jcrew with a coarse thread, which compresses a spring 4 upoi 'he top valve 3; this top valve fits into a slot in the handle ' 66 and into a slot in the main valve 6, so that the handle and the two valves must turn simultaneously. In the position shown in the drawing, which is for releasing the brakes, the top valve 3 leading to the atmosphere is kept closed by the compression of the spring 4, and the air passes freely fro«m the main reser- voir to the brake-pipe through the openings of the main valve and the body of the brake-valve. After the brakes are off, the handle is moved against the second stop, a short distance to the right, which turns the main valve so that the main passages to the break-pipe are closed. Air can, however, pass through the small valve 7, and thence to the brake-pipe through a small opening not shown in the drawing. This small valve 7 is held down by a spring whose resistance is equal to 20 lbs. per square inch, hence the pressure in the main reservoir will be 20 lbs. greater than that in the brake- pipe, which surplus pressure insures the certain release of the brakes when desired. To apply the brakes the handle is moved still further to the right, when the opening from the small valve 7 is also closed, cutting off all communication from the main reservoir to the brake-pipe, at the same time the action of the screw lifts the handle and relieves the spring 4 from pressure, when the air in the brake-pipe lifts the valve 3, and escapes, until an equilibrium is established between the air pressure and the pressure of the spring on the valve 3, thus reducing the pressure in the brake-pipe to an extent cor- responding to the distance which this handle is moved. To apply the brakes suddently the handle is turned the entire distance to the right, which relieves the spring ot all compres- sion, allowing the valve 3 to rise, and all of the air in the brake-pipe to escape. After the train is stopped, the brakes are released by turn- ing the handle to the position shown in the drawing. The pump-governor is shown in the cut, the object of which is to automatically cut off the supply of steam to the pump when the air pressure in the train-pipe exceeds a cer- tain limit, say 70 lbs. The operation of this governor is as follows: The wheel 8 is screwed down so as to permit the valve 10 to be unseated by the excess of pressure on the upper side of the valve per- mitting steam to pass through the openings A and B to the pump. A connection is made from the train-pipe to the up- per end of the governor, and the compressed air passes around the stem 14 to the upper side of the diaphragm plate 18, which is held to its position by the spring 16, which latter Is of sufficient strength to resist a pressure of say, 70 lbs< TO TRAIN PIP£ I UMP-GOVERNOR, 68 per square inch on diaphragm. As soon as the air pressure on the diaphragm i8 exceeds this amount, it forces the dia- phragm down, unseating the valve 13, and allowing the steam on the upper side of the valve 10 to escape through the exhaust 6, which causes an excess of steam pressure on the lower side of the valve 10, forcing the valve against its seat, and cutting off the supply of steam to the pump. When the pressure in the train-pipe is diminished by ap- plying the brakes, the diaphragm is restored to the position shown by the action of the spring 16. The valve 13 is seated by the spring 12, and the steam pressure passing through the portC, accumulates on the upper side of the valve iO, forcing it down, and opening the passage for steam to the pump until the air pressure is again restored to the required limit of 70 lbs. The use of the governor not only prevents the carrying of an excessive air pressure by the engineers^ which may result in the sliding of the wheels, but it also causes the accumulatiou of a surplus of air pressure in the main reservoir while the brakes are applied, which insures the release of the brakes without delay. It also limits the speed of the pump and con- sequently the wear. EQUALIZING VALVE. The proper application of the brakes depends upon the amount of air discharged from the train pipe, and the manner in which it is discharged. The amount of air to be dis- charged -also depends upon the length of train. As stated in the general description of the brake apparatus, the brakes are applied by reducing the pressure in the train pipe, and are released by increasing the pressure. On long trains engineers have found it very difficult to discharge the air in such a way that they will not first cause a large reduc- tion in the front portion of the pipe, and then an increase tending to release the brakes on the tender and two or three cars next; the increase of pressure being due to the expan- sion of the air in the pipes of the rear portion of the train. The equalizing valve which is shown in Plate 6 (which serves also as a large drain cup), is a device which automatically provides for the proper discharge of the air on all of the vehicles, 'back of the tender, the engineer having to discharge only the required amount from his brake-valve, and always a given amount for a certain degree of application, whether the train consists of one or fifty cars. In the position shown, the air from the equalizing reservoir passes through the ports of the equalizing valve as shown by 09 the arrows and into the train pipe. When the pressure m the equalizing reservoir is reduced slightly to apply the brakes, the piston 15 moves down carrying the valve 11 from its seat and permitting the air in the train pipe to escape through the ports d^ e and g, until the pressure in the train pipe equals that in the equalizing reservoir, when the piston and valve 1 1 return gradually to the position shown. When it is desired to apply the brakes quickly with full force a con- siderable reduction is made in the pressure in the equalizing reservoir and the piston moves down its entire distance car- rymg with it the slide valve 4 and uncovering the upper port g^ while air is also allowed to escape through the port /and the lower port g^ thus permitting a rapid escape of the press- ure in the train pipe until it equals that in the reservoir, when the valve returns to the position shown. INSTRUCTIONS. General, — In making up trains all couplings must be united so that the brakes will apply throughout the entire train. The cocks in the brake-pipe must all be opened (handles point- ing down), except that on the rear of the last car, which must be closed. In detaching engines or cars the couplings must invariably be parted by hand; the cocks in the main brake-pipes must always be closed before separating the couplings, to prevent application of the brakes. If the brakes are applied when the engine is not attached to the train or car, they can be released by opening the re- lease cock usually put in the end of the brake-cylinder. The adjustment of the break-gear should be such, that when the brakes are full on, the pistons in the brake-cylinders will not have traveled to exceed eight or nine inches. Ihis will allow for wear of shoes, stretching of rods, springing of brake-beams, etc. In narrow gauge freight apparatus the adjustment must be such that the piston will not travel more than five or six inches. Great care must be exercised when taking up the slack in the brake connections to have the levers and pistons pushed back to their proper places and the slack taken up by the under connection, or dead levers. The brake-cylinders must always be kept clean so that they will readily release when the air has been discharged, and should be oiled once in three months. The last date of oiling should be marked on the cylinder with chalk. I For the automatic break the handle of the four-way cock must be turned horizontally. If turned down it will be 70 changed to the simple air-brake; if turned midway between these two positions, it will close communication with the brake-cylinder and reservoir, and should be so turned when desirable to have the brakes out of use on any particular car on account of the breaking of rods, etc. It is very important, in order to avoid detentions, to keep the handles of these four-way cocks in their proper positions. In cold weather the triple valve should be drained fre- quently, to let out any water that may have collected. Slack the bottom nut of the triple valve about half a turn, let the water escape and screw it up again. The valve for the ap- plication of the brakes from the inside of the car should be kept tight, and must be examined by the inspectors. Enginee7's must see that the steam-cylinder is kept well lubricated; that the air-cylinder is sparingly lubricated with a small quantity of 28^ gravity West Virginia well oil; (tallow or lard oil must not be used in the air-cylinder); that the pump is constantly run, but never faster than is necessary to maintain the required air pressure; and that air from 50 to 60 pounds pressure for low speed or way trains, and from 70 to 80 pounds pressure for express trains is carried. For ordinary stops the brakes should be applied lightly by opening the valve or cock and closing it gently when the pressure has been reduced from 4 to 8 pounds on the gauge. The brakes are fully applied when the pressure shown on the gauge is reduced 20 pounds. Any further reduction is a waste of air. In releasing the brakes, the handle of the brake-valve must be moved quite against the stop and be kept there for about ten seconds, and then moved back against the inter- mediate stop, which is the feed position, and where it must remain while the train is running. Engineers, upon finding that the brakes have been ap- plied by the train men or automatically, must at once aid in stopping the train by turning the handle of the brake- valve toward the right, thus preventing escape of air from the main reservoir. The slioes of the driving-wheel brakes should be so ad- justed by turning the screws that the piston moves up from 3 to 4 inches when the brakes are applied. It is important to drain the water out of the main reservoir once a week, especially in winter time, and oftener if the pump-rod is not kept well packed. If cars having different air pressures be coupled together, the brakes ^v;i I apply themselves on those which have the highest pressure. To insure the certain release of ait the brakes in the train, and also that trains may be charged quickly, the engineer must carry the maximum piessure in the main reservoir before connecting to a train, and then put the handle of his brake- valve in the release position until the train is charged with air. If the brakes on the engine and tender thus apply themselves by being coupled to a train not charged, they should at once be taken off by opening the re- lease cock from the brake-cylinders, which ought to be so arranged as to be worked from the foot-plate. Train-Men. — After making up or adding to a train, or after a change of engines, the rear brakeman shall ascertain whether the brake is connected throughout the train. When the hose couplings are not used for connecting the brakes between two vehicles, they must be attached to their dummy couplings. When there is occasion to apply the brakes from the cars, the valve must be held open to allow the air to escape until the train is brought to a stand-still, but this method of ap- plication should only be used in cases of emergency. Train-men must in all cases see that the hand-brakes are off before starting. Before detaching the engine or any carriages, the brakes must be fully released on the whole train. Neglecting this precaution, or setting the brakes by opening a valve or cock when the engine is detached, may cause serious incon- venience in switching. The pipes and joints must be kept tight, and when leaks are discovered they should be corrected, if serious, before the car is again used. HOW TO APPLY AND RELEASE THE WESTING- HOUSE AUTOMATIC BRAKE. The brakes, as has been explained, are applied when the pressure in the brake pipe is suddenly reduced, and released when the pressure is restored. It is of very great importance that every engineer should bear in mind that the air pressure may sometimes reduce slowly, owing to the steam pressure getting low, or from the stopping of the pump, or from a leakage in some of the pipes when one or more cars are detached for switching pur- poses, and that in consequence it has been found absolutely necessary to provide each cylinder with what is called a leak- age groove, which permits a slight pressure to escape with- out moving the piston, thus preventing the application of the 72 brakes when the pressure is slowly reduced, as would result from any of the above causes. This provision against the accidental application of the brakes must be taken into consideration, or else it will some- times happen that all of the brakes will not be applied when such is the intention, simply because the air has been dis- charged so slowly from the brake-pipe that it only represents a considerable leakage, and thus allows the air under some cars to be wasted. It is thus very essential to discharge enough air in the first instance, and with sufficient rapidity, to cause all of the leak- age grooves lO be closed, which will remain closed until the brakes have been released. In no case should the reduction in the brake-pipe for closing the leakage grooves be less than four or five pounds, which will move all pistons out so that the brake-shoes will be only slightly bearing against the wheels. After this first reduction the pressure can be re- duced to suit the circumstances. '^^ On a long train, if the engineer's brake-valve be opened suddenly, and then quickly closed, the pressure in the brake- pipe, as indicated by the gauge, wiU be suddenly and consid- erably reduced on the engine, and will then be increased by the air pressure coming from the rear of the train ; hence it is imporiant to always close the engineer's brake-valve slowly, and in such a manner that the pressure as indicated by the gauge will not be increased, or else the brakes on the engine and tender, and sometimes on the first one or two cars will come off when they should remain on. It is likewise very important, while the brakes are on, to keep the engineer's brake-valve in such a position that the brake-pipe pressure cannot be increased by leakage from the main reservoir, for any increase of pressure in the brake, pipe causes the brakes to come off. On long down grades it is important to be able to control the speed of the train, and at the same time to maintain a good working pressure. This is easily accomplished where the pressure-retaining valve is not in use, by running the pump at a good speed, so that the main reservoir will accumulate a high pressure while the brakes are on. When, after using the brakes some time, the pressure has been reduced to sixty pounds, the train pipes and reservoirs should be recharged as much as possible before the speed has increased to the maxi- mum allowed. A greater time for recharging is obtained by considerably reducing the speed of the train just before re- charging and by taking advantage of variation in the grades. 73 There should not be any safety-valves or leaks in the main reservoir, otherwise the necessary surplus pressure fcttr quickly recharging cannot be obtained. To release the brakes with certainty it is important to have a higher pressure in the main reservoir than in the main pipe. If an engineer feels that some of his brakes are not off, it is best to turn the handle of the engineer's brake- valve just far enough to shut off the main reservoir, and then pump up fifteen or twenty pounds extra, which will insure there- lease of all of the brakes; all of which can be done while the train is in motion. For ordinary stops great economy in the use of air is effected by, in the first instance, letting out from eight to twelve pounds pressure, while the train is at speed, taking care to begin a sufficient distance from the station, BRAKE POWER. To obtain the best results, it is important to have the brak- ing force proportioned to the weight of the car, or more par- ticularly speaking, to the load carried by those wneels upon. w^hich brakes act. After long experience it has been decided to recommend such a proportion of brake levers that a press* ure of fifty pounds per square inch on the brake piston will bring a force against the brake-blocks on each pair of wheels equal to the load carried by them; thus, owing to a great variation of cars, it is impossible to have uniform brake levers. For convenience it has been found best to cut the brake connection which joins the brakes of both trucks and to inter- pose at this point the brake-cyHnder, having with it two levers and a tie-rod. With this arrangement it is only necessary to get the proper portion of these cylinder levers. The following rules will enable those whose duty it is to attach brakes to proportion the levers, so as to carry out tile foregoing recommendation. RULE FOR CALCULATING CAR LEVERS. The air pressure is rated at fifty (50) pounds per squarr inch on piston, when the brakes are fully applied. (50 lbs. per square inch gives about 4,000 lbs. for lo-inch cylinder^ and 2,500 lbs. for 8-inch cylinder.) To find the leverage regiiired. — Divide the weight of the caj resting upon the brake-wheels by the zvhole pressure on piston. To find proportion of brake beam levers, — Divide the whoit length of lever by short end. 74 To find the total brake beam leverage. — Multiply propor- tion of lever by two (2) for the Hodge system, and by four (4) for the Steve7ts\ To find proportion of cylinder lever. — Multiply the whole iength of lever by either the required leverage, or the total brake beam leverage, and divide by the sum of both, the result will give the length of one end of the lever. If the required leverage is greater than the totalhrake beam leverage, the long end of the lever must go next to the cylin- der; if less, the short end must go next to the cylinder. Dead levers must be made in the same proportion as the other truck levers. Exa niple— Hodge Syste77i . Weight of car 36,000 lbs. Total pressure on lo-inch piston 4,000 " Total length brake beam lever 28 inches. Length of short end of brake beam lever 7 " Total length of cylinder lever 24 " 36,000 -f- 4,000 = 9, leverage required. 28-^ 7 = 4X2=8, total brake beam leverage. 24 X 8 = 192 -f- (8 + 9) = 1 1.3, short end cylinder lever. 24 — 1 1.3 = 12.7, long end cylinder lever. Exai7iple — Stevens'* System, Total length of cylinder lever 36 inches. 36,000 — 4,000=9, leverage required. 28-T-7 = 4>^4= ^^> total brake beam leverage. 36 X 9 =324-7- (9+ 16) = 12.96, short end cylinder lever. 36 — 12.96 = 23.04, long end cylinder lever. INFLUENCE OF ROADS AND WEATHER ON TRACTION. According to tests by E. Whyte-Smith, and communicated to the Institute of Electrical Engineers, the pull ■ required per ton of vehicle for various roads and for three different conditions of weather is given in the following table: Asphalt, 22 23 22^ Wood, 22 31 36 Pull Macadam (good). 52 50 49 > in lbs. Macadam, . 60 51 50 per ton. Macadam (soft), . 97 51 52 J /5 COLD CHISELS. □^^« I Figures i and 2 are drawings of flat \\ \ I chisels. The difference between the two is 11/ ^^^U as the cutting edge should be parallel c==* V with the flats on the chisel, and as Fig. i **** ^"^ has the widest flat, it is easier to tell with it when the cutting edge and the flats are parallel; therefore the broad flat is the best guide in holding the chisel level to the surface to be chipped. Either of these chisels is of a proper width for wrought iron or steel, because chisels used on these metals take all the power to drive that can be given with a hammer of the usual proportions for heavy clipping, which is: Weight of hammer, i^ lbs.; length of hammer- handle, 13 in. ; the handle to be held at its end, and swinging back about vertically over the shoulder. If so narrov/ a chisel be used on cast iron or brass with full force hammer blows, it will break out the metal mstead of cutting it, and the break may come below the depth wanted to chip, and leave ugly cavities. So for these metals the chisel must be broader, as in Fig. 3, so that the force of the blow will be spread over a greater length of chisel edge, and the edge will not move forward so much at each blow, therefore it will not break the metal out. Another advantage is that the Droader the chisel the easier it is to dY y^ f / hold its edge fair with the work U,^^^ — %^^/^ surface, and make smooth chipping. The chisel-point must be made as -^^ ' thin as possible, the thickness shown in sketches being suitable for new chisels. In grinding the two faces to form the chisel, be care- ful to avoid grinding them rounds as shown in a in the mag- nified chisel ends in Fig. 4; the proper way is to grind them flat, as in b in the same sketch. Make the angle or edge of these two faces as sharp or acute as you can because the chisel will then cut easier. For cutting brass, hold the chisel about the angle shown in c. Fig. 5; for steel, that at d same figure. The difference is, that with hard metal the more acute angle dulls too quickly. For heavy chipping, the point may be made flat as in Fig. i., or curved as in 70 jt«^ 1 ^1 jy.« Fig* 3' 9 which is the best, because the corners are relieved from duty, and are therefore less liable to break. The advantage of the curve is greatest in fine chipping, because, as seen in Fig. 6, a hner chip can be taken without cutting with the corner, and these corners are exposed to the eye in keeping the chisel edge level with the work surface. In any case do not grind the chisel hollow in its length, as in Fig. 7, or as shown exaggerated in Fig. 9, because, in that case the corners will dig in and cause the chisel to be beyond control; besides that, there will be a force, that, acting on the wedge principle, will operate to spread the corners and break them off. Do not grind the faces wider on one side than on the other of the chisel, as in Fig. 8, because, in that case, the flat of the chisel will form no guide to let you know when the cutting edge is level with the work surface. Nor must /■^-wv y°^ grind it out of square with the chisel body, as / /y^ ill ^ ig- io> because, in that case, the chisel will (^^__^ ^ be apt to jump sideways at each hammer-blow. »'**% A quantity of metal can be removed quicker by using the cape chisel in Fig. 11, to first cut out grooves, spacing these grooves a little narrower apart ^ than the width of the flat chisel, and thus relieving its corners. The chisel end must be shaped as at a and b^ and not as at c in Fig. II, so as to be able to move it side- ways, to guide it in a straight line, and the parallel part at c will inter- fere with this, so that if the chisel is started a very little out of line, it will go still further out of line, and cannot be moved sideways to correct the fault, round-nosed chisel. Fig. 12, must not be made straight on its convex edge; it may be straight from -^ to ^ but from ^ to the point, it must be beveled, so that by altering the height of the chisel head it is possible to alter the depth of the cut. The diamond point chisel in Fig. 14 and 15, must be shaped to suit the work, because if it is not to be used to cut out the corners of very deep holes, you can bevel The n It at m^ and these bring its point ^, central to the body of the steel, as shown by the dotted line ^, rendering the corner x less hable to break, which is the great trouble with this chisel; but in cutting deep holes the bevel at m must be omitted, and you must make the edge straight, as at r in Fig. 15.^ The side chisel obeys the same rule, so you may make it ^^ bevel at w, as in Fig. 16, for shallow holes, ana? /h^l lean it well over in using, and make the side v w Y\ N straight along its whole length for deep holes ; but in all chisels for slots or mortises it is desirable to have if circumstances will permit, some bevel on the side that meets the work, so that the depth of the cut can be regulated by moving the chisel head. In all these chisels, the chip on the work steadies the cutting end, and it is clear, th?t the nearer you hold the chisel at its head the steadier yoi can hold it, and the less the Hability to hit your fingers, while the chipped surface will be smoother. To take a chip off wrought iron, if it is a heavy chip, tand well away from the vice, as an old hand would do, in- stead of close to it; if, instead, you wish to take a light chip, you must stand nearer to the work, so that you can watch the chisel's action and keep its depth of cut level. In both cases you must push the chisel forward to its cut, and hold it as steadily as possible. It is a mistake to move it at each blow, as many do, be- cause it cannot be so accurately maintained at the proper leight. Light and quick blows are always necessary for the finishing cuts, whatever the kind of metal may be. TURNING OR LATHE TOOLS FOR METALS. Few lathe tools, except scrapers, can be used indiscrimi- [lately for cast iron, wrought iron or brass; each metal needs its particular set of tools, differing not so much in the shape i^f their cutting edges, as in the angles which they make with :he surface of the work to be turned. Thus, Figs. 17, iSv 7» in are each intended to represent in profile the ordinary roushing-dow.1 tool, but their angles are very dififerent the Som the other. Fig. 17. beingcnly suitab e for 'trough iron. Fig. 18 for cast iron and Fig. 19 for brass. In all 1- \if» these everything (temper of course excepted) depend upon tKgle a^t whkh the tools are ground. The brass tool with the flat face would not cut the iron, but would simply scratch if while the iron tools would hitch in the brass and tend to « chatter " or " draw-in. " Neither would the tool ground at an acute'angle for wrought iron, cut cast metal, but would itself become broken off at the tip, while the thicker casc iron tool would not take clean shavings off wrought iron, -b ig, 20 is a common roughing tool for cast iron. The side view gives a proper __„_ \- angle to insure a clean cut without f- ^^ j ^». breaking the top across in the di- -^J -^^ ' rection of the dotted line. The ^ " angle is drawn on the supposition , ., , .-, . t,„. that the toolis held horizontally, as indeed it should be but a tool that will not cut nicely ^^. ^^^^^^^^^^^^^^l^f^^^^^^^^ often work by inclining it at a slight angle, /either is the angle at which a tool should be grouna, m order to cut well horizontally, necessarily the same. It should be about 65^^ with the verical for cast iron, but may vary slightly either "^Yn fact, not one workman in ten could say what angle he trrinds his tools to ; he simply judges the proper angle by his 4e The angle which the front of the tool makes with the work may vary somewhat more than the upper face, depend- Lg up^n the diameter of the work to be turned but should aot slope more than 4^ or 5° from the vertical for cast iron {Fig. 18). If it becomes excessive the tool is weak and soon breaks off. : These details may seem trivid, but they are really of the utmost importance. These sketches are taken from tools ui 79 actual use and doing their work well. Fig 21 shows a round nose, Fig. 22 a parting tool, Fig. 23 a knife-tool for finishing edges and faces of flanges, and ends and sides of work, eithei right or left-handed (Fig. 24). The end views of these tools show the upper and clearance angles, which, are about the same as in Fig. 18, but may vary somewhat according to the work required. Figs. 25 are boring-tools for hollow cylinders, tools capa- ble of much modification, their cutting edges not only taking the forms of all other tools, but each form also being often right and left-handed. In reference to the more usual shape, that of the round nose for boring, when used simply as a roughing tool, the shape ^ showing it / • -) in place, with -the axis of the cutting C ^ ] I !/ angle in the direction of the dotted G S J X line, is better than that of «, because U in b the true cutting edge is carried *■" forward. Hence, in work-shops the cutting tools generally take the form b^ and the scrapers form a. Fig. 26 is a square nose for taking finishing cuts, and Fig. I JV^Jlt JWi, ^^'^^ 27 is a tool for scraping; Fig. 28 is a spring tool, also used for finishing a turned surface; Figs. 29 and 30 are for finish- ing hollows and rounded parts of work, and are either kept in different sweeps or ground to circles as wanted. These latter forms are only used for smoothing and polishn.g^ and, as they act simply as scrapef s, are flat on their upper surfaces. For grinding tools, a very handy little grind- stone may be made in this fashion (Fig, 31). A piece of broken grindstone, 2 inches thick, is * . . rudely clipped round to 7 inches in diameter, and * [ ^ a ^ ixich hole bored through the center with a common stone-bit; two wooden washers, a\ ^ ^' inch thick by 4 inches in diameter, also have Yz 50 incn iiolesj bored in their centers. A % inch bolt, b, thrust through the whole keeps them firmly together with the stone in the center. As the stone is intended to work chucked between cen- ters, a small drilled hole is run both into the bolt head and into the screwed end, and a V shaped slit, . ON 1 1-4 ON ON OnoO t^ t^ M CO uS t^ On •-< 2: 1 ONOO i>.>0 i/~> '^ CO r- < t^iori o r^Tj-N On 00 i>*vO i^ CO c>< O ON ©•-t COlOt^ONi-I CO'^ l-l 1=1 l-=J % C^ '^ I^ C^ VO O LOOO C^ On OOnO lococ^ OOO X:^'^ O i-J coi-Ot>*ON>-i *••< ■^vd HH l-X r.H c- 1 u 8 O *-* C^ CO CO --^ u-^ vovO 5^* OOVO TfC^ OOOVO "^M r O ►-J cOLOt^CNO' N rf vO °^ l-H hH l-l -H "^ 8. O 00 t^vO vO i-O -^ CO N !-• t-< onno '^c^ ooovo '^^^^ ooo d C< 30 o > 0- l>-i-0(N ONt^i-OroO r-^w-ic^ r^u-iroOOOvO COC^ On1>-ij^ O »-i CO lO l>»00* d N Tj- to r^ On hH HH 1-4 M M l-l < CO c O o oo rj- Q Vo >-i oo CO OnvO i-" r^ <:"0 00 VO ^ 1^ OnvO ""^ >-« ON r^ ""^ C^ d CS* "^vO X>. ON "-^ CO '^vo 00* d % TtONCOt-».MvO O O On ^00 C»Tfci Ovo '<^»-" ^ o "-H CO i^vd 00 d c4 Tfiot^dsd o o vO CNMi^t^O coo OCl^^ O0vocoot^»^r< Oi:^'<^'-"00vo CO c^ -^vd !>. d- « CO ^vd 00* ON t-J „ ,«, HI hH H^ Ml M z o hH CO rt" VJ-) r-oo O >-* ^) coiovo r^ H-I CO Lovd 00 d ^i CO Lo r^oo d n Q in o CO ONONONOoo OO oonq ooo ro O r-^ >-0 N OnvO CO O t^ "^ >-' 00 c4 r+- i-O I>- On O N ^vO r^ ON •-' N < JO 3amB4 VO c8 8 8 §-vo 00 q the amount of lead you want, and fasten it there; put the reverse lever in the back notch and turn the back-up eccentric back until the port is open, the same as it was with the go-ahead, and fasten eccentric Where only one eccentric it slipped, it is best to set it by marking the stem; that plan is the quickest, as you do not have to take off the cover. You will readily see that when one side is on /''.le center, the engine will go either way, as steam is adm^ -^- to one side or the other of the piston on the other sir* - Q^ locQ« motive, as it is in the center of cylinder, and by Cuting the eccentrics to give lead on the center, and by ti. xiing them the right way, you can't get them wrong. A goo\.' engineer: will always save himself all this trouble and delay on 'ch.Q rocA by marking the eccentrics in their proper position, L '^ ^ ?.s running a locomotive without eccentric keys. CHIMNEYS. The following table shows the proportion of sizes of chim neys to the horse-power of the boiler using the chimney. The measurements givnn for the diameter is for ?;//^'r;?^/ diam- eter. By referring back to the article on " Steam Boilers" commencing at page 45, the rules given for firegrate surface can be utilized in connection with this table in planning for the steam power of a plant. This table has been carefully compiled and arranged, and the proportions given may be accepted as correct. Too little attention is paid to chimneys, and the furnace is often blamed for poor resuhs wlien the ckimney is the part in wrong. Proper draught is all-import- ant, and one chimnf^"- should never be made to do the work of two ^ o pa U^ O (^ w o Oh w p^ O w o PLh < H I— I >^ W l-H u o CD W N C/2 •5J sJBnbs Bsjy IBnioy N. M Ti-OO H '^^ t^ N tv. ThVO t^OO 00 00 t^ t>. Tj- w O^ 0\ (y, mvO IT) o\vo t^ N w •* >-" N H N ro CO -^ u-i t^oo 0^ N lA ON rooo rnoo' 4- O •ysjBnbg B9jy 3Al5D3jgg c^ t^oo 00 00 00 r^ tv.vo -* m oo rooo mvo o m ^■^0 t^lOrfTi-lOt^Tl-iO ooo t^ t^ •-> •-< W « CO -^ lOvO l> rovo lo ON 'i- vo Hi-iiHC>)W0»rO'^- ^ H M 01 c* N rororocoTi-Tj-io lo^o c^ t^-;o oo 1— « U Pi 8 * M w fo t^ N t^ On f-i CO lO r^ w M « M M i-i M N Os en a oo o^vo muD 00 (N T)-vo 00 M M ., M M i 0> CO (N vO ■* t^ -*vO 00 o cot^roo OnOn CO mo t^ On iH N ■<*- M ID N COOO VO 00 Th t^vo r>« On (N t^ ro 1- w CO -^ m t>.oo w 8 f^ O^OO oo On to r(- »r> OOw LO-^Tj-vO OnCO •- (N C4 CO ^ lOvO 00 a CO M COOO lO t^O HI -^t^O -^roo) CO WHMWNCOTtl/, C) CO t^ CO COVO M M VO 00 O COvO ON CO -. W M M I-I M CO c^ M 00 oo in N COVO w -"I- in c^ w inoo w v8 inoo Ti- « N in M M CO m t^ On H Tf 1-4 HI CO in On in ■* OJ CO -^NOOO •saqou I UI Bid 00 M f t^ O fO» CO 5* 03 91 DEFINITIONS AND USEFUL NUMBERS. ARITHMEIICAL SIGNS USED IN THIS BOOK. + Plus, or more, the sign of addition, as 2 + 2 = 4. " — Minus, or less, the sign of subtraction, as 4 — 2 =2. X signifies multiplied into or by-, as 3 X 3 .= 9. -f- signifies divided by, as 10 -^ 5 = 2. = signifies equality, or equal to, as 4 + 4 = S. : :: :, the sign of proportion, as 2 ; 4 :: 3 : 6; which reads thus: as 2 is to 4 so is 3 to 6. [j y , the sign of the square root, as ^^49 = 7; that is. 7 is the square root of 49, or 7 is the number which, if multi- plied by itself, produces 49. 7^ means the square of 7, or that 7 is to be squared or multi- plied by itself. The square of any number is the product of the number multiplied by itself. 73 means the cube of 7, or that 7 is to be multiplied by 7, and again by 7. The cibe of any number is the product of that number multiplied by itself, and again by itself ' S ^UARE MEASURE AND CUBIC MEASURE. 144 square inches = I square foot. 9 square feet = i square yard. ] 728 cubic inches = i cubic foot. 27 cubic feet = i cubic yard. DEFINITIONS OF TERMS WHICH ARE EMPLOYED IN THE FOLLOWING RULES. A c ^ A Point has a position witliout mag- nitude, as at C, Fig. i. 6 E F A Line has length without breadth, Figs. 1 and 2. as D E, Fig. 2. Right Line is the shortest ( between any two points, r P, Fig. 3. A Right Line is the shortest distance £_ J; Fig.3. A Superficies has length and breadth only. Fig. 4. Fig. 4. 92 Fig. 9. A Solid has length, breadth and thickness. Fig- S- An Angle is the opening of two lines hav- ing different directions, and is either Right, Acute, or Obtuse. A Right Angle is made by a line being drawn perpendicular to another, as in Fig. 6. «■ Fig. 6. 7. An Acute Angle is less than a Right Angle„ Fig. 7. An Obtuse Angle is greater than a Right Angle. Fig. 8. Fig. 8 A Triangle is a figure bounded by three straight lines. Figs. 9, 10, II. Tig. 9. An Equilateral Triangle is a Triangle of which the three sides are equal to each other. Fig. 9. An Is<^sceles Triangle has tv/o of its sides equal. Fig. 10. Fig. 10, A Scalene Triangle has all its sides unequal. Fig. II. Fig. 11. 93 A Right-angled Triangle has one Right Angle. Fig. 12. Fig. 12- A Square is a 4-sided figure having all its sides equal, and all its angles Right Angles. Fig. 13. Fig. 13. A Rectangle is a 4-sided figure, having its angles Right Angles, and of which the length _ _ exceeds its breadth. Fig. 14. ±'ig. 14. An Arc is any part of the circum- ference of a circle, as A c B, Fig. A Chord is a right line joining the extremities of an Arc, as A B, Fig. 15- A Segment of a Circle is any part bounded by an Arc and its Chord, as the Segment A c B, Fig. 15. A Diameter is a straight line passing through the center of a Circle, and bounded by the circum- ference at both ends, asG h. Fig. 15. A Semicircle is half a Circle, as G c H, Fig. 15. The Circumference of a Circle is the outside boundary line described on the center with a length equal to the radius. A Quadrant is a Quarter Circle, as G o i. Fig. 15. A Tangent is a Right Line that touches a Circle without B cutting it, as E F, Fig. 15. B Concentric Circles are Circles hav- ing the same center, and the space included between their circumfer- ences is called a Ring. Fig. 16. Fig. 15. Fig. 16. 94 USEFUL NUMBERS IN CALCULATION. Lbs. Pounds Diameter of Circle Circumference Cubic inches Cubic feet Cylindrical in. Cylindrical feet Diameter of circle Side of a square Square of the } diameter f Radius of circle Cubic inches Cylindrical inches Cubic ft. of water Gallons of water X X X X X X. X X X X X X .009 = Hundredweights. .00045 =T Tons. 3.I4I6 = Circumference. •3183 = Diameter. .003607 = Gallons. 6.232 = Gallons. .002832 = Gallons. 4.895 = Gallons. .88622 = Side of equal sq. 1. 128 = Diam. of circle of equal area. .7854 = Area of circle. 6.2831 = Circumference. 277.274 = Gallons. 353-03 = Gallons. 35.9 =- Tons. 10 = Pounds weight. MENSURATION. To find the circ'iivifere7ice of a circle when the diameter is given. — Multiply the diameter by 3.1416; the product is the circumference. A common method of calculating the circumference is to multiply the diameter by 3, and add \ of the diameter to the product. The sum is the circumference, very nearly. Or, what amounts to the same thing, multiply the diameter by 22, and divide the product by 7. Another method of finding the circumference is to multi- ply the diameter by 3, and add -fg- inch to the product for every foot-length in the product. The reason for adding -fg inch for each foot of the product, is, that it is the same in effect as the addition of I of the diameter. As the product is equal to three times the diameter, the addition to be made per foot of product should be only a third of the addition per foot of diameter; that is, instead of } of the diameter the addition is j- rate of -i^jj inch per foot of the product. To find the diameter of a circle when the circumfer- ence is given — Multiply the length of the circumference by the decimal .3183; the product is the diameter. 3 of 7, or 2T of the product, which is at the 95 Or, divide the circumference by 3.1416; the quotient is the diameter. Or, multiply the circumference by 7, and divide the product by 22; the quotient is the diameter, very nearly. To find the area of a circle. - Square the diamreter — that is to say, multiply the diameter by itself, say, in inches — and multiply the product by the decimal .7854. The product is the area of the circle in ^ square inches. To find the length of an arc of a circle. — From 8 times the chord, a D, Fig. 17, of half the arc A D E, subtract the chord of the whole arc, A E, and divide the remainder by 3. The quotient is the eighth of the arc, nearly. ^ I5g. 17. To fi7id the diameter when the chord of an arc and the versed si^te are given. — Divide the square of half the chord by the versed sine, and to the product add the versed sine. The sum ?.s the diameter. Note. — The versed sine is the height of the arc. rea of a segment of a ring. A^ Fig. 18. /o find the ^ . _ - 'Multiply half the" sum of the bounding -ires by their distance apart; the product is the area. Thus, let the arc A x D be 90 inches long, and the arc B C4f) inches long, and the distance a B or C D iSinc/ieslong; then 90" + 40" = 130; and 130 -^ 2 == 65; and 65 X 18'' = 1 1 70 square inches, the area. To find the a^'ea of a :iegment of a circle. — To % of the product of the chord a b and versed ine c D of the segment, add the cube of the versed sine divided by twice the chord; and the sum is the area, nearly. Thus — Given the chord a B as 20 inches, and Fig. 20. the versed sine 3 inches; recjuired the area. 20 X 3 = 60; and 60 X 2 -^ 3 -= 40. Then 3 inches cubed =3 X3 X3 = 9X3=27; 96 and 27 -T- (20 X 2) = .675; and .675 + 40 = 40.675 = area nearly. When the segment is greater than a semicircle, find the area of the remaining segment and deduct it from the area of the whole circle, the remainder is the area of the seg- ment. To find the area of a sector of a circle. — Multiply half the length of the arc by the radius of the circle. The product is the area of the sector. See Fig. 17. To find the cifcti77iference of an ellipse. — Add the two dia- meters together; divide the sum by 2, and multiply the quotient by 3. 1416. Or, multiply the sum of the two dia- meters by 1.5708. The product in either process, is the circumference, nearly. Thus — what is the circumfer- ence of an ellipse of which the diameters are 10 and 14? 14 + 10 = 24; and 24 X i«57o8 = 37-6992; or, 10 + 14 = 24; and 24 -f- 2 = 12; and 12 X 3.1416= 37.6992 = the circumference of the ellipse. To find the area of an ellipse. — Multiply the two diameters together, and multiply the product by .7854. The final product is the area. Tofifidthe area of a square. — Multiply the length of one side by itself, or square the side. The product is the area. For example, a square has each side 12 inches long; what is the area? 12 X 12= 144 square inches is the area of the square. To find the area of a rectangle. — Lvlultiply the length by the breadth; the product is the area. For example, a rect- angular plate is 24 inches long and 12 inches wide; what is the area? 24 X 12 = 288 square inches. To find the cubic content of a rectangular or cubical body. -^ Multiply the length by the breadth, and multiply the product by the depth. \ The last product is the cubic content, ^fk For example, a box or cistern is 5 feet j long, 2^2 feet wide, and 3 feet deep; ^ what is the cubic content? 5 feet mul- tiplied by 25^ feet makes an area of 22. 12^ square feet; and 12^ feet multiplied by three is equal to 37^ cubic feet. X [M^ x \ 9/ To find the cubic content of a square-ended cylinder,'-^ /ind the area of one end by the rule for the area of a circle, and multiply the area by the length. The product is tlie Rubic content of the cylinder. 30' •Pig. 23. Note, — The dimensions are to be taken all in inches or ali feet. The square measure and the cubic measure^ corres- pondingly, will be in inches or in feet. Exa7nple. — A cylinder is 22 inches in diameter and 36 inches in length; what is the cubic content? 22 inches. .7854 22 484 — 380. 1336 square inches, area of the end. 44 31416 44 62832 31416 484 380-1336 36 22808016 I 1404008 13684.8096 cubic inches, solid content. B D Fig. 24 may be calculated by squaring the side by 4, and multiplying by 1.732 To find the area of a trt* angle. — Multiply the length of the base a b by the perpen- dicular height c D, and divide the product by 2. The quo- tient is the area of the tri- angle. When the triangle is equi- lateral, or equal sided, the area dividing the square 98 To find the cubic content of a sphere. — Multiply the cube of the diameter by the decimal .5236; the product is the cubic content. For example, let the diameter be 12 inches. The cube of 12, or 12 X 12 X 12 = 1728, and 1728 X .5236 = 904.78 cubic inches. To find the content of a segment of a sphei-e. — Square the radius, or half diameter, of the base, and multiply the square by 3. To the product add the square of the height of the segment, and multiply the sum by the height and by the decimal .5236. The product is the content of the segment. To find the content of a frustuvi of a cone. — Square the diameter of each end, and multiply one diameter by the other ; add together the two squares and the product, and multiply the sum by the height of the frustum and by .2618. The final product is the concent. To find the content of a friLsttun of a square pyramid, — Add together the areas of the two ends and the product of the lengths of side of the ends; multiply the sum of the height, and divide the product by 3. PRACTICAL GEOMETRY FOR MECHANICS, EN- GINEERS, BOILER-MAKERS, ETC. To bisect a given right line. — That is, to divide it, or square it across in two equal parts. Let A B, Fig. 25, be the given right line. r5> ./ Av- ( r > , I \ \ /^^-^ B IB i'D Fiff 26. ^ Fig. 25. Then, with any radius greater than a e — that is greater than half the length of the line — and on A and B, as centers, de- scribe two arcs cutting each other at C and D, draw the hne C E D through the intersections. Then c E D will be at right angles to A E, and the line A B is divided into two equal parts at E. 99 To draw a perpendicular to a. straight line from one of its extremities, — Let A B, Fig. 26, be the given line, and B the extremity from which the perpendicular is to be drawn. Take any point, C, and with the radius C B describe an arc of a circle, A B D; draw a line from A, through c, cutting the arc at D; then, a line drawn through the intersection at D from B will be perpendicular to A B. To drdiv a perpendicular to a right line from a point with- out the line; that is, when the point is not on the line. Let A B, Fig. 27, be the given line, and C the point through which the per- pendicular is to be .jj drawn. Then, on c as ^. "" I '' 2 a center, with any radi- I us greater than the dis- j tance to the line A B, I describe an arc cutting \}y' A B at E and D; and on ^^'^K E and D as centers, with p. „- any radius greater than ^* E D, describe two arcs cutting each other at F £; a line drawn through F and C will be perpendicular to A B. To draw a line parallel to E y ^ I' a given sti'aight line. — First, *^*''" --- .■--'""'-'-;; to draw the parallel at a giv- en distance. Let A B, Fig. 28, be the given line. Open —I t the compasses to the distance C 3> required, and from any two Fig. 28. points, c and D, describe arcs E and F. Draw the line G H, touching tlie arcs. It is the required parallel. Q c 5— jj Second, to draw a parallel / ^"-^ ; through a given point. Let c, / ^^-v^^ / Fig. 29, be the point. From I ''--. / C draw any line C D to A B. A— ^Jt" ^ B On C D, as centers, describe „. arcs D E and c F. Cut off i) E equal to c F, and through the points C and E draw the parallel G 11. loo X To draw a rectangle from the center lines. — Draw the line A B, Fig. 30, equal to one of the center lines, bisect it // £ C ^^ ^' draw the other - center line, D E, through c, at right angles to A B; then with c D as a radius, and on B and A as « centers, d e s cr i b e arcs at H, j, F, and g; again with C A as radius, on E and D as centers, de- scribe arcs cutting - the arcs at H, j, F, '"and G. Join the i n t e t s e ctions by D Fig. 30. straight lines, these will be at right angles and will form a rectangle. To draw a square on a given line. — Let A B, Fig. 31, be the given line. Erect a perpendicu- lar at B, and on B as a center, with B A as a radius, describe an arc at D, and on D as a center describe another arc at c. On A as a center, with the same radius describe an arc cutting the other arc at C. Join the intersections ri{?. 31. by straight lines, and the square is formed. If truly square, it should measure the same length in the two diagonal directions; that is, the distance A d should be equal to the distance B c. a To bisect an a7igle. — That is, to divide it in two equal angles. On the point of the angle. A, Fig. 32, as a center, with any radius, describe an arc cutting the sides of the angle at D and E, and on D and E as centers, describe two arcs cutting each other at F. The line drawn through A and 2" will bisect the angle. lOI ..€,.-' Upon a given right line to const?'tici an equilateral triangle. — Let A. B, Fig. 33, be the given right hne; then on A and B, with A B as radius, describe two arcs cutting each other at C, join A C and B c, and the triangle ABC, thus formed, is an equilateral triangle. rig. 33. In a given circle to i^iscrihe a sqnai-e. — Draw any two diameters at right angles to each other, and join the extremities, as in Fig. 34.^ To inscribe an octgcgon. — First in- scribe the square, then bisect the quarter circles and join the extremi- ties. Or, bisect the angle A O D, Fig. 34, by the line o F. Then D F is the length of tbe side of the octagon. Fisf. '^4. To draw a 'circle through three given points, no matter how they may are placed. — This is a very useful problem, as it enables any one to determine the diameter of the circle of which an arc is a part. Place the three points, I, 2, 3, anywhere. With any radius greater than half the distance ^ be- tween two of the points, I and 2, and on these points as centers, de- scribe two arcs cutting each other at A and B. Similarly, describe in- tersecting arcs on the points 2 and 3 as cen- ters. Draw straight lines through the mtersections respect- ively, meeting at^O. Then o is the center from which the arc is to be described, with the radius o I, which will pass through all the three points. Fig. 35. I02 To draw a straight une equal in length to a given arc of a circle. — Divide the chord A B into four equal parts; set off one of these ^^^ --^C parts from B to c, and join c D. The line C D is equal to the length of half the given arc nearly. Fig. 36. To describe a rectangle wheii the length of the diagonal and that cf one of the ends is gii'cn. — Draw tlie diagonal A B. Bisect it at the center o, and with o a as radius, describe a circle. Set off the length of the end from a, cut- ting the circle at D, and from B cutting the circle at C, and ioin A C, C B, B D, and D a, to form the rectangle required. ^&- 37, Fig 38. To cojistriict a square whose diagonal only is givejio — Divide the diagonal into seventeen ec[ual parts. Twelve of these parts are the measure of the side of the square. From A take up twelve parts in the compasses, and draw arcs of a circle at B and at C; and on d as a center^ with the same radius, draw arcs, cutting those at C and D, and join the intersec- tions to form the square A B D c. Another viethod. — Bisect the diagonal at O, by the perpendicular line c D; and on the center o and with the radius o B, describe arcs at c and D. Join the intersections to form the square A C B D. To draiv a square equal in area to a given ciirle. — D ivi de t h e diame - ter A B into fourteen equal parts: ^^fiT* 39. set off eleven of these from A to o. I03 and from o draw the perpendicular o c, cutting the circle at c; and draw A c. Then A c is the side of a square of which the area is equal to that of the circle. To complete the square, from C draw a line through the center of the circle, cutting the c i re um f e r e n ce at E; and from A draw the straight line A E F, through the point E. This line is at right angles to A C. With the radius A c, and on A as a center, describe arj arc at F ; Cand on F, with the same radius, draw an arc at G. From c, again, draw an arc cutting the former at G with the same 'ra- dius. Join the ia- iersections, and the square is completed, circle by .886226: the Fig. 40. Or, multiply the diameter of the product is the side of a square of equal area. To ih-aw a square equal in area to a given triangle. — Let B P A be the given triangle. Draw the perpendicular p c from the summit P, and bisect it. Produce the side of the triangle B a, and set off A E equal to the half of p c. Divide E b into two equal parts at D; and on D as center, with d B as radius, describe the semicircle e b. Draw the perpen- dicular A F, cutting £ i4 O C Fig. 41. the circle at F; then A F is the side of a square equal in area to that of the given triangle. I04 ' Another method. — A right-angled triangle being given, to construct a square of the same area. Divide the diagonal into thirty-four equal parts ; set off ten of these parts from Fig. 42. A, ana ten from B, leaving fourteen in the middle. Draw G C and G E through the ten divisions, parallel to F E and c F respectively. The square c F E G has an area equal to that of the triangle A B F. To produce a circle equal in area to a given square, — . Given the square A b c D; draw the diagonals and divide A -^ B Fig. 43. half a diagonal, o c, into fifteen equal parts. On o as center, and with a radius of twelve of these parts, describe a circle. This circle is of the same area as the square. Or, multiply the side of the square by 1. 12837. The prod- uct is the diameter of a circle equal in area to the square of which the side is given. 505 D C / / B / / '/ ^ -''' / The square is divided into four triangles, each of which IS one-fourth of the square in area. The quar- ter circles, whose figures differ of course materially/ from those of the triangles, have each the same area as one of the triangles. To find the side of a square which shall con- tain the area of a given squa7'e any even mimber of times, — Draw the given ^ H ^ E square A E. The diagonal ^*ff- 44. ' F G is the side of a square of double the area of the given square. Set-off E H, equal to the diagonal F G; then the square E B has four times the area of the given square. Set-off again e i, equal to the diagonal H J of t h e square EB, and draw the square E C on that base; the square E c has twice the area of E B, or four tm":es that of the square E A. Set off E L equal to erected on that base, has twice the area of E C. And so on. To dj'aw an ellipse approximately^ of a given leftgth without regard to breadth.- — Divide the given length into three equal parts at o and V; and on o and V as centers, with A O as radius, describe two circles cutting each other at I and Kon I and K as Fig. 45. the diagonal i K; the square E D, c Fig. 46ib io6 with the diameter of the circle A o v as radius, describe centers arci; D E F g, to complete the form of an ellipse. If the radius of the ends is too large and flat, divide the given length into four equal parts, Fig. 45A, and describe three circles as shov^^n; and on H and F as centers, describe the lateral arcs to touch the first and third circles, and so complete the figure. To di'aio an ellipse when the length and breadth are given — Draw the diametrical lines at right angles to each other, intersecting at O. . Set out the length and breadth of the figure on these lines equally from the center o. Set off the length O D with the compasses on tlie longer diameter from x^ ^r^ ^^ and on o as a center, with the radius o E, desc^ihe the Fig 46. quadrant E F. Draw the line or chord E F, and set off the half of it from E to G. On o as a center, with o G as radius, describe the circle G H j i; then i and G are the centers for the segmental arcs at A and B, and H and j are the centers for the latf^'-^V arcs at c and d. I07 TABLK OF SQUARE AND CUBE ROOTS, ^^ No. Square Cube No. Square Cube No. 1 42 Square Cube Root. I . Root. Root. Root. Root. Root. I 6 2.449 1. 817 6.481 3-476 1-16 1-031 1.020 1-4 2.5 1.832 43 6-557 3-503 1-8 1.060 1 .040 1-2 2-550 1.866 44 6.633 3-530 3-16 1.089 1.059 3-4 2 - 599 1.890 45 6.708 3-557 1-4 1.118 1.077 7 2.646 1-9^3 46 6.782 3-583 5-16 1.146 1.095 1-4 2 .692 1 • 935 47 6.856 3-609 3-8 1-173 1. 112 1-2 2-739 1-957 48 6.928 3-634 7-16 1.199 1.129 3-4 2.784 1.979 49 7- 3-659 1-2 1.225 1-145 8 2.828 2. 50 7.071 3-684 9-16 1.250 1.161 1-4 2.872 2.021 51 7.141 3.708 5-8 1-275 1.176 1-2 2.915 2.041 52 7.211 3-733 11-16 1.299 1-191 3-4 2.958 2.061 53 7.280 3-756 3-4 1-323 1.205 9 3- 2.080 54 7-348 3-780 13-16 1.346 1.219 1-4 3.041 2.098 55 7.416 3 803 7-8 1.369 1-233 1-2 3.682 2. 118 56 7-483 3.826 15-^6 1.392 1.247 3-4 3.122 2.136 57 7-550 3-849 2 1.414 1.260 10 3-162 2.154 58 7.616 3-871 1-16 1.436 1.273 11 3-317 2.224 59 7.681 3 '895 1-8 1.458 1.286 12 3-464 2.289 60 7.746 3-9^5 3-16 1.479 1.298 13 3.606 2.351 61 7.810 3-937 1-4 1.5 1-310 14 3-742 2.410 62 7.874 3-958 s-^^. 1. 521 1 . 322 T-S 3-873 2.A66 63 7-937 3-97Q 3-8 1-541 ^•334 16 4- 2 . s20 64 8. 4- 7-16 1.561 1.346 17 4-123 2-57^ 65 8.062 4.021 1-2 1.581 1-358 18 4-243 2. 621 66 8.124 4.041 9-16 1.600 1.369 19 4-359 2.668 ^1 8.185 4.061 5-8 1.620 1.3S0 20 4-472 2.714 68 8.246 4.082 11-16 1-639 I -391 21 4-583 2.759 69 8.307 4.102 3-4 1.658 1-402 22 4.690 2.802 70 8.367 4.121 13-16 1.677 I -412 23 4.796 2.844 71 8.426 4.141 7-8 1.695 1.422 24 4.899 2.885 72 8.485 4.160 15-16 1.714 1-432 25 5. 2.924 73 8-544 4.179 3 1.732 1.442 26 5-099 2.963 74 8.602 4.198 1-8 1.768 1.462 27 5.196 3- 75 8.660 4.217 1-4 1.803 1.482 28 5-292 3-037 76 8.718 4.236 3-8 1-837 ^•5 29 5.385 3-072 77 8-775 4-254 1-2 1.871 1-518 30 5-477 3.107 78 8.832 4-273 5-8 1.904 1-535 31 5.568 3-141 79 8.888 4.291 3-4 1.936 1-553 32 5-657 3-175 80 8.944 4-309 7-8 1.968 1-570 33 5-745 3.208 8i 9- 4 .327 4 2. 1.587 34 5.831 3.240 82 9.056 4 -.345 1-4 2.o6i 1-6x9 35 5.916 3.271 83 9. no 4.362 1-2 2.121 1-651 36 6. 3-302 84 9.165 4-379 3-4 2.179 i-68i 37 6.083 3 • 332 85 9.220 4-397 5 2.236 1.710 38 6.164 3-362 86 9.274 4.414 1-4 2.291 1.738 39 6.245 3-391 87 9.327 4-431 I--2 2-345 1.765 40 6.325 3.420 88 9.381 4-448 3-4 2 398 1.792 41 6.403 3 448 89 9-434 4-465 io5 Table of Square and Cube Roots.— Continued, No. Square Cube No. 138 Square Cube No. Square Cube Root. Root. Root Root. Root. Root. $o 9.487 4.481 11.747 5.167 186 13.638 5.708 91 9-539 4 498 139 XI. 789 5 180 187 13.674 5.718 92 9-592 4 514 140 11.832 5 192 188 13.711 5.728 93 9.644 4 531 141 11.874 5 204 189 13.747 5-738 94 9-695 4 547 142 11 .916 5 217 igo 13.784 5.748 95 9-747 4. 563 143 11.958 5 229 191 13.820 5.758 96 9.798 4 579 144 12. 5 241 192 13.856 5.769 97 9.849 4 595 145 12.041 5 253 193 13.892 5.779 98 9.899 4 610 146 12.083 5 265 194 13.928 5.788 99 9-950 4 626 147 12. 124 5 277 195 13.964 5-798 100 10. 4- 641 148 12.165 5 289 196 14. 5.808 101 10.049 4 657 149 12 . 206 5 3oi 197 14-035 5-818 102 10.099 4- 672 150 12.247 5 313 198 14.071 5.828 103 10.148 4- 687 151 12.288 5 325 200 14.142 5.848 104 10.198 4 702 152 12.328 5 335 202 14.212 5.867 105 10.246 4 717 153 12.369 5 348 204 14.282 5.886 106 10.295 4 732 154 1 2 . 409 5- 360 206 14.352 5-905 107 10.344 4 747 155 12.449 5 371 208 14.422 5.924 108 10.392 4 762 156 12.490 5 383 210 14.491 5-943 109 10.440 4 776 157 12.529 5 394 212 14.560 5.962 110 10.488 4 791 158 12.569 5 406 214 14.628 5.981 III 10.535 4 805 159 12.609 5 417 216 14.696 6. 112 10.583 4 820 160 12.649 5 428 218 14-764 6.018 "3 10.630 4 834 161 12.688 5 440 220 14.832 6.036 114 10.677 4 848 162 12.727 5 451 222 14.899 6.05s "5 10.723 4 862 163 12.767 5 462 224 14.966 6.073 116 10.770 4 877 164 12.806 5 473 225 15- 6.082 117 10.816 4 890 165 12.845 5 484 226 15.033 6.091 118 10.862 4 904 166 12.884 5 495 228 15.099 6.109 119 10 . 908 4 918 167 12.922 5 506 230 15.165 6.126 120 10.954 4 632 168 12.961 5 517 232 15.231 6.144 121 11. 4 946 169 13. 5 528 234 15.297 6.162 122 11.045 4 959 170 13-038 5 539 236 15.362 6.179 123 11.090 4 973 171 13.076 5 550 238 15.^27 6.197 124 II. 135 4 986 172 13.114 5 561 240 15.^91 6.214 125 11.180 5 173 13-152 5 572 242 15.556 6.231 126 11.224 5 013 174 13.190 5 582 244 15.620 6.248 127 11.269 5 026 175 13.228 5 593 246 15-684 6.265 128 11-313 • 5 039 176 13.266 5 604 248 15.748 6.282 129 11-357 5 052 177 13-304 5 .614 250 15.811 6.299 130 11. 401 5 065 178 13-341 5 625 252 15.874 6.316 131 11-455 5 078 179 13-379 5 635 254 15.937 6.333 132 11.489 5 091 180 13.416 5 646 256 16. 6-349 133 11.532 5 104 181 13.453 5 .656 258 16.062 6.366 134 11.575 5 117 182 13-490 5 667 260 16.124 6.382 135 11.618 5 129 183 13-527 5 677 262 16.186 6.398 136 11.661 5 142 184 13-564 5 687 264 16.248 6.415 137 11.704 5 155 185 13.601 5 .698 266 16.309 6.431 I09 Table of Square and Cube Roots.-- Continued, No. Square ) Cube No. Square Cube No. Square Cube Root. Root. Root. Root. Root. Root. 268 16.370 6.447 360 18.973 7-113 500 22.360 7-937 270 16.431 6.463 361 19- 7.120 505 22.472 7 963 272 16.492 6-479 362 19.026 7.126 510 22.583 7 989 274 16.552 6.495 364 19.078 7.140 515 22.693 8 oic; 276 16.613 6.510 366 19.131 7-153 520 22.803 8 041 278 16.678 6.526 368 19.183 7.166 525 22.912 8 067 280 16.733 6.542 370 19-235 7.179 530 23.021 8 092 282 16.792 6-557 372 19.287 7.191 535 23.130 8 118 284 16.852 6-573 374 19-339 7.204 540 23-237 8 143 286 16.91T 6.588 376 19.390 7.217 545 23-345 8 168 288 16.970 6.603 378 19.442 7.230 550 23-452 8 193 289 17- 6.610 380 19-493 7-241 555 23-558 8 217 290 17.029 6.619 382 19-544 7.225 560 23.664 8 242 292 17.088 6.634 384 19-595 7.268 S65 23.769 8 267 294 17.146 6.649 386 19.646 7.281 570 23-874 8 291 296 17.204 6.664 388 19-697 7.293 575 23-979 8 315 298 17.262 6.679 390 19.748 7.306 580 'H.083 8 339 300 17.320 6.694 392 19.798 7-318 585 24.186 8 363 302 17.378 6.709 394 19.845 7-331 590 24.289 8 387 304 17-435 6.72:? 396 19.899 7-343 595 24.392 8. 410 306 17.492 6.738 398 19.949 ^•355 600 24.494 8 434 308 17-549 6.753 400 20. ( 7.368 605 24.596 8 457 310 17.606 (^.1(^1 402 20.049 7-5S0 610 24.698 8 480 312 17.663 6.782 404 20.099 7.395 615 24-799 8 504 314 17.720 6.796 •406 20.149 7.404 620 24.809 8 527 316 17.776 6. 811 408 20.199 7.416 625 25. ^ 8 549 318 17.832 6.825 410 20.248 7.428 630 25.099 8 572 320 17-888 6.839 412 20.297 7-441 635 25.199 8 595 322 17.944 6.854 414 20.346 7-453 640 25.298 8 617 324 18. 6.868 416 20.396 7-465 645 25-396 8 .640 326 18.055 6.882 418 20.445 7.476 650 25-495 8 652 328 18.110 6.896 420 20.493 7.488 655 25-592 8 1^ 330 18.165 6.910 422 20.542 7-5 660 25.690 8 332 18.220 6.924 425 20.615 7-518 665 25.787 8 .728 334 18.275 6.938 430 20.736 7-547 670 25.884 8 -750 336 18.330 6.952 435 20.857 7-57^ 675 25.980 8 .772 338 18.384 6.965 440 20.976 7-605 680 26.076 8 -793 340 18.439 6.979 445 21 .095 7.634 685 26. 172 8 .815 342 18.493 6.993 450 21 .213 7.663 690 26.267 8 836 343 18.520 7. 455 21.330 7-691 695 26.362 8 .857 344 18.547 7.006 460 21.447 7.719 700 26.457 8 879 346 18.601 7.020 465 21.563 7-747 705 26.551 8 900 348 18.654 7-033 470 21.679 7-774 710 26.645 8 921 350 18.708 7.047 475 21.794 7.802 715 26.739 8 942 352 18.761 7.060 480 2i.go8 7.829 720 26.832 8 962 354 18.814 7.074 485 22.022 7-856 725 26.925 8 983 356 18.867 7.087 490 22.135 7-883 730 270O18 9 004 358 18.920 7.100 495 22.248 7 910 735 27 110 024 no Table of Square and Cube Roots. — Continued. No. Square Cube No. 820 Square Cube No. 900 Square Cube Root, Root. Root. Root. Root. Root. 740 27.202 9-045 28.635 9-359 30. 9.654 745 27.294 9.065 \^^ 28.722 9.37S 905 30.083 9.672 750 27.3S6 ■ 9.085 830 28.80Q 9-397 910 30.166 9.690 755 27.477 9.105 835 28.896 9.416 ^^^ 30.248 9.708 760 27.568 9.125 840 28.982 9-435 920 30-331 9-725 765 27.658 9-145 845 29.068 9-454 925 30-413 9-743 770 27.748 9.165 850 29-154 9.472 930 30.496 9.761 775 27.838 9.185 855 29.240 9.491 940 30.659 9.796 780 27.928 9.205 860 29-325 9-509 950 30.822 9.830 785 28.017 9.224 865 29.410 9-528 960 30-983 9.864 790 28.106 9 244 870 29-495 9-546 970 3^-144 9.898 795 28.195 9-263 875 29.580 9-564 980 31-304 9-932 800 28.284 9.283 880 29.664 9-582 990 31.464 9.966 805 28.372 9.302 • 885 29.748 9.600 1000 31.623 10. 810 28.460 9.321 890 29.832 9.619 1 100 33.166 10.323 815 28.548 9-340 895 29.916 9-636 1200 34.641 10.627 HOW TO GEAR A LATHE FOR SCREW-CUTTING. There is a long screw upon every screw-cutting latbe, called the lead-screw. This lead-screw feeds the carriage of the lathe while cutting screws, and has a gear wheel placed upon its end which takes motion from another gear wheel attached on the end of the spindle. Each of these gear Wheels contain a different number of teeth, so that different threads may be cut. All threads are cut a certain number to the inch, from one to fifty or more. In order to gear your iathe properly to cut a certain number of threads to the inch, you will first multiply the number of threads to the inch you wish to cut by ^, or any other small number, and this will give you the proper gear to put on the lead-screw. Now, with the same number, 4, multiply the number of threads to the inch in the lead-screw, and this will give you the proper gear to put on the spindle. Example.— Yow wish to cut a screw with ten threads to the Inch. Multiply 10 by 4 and it will give you 40: put this gear on the lead-screw. The lead-screw on your lathe has 7 threads to the inch; multiply 7 by 4, and you will have 28. Put this gear on your spindle, and your lathe is geared to cut 10 threads to the inch. iir The rule above is for those lathes which have not a stud grooved into the spindle. As this stud runs with but half the speed of the spindle, you must change the rule somewhat. First, multiply the number of threads to the inch you wish to cut, by 4 (or some other small number), and this will give you the proper gear to put on your lead-screw. Next multi- ply the number of threads to the inch on your lead-screw by the same number, and multiply this product by 2^ and this will give you the proper gear to go on your stud. Example. — Using same numbers — 10 tim. : 4 is 40. Put this gear on your lead-screw; 7 times 4 is 28, and 2 times 28 is 56^ put this gear on your stud, and your lathe is grooved io cut 10 threads to the inch. KITCHEN AND TABLE WASTES. Good management, both on the farm and in the house- hold, demands that all sources of waste be guarded against and that all by-products be utilized to the best advantage > That the kitchen and table wastes are more important sources of loss than are generally realized is brought out quite strikingly by investigations made by the New Jersey authorities. It is calculated that there could be gathered annually from 20,000 people about 2,080 tons of garbage, with an analysis and value equal to good barnyard manure. By treating with suitable solv-ents and drying the residue there could be secured 388^ tons of fertilizer, worth $14.69 per ton, and over 82 tons of grease, which sells for an aver- age of $70 wherever this system is in operation. By cre- mation there would result 83 1-5 tons of ashes, worth $28.53 pel' ton. The total population of the cities and towns of New Jersey is approximately 918,722 and the garbage of this number of people would amount to 95,516 tons per year, from which could be manufactured 17,848 tons tankage, worth $262,180, and 3,726 tons of grease, worth $260,800, a total of $522,980. Should all this garbage be thus manipulated, there would be an increase in the plant-food supply to the extent of 45 per cent, of the tonnage of complete fertilizers used in that state during one year, which could not help but diminish the cost of fertilizers to the agriculturist. THE THEORY OF THE STEAM ENGINE. For many years engineers cared nothing about the theory of the steam engine. They went on improving and developing it without any assistance from men of pure science. Indeed it may be said with truth that the greatest improvement ever effected, the introduction of the com- pound engine, was made in spite of the physicist, who always asserted that nothing in the way of economy of fuel was to be gained by having two cylinders instead of one. In like manner, the mathematical theorist was content to make cer- tain thermo-dynamic assumptions, and, reasoning from them, to construct a theory of the steam engine, without troubling his head to consider whether his theory was or was not con- sistent with practice. Within the last few years, however, the theorist and the engineer have come a good deal into contact, and the former begins at last to see that the theory of the steam engine is laid down by Rankine, Clausius, and other writers, must be deeply modified, if not entirely re- written, before it can be made to apply in practice We have recently shown what M. Hirn, who combines in himseh practical and theoretical knowledge in an unusual degree, has had to say concerning the received theory of the steam engine, and its utter inutility for practical purposes ; and papers recently read before the Institutions of Mechanical and Civil Engineers, and the discussions which followed them, have done something to convince mathematicians that they have a good deal to learn yet about the laws which determine the efficiency of a steam engine. It has always been the custom to class the steam engine with other heat engines. It is now known that nothing can be more errone- ous. The steam engine is a heat engine std geiieris, and to confound it with a hot-air engine, or any motor working with a non-condensible fluid, is a grave mistake. It is not too much to say that many engineers now understand the mathematical theory of the steam engine better than do men making thermo-dynamics a special study. But there remains a large number of engineers who do not as yet quite see their way out of certain things which puzzle them, or which they fail to understand. There are, indeed, phe- nomena attending tne use of steam which are not yet quite comprehended by any one, and we may be excused if we say nmething about one or two points which require elucidation. One of these is the mode of operation of the iteam ^^wCet. It is a very crude statement that it does good be- cause it keeps the cylinder hot. It might keep the cylinder 113 hot, and yet be a source of loss rather than gain ; and, asd matter of fact, it is doubtful now if the application of steam jackets to all the cylinders of a compound engine is advisa- ble. It is well known, too, that circumstances may arise, under which the jacket is powerless for good. Thus, for example, the late Mr. Alfred Barrett, when manager of the Reading Iron Works, carried out a very interesting series of experiments with a horizontal engine, in order to test the value of the jacket. This engine had a single cylinder fitted with a very thin wrought -iron liner, between which and the cylinder was a jacket space. The jacket was very carefully drained, and could be used either with steam or air in it. Experiments were made on the brake with and without steam in the jacket. The result was a practically infinitesi* mal gain by using steam in the jacket. In one word, the loss by condensation was transferred from the cylinder t(? the jacket. On the other hand, it is well known that single cylinder condensing engines must be steam jacketed if they are to be fairly economical. Circumstances alter cases, and the circumstances which attend the use of the jackets ar2 more complex than appears at first sight. In considering the nature of the work to be done, we must repeat a fundamental truth which we have been the first to enunciate. A steam engine can discharge no water from it which it did not receive as water, save the small quantity which results from loss by external radiation and conduction from the cylinder, and from the performance of work. At first sight, the proposition looks as though it were untrue. Its accuracy will, however, become clear when it is carefully considered. After the engine has been fully warmed up, the cycle of events is this: Steam is admitted to the cylinder from the boiler. A portion of this is condensed. It parts with its heat to the metal with which it is in contact. The piston makes its stroke, and the pressure falls. The water mixed with the steam is then too hot for the pressure. It boils and produces steam, raising the toe of the diagram in a way well understood and needing no explanation here. During the return stroke the pressure falls to its lowest point, and the water, being again too hot for the pressure, boils, and is con- verted into steam, which escapes to the atmosphere or con- denser without doing work, and is wastea, The metal of the cylinder, etc., falls to the same temperalure as the water. At the next stroke the entering steam finds cool metal to come into contact with, and is condensed, as we have said, and so orj\ But the quantity condensed during the steam stroke is precisely equal to that evanorated during the 114 exhaust stroke, and consequently no condensed steam can leave the engine as water. Let us suppose, for the sake of argument, however, that an engine using 20 lbs. of 100 lbs steam per horse per hour, discharges two pounds of water per horse per hour. As each of these brought, in round numbers, ]i/6^ thermal units into the engine, and takes away only 212 units, it is clear that each pound must leave behma it 973 units ; conse- quently the cylinder will be hotter at the end of each revolu- tion than it was at the beginning, and the process would go on until condensatic^ must entirely cease. It will be urged, however, that a steam jacket certainly does discharge water, and that in considerable quantity, which it did not re- ceive ; and, a? tols is apparently indisputable, we are here face to face with one of the puzzles to which we have referred. The facta however, is in no wise inconsistent with what is ad- vanced. If an engine with an unjacketed cylinder regularly receives water from the boiler, that engine will discharge precisely an equal weight of water. The liquid will pass away in suspension in t he exhaust steam The engine has no power whatever of converting it into steam. The case of a jacketed engine is different. Such an engine will evap- orate in the cylinder water received with the steam, but it can only do so at the expense of the steam contained in the jacket. For every i lb. of water boiled away in the cylinder I lb. of steam is condensed in the jacket ; and the corollary is that, if an engine were supplied with perfectly dry steam, there would be no steam condensed in the jacket, save that required to meet the loss due to radiation and the conver sion of heat into work. The effect of the jacket will be to boil a portion of the water during the close of the stroke and so to keep up the toe of the diagram, and so get more work out of the steam. If, however, the steam was deliv- ered wet to the engine, it is very doubtful if the jacket could be productive of much economy. The water would be con verted into steam during the exhaust stroke, and no equiva lent would be obtained for the steam lost in the jacket. In a good condensing engine about 3 lbs. of steam pe horse per hour are condensed in the jacket. The cylinde will use, say, 15 lbs. of steam, so the total consumption i 18 lbs. per horse per hour. It is none the less a fact, al though it is not generally known, that the average Lancashir boiler sends about 8 per cent, of water in the form of in sensible priming 'Vith the steam. Now, 8 per cent, of i lbs. Is 1.44 lbs., so that in this way we have nearly one-hal the jacket condensation accounted for as just explained One horse-power represents 2,562 thermal units expended per hour, or, say, 2.6 lbs. of steam of 100 lbs. pressure con. densed to less than atmospheric pressure; and 1.44— • 260=- 4.04 lbs. per horse per hour, as the necessary jacket condensation, if no water is to be found in the working cylinder at the end of each stroke. That this quantity is not condensed only proves that the -^.vater received from the boiler, or resulting from the perform:urice of work, is not all re-evaporated. Something still remains to be written about the true action of the steam jacket, but this we must reserve for the present. We have said enough, we think, to show that, as we have stated, the jacket has more to do than keep the cylinder hot. With jacketed engines, more than any other, it is essential that the steam should be dry. In the case of an. unjacketed engine, water supplied from the boiler will pass through the engine as water, and do little harm; but, if the engine is jacketed, then the whole or part of this water will be converted into steam, especially during the period of exhaust, when it Ccan do more good than if it were boiled away in a pot in the engine-room. This is the principal reason why such conflicting opinions are expressed concern- ing the value of jackets. That depends principally on the merits of the boiler. TREATMENT OF NEW BOILERS. No ne^v boiler should have pressure put upon it at once. Instead, it should be heated up slowly for the first day, and whether steam is wanted or not. Long before all the joints are niade, or the engine ready for steam, the boiler should be set and in working order. A slight fire should be made and the water warmed up to about blood heat only, and left to stand in that condition and cool off, and absolute pressure should proceed by very slow stages. Persons who set a boiler and then build a roaring fire under it, and get steam as soon as they can, need not be surprised to find a great many leaks developed; even if the boiler docs not actu- ally and visibly leak, an enormous strain is needlessly put upon it which cannot fail to injure it. Of all the forces en- gineers deal with, there are none more tremendous than ex« mansion and contraction. Ii6 COMPARATIVE ECONOMY OF HIGH AND SLOW SPEED ENGINES. In nearly every case where a flour mill is built, it is intended to be a permanent investment. The very nature of the milling business makes it necessary that the plant shall be built and operated, not for one, two or three years, but for a long term of years. It is the ambition of every mill owner, when he builds a mill, to make it the foundation of a permanent business, and, if he is wise, he will build such a mill and select such machinery as will prove economical, not in first cost, but in the long run. In no part of the milling plant is this more important than in the power outfit of steam mills, and, as most of the mills now being built are steam mills, the comparative economy of different kinds of steam engines becomes an important subject for considera- tion. No matter whether the mill is large or small, unless it is so advantageously located as regards its supply of fuel that the cost is practically nothing, any wastefulness in the consumption of fuel creates a steady drain on the earning of the mill which will seriously affect the balance of the profit and loss account, and, where fuel is expensive, may result in transierring the balance to the wrong side of the account, In selecting a power plant, it is a mistake, frequently made, to consider the first cost of the plant as of the highest importance, and any saving in this direction as so much clear gain. Especially is this the case in flouring mills of small capacity, where the builder's capital is limited, and where the idea is to get as much mill for as little money as possible. In such case, any money borrowed from the power plant to put into the balance of the mill, is bor- rowed at a ruinously high rate of interest, and it is, more- over, borrowed without any chance of repayment, except by throwing out the cheap plant and substituting the higher priced and more economical one at great expense. In no way is the miller more often misled than by the claims of the builders of the high-speed automatic engines, where the name automatic is relied upon to cover a mul- titude of sins in the direction of low economy. In this connection, some facts from a paper by J. A. Powers are instructive: After carefully analyzing the problem and considering the requirements of the load to be driven in electric lighting stations, which are more favorable for the high speed engines than is the case in flouring-mill work, Mr. Powers reaches the conclusion as to the different styles of 117 engines in f!ie consumption of steam, as stated by engine builders : Steam per H. P . per hour. High speed engines 28 to 32 lbs . Corliss engines, non-condensing 24 to ?6 lbs. " " condensinp^ 20 to 21 lbs. " " compound condensing 15 to 16 lbs. With an evaporation of eight pounds of water per pound of coal, the coal consumption would be as follows : C^oal per H. P. per hour High speed engine ., 3.50 to 4 lbs. Corliss engines, non-condensing 3 to 3.25 lbs, " " condensing 2.50 to 2.62 lbs. " " compound condensing 1.87102 lbs. As the interest on the first cost of the steam plant should properly be charged against its economy, the following statement of comparative first cost is given: High speed engine $31 to $36 per H. P. Corliss engines, non-condensing 42 to 46 " " " condensing 43 to 48 " ** *' compound condensing 52 to 57 ** The comparison of first cost and fuel saving is as follows : Coal. ^ Cost. Consumption. High speed engine 100 per cent. 100 per cent. Corliss engine, non-condensing.... 131 ** 62 " " ** condensing 136 ** 56 ** ** " compound cond'g.. 163 ** 44 ** If the cost of coal is taken at $3 per ton and interest h figured at six per cent., which figures may be considered a fair average, the results, based on the foregoing figures, fcr a plant of 403 horse-power, will be as follows : Cost of Coal Saving in Coal per day. over High Speed. High speed engine $24.75 $ Corliss engine, non-condensing. . . 18. go 5.85 " " condensing 15-24 9-5i " " com'd condensing 11.64 i3-ii Interest Loss in Interest per day. over High Sp eed. High speed engine $2.36 $ Corliss engine, non-condensing 3.08 .72 " " condensing 3.15 .79 " " com'd condensing. 3.75 1.39 And the saving per day over the high speed engine h: Corliss engine, non-condensing » $ 5.13 " " condensing 872 " " compound condensing 11 72 So far as the steam consumption is concerned, res alts in every-day work show that the comparison is made as favor- ii8 able as possible for the high speed engine, for, while records of actual tests of Corliss engines show that the figures given are not understated, the average of high speed engines after running a short time is not nearly as low as thirty-two pounds per indicated horse power per hour. So far as the cost of the respective plants are concerned, we should be inclined, especially for small plants, to put the average cost of the high speed plant a little lower than that, of the Corliss a little higher, but this change would not materially affect the result so far as comparative economy is concerned To bring the matter in shape to fairly apply to the requirements of the average lOO barrel mill, it may be assumed that the power required will be 50 horse power. In the absence of exact data as to the cost of the high speed plant, and to give it as favorable a showing as possible, the cost of the respective plants may bfe stated as follows : High speed $1,500 Corliss, non-condensing 2,700 " condensing 3,200 '* compound condensing 4,300 The economy, would then be : Water per H. P. per hour. H. High speed 32 lbs. Corliss non-condensing 26 lbs. " condensing 20 lbs. ** compound condensing 16 lbs. And with coal and rate of interest assumed as above, based on a continuous run of 280 days, 24 hours per day, the comparison is summarized as follows : Cost of Fuel per Year High speed $2,016 C^orliss, non-condensing 1,638 ** condensing 1,260 " comp'd condensing 1,008 The ratio of saving to difference in cost between the high speed plant and the others, may be stated as follows : Between high speed and Corliss non-conden :ng, 25 percent. ** *' ** condensing 38^ " " ** ** comp.condens'g 30 " Or, in other words, it would take four years to save the difference in cost using the non-condensing Corliss, a little over two and one-half years if condensing, and three and one- half years if compound condensing. In either case, the sav- ing would be steadily continued, long after the cost of the plant had been wiped out. Coal per P. per hour. 4 lbs. 3-25 lbs. 2.5 lbs. 2. lbs. nterest. $ 90 162 Total. $2,106 i,8co 192 258 1,452 1,266 119 RULE FOR SAFETY VALVE WEIGHTS. There seemt: to be a steady demand for this rule. The following is an easily remembered formula which may be of service to some : D2 X .7854 X P— D W + F ' L ==^^- Now, this looks somewha^t formidable to those who are not familiar with calculations in any form, but a few words and a little study will make it clear to most persons. The explanation is this : D^ means that the diameter of the valve is to be mult plied by the same figure. If the valve is 4" diameter multi- ply it by 4. If it is 2" multiply it by 2; if 3/^" multiply it ^y 3)4' This is called squaring the diameter. Now multi- ply the sum by .7854 and observe the decimal. This gives the area, as it is called, or number of square inches in the valve exposed to pressure. Of course, the end of the valve exposed to steam has been measured — not the top of it. Now multiply the sum last found by the pressure to be car- ried on the boiler, say 60, if it is 60 pounds. This gives the force pressing on the bottom of the valve to blow it off its seat. Take half the w^eight of the lever and whole weight of valve and stem from this last sum, and then multiply by the distance from the center of the valve-stem to the center of the hole in the short end of the lever. Divide the sum so found by the whole length of the lever. Then you have the weight of the ball to go on the end to give 60 lbs. per square inch on the boiler. This is, in brief, the rule ; but it is of no earthly use to thc?se who are not familiar with ordinary arithmetic, for they will be very likely to make serious errors in the result by mis- takes in figuring. The steamboat inspection law demands that candidates for marine licenses shall know this rule; but in many casr?s it would be just as useful to demand that a man should be able to jump twenty-five feet from a standstill, for those who are incompetent can learn the rule as above given, and pass mus- ter, without being practical working engineers, while those who have mathematical abilities and practical experience also, are only affronted by such appeals to the knowledge they have of their calling. The qualifications and abilities of engineers for their positions are in nowise determined by such trifling exercises as these. 120 Amount of horse power transmitted by single bolts to puU I leys running loo revolutions per miaute when the diameter oi the driving pulley is equal to the diameter of the driven pulley. Diameter of Pulley. Width of Belt in Inches. la. S 9 II 12 J3 f& 20 21 22 23 24 26 27 28 29 30 31 32 33 34 35 H.P. •44 .47 .51 •55 .58 .62 .65 .69 •73 .8 .87 '95 1.02 1.09 1.16 1.2^ I-3I 1-39 1.45 1.52 1.6 1.67 3-8 3-9 4.1 4.2 4.4 4-5 4.7 4.8 4.9 5.1 H. P. •54 59 .64 -68 -n '11 .82 .86 .91 I. 1.09 1. 18 1.27 1.3.6 1.45 1.55 1.64 1.82 1. 91 2. 2.09 4.4 4.5 4.7 4.9 51 5-3 6.2 6.4 3 3>^ 4 4/2 5 6 HP H. P. H.P. H.P. H.P. H.P .65 .76 •87 .98 1.09 1.31 •71 •f^ .95 1.07 1. 19 1.42 .76 .89 I.OI 1. 14 1.27 '•53 .82 •95 1.09 '•23 r.36 1.64 .87 1.02 m6 1-31 1.45 1.75 •93 1.08 I 2\ 1.39 1-55 1.86 98 1. 15 ' 3J 1.48 1.64 1.97 1^4 1. 21 1.39 1.56 1.74 2.0^ 1.09 1.27 1.45 1.63 1. 81 2.18 1.2 1.4 1.6 1.8 2. :2,62 1.31 1-53 1-75 '•97 2.18 1.42 1.65 1.89 2.12 2.36 2.83 1.52 1-77 2.02 2.27 2.53 •3-<>5 1.64 1.91 2.19 2.46 2.73 3.29 J. 74 2.03 2.32 2.61 291 3-4^ 1,85 2.16 2.47 2.78 309 Z'l^ r.96 2.29 2.62 2.95 3-27 392 2.07 2.42 2.76 ^u 3-45 4.14 2.18 2.^5 2.91 3-27 3-64 4-36 2.2Q 2.67 3-05 3-44 6-82 4.58 2.4 2.8 3-2 3.6 4 4.8 2.5» 2.93 3-35 3-75 4.18 5.02 5-2 7- 8.7 10.5 12.2 14- 5.5 7-3 9.1 10.9 12.7 I4S 5-7 7.6 9-5 ''•3 13-2 15. r 5.9 7.8 9.8 11.8 n-i 15.6 6.1 8.1 10.2 12.2 14-3 16.3 6.3 6.6 8.4 10.5 12.6 14.8 16.9 •8.7 10.9 13- 1 15.3 17.4 6.8 9- "•3 135 15.8 la 7. H II. 6 14 16.3 18.6 7.2 9.6 12. 14.4 16.8 19.2 H 9-9 12.4 14.8 17-3 19.8 7.6 10,2 12.7 153 17-9 20.4 I2i Amount of horse power transmitted by smgle belts to pul- leys running ICX) revolutions per minute when the diameter ol the driving wheel is equal to the diameter of the driven puUey. Diameter of Width of Belt • IN Inches. Pulley. 2 2/2 3 ?>% 4 A'A 5 6 In. H.P. H. P. H. P. H. P. H. P. H.P. H. P. H.P. 36 5-2 6.5 7.8 10.5 13- 1 '5-^ 18.3 20.9 37 5.4 6.7 8.1 10.8 13.5 16.2 18.9 21.5 38 5-5 6.9 l'^ II. 13.8 16.6 19.3 22.1 39 S'1 7.1 8.5 II-3 14.2 17- 19.9 22.7 40 5.8 7.3 %.7 11.6 14.6 17.5 20.4 23.3 42 6.1 7.6 9.2 12.2 ^1*3 I8.2 21.4 24.3 44 6.4 8. 9.6 12.8 16. 19.2 22.4 25.6 46 6.7 8.4 10. 13-4 16. 20.1 23.4 26.8 48 7. 8.8 10.4 14. 17.4 21. 24.4 28. 50 7.2 9- 10.9 14.6 18.2 21.8 25.4 29. 54 7.8 9.8 11.8 15-6 19.6 2^.6 26.4 31.2 60 8.8 10.8 13-1 17.4 21.8 26.2 30.6 34.8 66 9.6 12. 14.4 19.2 24. 28.8 33.6 384 72 10.4 13- 15.6 21. 26.2 3'-i z(>^(> 41.8 78 11.4 14.2 17. 22.6 28.4 34- f 30.8 ^^i 84 12.2 15.2 19.4 24.4 30.6 36.4 42.8 48.6 26 3-8 4-7 57 7-? 9-5 11-3 13.2 I5-J 27 3-9 4.9 5.9 7.8 9.8 11.8 ^2>'7 156 28 4.1 5-1 6.1 8.1 10.2 12.2 14.3 16.3 29 4.2 5-3 ^A 8.4 10.5 12.6 14.8 16.9 30 4.4 5-4 6.6 8.7 10.9 13- 1 15.3 17.4 31 4-5 5-6 6.8 9- II-3 13-5 15.8 18. 32 4-7 5.S 7. 9-3 II. 6 14. 16.3 18.6 33 4.8 6. 7.2 9.6 12. 14.4 16.8 19.2 34 4.9 6.2 7.4 9.9 12.4 14.8 17-3 19.8 35 5-1 6.4 7.6 10.2 12.7 153 17.9 20.4 36 5-2 6.5 7.8 10.5 131 15.7 18.3 20.9 37 5.4 6.7 8.1 10.8 135 16.2 18.9 21-5 38 5-5 6.9 l'^ II. 13.8 i66 19.3 22.1 39 5-7 7.1 8.5 II. 3 14.2 17. 19.9 22.7 40 5-^ 7.3 ^'7 II. 6 14.6 17.5 20.4 23-3 42 6.1 7.6 9.2 12.2 15-3 18.2 21.4 25.? 44 6.4 8. 9.6 12.8 16. 19.2 22.4 HOW TO TRUE AN EMERY WHEEL. A P. e'Tiery wheel may be trued by ^asing a bar of rough iroD -yr ( opper as a turning tool. , 122 HOW TO FIND THE DIAMETER OF HIGH AND LOW PRESSURE CYLINDERS AT DIF- FERENT PRESSURES. The following is a table from actual practice giving the diameters of the high and low pressure cylinders at different boiler pressures, the piston speed being taken at 420 ft. minute : r^ ^ . Boiler pres- Boiler pres- Boiler pres- la. sure 45 lbs. sure 80 lbs. :sure 125 lbs. 1^ Diam. H.P. Diam. H.P. Diam. H.P. 5^ cyHnder. cylinder. cylinder. 10 7Xin. 4 in. SVs in. 3X in- 20 10 5^ 5- A'A 25 iiK 6j^ 5K 5/s 30 I2>/8 7>^ 6X S% 40. hX 8X 7/8 6^8 50 16 9X 8 7^^ 100 22>^ 13 iiX loYi 150 27^ 16 14 12^8 ANIMAL POWER. Average power of a man working to the best advantage is lifting 70 lbs. I ft. in i second for 10 hours per day, or 4,200 fr. lbs. per minute, =0.127 horse-power. The average work of a horse in a day of 8 hours is 22,500 lbs. raised I ft. in I minute, or 0.68 of the theoreti- cal horse-power. A horse can only exert a theoretical horse -power for 6 hours per day. I indicated horse-power =1.4 times the average power of a horse. The strength of a horse is equivalent to that of 6 men. HOW TO MAKE A STRONG FLANGE JOINT. To make a flange joint that won't leak or burn out on steam pipes, mix two parts white lead to one part red lead to a stiff Toutty ; spread on the flange evenly, and cut a liner of gauze wire — like mosquito net wire — and lay on the putty, of course cutting out the proper holes ; then bring the flanges *«fair," put in the bolts and turn the nuts on evenly. For a permanent joint this is A i. 123 DENSITY OF WATER. Tempera- ture F. Comparative Volume. Water 32"-=!. Comparative Density. Water 32^=1. Weight of I Cubic Foot. 32 I .00000 I. 00000 62.418 35 0.99993 1.00007 62.422 40 0.99989 I. 0001 I 62.425 45 0.99993 1.00007 62.422 46 I. 00000 I .00000 62.418 50 I. 00015 .99985 62.409 55 1.00038 .99961 62.394 60 1.00074 .99926 62.372 65 I.00119 .99881 62.344 70 I. 00160 .99832 62.313 75 1.00239 .99771 62.275 80 1.00299 .99702 62.232 85 1.00379 .99622 62.182 90 1.00459 .99543 62.133 95 1.00554 .99449 62.074 ICX) 1.00639 -99365 62.022 105 1.00739 .99260 61.960 no 1.00889 .99119 61.868 115 1.00989 .99021 61.807 120 1.01139 .98874 61.715 125 I. 01 239 .98808 61.654 130 I. 01 390 .98630 61.563 135 I. 01539 .98484 61.472 140 1.01690 •98339 61.381 145 1-01839 .98194 6l;29I 150 1.01989 .98050 61.201 155 I. 02 164 .97882 61.096 160 1.02340 .97715 60.941 165 1.02589 .97477 60.843 170 J . 02690 .97380 60 783 175 1.02906 .97193 60.665 i8o I. 03 100 .97006 60.543 185 1.03300 .96828 60.430 190 I .03500 .86632 60.314 195 1.03700 .96440 60. 198 2CX) I .03889 .96256 6o.o8r 205 I. 0414 .9602 59.937 210 I .0434 .9584 59 822 "12 1.0444 .9575 59.769 i24 CALKING STEAM BOILERS. No well-made boiler ought to require to be heavily calked, and to provide for light calking it is imperative that the plates of a boiler should be effectually and thoroughly cleaned of all fire scale before being riveted up. Good boiler vi^ork should be very nearly tight without calking, but it is difficult to attain this degree of excellence with hand work. Hydraulic riveting, in which the plates are forcibly pressed together before the rivet is closed and made to fit the hole, will, if carefully doue, be found to give a tight boiler without calking. It is obvious that tightness can only be secured by insuring metallic contact. If all the rivets fill the holes per- fectly, no leakage can percolate past the rivet heads. If any rivet heads require calking, they should be cut out and a fresh rivet inserted, as a leak is a sure indication that the rivet does not fill the hole, and is possibly imperfectly closed in addition. It is also obvious that to insure a tight boiler the surfaces of the plates must be in metallic contact, and must remain so when the boiler is subjected to the working pressure which, with the alterations of temperature, will pro- duce certain inevitable changes in the form of the boiler. It is obviously necessary that the surfaces of the plates should be smooth in order to insure metal- lic contact, and that this cannot be attained unless the scale covers the plates completely, or is wholly detached. As a slight pin-hole in the magnetic oxide with which steel plates are coated will cause aleak- age, and under certain circumstances, set i^ a galvanic and corrosive action, it is advisable to easily done with irori Fig. I. Fig. 2. wholly detach the scale. This is plates, but steel plates cannot be completely cleaned of mag- netic oxide by the usual mechanical methods. An excellent and effective method is that used at the Crewe Works of the London & Northwestern Railway (England). The plates are brushed over with muriatic acid diluted with water, and applied with a brush or pad made with woolen waste- This 125 loosens and detaches all the scale, and the plates rae then cleaned by a solution of lime, which effectually removes any surplus muriatic acid. If the plates are not wanted imme- diately, they can be protected from rust by a coat of turpen- , tine and oil. If these precautions be not taken, the scale or idirt upon the plates becomes crushed to powder by the squeeze of the riveter, and a close metal to metal joint is i en- dered impossible, and the consequent leakage must be stopped by calking. With clean plates much calking is not neces- sary, nor should it be countenanced, for, after all, calking is only an evidence of, and a concession to, more or less in- ferior, or, at least, imperfect workmanship. Some boiler-makers firmly believe that calking should be performed both internally and externally, and we may fre- quently hear this double calking expatiated upon as adding to the value of a boiler. As a matter of fact, however, in- ternal calking should never be resorted to. By internal calk- ing we mean specially to indicate the calking of edges ex- posed to steam or water, especially the latter, for long expe- rience has shown, with very little room for doubt, that internal calking has frequently been either a cause or an aid m the initiation of corrosive channeling of the plates along the line of the rivet seams. Though channeling is commonly met with along the longitudinal seams, being started, more fre- quently than by any other cause, by the want of perfect cir- cularity of the boiler, yet it is aggravated by the calking of the edge of the plate which borders the channeling, and the explanation is that an abnormal stress is set up in the plate upon which the calked edge is forced down, and too fre- quently the calking tool itself is driven so severely upon the plate surface as to cause an injury which develops as chan- neling when other conditions, such as bad water, etc., are present. These causes have been mainly coiitributory to the modern practice of outside calking only, and, with proper workmanship, this is all that should be required, but the best practice rejects any calking at all in the strict acceptation of the term, and demands that the edges of the plates shall be planed and "fullered;" fullering being the thickening up of the whole edge of the plate by means of a tool having a face equal to the plate thickness. With such a tool as this, it is impossible to wedge apart the plates forming the joint, and so frequently done in the manner shown (exaggerated) in Fig.%, when the narrow edge of the calking tool, driven per- haps by a heavy hammer, actually forces the plates apart and insures a tight joint only by the piece of damaged plate corner which remains driven fast into the gap. 1,J^ In contrast io this. Fig. 2 may he taken to fairl> I'epre' Bent the correct action of the more con*ect fullering tool, the plate edge being simply thickened, and contact between the two plates rendered certain for some distance in from the edge. To thus thicken, or " fuller " a plate, requires con- siderable power, and yet, even the use of a more than usually heavy hammer will not cause injury, as it certainly would do in careless hands, if used with a narrow calking tool. All modern first-class boiler work in Eng^land is inviarabiy ful- lered, and, though the practice of inside calking is still fol- lowed by firms who " fuller, " nevertheless, outside work is gaining the day. A further advantage of the " fulling " tool may be named. If inside calking be still practiced, the tendency to cause grooving will be less marked than with the narrow tool, and where, as at times, it is absolutely necessary to internally calk, as may sometimes happen, the iast is a great point in favor of the broad tool. The foregoing remarks are suggested by a few notes on calking in an engineering work, wherein calking tools are described as having from }i to 3-16 of thickness, and "best work" as being calked both inside and out. In itself, calking properly carried out, and lightly performed on good, close-riveted joints, is not necessarily bad, but too frequently is badly performed by careless workmen and boys, and hence ** fullering," which is better practice, and is also a safeguard against carelessness, is to b'^^ preferred to the old method. HOW TO THAW OUT A FROZEN STEAM-PIPE. A good way to thaw out a frozen-up steam pipe, is to take some old cloth, discarded clothes, waste, old carpet, or anything of that kind, and lay on the pipe to be thawed ; then get some good hot water and pour it on. The cloth will hold the heat on the pipe, and thaw it out in five min- utes. This holds good in any kind of a freeze, water- wheel, or anything else. How many people, outside of practical men, know that steam is an invisible gas until the moisture it bears is con- densed by contact with cold air. Such is a fact, neverthe- less, as we may readily see by boiling vvater in a glass vessel. The bubbles that rise to the surface of the water are appar- ently empty — the white vapor appears after they burs c in the air at the surface of the water. 127 THE PREVENTION OF ACCIDENTS FROM RUN. NING MACHINERY. A German commission was appointed to investigate acci« dents in mills and factories, and draw up a series of rules fot their prevention. Some of these rules are as follows: SHAFTING. All work on transmissions, especially the cleaning and lubricating of shafts, bearings and pulleys, as well as the binding, lacing, shipping and unshipping of belts, must be performed only by men especially mstructed in, or charged with, such labors. Females and boys are not permitted to do this work. The lacing, binding or packing of belts, if they lie upon either shaft or pulleys during the operation, must be strictly prohibited. During the lacing and connecting of belts, strict attention is to be paid to their removal from revolv- ing parts, either by hanging them upon a hook fastened to the ceiling, or in any other practical manner; the same applies to smaller belts, which are occasionally unshipped and run idle. While the shafts are in motion, they are to be lubricated, or the lubricating devices examined only when observing the following rules: a. The person performing this labor must either do it while standing upon the floor, or by the use of b. Firmly located stands or steps, especially constructed for the purpose, so as to afford a good and substantial footing to the workman, c. Firmly constructed sliding ladders, running on bars. d. Sufficiently high and strong ladders, especially constructed for this purpose, which, by appropriate safe- guards (hooks above or iron points below), afford security against slipping. The cleaning and dusting of shafts, as well as of belt or rope pulleys mounted upon them, is to be performed only when they are in motion, either while the workman is standing : a, on the floor ; or <5, on a substantially con- structed stage or steps ; in either case, moreover, only by the use of suitable cleaning implements (duster, brush, etc.), provided with a handle of suitable length. The cleaning of shaft bearings, which can be done either while standing upon the floor or by the use of the safeguards mentioned above, must be done only by the use of long-handled implements. The cleaning of the shafts, while in motion, with cleaning waste or rags held in the hand, is to be strictly prohibited., All shaft -bearings are to be provided with automatic lubricating apparatus. 128 Only after the engineer has given the well understood signal, plainly audible in the work-rooms, is the motive en- gine to be started. A similar signal shall also be given to a certain number of work-rooms, if only their part of the machinery is to be set in motion. If any work other than the lubricating and cleaning of the shafting is to be performed while the motive engine is standing idle, the engineer is to be notified of it, and in what room or place such work is going on, and he must then allow the engine to remain idle until he has been informed by proper parties that the work is finished. Plainly visible and easily accessible alarm apparatus shall be located at proper places in the work-rooms, to be used in cases of accident to signal to the engineer to stop the motive engine at once. This alarm apparatus shall always be in working order, and of such a nature that a plainly audible and easily understood alarm can at once be sent to the enginef^r in charge. All projecting wedges, keys, set-screws, nuts, grooves, or other parts of machinery, having sharp edges, shall be sub- stantially covered. All bells and ropes which pass from the shafting of one story to that of another shall be guarded by fencing or casing of wood, sheet-iron or wire netting four feet six inches high. The belts passing from shafting in the story under- neath and actuating machinery in the room overhead, thereby passing through the ceiling, must be inclosed with proper casing or netting corresponding in height from the flooi to the construction of the machine. When the con- struction of the machine does not admit of the introduction of casing, then, at least, the opening in the floor through which the belt or rope passes should be inclosed with a low casing at least four inches high. Fix:jd shafts, as well as ordinary shafts, pulleys and fly- wheels, running at a little height above the floor, and being within the locality where work is performed, shall be securely covered. These rules and regulations, intended as preventions of accidents to workmen, are to be made known by being con- spicuously posted in all localities where labor is performed. ENGINEERS. The attendant of a motive engine is responsible for the preservation and cleaning of the engine, as well as the floor of the engine-room. The minute inspection and lubrication 129 of the several parts of the engine is to be done before it is set in motion. If any irregularities are observed during the performance of the engine, it is to be stopped at once, and the proper person informed of the reason. The tightening of wedges, keys, nuts, etc., of revolving or w^orking parts, is to be avoided as much as possible during the motion of the engine. When large motive engines are required to be turned over the dead point by manual labor, the steam supply valve is to be shut off. After stoppage, either for rest or other cause, the engine is to be started only after a well-understood and plainly audible signal has been given. The engineer must stop his engine at once upon receipt of an alarm signal. The engineer has the efficient illumination of the engine- room, and especially the parts moved by the engine, under his charge. The engineer must strictly forbid the entrance of unau thorized persons into the engine-room. An attendant of a steam or other power motor, who \a charged with the supervision of the engine as his only duty, is permitted to leave his post only after he has turned the care of the engine over to the person relieving him in the discharge of his duties. The engineer is charged with the proper preservation of his engine, and means therefor. He must at once inform his superior of any defect noticed by him. The engineer on duty is permitted only to wear closely fitting and buttoned garments. The wearing of aprons or neckties with loose, fluttering ends, is strictly prohibited. GEARING. Every work on gearing, such as cleaning and lubricating shafts, bearings, journals, pulleys and belts, as well as the tying, lacing and shipping of the latter, is to be performed only by persons either skilled in such work, or charged with doing it. Females and children are absolutely prohibited from doing such work. When lacing, binding or repairing the belts, they must either be taken down altogether from the revolving shaft or pulley, or be kept clear of them in an appropriate manner. Belts unshipped for other reasons are to be treated in the same manner. The lubricating of bearings and the inspection of luori- cating apparatus must, when the shafting is in motion, be performed either while standing upon the floor or by the use I30 of steps or ladders, specially adapted for this purpose, or proper staging or sliding ladders. The lubrication of wheel work and the greasing ol belts and ropes with solid lubricants is absolutely prohibited during the motion of the parts. In case of accident, anyworkman is authorized to sound the alarm signal at once by the use of the apparatus located in the room for this purpose, to the engineer in charge. The following rules, classified under proper sub-heads, are published by the Technische Verein, at Augsburg: TO PREVENT ACCIDENT BY THE SHAFTING. While the shafts are in motion, it is strictly prohibited: a. To approach them with waste or rags, in order to clean them. b. In order to clean them, to raise above the floor by means of a ladder or other convenience. It is allowable to clean the shafting and pulleys only while in motion. These parts of the miachinery must be cleaned by means .vf a long-handled brush only, and while standing upon the floor. The workmen charged with these or other functions about the shafting must wear jackets with tight sleeves, and closely buttoned up ; they must wear neither aprons nor neckties with loose ends. Driving pulleys, couplings and bearings are to be cleaned only when at rest. This labor should, in general, be performed only after the close of the day's work. If performed during the time of an accidental idleness of the machinery, or during the time of rest, or in the morning before the commencement of work, the engineer in charge is to be informed. HOW TO FIND THE HORSE-POWER OF AN ENGINE. Multiply the square of the diameter of the cylinder by 0.7854, and, if the cut-off is not known, multiply the product by four-fifths of the boiler pressure; multiply the last product by the speed of the piston in feet per minute (or twice the stroke in feet and decimals, multiplied by the revo- lutions per minute). Divide the final product by 33.<^oo. and the horse-power will be the answer. 131 ECONOMY IN THE USE OF AN INJECTOR. The following is an interesting discussion of the economy dae to the use of an injector, in comparison with a direct- acting steam-pump, both with and without a feed-water heater, and a geared pump with heater. Although the in- vestigation is theoretical, it seems to be based on reliable data, so that the results, as summarized in the following table, difter little, in all probability, from the figures which would be obtained by actual experiment : Temperature Relative amount Per cent, of M anner of feeding of feed- of coal required fuel saved boiler. water. for feed over first Fahrenheit. apparatus, in equal times. case. ^. D ire c t- acting ) steam-pump, >• 6o 100 0. no heater ) 2. Injector, no heater 1500 98.5 I . :; 3- Injector, with { heater j" 200 93-8 6.2 4- D irec t- acting ) steam-Dump, V 2000 87.9 12 ,1 with heater. . . ) 5- Ge a red-pump, actuated by the main en- } 2000 86.8 13.3 gi n e , with heater J This does not make the comparison between the eco- nomical performance of an injector and pump actuated by the main engine, wi.hout heater in each case, or, in other words, he does not consider one of the most general divisions of the problem. Some experiments made on the Illinois Central Railroad may be briefly cited to supplement the dis- cussion. The figures given represent averages of eight trips of 128 miles in each case : Pounds of coal per trip. . . Pounds of water per trip. Pounds of water evapo- rated per pound of coal Feeding with pump. 9.529 48,888 5-H Feeding with injector. 8,736 46,826 Per cent, of grain for injector 9.08 4.04 5.26 4.28 In the experimei/ts with pump, the trains were slightly heavier than when the injector was used, and more time was 132 lost in switching and standing, for which reason the experi- menters considered that the economy of coal consumption /or the injector should he reduced from 9.08 to 6.21 per cent. Some incidental advantages were observed in the case of the injector, the boiler steamed more freely, and there was less variation of pressure. TELEPHONES. Telephones are of two kinds— magneto and electric. In one sense of the word they both work on the same principle, namely: A series of pulsations, corresponding in length and SECTION OF A BLAKE TRANSMITTER Strength to the sound waves made by the voice, cau-se simi- lar pulsations in the receiving end of the telephone circuit, and these pulsations in turn make sound waves which reach the ear. Magnetism and electricity work together in a tele- phone. If a wire is moved just in front of the poles of a magnet, whether it be an electro or a permanent magnet, a current of electricity is induced in the wireu If a current of electricity is set to flowing around a piece of soft iron, that 533 piece of iron becomes an electro-magnet aL:e stated that the depth between the top of the bars and tne crown of the furnace should not be less than two feet si* inches where the grate is but four feet long ; increasing \n the same ratio where the length is greater ; and secondiy, that the depth l^elow the bars should not be less, although depth there is not so essential either practically or chemicaliy. I50 PROPERTIES OF SATURATED STEAM • PRESSURE. Volume. Total heat required Tempera- Latent to generate ture in Heat in T lb. of Steam Gauge. Fahrenheit Com- Cubic Feet Fahren- Steam from Total Degrees pared with Water. of Steam from I lb. of Water. heit Degrees. Water at 32 dcig. under constant pressure. In Heat Units. o 15 212.0 1642 26.36 965.2 1146. I 5 20 228.0 1229 19.72 952.8 1150.9 o 25 240.1 996 15.95 945-3 1154-6 iS 30 250.4 838 13-46 937-9 1157-8 20 35 259-3 726 11.65 931.6 1160,5 25 40 267.3 640 10.27 926.0 I 162. 9 30 45 274.4 572 9.18 920.9 I I 65. I 35 50 281.0 518 8.31 916.3 1167.1 40 55 287.1 474 7.61 912.0 I I 69.0 45 60 292.7 437 7.01 908.0 1170.7 50 65 298.0 405 6.49 904.2 IT72.3 55 70 302.9 378 6.07 900.8 1173-8 60 75 307-5 353 5.68 897-5 1175.2 65 80 312.0 333 5 35 894-3 1176.5 70 85 316.1 314 5.05 891.4 1177.9 75 90 320,2 298 4.79 888.5 1179-1 80 95 324.1 283 4.55 8858 1180.3 85 100 327-9 270 4-33 883.1 1181,4 90 105 331-3 257 4.14 880.7 T182.4 95 ITO 334-6 247 3-97 878.3 1183.5 TOO 115 338.0 237 3-80 875.9 1184.5 no 125 344.2 219 3.51 871.5 1186,4 120 135 350.1 203 3.27 867.4 1188.2 130 145 355-6 190 3.06 863.5 1189.9 140 155 361.0 179 2.87 859-7 1191.5 150 165 366.0 169 2.71 856.2 1192.9 160 175 370.8 159 2.56 852.9 1194.4 170 185 375-3 151 2.43 849.6 1195-8 180 195 379-7 144 2.31 846.5 1197.2 This table gives the value of all properties of saturated steam required in calculations connected with steam boilers. SODA ASH IN BOILERS. An English boiler inspection company recommends that soda ash be used to prevent scale, instead of soda crystals; and that it be pumped in regularly and continuously in solu- tion, with the feed, instead of spasmodically dumped in solid through the manhole. Tungstate of soda, instead of either soda ash or soda crystal, has been recommended strongly by some high authorities in lieu "^ the above. *5^ STEAM COAL. Steam coal, being, as everybody knows, unquestionably the most important and largest expense in the manufacture of steam, is deserving a most careful investigation by engi- neers and owners, who, unlike chemists and college pro- fessors, consider the subject wholly in a practical way, as relating to the coal bills of their establishments. Useful knowledge of every-day economy of coal is seldom gained by " tests" conducted by experts, for several reasons so plain that they will not require explanation, ist. The cost of the fuel used in tests, whatever may be stated, is too high, aver- age or " every-day " coal not being used. The experiments are made with picked men and picked fuel, for brief periods, with everything at its best, and the results attained, if looked for in the ordinary run of business, will be disappointment in the results of the wholesale order. 2d. Men, working as firemen, twelve or fourteen hours per day in the hot furnace rooms, cannot be expected, with the ordinary appliances, to watch where every lump of coal falls when feeding the fur naces, nor to clean the grates any oftener than they are com- pelled to do. 3d. Moreover, too many employers favor the low wages plan, and, for the apparent saving of a few dol- lars per month, waste many times the amount in the^.r fur- nace doors, and render their establishments most disagree- able to their neighbors, by a free distribution of unconsumed carbon, or what is commonly called soot, and of which most people have no appreciation. 4. Little or no encourage- ment is given for careful or economical firing, as a rule. The fireman who oftentimes wastes as much as his entire wages, secures the same pay as the man working. alongside of him who saves it all. It may be remarked that this is " not business," but many are the concerns who run their steam plants upon this system. Careful handling of coal in firing pays better than any other thing about a steam plant, and it is the wisest economy to secure good and careful men lo do it. As is well understood, the conditions or circumstances attending the combustion of coal for steam purposes, embra- ces a wide range. A very few establishments work under conditions that admit of a high attainment of economy by having a fixed performance of duty, and their plants well proportioned to the regular work, but by far the largest number having a fluctuating demand for steam, and in that respect are largely at a disadvantage. Many furnaces are badly constructed, others suffer from an insufficiency of 152 draft, and in many cases there seems to be no end of compli- cations detrimental to best results^. These practical difficulties and uncertainties, which are well known to every experienced engineer, render any investiga- tion worthy of the name, slow and laborious. It has taken considerable time and research to arrive at the conclusion, though differing from the preponderance of hearsay or guess-work evidence, that now, at least, " the highest priced coal is not the cheapest for steam prodiiction^'''^ and that, in fact, the reverse is undoubtedly true, especially in the Western country Late improvements in the con- struction of grate bars ha^e undoubtedly added largely to the value of Western soft coals. The great difficulty, in former times, of ridding the furnaces of the incombustible part of these very valuable coals has now been removed by improvements, and there is no doubt but what a large num- ber of extensive establishments in the West are now, and for some time past have been, obtaining the same duty from the Illinois bituminous coals that they in former years obtained from the high-priced Eastern coals. BLOWING OFF UNDER PRESSURE. A boiler can be seriously impaired by blowing it down under a high pressure, and with hot brick work. The heat from the latter will granulate the iron and reduce its tensile strength. A boiler should not be blown right down under a higher pressure than twenty pounds, and not less than four hours after /he fire has been drawn. When a boiler is exposed to cold air, especially in the winter, it js advisable that the damper be closed and the doors thrown open, or vice-versa. If both are left open, the strong draught of cold air will cool off the flues faster than the shell; which abuse, if kept up, would reduce the length of the life of the boiler. THE TOTAL PRESSURE. A boiler eighteen feet in length by five feet in diameter, with forty-four inch tubes, under a head of eighty pounds of steam, has a pressure of nearly 113 tons on ea^h head, 1,625 tons on the shell and 4,333 tons on the tubes, making a total of 6,184 tons on the whole of the exposed surfaces. This calculation is made by finding the total square inches under pressure, and multiplying the totals by the pressure, in ihis case, 80 i^ounds to the square inch. 153 'able Showing Safe Working Steain Pressure for Iron Boilers of different sizes, using a Factor of Safety of Six. f. \ X 'A h X 1 fi X 5. 16 % y% X h v% 1 IG IB 7. 1 « ^8 4 34 Longitudinal Seams, Single Riveted. Tensil Strength of Iron INCH. X A 45,000 50,000 Lbs. Lbs. Press- Press- ure. ure. LBS. LBS. 104 ir6 130 145 99 no 123 137 94 104 117 130 89 99 112 124 B5 95 107 118 82 91 102 113 78 87 98 109 118 131 75 83 94 104 112 125 72 80 90 100 108 120 87 96 104 116 121 135 78 87 94 104 109 121 85 95 99 in 112 117 78 87 91 102 102 117 55,000 Lbs. Press- ure LES. 127 159 121 151 115 143 109 136 104 130 1 03 125 96 120 144 92 115 138 88 no 132 106 127 148 95 115. 134 104 121 138 96 n2 128 Longitudinal Seams, Double Riveted. . Tensil Strength of Iron. 45,000 Lbs. 50,000 Lbs. Press- Press- ure. ure. LBS. LBS. 156 139 174 119 148 132 164 113 125 140 156 107 119 134 149 102 114 128 98 122 142 109 136 94 104 n8 131 142 157 90 100 113 125 134 86 108 150 96 120 130 144 lOI n2 120 140 134 156 94 104 113 125 131 145 102 114 120 133 137 152 94 104 no 122 125 140 55,000 Lbs. Press- ure. LBS. 152 191 145 181 138 172 131 163 125 156 120 150 ii5 144 173 no 138 166 106 132 158 122 148 172 114 138 160 125 146 167 115 134 15.^ 154 brEAM HEATING. The advantages of steam heating are set forth by Prof. W. P. Trowbridge, in the No7'th Ainerican Review^ as follows : 1. The almost absolute freedom from risk of fire when the boiler is outside of the walls of the building to be heated, and the comparative immunity under all circumstances. 2. When the mode of heating is the indirect system, with box coils and heaters in the basement, a most thorough ventilation may be secured, and it is in fact concomitant with the heating. 3. Whatever may be the distance of the rooms from the source of heat, a simple steam pipe of small diameter con- veys the heat. From the indirect heaters underneath the apartments to be heated, a vertical flue to each apartment places the flow of the low heated currents of the air under the absolute control of the occupants of the apartment. Uniformity of temperature, with certainty of control, may be thus secured. 4. Proper hygrometric conditions of the air are better attained. As the system supplies large volumes of air heated only slightly above the external temperature, there is but little change in the relative degree of moisture of the air as it passes through the apparatus. 5. No injurious gases can pass from the furnace into the air flues. 6. When the method of heat is by direct radiation in the rooms, the advantage of steadiness and control of tem- perature, suflicient moisture and good ventilation, are not always secured; but this is rather the fault of design, since all these requirements are quite within reach of ordinary contrivances. 7. One of the conspicuous advantages of steam heating is that the most extensive buildings, whole blocks, and even large districts of a city may be heated from one source, the steam at the same time furnishing power where needed for ventilation or other purposes, and being immediately avail* able also for extinguishing fires, either directly or through force pumps. STOPPING WITH A HEAVY FIRE. When it becomes necessary to stop an engine with a heavy fire vn the furnace, place a layer of fresh coal on the fire, shut tne damper and start the injector or pump for the purpose of keeping up the circulation in the boiler. 155 ANALYSIS OF BOILER INCRUSTATION. BY DR. WALLACE. Carbonate of lime 64.98 Sulphate of lime 9. 33 Magnesia 6.93 Combined water . , 3. 15 Chloride of sodium 23 Oxide of iron. . . ., „ 1. 36 Phosphate of lime of alumina 3. 72 Silica 6.60 Organic matter 1.60 Moisture at 212 degrees F 2.10 100. CLEANING BOILER TUBES. The method of cleaning boiler tubes depends upon the kind of fuel used. A steam jet will not answer where wood and soft coal are used, but will do for hard coal, though in any case a scraper is indispensable, where a steam jet is not. Soot and dust will collect in the tubes and burn on so as to require more than a jet of steam to move it. A steam jet or blower should be used only where dry steam is at hand, but by no means with wet steam. Before using the jet, thor- oughly blow all the water out of it and heat it up. We have seen some men put the point of the jet in a tube and turn on steam before warming, and then wonder what caused the brick work to crumble away at the back end . CLEANING BRASS. The government method prescribed for cleaning brass, and in use at all the United States arsenals, is said to be the best in the world. The plan is, to make a mixture of one part of common nitric, and one-half part sulphuric acid in a stone jar, having also a pail of fresh water and a box of saw-dust. The articles to be treated are first dipped into the acid, then removed into the water, and finally rubbed with the saw-dust. This immediately changes them into a brilliant color. If the brass has become greasy, it is first dipped into a strong solution of potash or soda, in warm water. This dissolves the grease, so that the acid ha.*^ power to act. THE THERMAL UNIT Is the heat necessary to raise one pound of water at 39^ F, one degree^ or to 40^ F. 156 SMOKE — HOW FORMED. When fresh coal is placed on a fire in an open grate, smoke arises immediately; and the cause of this smoke is not far to seek, as it will be easily miderstood that, before fresh coals were put upon the fire within the grate, the glowing coals radiated their heat and warmed the air above, and thereby enabled the rising gases to at once combine with the warmed air to produce combustion; but, when the fresh coals are placed upon the fire, they absorb the heat, and the air above remains cold. By gases, is meant the gases arising from coals while on or near the fire, and it may not be known to every one that we do not burn coals, oils, tallow or wood, but only the gases arising from them. This can be made clear by the lighting of a candle, which will afford the information required. By lighting the candle, fire is set to the wick, which, by its warmth, melts a small quantity of tallow directly absorbed by the capillary tubes of the wick, and thereby so very finely and thinly distributed that the burning wick has heat enough to be absorbed by the small quantity of dissolved tallow to form the same into gases, and these gases burning, combined with the oxygen in the atmosphere, give the light of the candle. A similar process is going on in all other materials; but coal contains already about sev- enteen per cent, of gases, which liberate themselves as soon as they get a little warm. The smaller the coal, the more rapidly will the gases be liberated, so that, in many cases, only part of the gases are consumed. The fact is, that the volatile gases from the coal cannot combine with cold air for combustion. Still combustion takes place in the following ways. The cold air, in the act of combination, absorbs a part of the warmth of the rising gases, which they cannot spare, and, therefore, must con- dense, so that small particles are formed, which aggregate and are called smoke, and when collected, produce soot; but as long as these particles and gases are floating, they cannot burn or produce combustion, as they are surrounded by a thin film of carbolic acid. It is only when collected and this acid driven off, that they are consumed. It has now been shown that cold is the cause of smoke, which may be greatly reduced by care. In the open fire grate the existing fire ought to be drawn to the front of the grate, and the fresh coal placed behind, or in the back of the fire. 'The fire in the front will then burn more rapidly, warm the air above, and prepare the raising gases for com- i)/ Ibustion. In this way smoke is diminished, as the gascs from the coals at the back rise much more slowly then when placed upon the fire and the air partly warmed. WHAT IS LATENT HEAT? Heat has its equivalent in mechanical work, and, when heat disappears, work of some kind will take its place. When a body changes from the liquid to the gaseous form, the molecules have to be separated and placed in different positions with regard to each other. This calls for an ex- penditure of work. This work is supplied by heat, which disappears at the time. One can hold his hand in steam es- caping from a safety valve of a boiler for this reason. The heat of the steam disappears in pushing apart and rearrang- ing the molecules of the steam as it expands when it leaves the safety valve. The term latent heat, as commonly used, means the amount of heat which disappears when v/ater changes from a liquid into steam. This is considerable, as will be seen by consulting any table of the heat contained in steam, and the water from which it comes. Water at 212° contains 180 units of heat. Steam at 212^^ contains 1,146 units of heat. The latent heat is the difference of 966 uni':s. Such a large quantity disappears when liquid water changes to steam, that boiling cannot be raised above 212", no matter how hard it is boiled. The heat becomes latent, and the mechanical work, or rather molecular work, is sufficient to take up all that is supplied by the fire. The specific heat of air at constant pressure being 0.2377, the specific heat of water, which is i, is, therefore, 4.1733 times greater under ordinary circumstances. A pound o( water losing i^ of heat, or one thermal unit, will consequently raise the temperature of 4.17 pounds, or, at ordinary temperatures, say 50' of air, i^. A pound of steam at atmospheric pressure, having a temi)erature of 212^ F., in condensing to water at 212^^ F., yields 966 thermal units, which, if utilized, would raise the temperature of 5X9663 ^,830' of air i^, or about 690' from 5^ to 70'^ F. 158 MISTAKES IN DESIGNING BOILERS. One of the greatest mistakes that can be made in design- ing boilers, and the one that is most frequently made of any, consists in putting in a grate too large for the heating sur- face of the boiler, so that with a proper rate of combustion of the fuel an undue proportion of the heat developed passes off through the chimney, the heating surface of the boiler being insufficient to permit its transmission to the water. This mistake has been so long and so universally made, and boiler owners have so often had to run slow fires under their boilers to save themselves from bankruptcy, that it has given rise to the saying, " Slow combustion is necessary for econ- omy." This saying is considered an axiom, and regarded with great veneration by many, when the fact is, if the truth must be told, it has been brought about by the waste- fulness entailed by boiler plants and proportioned badly by ignorant boilermakers and ignorant engineers, who ought to know better, but don't. 'Let us consider the matter briefly : Suppose w^e are running the boiler at a pressure of 80 lbs. per square inch, the temperature of the steam and water inside will be about 325 degrees F. ; the temperature of the fire in the furnace will, under ordinary conditions, be about 2,500 degrees F. Now, it should be clear to the dullest comprehension, that we can transmit to the water in the boiler only that heat due to the difference between the temperature in the furnace and that in the boiler. In case of the above figures, about seven-eighths of the total heat of combustion is all that could, by any possibility, be utilized, and this would require that radiation of heat from every source should be absolutely prevented, and that the gases should leave the boiler at the exact temperature of the steam inside, or 325 degrees. To express the matter plainly, we may say that the utilization of the effect of 2. fall of temperature of 2.175 degrees is all that is possible. Now, suppose, as one will actually find to be the case in many cases if he investigates carefully, that the gases leave the flues of another steam boiler at a temperature between 500 and 600 degrees. The latter temperature will be found quite common, as it is considered to give "good draft." This is quite true, especially as far as the " draft " on the owner's pocket-book is concerned, for he cannot possibly utilize under these conditions more than 2,500 — 500=2,000 degrees of that inevitable difference of temperature to which he is confined, or four-fifths of the total, instead of the 159 seven-eighths, as shown above, where the boiler was running just right, and any attempt to reduce the temperature of the escaping gases by means of slower " combustion," as he would probably be advised to do by nine out of ten men, would simply reduce the temperature of the fire in his fur- nace, and the economical result would be about the same. His grate is too large to burn coal to the best possible advan- tage, and his best remedy is to reduce its size and keep his fire as hot as he can. This is not speculation, as some maybe inclined to think. Direct experiments have been made to settle the question. The grate under a certain boiler was tried at different sizes with the following result: With grate six feet long ratio of grate to heating surface was I to 24.4. With grate four feet long ratio of grate to heating surface was o to 36.6. The use of the smaller grate gave, with different fuels and all the methods of firing, an average economy of nine per cent, above the larger one, and, when compared by burning the same amount of coal per hour on each, twelve per cent, greater rapidity of evaporation and economy were obtained with the smaller grate. AVERAGE BREAKING AND CRUSHING STRAINS OF IRON AND STEEL. Breaking sti^ain of wrought iron =23 tons^ Crushing strain of wrought iron =17 tons | Breaking strain of cast iron about "]% tons [ Per square inch Crushing strain of cast iron =50 tons. ... 1 of section. Breaking strain of steel bars about 50 tons | Crushing strain of steel bar? up to ii6 tons J PITTING OF MQD DRUMS. Mud drums have frequently been known to pit through their close connection to the brick work with which they are covered. When the boiler is filled with cold water, the iron will sweat. This moisture mixing with the lime of the brick work will, after a length of time, injure the iron. Mud drums are injured on the inside by a similar chemical action. The sediments of lime, etc., deposit there where their action goes on undisturbed by any circulation. To prevent pitting on the inside from this cause, blow down fre- quently, and, on the outside, keep the brick off the plates, so that all moisture can pass off. i6o TABLE OF SPECIFIC GRAVITIES. Weight of a Cubic Inch in Lbs. Copper, cast 3178 Iron, cast 263 Iron, wrought , ^276 Lead 4103 Steel 2827 Sun-metal , •3^77 DIVISIONS OF DEGREES OF HEAT. The thermometer is an instrument for measuring sensible heat. It consists of a glass tube of very fine bore, terminat- ing in a bulb. This bulb is filled with mercury, and the top of the tube is hermetically sealed after all the air has been expelled. The instrument is then put into steam arising from boiling water; and, when the barometer stands at thirty inches, a mark is placed on a scale affixed opposite the place the mercury stands at. It is again put in melting ice, and the scale again marked. The space between these marks is divided into spaces called degrees. In this country and England it is divided into 180 equal parts, calling freezmg point 32°, so thar the boiling point is 212^ ; and zero or o is 32^ belowfreezing point, and this scale is called Fahrenheit's. On the continent two other scales are in use; the Centi- grade, in which the space is divided into 100 equal parts, hence the name ; and Reaumur's, in which the space is divided into 80. In both of these scales freezing point is o, or zero ; so that the boiling point of centigrade is 100^, and Reaumur 80°. THE LAW OF PROPORTION IN STEAM ECONOMY. The basis of steam engineering science consists in closely adhering to the absolute ratio or proportion of the different parts of the steam-plant, representing the power of the en- gine and boiler to the amount of the work to be done. To use an extreme illustration, it is not scientific to construct a hundred horse power boiler — say i ,500 square feet of heating surface — to furnish steam for a six-inch cylinder; nor is it in proportion to use a cylinder of the latter size to drive a sewing machine. It may be said truthfully that the law of true proportion between boiler, engine and the desired amount of work is less understood than ctlmost any other in the range of mechanical practice. i6i V^ALUABLE INFORMATION FOR ENGINEERS. To find the capacity of a cylinder in gallons, multiply the area in inches by the length of stroke in inches, and it will give the total number of cubic inches ; divide this by 231, and you will have the capacity in gallons. The U. S. standard gallon measures 231 cubic inches, and contains 8;^ pounds of distilled water. The mean pressure of the atmosphere is usually estimated at 14.7 pounds per square inch. The average amount of coal used for steam boilers is 12 pounds per hour for each square foot of grate. The average weight of anthracite coal is 53 pounds to one cubic foot of coal ; bituminous, about 48 pounds to the cubic foot. Locomotives average a consumption of 3,000 gallons of water per 100 miles run. To determine the circumference of a circle, multiply the diameter by3.i4i6. To find the pressure in pounds per square inch of a column of water, multiply the height of the column in feet by .434, approximately, every foot elevation is equal to ^ pound ]3ressure per square inch, allowing for ordinary friction. The area of the steam piston, multiplied by the steam pressure, gives the total amount of pressure that can be exerted. The area of the water piston, multiplied by the pressure of water per square inch gives the resistance. A margin must be made between the power and tlie resistance to move the pistons at the required speed, from 20 to 40 per cent., according to speed and other conditions. To determine the diameter of a circle, multiply circum- ference by .31831. Steam at atmospheric pressure flows into a vacuum at the rate of about 1550 feet per second, and into the atmosphere at the rate of 650 feet per second. To determine the area of a circle, multiply the square of diameter by .7854. A cubic inch of water evaporated under ordinary atmos- pheric pressure is converted into one cubic foot of steam (approximately). By doubling the diameter of a pipe, you will increase its capacity four tinier. In calculating horse-power of tubular or flue boilers, con- sider 15 square feet of heating surface equivalent to one nominal horse-power. ^j2 HOW TO TEST BOILERS. The safe-working pressure of any boiler is found by- multiplying twice the thickness of plate by its tensile strength in pounds, then divide by diameter of boiler, then this result divide by six. This gives safe working pressure. EXAMPLE. Twic^ thickness plate X tensile strength -5- diameter of boiler in inches-^6=safe working pressure + one-half more = maximum test pressure. Diameter of boiler, 60". Thickness of plate, y^". Tensile strength of plate, 60,000 lbs. I"x6o,ooo-^6o= i,ooo-f-6=i66j^ lbs., which is the safe working pressure + 83^ lbs. = 250 fbs., which is the maximum test pressure. After the safe pressure has been found as above, the usual way is to add one-half more for a test pressure, then apply by hydraulic pressure as high as the test pressure, and, if the boiler goes through this test all right, it is safe to run it at two-thirds of test pressure. Before putting hydraulic pressure on an old boiler, empty the boiler, go over it carefully with the hammer for broken braces, weak and corroded spots, figure for safe pressure on the thinnest place found in boiler, fill boiler full of cold water, and gradually heat it until the desired pressure is reached. By this mode of testing by hot water pressure, the heated water is expanded, and is more elastic than when cold, and is not so liable to strain the boiler. Before allowing the pressure to be applied, see that the boiler is properly braced and stayed, and that the rivets are of proper size. All flat surfaces, such as found in fire-box boilers, should have stays not over 5 or 6 inches apart, for all ordinary pressure and boiler heads not over 7 inches apart. On account of the loss of strength in the plates by rivet holes, some authorities allow only 70 per cent, of the safe pressure given above, for double-riveted boilers, and 56 per cent, for single-riveted boilers; EXAMPLE. 166 Tbs. safe pressure in first example x 70 per cent, for double-rivets = 116.20 lbs. safe pressure for double-riveted boiler. 166 Tbs. safe pressure in first example X56 per cent, for single-riveted seams == 92.96 lbs. safe pressure for single- riveted boilers. SCALE IN BOILERS Mr. T. T. Parker writes as follows to the American Machinist : If there is one thing more than another that the average engineer is careful with, it is the use of boiler compounds. With an open exhaust heater and an overworked boiler, and using water from a drilled well sixty feet deep in limestone, I have had to be rather careful to avoid scale and foaming. I offer some notes from my experience under the above conditions. In using compounds containing sal soda, I had to use 40 per cent, more cylinder oil, and this invariably reacted, through the heater and feed water, on the boiler, and pro- duced foaming. I have used six compounds warranted to cure foaming with above results. The compounds were tannic acid and soda. Changing to the use of crude oil, I found that the volatile parts went over to the engine, and saved 10 per cent- cylinder oil over when using nothing, and 50 per cent, over the use of sal soda. There is a peculiar easy manner of making steam that is very different from the same boiler using sal soda . The results on scale are as follows : In changing to a different solvent, the results for a few runs were very good, and then it seemed to lose its virtue while losing double quantity ; result, foaming. With crude oil used continually, I have had scale from one-eighth inch thick, but never any thicker, as it came off clean, and was very porous. I prefer oil to any acid or alkali solvent. For cleaning a scaled boiler I would recommend alternate use of oil and sal soda, but the remedy is heroic. If the boiler is not clean in two weeks, I miss my guess. I have tried kerosene, and found it too volatile to be of value in a limestone district. In summing up the results, I believe : First — With an open exhaust heater, use only the best cylinder oil, which should be at least 80 per cent, petroleum. Second — If the crude oil does not keep the scale all out, alternate one run with sal soda. Now, I only offer this as my experience, knowing full well that the conditions are never absolutely the same. But I know of a plant (in this city) where the boiler is not worked up to its full capacity, and which is kept entirely free from scale, using hard water, by the alternate use of sal soda and crude oil. 164 WAGES IN TWO COUNTRIES. The poverty and low state of social civilization of the Spaniards is indexed quite accurately by their wage rates. For instance, the average weekly pay of a bricklayer in Spain (Malaga) is $3.80; in the United States $21.18; of a mason, $3.30 in Spain, $21.00 in the United States; of a carpenter, $3.90 in Spain; $15.25 in the United States; of a blacksmith, $3.90 in Spain; $16.02 in the United States; of a tinsmith, $3 in Spain, $14.35 i^ ^^^ United States; of printers, $4.50 in Spain, $16.42 in the United States; of laborers, porters, etc., $2.75 in Spain; $8.88 in the United States. While rents and possibly a few native products are lower in Spain than in the United States, the difference ;omes nowhere equaling the wide disparity in wages. Moreover in a comparison of this sort the quality of the living must be considered as well as the nominal cost. Thus lower rents nearly always imply inferior accommoda- tions, and, to the average Spaniard, most of the comforts and conveniences in ordinary use here are unattainable lux- uries. That the low rate of Spanish wages does really mean a proportionately low consumption and stanc^ard of living, is substantiated by one or two significant facts of another character; for instance, the per capita annual consumption of woolen goods in Spain is only 9 shillings' worth, as against 18 shillings in the United States; of sugar, 5 pounds per annum in Spain, 43 pounds in the United States; of beef, 16 pounds per annum in Spain; 62 pounds in the United States; of all meats, 49 pounds in Spain; 120 pounds in the United States; of butter, none in Spain; 16 pounds in the United States; of coffee, 4 pounds in Spain; 115 pounds in the United States. A NOVEL DYNAMO. At the central station of Puteaux, Paris, a novel form of dynamo was installed in 1898, which combines the efti- ciency of a low-speed engine and the high-tension alternat- ing-current dynamo. The engine and dynamo are built together, the latter comprising an integral part of the engine, as the flywheel is used to carry the field magnets of the dynamo. The engine is of the high-speed Corliss type, revolving at a speed of 60-120 revolutions per minute. I6S The armature is fixed, but may be slid out of the magnetic field by a lateral movement. It remains motionlesss be- tween two sets of magnetic poles and is supported by a pillar of cast iron, through which the crank shaft passes. The exciting current can be obtained either from a small auxiliary dynamo or from a shunt circuit taken from the main leads. The current is subsequently reduced by a transformer and supplied at a pressure of 200 volts; the entire operation showing a high degree of efficiency. THE LARGEST ARMATURE. The largest armature for the largest generator of elec- tricity ever made in the world for a trolley railroad was completed in Cleveland, Ohio, in January, 1898, and was shipped from the works of the Walker Company for Brook- lyn, N. Y. The whole generator, when assembled, is 20 feet high, 20 feet long and 15 feet wide, or equal in height to four ordinary-sized men. It is for the Brooklyn Heights Railway Company. The armature, which is the revolving part of the generator between the magnets, weighs 90,000 pounds. It is *j}i feet wide and lo^ feet high. WEIGHT OF 1 CUBIC IN. OF VARIOUS METALS. Weight in lbs. Weight in ounces. Steel, . . . 0.2833 4.533 Cast iron, . . . 0.263 4.208 Wrought iron, . . 0.2777 4-444 Copper. . . . 0.3225 5.159 Brass, . . . 0.308 5.333 Coke. — 4 bushels = i sack. Petroleum. — i ton^275 galls. WEIGHT OF FUELS. Coal. — A bushel= 742/^ lbs. A sack = 224 " AVERAGE WEIGHT OF ANIMALS. Cart-horse, 14 cwt. Ox, 7 to 8 «« Cow, 6>^ to 8 " Average weight of a man, 140 lbs. A dense crowd of people, 85 lbs. per square foot. Riding-horse, ii cwt. Pig, I to iy2 '' Sheep, I *• 1^5 PROPORTIONS OF STEAM BOILERS. In a recent communication to the Socieie Scientifique Industrielle of Marseilles, M. D. Stapfer remarked that, as he had never met with any good practical rules for the pro- portions of boilers for steam engines, he had taken the trou- ble to examine a very large number of different types, which were working satisfactorily, and from them had deduced the following rules : The water level in the boilers of torpedo boats was usually placed at two-thirds the diameter of the shell, and in marine, portable and locomotive boilers at three- fourths this diameter. The surface from which evaporation took place should, however, be made greater as the steam pressure was reduced — -that was to say, as the size of the bubbles of steam became greater. To produce lOO Hbs. of steam per hour, at atmospheric pressure, this Surface should not be less than 7.32 square ft., which may be reduced to 1.46 square ft. for steam at 75 lbs. pressure, and 0.73 ft. for steam at a pressure of 150 lbs. It is for this reason that triple-expansion engines can be worked with smaller boilers than were required with engines using steam of lower pres- sure. The amount of steam space to be permitted depends upon the volume of the cylinder and the number of revolu- tions made per minute. For ordinary engines it may be made a hundred times as great as the average volume of steam generated per second. The section through the tubes may be one-sixth of the fire-t,"ate area when the draught is due to chimney from 27 ft. «. j 33 ft. high, which in general corresponds to a fuel consumption of 12.3 pounds of coal per square fooc cf grate surface per I:..~»ur. This area may be reduced to one-tenth that of the. grate when forced draught is employed. TESTING BOILER PLATES. A good every-day shop plan of testing boiler plates is to cut ©flf a strip I % inches wide and of any convenient length. Drill a quarter-inch hole, and enlarge it to three-quarters of an inch by means of a drift -pin and hammer. If the plate shows no signs of fracture, it may be considered of good quality. Another method is to cut oft' a narrow strip, heat it to a cherry red and cool suddenly. Grip the piece in a vise, and bend it back and forth at right angles by means of a piece of gas pipe dropped over the end. The number of tim^es the piece can stand this bending is the measure of its quah'ty. A good piece of soft steel boiler-plate should stand velve or fifteen bendings without showing fracture. i67 MANIPULATION OF NEW ENGINES. After engines have been set up, they must be adjusted to /heir work. It is not every man that can do this properly, for it requires experience and consideration to determine exactly what is to be done. A new engine is a raw machine, ho to speak, and, no matter how carefully the work has been done upon it, it is not in the same condition that it will be in a few weeks, or after the actual work it does has worn its bearings smooth and true. In the best machine-work, there are more or less asperities of surface, and very much more friction than than there will be later on. Bearings and boxes are not fitted under strain ; they are fitted as they stand, independently in the shop, and this entails a condi- tion of things which actual work may show to be faulty. For this reason an engineer should not go at a new engine hammer and tongs, and try to suppress at once every slight noise or click that he may hear. Neither should he key up solid, or screw down hard, the working shafts and bearings, for the first few days. It is much bbtter to let the things run easily for a while, at the expense of a little noise, rather than to risk cutting before the details get used to each other. Many good engines have been disabled by too great zeal on the part of those in charge, when a little forbearance would have been much better. Pounding, caused by bad adjust- meny,^ i;:z.'^ c;^/^^)^ fi tiJL' c« ^ PI ^ CJ !=l M 0) J;^ ^ 666 i83 SWITCHING FROM THE ENGINE CAB. A device that will enable the engineer, from his cab, to switch his locomotive at pleasure, while the conductor on the caboose or rear car closes the switch again, would surely be a novelty in railroading, amounting to a revolution. Yet a Cleveland inventor claims to have solved the problem, and to be able to demonstrate its practicability with a working model. Not to go into the details, it may be sufficient to say that the " central throw " switch is shifted by a double- flanged shoe, of any length, dropped from beneath any front or rear truck, while the train is in motion, first overthrowing the crank that draws the lock-plate off the fixed rail, then moving the lug of the angle connected with the fly-rail to the right or left, as indicated by the target on the engine or caboose, after which the lock slides forward and grasps the fixed rail, holding the " fly " in alignment, making a continuous rail. Thus, a switch is carelessly left open, ar,d a passenger train is approaching. The engineer detects the danger ; the improvised " shoe" is dropped to the rail ; it strikes the lug, the switch is closed, and, a collision avoided. On the other hand, a train may be side-tracked by the same simple operation from the cab. Of course, this would do away with switchmen and frog accidents, and a great many other disad- vantages incident to the present method, should the invention come into practical use. This, aiecessarily is yet to be dem- onstrated by actual test, under varying conditions, before success can be confidently claimed ; but the device is certainly of general interest. ELECTRIC LIGHTING. In an address before the Montauk Club of Brooklyn, Mr. Charles W. Price stated that over $600,000,000 had been invested in electric lighting in the United States; and that the total horse power required in the electric lighting of Greater New York was not less than 200,000 horse power; that in the last thirteen years since the birth of the electric railway there had been an expenditure of more than $1,700,000,000, and that now any one could travel by electric cars from Paterson, N. J., via New York, to Port- land, Maine, with only three insignificant interruptions which collectively amount to less than fifteen miles. Between Chicago and Milwaukee, a distance of 85 miles, a series of trolley lines connect th*^ two cities by electric cars. i84 MANILLA ROPE TRANSMISSION, ^ A four-strand, hard-laid manilla rope, having a core, or "heart-yarn," is probably the best rope for transmission pur- poses, although three-strand rope is generally recommended, says a writer in the Ainerican Miller. Of course it is im- portant to have the rope laid in tallow, as that greatly pro- longs its life. The matter of splice is also important. Sea- men all agree that the long splice is the best, but the expe- rience of rope-transmission men is almost universally in favor of a short splice. The length of a long splice in an inch diameter rope will be five or six feet, while a short one is two and two and a half feet. I think this is what the sailors term "a short splice." I have seen a short splice suc- ceed where long ones have repeatedly failed. I have known of a manilla rope used out of doors being painted with oil, and then varnished. It seenjs to w^ork well. Tar is certainly unsuitable as a dressing for transmission rope. In the first place it weakens it; in the second, its sticking to the pulley or sheave would be a detriment rather than an improvement. There is no difficulty about the ropes sticking on rhe sheave, if properly designed and constructed. SAFE WORKING PRESSURE FURNACE FLUES. In a report to his company, the chief engineer of the Engine, Boiler and Employers' Liability Insurance Company, purposes the following rule for the safe-working pressure for cylindrical furnaces in flues : Safe-working pressure 50/2 d where /^thickness of plate in thirty-second of an inch. i=length of flue in feet. ^/=diameter in inches. RIVETLESS STEEL SLEEPERS. Mr. H. Hipkins has invented a rivetless steel sleeper fot railroads. The lips or jaws for holding the rails in place are stamped out of the solid plate, and are stiffened by corruga- tions or brackets, which are also raised from the solid plate out of the hollow at the back of each jaw. A center strip is provided for the rail to rest upon, dispensing with all rivets and loose parts. These sleepers can be laid rapidly, and they are claimed ^o be especially adapted to use underground in mires 185 TAKE CARE OF YOUR AUTOMATIC SPRINK- LERS. Many business blocks, workshops, Stores, etc., have been expensively fitted up with automatic sprinklers as a safeguard against fires, a certain temperature of heat fusing the metal, opening a valve and letting on a flow of water. But an in- spection of the perforated pipes in a majority of instances will reveal the fact that the apparatus has been neglected. Cob- webs and dust cover the pipes, the sprinklers have been per- mitted to corrode and unsolder, and, should a fire chance to occur and the friendly services of the sprinklers ever be required, they would be found almost useless, and for all the work they would perform in the line of throwing cold water on the devouring elements, the premises might as well have remained "unprotected." HOW TO OVERCOME VIBRATION. How to put the smith shop in an upper story \vithout having the working on the anvils jar the building, has been a problem that has frequently given manufacturers trouble. A mechanical engineer says it may be safely done by placing a good heavy foundation of sheet lead on the floor, and on that putting a good 'hickness of rubber belting. Another person who is interested in the problem has tried the experiment, with some success, of placing the block, not on the floor, but on the joist direct, making a cement floor up to the block, and over the wooden floor, reaching back beyond the reach of sp3rks. It is sometimes said thaE blacksmith shops never burn, but they keep right on burning in spite of theory, and cement floors ought to be helpful in guarding airainst fires. SAWMILL OPERATED BY AIR. The only sawmill in the world where the machiney is operated by compressed air is located in Oronto, Me., and the water wheel and the air compressor are below the floor of the mill, with also large storage tanks. Pipes lead the air to the various machines, whic^ technically are known as the carriage, nigger, log-leade^*. !c'2"flipP^^» band log-saw and two cut-off saws. *'• i86 ALLOYS AND SOLDERS. ALLOYS. ^ = .5 HOW TO ANNEAL SMALL TOOLS. A very good way to anneal a small piece of tool steel is to Aeat it up in a forge as slowly as possible, and then take two fireboards and lay the hot steel between them and screw them in a vice. As the steel is hot, it sinks into the pieces of wood, and is firmly imbedded in an almost air-tight charcoaj bed, and when taken out cold will be found to be nice and soft. To repeat this will make it as soft as could be wished. AN EXPERIMENT WITH A f.OCOMOTIVE. A locomotive engineer who takes an intelligent interest m operating his engine economically, relates the particulars of runs where careful efforts were made to test the differ- ence in the consumption of coal that resulted with the re- verse lever hooked back as far as practicable and the throttle full open, and running with a late cut-off, and the steam throttled, or the difference between throttling and cu'ttingoff short. First Case — A train of 19 loaded and 12 empty cars, rated at 25 loads. Run from Mansfield to Lodge, distance, 8.6miles, nearly level. Forced the train into speed, and then pulled the reverse lever to the center notch, and opened the throttle wide. The engine jarred a good deal, due, doubtless, to the excessive compression, but the speed was maintained. Twenty-two minutes were occupied by the run, a speed of 23 miles per hour, and 17 shovelfuls of coal were con- sumed in keeping up steam. By weighing, it was found a shovelful averaged 14 pounds, making the coal used per train mile average 27.7 pounds. Second Case — A train of 25 loads and six empties, rated as 28 loaded cars. Ran, as in the first case, from Mansfield to Lodge. Pulled the train into speed in as nearly as possi- ble the same time as in the previous test, but, when the speed was attained, kept the reverse lever in the nine-inch notch, and throttled the steam to keep down the speed. Although the train was rated two loads heavier than the pre- vious one, it consisted mostly of merchandise, while the other vvas heavy freight, and handled decidedly easier. Hav- ing pulled both trains over 40 miles before arriving at Mans- field, there was full means of judging which was the easier train to handle. The run was made in 24 minutes, two minutes longer than in the other case, and 32 shovelfuls of coal were used, being at the rate of 52 pounds per train mile. In both 'nstances the fire was as nearly as possible the same depth at the beginning and end of the run. Our correspondent thus concludes his narrative: " It is interesting to know that on the first occasion 238 pounds of coal were used to do the same work in less time than 448 pounds were required to do under the changed circumstances of the second trip; showing that a gain of 88 per cent, may be effected by running with full throttle and early cut off.'^ i89 THE MORSE CODE. As all moto-vehicles must be furnished with a sound- producing instrument, either a whistle, horn or bell, as well as with lamps, automobilists are readily enabled by the Morse code to signal or send a message, either by sound or by flashing signals, a considerable distance. Apart from this, a knowledge of the Morse is invaluable to the trav- eller, soldier, and seaman. A C E - H I -- J - «- ^ ^ s <• * * K -i- - — T — L - — > - • U M y • . • -■ N W — ^ — X — - - — p • .. «- •• Y — -• — •^ Q -i^ ... - — Z «>• — - -• R Numerals, 4 7 5 8 6 9 .. • . • • ■M mm i^ mm • B 2 LIQUID FUEL BURNERS. These are mainly of two distinct types: gasifiers and sprayers. In the former the fuel, usually a heavy liquid hydrocarbon, flows into a chamber called a vaporiser, upon which impinges a flame. The liquid is converted into a liquid vapor or gas which burns in the free p.iesence of air with a yellow flame, or it can be mixed with air as in a Bunsen burner, when a blue flame is produced. A WARNING TO ENGINEERS. Never take the cap off a bearing and remove the upp^r brass to see if things are working well, for you never can replace the brass exactly in its former position, and you will find that the bearing will heat soon afterward, on account of your unnecessary interference. If there is any trouble, you will find it out soon enough. 190 WEIGHT AND AREAS OF SQUARE & ROUND BARS OF WROUGHT IRON And Circumference of Round Bars. One cubic foot weighing 480 lbs. Thickness Veigbl 27.563 28.223 28.891 29.566 21.648 22.166 22.691 23.221 16.493 16.690 16.886 17.082 A A 100.8 103.1 105.5 107.8 79.19" 81.00 82.83 84.69 30.250 30.941 31,641 32.348 23.758 24.301 24.850 25.406 17.279 17.475 17.671 17.868 1 110.2 112.6 115.1 117.5 86.66 88.45 90.36 92.29 33.063 33.785 34.516 35.254* 25.967 26.535 27.10G 27.688 18.064 .a8.261 ^i8.457 18.653 SQUARE AND ROUND BARS., (continued) "Wpigbl of Weight of Area of Area of Circumfereuw » Diameter D"" O B" □ B.r O Bar of O Bar. in Inches. One Foot long One fool long. m sq. inches. in sq. inchus, 28.274 in inches; 6 120.0 94.25 36.000 18.850 t 122-5 96.22 36.754 28.866 19.046 126.1 98.22 37.516 ' 29.465 19.242 127.6 100.2 38.285 30.069 19.439' 130.2 102.3 39.063 30.680 19.635 132.8 104.3 39.848 31.296 19831 135.5 106.4 40.641 31.919 20.028 A 138.1 108.5 41.441 32.548 20.224 [^ 140.8 110.6 42.250 33 183 20.420 '9 143.6 112.7 43.066 33.824 20.617 1 146.3 114.9 43.891 34.472 20.813 U 149.1 117.1 44.723 35.125 21.O09 1 151.9 119.3 45.563 35785 21.2J06 li 154.7 121.5 46.410 36.450 21.402 1 157.6 123.7 47.266 37.122 21.598 A 160.4 126.0 48.129 37.800 21.79^ V 163.3 128.3 49.000 38.485 21,991 ' t's 166.3 130.6 49.879 39.175 22.187 J 169.2 132.9 50.706 39.871 B2.384 A^ 172.2 135.2 51.660 40.574 22.580 'J 175.2 137.^ :&2.563 41.282 22.777 f5 178.2 140.0 53.473 41.997 22.973 '? 181.3 142.4 54.391 42.718 23.169 X 184.4 144.8 55.316 43.445 23.360 } 187.5 147.3 56.250 44.179 23.562 iV 190.6 149.7 57.191 44.918 23.758 i 193.8 152.2 58.141 45.664 2^955 ii- 197.0 154.7 59.098 46.415 24.151 24.347 'f 200.2 157.2 60.063 47.173 ft 203.5 159.8 61.035 47.937 ?4.544 i 206.7 162.4 62.016 48.707 L4.740 H ■ 210.0 164.9 63.004 49.483 24.930 594 SQUARE AND ROUND BARS. (continued.) irca of □ Bar Id sq. inchos. 64.000 65.004 66.016 67.035 68.063 69.098 70.141 71.191 72.250 73.316 74.391 75.473 76.663 77.660 78.766 79.879 81.000 82.129 83.266 84;410 85.563 86723 87^91 69.066 90.250 91.441 < 92.641 93.848 96.063 96.285 97.516 98.754 Area of O Bar in sq. inches. 50.265 51.054 51,849 52.649 53.456 54.269 55.088 65.914 66.745 67.583 58.426 69.276 60.132 60.994 61.862 62.737 63.617 64.504 65.397 66.296 67.201 68.112 69.029 69.953 70.882 71.818 72.760 73.708 74.662 75.622 76.589 77.561 Circumfercnct of O B^ in inches. 30.631 30.827 31.023 31.22a 195 SQUARE AND ROUND BARS. (CONUINUED.) TJiickness XDiameter ts^shea. > Weight of □ Bar One Foot long. Weight of O Bar One Foot long. Area of □ Bar in sq. inches. Area of O Bar in sq. inches. 10 333.3 .^37.5 341.7 346.0 261.8 265.1 268.4 271.7 100.00 101.25 102.52 103.79 78.540 79.525 80.516 81.513 1 350.2 354.5 358.8 863.1 276.1 >78.4 2181.8 286.2 105.06 106.35 107.64 108.94 82.516 83.525 84.641 86.562 i t 367.5 371.9 376.3 380.7 288.6 292.1 295.6 299.0 ' \ 10.25 Si::l.57 112.89 114.22 86.590 87.624 88.664 89.710 t 385.2 389.7 394.2 398.8 302.5 306.1 309.6 313.2 115.66 116.91 118.27 119.63 90.763 92.886 93.966 11 t 403.3 407.9 412.6 417.2 316.8 320.4 324.0 327.7 121.00 122.38 123.77 126.16 95.033 96.116 97,205 98.301 } 421.9 426.6 431.3 436.1 331.3 335.0 338.7 342.5 126.56 127.97 129.39 130.82 99.402 100.51 M)1.62 102.74 i 440.8 445.6 450.6 455.3 346.2 350.0 353.8 357.6 132.25 133.69 , 135.14 136.60 103.87 105.00 106.14 107.28 1 460.2 465.1 470.1 476.0 361.4 365.3' 369.2 373.1 138.06 139.54 141.02 142.60 108.43 109.59 110.75 111.92 Girdunferenoi of O Bar in inches. 31.416 31.612 31.809 32.005 32.201 32.398 32.694 32.790 32.987 33.183 33.379 33.576 33.772 33.968 34.165 34.361 f ' 84.658 34.754 34.950 35.147 35.343 35.539 36.736 36.932 36.128 36.325 36.521 36.717 36.914 37.110 37.306 37,603 X96 Weight of Sheets of \A^rought Iron, Steel Cofm per and Brass. (From Haswell.) WeigMper Square Foot. Thickness by Birmingham Gauge, .G«ige. Thickness in inches. Iron. Steel. 18.46 Copper. Brass. 0000 .454 18.22 20.57 19.43 iOOO .425 17.05 17.28 19.25 18.19 ^00 .38 15.25 15.45 17.21 16.20 .34 11 64 a3.82 15.40 14.55 1 .3 12.04 12.20 13.59 12.84 2 .284 11.40 11.55 12.87 12.10 3 .259 10.39 10.53 11.73 11.09 4 .238 9.55 9.68 10.78 10.19 6 .22 8.83 8.95 9.97 9.42 6 .203 8.15 8.25 9.20 8.09 7 .18 7.22 7.32 8.15 7.70 8 .105 6.62 6.71 7.47 7.00 9 .148 5.94 6.02 6.70 6.33 10 .134 5.38 5.45 6.07 5.74 11 .12 4.82 4.88 5.44 5.14 12 .109 4.37 4.43 4.94 4.07 13 .095 3.81 3.86 4.30 4.07 14 .083 3.33 3.37 3.76 3.55 16 .072 2.89 2.93 3.26 3.08 10 .065 2.61 2.64 2.94 2.78 17 .058 2.33 2.36 2.63 2.48 (18 .049 1.97 1.99 2.22 2.10 19 .042 1.69 1.71 1.90 1.80 '20 .035 1.40 1.42 1.59 1.50 •21 .032 1.28 1.30 145 1.37 /22 .028 1.12 1.14 1.27 1.20 23 .025 1.00 1.02 1.13 1.07 24 .022 .883 .895 1.00 .942 25 .02 .803 .813 .906 .850 '26 .018 .722 .732 .815 .770 27 .016 .642 .651 .725 .685 .28 .014 .562 .569 .634 .599 I29 .013 .522 .529 .589 .550 30 .012 .482 .488 .544 .514 31 .01 .401 .407 .453 .428 ;32 .009 .361 .366 .408 .385 33 .008 .321 .325 .362 .342 34 .007 .281 .285 .317 .300 , 35 .005 .201 .203 .227 .214 Spfdfic G ,Weight C ravity, ubic Foot, 7.704 7.806 8.698 8.218 481.25 487.75 543.6 513.0 V »( " Inch, .2787 .2823 '^149 .2979 ii9/ ^A/'eight of Sheets of Wrought Iron, Steel, Cop* per and Brass. From Haswell. Weight per Square Foot. Thickness by American (Brown 8z Sharpe's) Gauge. No. of Gauge. Thickness in inches. Iron. Steel. Copper. Brass. 0000 .46 18.46 18.70 20.84 19.69 000 .4096 16.44 16.66 18.56 17.53 00 .3648 14.64 14.83 16.53 15.61 .3249 13.04 13.21 14,72 13,90 1 .2893 11.61 11.76 13.11 12.38 2 .2576 10.34 10.48 11.67 11.03 3 .2294 9.21 9.^3 10.39 9.82 4 .2043 8.20 8.31 9.26 8.74 5 .1819 7.30 7.40 8.24 7.79 6 .1620 6.50 6.59 7.34 6.93 7 .1443 5.79 5.87 6.54 6.18 8 .1285 5.16 6.22 6.82 5.50 9 .1144 4.59 4.65 5.18 4.90 10 ,1019 4.09 4.14 4.62 4.36 11 .0907 3.64 3.69 4.11 3.88 12 .0808 3.24 3.29 3.66 3.46 13 .0720 2.89 2.93 3.26 3.08 14 < .0641 2.57 2.61 2.90 2.74 15 .0571 2.29 2.32 2.59 2.44 16 .0508 2.04 2.07 2.30 2.18 17 .0453 1.82 1.84 2.05 1.94 18 .0403 1.62 1.64 1.83 1.73 19 .0359 1.44 1.46 1.63 1.54 20 .0320 1.28 1.30 1.45 1.37 21 .0285 1.14 1.16 1.29 1.22 22 .0253 1.02 1.03 1.15 1.08 23 .0226 .906 .918 1.02 .966 24 .0201 .807 .817 .911 .860 25 .0179 .718 .728 .811 .766 26 .0159 .640 .648 .722 .682 27 .0142 .570 .577 .643 .608 28 .0126 .507 .514 .573 .541 29 .0113 .452 .458 .510 .482 30 .0100 .402 .408 .454 .429 31 .0089 .358 .363 .404 .382 32 .0080 .319 .323 .360 .340 33 .0071 .284 .288 .321 .3031 34 .0063 .253 .256 .286 .270 35 .0056 .225 .223 .254 . .240; 19^ WEIGHTS OF FLAT ROLLED IRON PER LINEAL FOOT. For Thicknesses from 1-16 in. to 2 in., and Width from i in. to 12^ in. Iron weighing 480 lbs. per cubic foot. Thickness in Inches. 1'' IK" IK'' .313 IH" 2" 2H'' 2K" 2^" 12'^ ^ .208 .260 .365 .417 .409 .521 .573 2.50 i .417 .521 .625 .729 .833 .938 1.C4 1.15 5.C0 A .625 .781 .938 1.09 1.25 1.41 1.56 1.72 7.50 i .833 1.04 1.25 1.46 1.67 1.88 2.08' 2.29 19.00 A 1.04 1.30 1.58 1.82 2.08 2.34 2.G0 2.8G 12.50 f 1.25 1.56 1.88 2.19 2.50 2.81 8.13 3.44 15.C0 1.46 1.82 2.19 2.55 2.92 3.28 8.C5 4.01 17.50 V 1.67 2.08 2.50 2.92 3.33 3.75 4.17 4.58 20,00 j's 1.88 2.34 2.81 3.28 8.75 4.22 4.C9 5.10 22.50 i 2.08 2.G0 3.13 3.G5 4.17 4.C9 5.21 5.73 25.C0 H 2.29 2.86 3.44 4.01 4.58 5.16 5.73 6.0O 27.50 2.50 3.13 3.75 4.38 5.00 5.63 6.25 6.88 30.C0 U 2.71 3 39 4.06 4.74 5.42 6.09 6.77 7.45 82. 50 i 2.92 3.G5 4.38 5.10 5.83 6.56 7.29 8.02 35.C0 H 3.13 3.91 4.69 5.47 6.25 7.03 7.81 8.59 87.50 t i 3.33 4.17 5.00 5.83 6.67 7.50 8.33 9.17 40.00 lA 3.54 4.43 5.31 6.20 7.08 7.97 8.85 9.74 42.50 li 3.75 4.69 5.63 6.56 7.50 8.44 9.38 10.31 45.C0 >t^ 3.96 4.95 5.94 6.93 7.92 8.91 9.90 10.89 47.50 )^i 4.17 5.21 6.25 7.29 8.33 9.38 10.42 11.46 50.00 Wz 4.37 5.47 6.56 7.66 8.75 9.84 10.94 12.03 52.50 If 4.58 5.73 6.88 8.02 9.17 10.31 11.46 12.60 55.00 ti^ 4.79 5.99 7.19 8.39 9.58 10.78 1198 13.18 57.50 u 5.00 6.25 7.50 8.75 10.00 11.25 12.50 13.75 60.00 1t\ 5.21 6.51 7.81 911 10.42 11.72 13 02 14.32 62.50 If 5.42 6.77 8.13 9.48 10.83 12.19 13.54 14.90 65.00 Ml 5.63 7.03 8.44 9.84 11.25 12.66 14.06 15.47 67.50 U 5.83 7.29 8.75 10.21 11.67 13.13 14.58 16.04 70.00 m 6.04 7.55 9.06 10.57 12.08 13.59 15.10 16.61 72.50 u 6.25 7.81 9.38 10.94 12.50 14.06 15.63 17.19 75.00 HI 6.46 8.07 9.69 11. -30 12.92 14.53 16.15 1776 77.50 2 6.67 8.33 10.00 11.67 13.33 15.00 16.67 18.33 80.00 3199 WEIGHT OF FLAT ROLLED IRON PER LINEAL FOOT. (continued.) 3" SH" 729 .625 .677 1.25 1.35 146 1.88 2.03 2.19 2.50 2.71 2.92 3 13 3 39. 3.65 375 4 06 4U 4.38- 474 5.10 5.00 5.42 5.83 5.63 6.09 6.56 6.25 6.77 7.29 6.88 7.45 8.02 7.50 8.13 8.75 8.13 8.80 9 48 8.75 9,48 10.21 9.38 10.16 10.94 10.00 10.83 11.67 10.63 1151 12.40 11.25 12.19 13.13 11.88 12.86 13.85 12.50 13.54 14.58 13.13 14.22 15.31 13.75 14 90 16.04 14.38 15.57 16.77 15.00 16.25 17.50 15.63 16.93 18.23 16.25 17.60 18.95 16.88 18.28 19.69 17.50 18.96 20.42 18.13 19.C4 21.15 18.75 20.31 21.88 19.38 . 20.99 22.60 20.00 21.67 23.33 SK" ..^ 4^" 4,4" 4K" 12" .781 1.56 2 34 3.13 .833 167 2 50 3 33 .885 1.77 2.66 3.54 .938 1.88 2.81 3.75 ,990 1.98 2.97 396 2.50 5.00 7.50 10.00 3.91 4 69 5.47 6.25 4 17 5 00 6.83 6.67 4.43 5.31 6.20 7.08 4.69 5 63 6.56 7.50 4.95 5.94 6.93 7.92 12.50 15.00 17.50 20.00 7.03 7.81 8.59 9.38 750 8.33 9.17 10.00 7 97 8.85 9.74 10.63 8 44 9 38 10.31 11.25 8.91 9.90 10.89 11.88 22.50 25.00 27.50 30.00 10.16 10.94 11.72 12.50 10.83 11.67 12.50 13.33 11.51 12.40 13.28 14.17 12.19 13.13 14.06 15.00 12.86 13.85 14.84 15-83 S2.5O 35.00 37.50 40.00 13.28 14.06 14.84 15.63 14.1-7- ISLOO 15.83 16.C7 L5,05 15.94 1&82 17.71 15.94 10.88 17.81 18.75 16.82 17.81 18.80 19.79 42.50" 45.00 47.50 50.00 16.41 17.19 17.97 18.75 17.50 18.33 19.17 20.00 18.59 19.48 20.36 21.25 19.C9 20.63 21.56 22.50 20.78 21.77 22.76 23.75 52.b0 55.00 57.50 60.00 19.53 20.31 21.09 21.88 20.83 21.67 22.50 23.33 22.14 23.C2 23.91 24.79 23.44 24.38 25.31 26.25 24.74 25.73 26.72 27.71 02.50 05.00 C7.60 70.00 22.66 23.44 24.22 25.00 24.17 25.00 25.83 26.67 25.68 26.56 27.45 28.33 27.19 28.13 29.06 30.00 28.70 29.C0 30.G8 31.G7 72.00 75.00 77.5a CO.OO VA«] WEIGHTS OF FLAT ROLLED IRON PEB LINEAL FOOT. (continued.) Thickness k Inches. 5" 5^" SK" 5K" 1.20 1.25 6M" 1.30 1.35 1.41 12" tV 1.04 1.09 1.15 2.50 i 2.08 2.19 2.29 2.40 2.50 2.60 2.71 2.81 5.00 A 3.13 3.28 3.44 3.59 3.75 3.91 4.06 4.22 7.50 i 4.17 4.38 4.58 4.79 5.00 6.21 6.42 5.63 10.00 -^z 5.21 5.47 573 5 99 6.25 6.51 6.77 7.03 12.50 1 6.25 6.56 6.88 7.19 7.50 7.81 8.13 8.44 15.00 A 7.29 7.66 8.02 8.39 8.75 9.11 9.48 9.84 17.50 ? 8.33 8.75 9.17 9.58 10.00 10.42 10.83 11.25 20.00 t\ 9.38 9.84 10.31 10 78 11.25 11.72 12.19 12.66 22.50 f 10.42 10.94 11.46 1198 12.50 13.02 13.54 14.06 25.00 H 11.46 12.03 12.60 13.18 13.75 14.32 14.90 15.47 27.50 f 12.50 13.13 13.75 14.38 15.00 15.63 16.25 16.88 30.00 if 13.54 14.22 14 90 15.57 16.25 16.93 17.60 18.28 32.50 i 14.58 15,31 16.04 16.77 17.50 18.23 18.96 19.69 35.00 H 15.63 16.41 17.19 17.97 18.75 19.53 20.31 21.09 37.50 1 16.67 17.50 1833 19.17 20.00 20.83 21.67 22.50 40.00 W-. 17.71 18.59 19.48 20.36 21.25 22.14 23.02 23.91 42.50 li 18.75 19.69 20.63 21.56 22.50 23.44 24.88 25.31 45.00 ^A 19.79 20.78 2177 22.76 23.75 24.74 25.73 26.72 47.5C ii 20.83 21.88 22.92 23.96 25.00 26.04 27.08 28.13 50.00 1^ 21.88 22.97 24.06 25.16 26.25 27.34 28.44 29.53 52.50 H 22.92 24.06 25.21 26.35 27.50 28.65 29.79 30.94 55.00 lA 23.96 25.16 26.35 27.55 28.75 29.95 81.15 32.34 57.50 li 25.00 26.25 27.50 28.75 30.00 31.25 32.50 33.75 60.00 1t\ 26.04 27.34 28.65 29.95 31.25 32.55 33.85 35.16 62.50 H 27.08 28.44 29.79 31.15 32.50 33.85 35.21 36.56 65.00 M-i 28.13 29.53 30.94 32.34 83.75 35.16 36.56 37.97 67.50 H 29.17 30.63 32.08 83.54 35.00 36.46 37.92 39.38 70.00 HI 30.21 31.72 33.23 34.74 36.25 37 76 39.27 40.78 72.50 ^^ » 31.26 32.81 34.38 35.94 37.50 39.06 40.63 42.19 76.00 HI * 32.29 33.91 35.52 37.14 38 75 40.36 41.98 43.59 77^0 e 33.33 35.00 36.67 38.33 40.00 41.67 43.33 45.00 20.00 SOI WEIGHTS OF FLAT ROLLED IRON PER LINEAL FOOT. (continued.) Thiebiesa in laehaa. 7" 7K" 1.51 7^" 1.56 7H" 1.61 8" 167 8K" 1.72 fe>^'' 8H" 12" A 1.46 1.77 1.82 2 50 i 2.92 3.02 3 13 3.23 3.33 3.44 3.54 365 50C A 4.38 4.53 4.69 4.84 5.00 516 5 31 5.47 7.50 4 6.83 6.04 6.25 6.46 6.67 688 7 08 7.29 10.00 ft 7.29 7.55 7.81 8.07 8.33 8.59 8.R5 9.11 12.50 i 8.75 9.06 9.38 9.69 10 00 10.81 10 63 1094 15.00 A 10.21 10.57 10.94 11.30 11.67 12.03 12.40 1276 1750 i 1167 12.08 12.50 12.92 13.33 13 75 14.17 1458 2000 ft 13 13 13 59 14.06 14.53 15 00 15 47 15 94 16.41 22 50' t 14.58 15 10 15.63 16.16 16 67 17 19 17 71 18.23 25 00 4 16.04 16.61 17.19 17 76 18.38 18.91 19 48 20.05 27.50 J 17.60 1813 18,75 19 38 20 00 20.63 21.25 2h88 30.00 ft , 18.96 19 64 20 31 20 99 2167 22.84 23 02 23.70 32.50 i 20 42 21 15 2188 22.60 23.33 24.06 24.79 25.52 35.00 ft 2188 22.66 23.44 24.22 25.00 25.78 26.56 27.34 37.50 l'' 23 33 24 17 25.00 25.83 26.67 27.50 28.33 2917 4000 ^I^ 24 79 25 68 26.56 27.45 28.33 29.22 30:10 30 99 42 50 u 26.25 2719 28.13 29.06 30.00 30.94 3188 32.81 45.00 ^t's 27.71 28.70 29.69 30.68 31.67 32.66 33.65 34 64 47.50 li 29.17 30.21 31.25 32.29 33.38 34.38 35 42 36.40 50 00 v« 30.62 3172 32.81 33.91 85.00 36.09 37 19 '38.28 52.50 If 32.08 33.23 34.38 35.52 36.67 37.81 38.96:4010 55.00 III 33.54 34.74 35.94 37.14 38.33 39.53 40 73 4193 57.50 n 35.00 36.25 37.50 38.75 40.00 41.25 42.50 43.75 60.00 u\ 36.46 37 76 39.06 40.36 41.67 42.97 44.27 45.57 62 50 lY 37 92 39.27 40.63 41.98 43.33 44.69 46.04 47.40 6,5.00 »H 39.38 40.78 42.19 43.59 45.00 4641 47.81 49.22 67.50 ii^ •40.g3 42.29 43.75 45.21 46.67 48.13 49.58 51.04 70.00 / HI 42.29 43.80 45.31 46.82 48.33 49.84 51.35 52.86 ^2^50 H 43.75 45.31 46.88 48.44 50.00 51.56 53.13 54.69 75.00 HI - 45.21 46.82 48.44 50.05 51.67 58.28 54.90 56.51 77.50 12 46.67 48.33 50.00 51.67 53.33 55.00 56.67 58.33 80.00 20i WEIGHTS OF FLAT ROLLED IRON PER LINEAL FOOT. (continued.) Thickness in Incbos. 9" 9H^'L 1.93 9K" 1.98 9K" 2.03 2.08 \0\" 10^'' 10|" 2.24 12" A 1.88 2.14 2.19 2.50 A 3.75 3.85 3.96 4.06 4.17 4.27 4.38 4.48 5.00 5.63 5.78 6.94 6.09 6.25 6.41 6.56 6.72 7.50 i 7.50 7.71 7.92 8.13 8.33 8.54 8.75 8.96 10.00 ,A 9.38 9.64 9.90 10.16 10.42 10.68 10.94 11.20 12.50 1 11.26 11.56 11.88 12.19 12.50 12.81 13.13 13.44 15.00 13.13 13.49 13.85 14.22 14.58 14.95 15.31 15.68^ -17.60 ■i 15.00 15.42 15.83 16.25 16.67 17.08 17.50 17.92 20.00 .A 16.88 17.34 17.81 18.28 18.75 19.22 19.69 20.16 22.50 .* 18.75 19.27 19.79 20.31 20.83 21.35 21.88 22.40 25.00 a 20.63 21.20 21.77 22.34 22.92 23.49 24.06 24.64 27.60 i 22.50 23.13 23.75 24.38 25.00 25.62 26.25 26.88 30.00 a 24.38 25.05 25.73 26.41 27.08 27.76 28.44 29.11 32.50 i 26.25J 26.98 27.71 28.44 29.17 29.90 30.63 31.35 35.00 ii 28.134 28.91 29.69 30.47 31.25 32.03 32.81 33.59 37.50 r' 30.00 ; 80.83 31.67 32.50 33.33 34.17 35.00 35.83 40.00 iiA 31.88 32.76 33.65 34.53 35.42 36.30 37.19 38.07 42.50 i-i 33.75 34.69 35.63 36.56 87.50 88.44 39.38 40.31 45.00 ■lA 35.63 36.61 37.60 38.59 89.58 40.57 41.56 42.55 47.50 :'r 37.50 38.54 39.68 40.63 41.67 42.71 43.75 44.79 50.00 ifV 39.38 40.47 41.56 42.66 43.75 44.84 45.94 47.03 52.50 u 41.25 42.40 43.54 44.69 45.83 46.98 48.13 49.27 65.00 43.13 44.32 45.52 46.72 47.92 49.11 60.31 61.51 67,50 ;' 4A 45.00 46.25 47.50 48.75 60.00 51.25 62.60 63^ 60.00 46.88 48.18 49.48 50.78 62.08 53.39 64.69 65.99 62.50 M 48.75 50.10 51.46 62.81 64.17 55.52 66.88 68.23 65.00 liJ 50.63 52.03 63.44 64.84 56.25 57.66 69.06 60.47 67.60 if 52.50 53.96 65.42 56.88 58.33 69.79 61.25 62.71 70.00 ^H 54.38 55.89 57.40 58.91 60.42 61.93 63.44 64.95 72.60 11 56.25 57.81 59.38 60.94 62.50 04.06 65.63 07.19 75.C0 ■m 58.13 50.74 61.35 62.97 64.58 66.20 67.81 69.43 77.50 2. 60.00 61.67 03.33 65.00 66.S7. 08.33. 7.0.00, 71.G7 80.00 '^^5 WEIGHTS OF FLAT ROLLED IRON PER LINEAL FOOT. (continued.) Thickness n ! jchcs. 11" 2.29 Hi" 2.34 11 r 11?" ?: 2.40 2.45 i 4.58 4.69 4.79 4.90 T^g 6.88 7.03 7.19 7.34 i 9.17 ,9.38 9.58 9.79 Y> 11.46 11.72 11.98 12.24 ). 13.75 14.03 14.38 14.69 16.04 16.41 16.77 17.14 h 18.33 18.75 19.17 19.58 IZ 20,63 21.09 21.56 22.03 t 22.92 23.44 23.96 24.48 ii 25.21 25.78 26.35 26.93 1 , 27.50 28.13 28.75 29.38 M 2979 30.47 31.15 31.82 i 32.08 32.81 33.54 34.27 H 34.38 35.16 35.94 36.72 1 38.67 37.50 38.33 39.17 liV 38.96 39.84 40.73 41.61 lU 41.25 42.19 43.13 44.06 1^ 43.54 44.53 45.52 46.51 U 45.88 46.88 47.92 48.96 1^ 48.13 4952 50.31 51.41 If 50.42 61.66 62.71 53.85 Vg 52.71 63.91 55.10 56.30 n 55.00 56.25 67.50 58.75 ItV 57.29 68.59 69.90 m.20 If 59.58 60.94 62.29 63.65 m 61.88 63.28 64.69 66.09 H 64.17 65.63 67.08 68.54 m 66.46 67.97 69.48 70.99 \i 68.75 70.31 7188 73.44 m 71.04 72.65 74 27 75.89 e 73.33 75.00 76.37 78.33 12' 2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00 22.50 25.00 27.50 30.00 32.50 35.00 37.50 40.00 42.50 45.00 47.50 50.00 62.50 55.00 67.50 60.00 62.60 65.00 67.50 70.00 72.50 75.00 77.50 80.00 2.55 5.10 7.66 10.21 12.76 15.31 17.86 20.42 22.97 25.52 28.07 30.63 33.18 35.73 40.83 43.39 45.94 48.49 51.04 53.59 56.15 58.70 61.25 66.35 68.91 71.46 74.01 76.56 79.11 81.67 12i" 12f" 2.60 2.66 5.21 5.31 7.81 7.97 10.42 10.63 13.02 13.28 15.63 15.94 18.23 18.59 20.83 21.25 23.44 23.91 26.04 26.56 28.65 29.22 31.25 31,88 33.85 34.53 36.46 37.19 39.06 39.84 4167 42.50 44.27 46.88 49.48 62.08 64.69 67.29 69.90 62.50 65.10 67.71 70.31 72.92 75.52 78.13 80.73 83.33 45.16 47.81 50.47 53.13 65.78 68.44 61.09 63.75 66.41 69.06 71.72 74.38 77.03 79.6^ 82.34 85.00 3 rt o ■3 » ■3-0 ^3 ^•3 |X gas Sag 1= ^.^4 Weight of Rivets, and Round Headed Without Nuts, Per loo. Bolts Length from under head. One cubic foot weighing 480 lbs, Length ■%'' J4" K" ^" %" V IK" IH'* Inches Dia. Dia. Dia. Dia. Dia. Dia. Dia. Dia. IH 5.4 12.6. 21.5 28.7 43.1 65.3 91.5 123. 1^2 6.2 13.9 23.7 318 47.3 70.7 98.4 133. 1% 6.9 15.3 25.8 34.9 61.4 76.2 105. 142. 2 7.7 16.6 27.9 37.9 55.6 81.6 112. 150. 2H 8.5 18.0 30.0 41.0 69.8 87.1 119. 159. 2/2 9.2 19.4 32.2 44.1 63.0 92.5 126. 167. 2^ 10.0 20.7 84.3 47.1 68.1 98.0 133. 176. 3 10.8 22.1 36.4 50.2 72.3 103. 140.^ 184 3M 11.5 23.5 88.6 53 3 76 5 109 147. 193. 3^2 12.3 24.8 40 7 56 4 80 7 114. 154. 201. s% 13.1 26.2 42.8 594 84.8 120. 161. 210. 4 13.8 27.5 45.0 62.5 89 125. 167. 218. 414 14.6 28.9 47.1 65.6 932 131. 174 227. 4% 15.4 30.3 49.2 68.6 97 4 136. 181. 236. 4M 16.2 31.6 51.4 717 102. 142. 188. 244. 5 18.9 33.0 53.5 74.8 106. 147. 195. 253. 5M 17.7 34.4 556 77.8 110. 153. 202. 261. 5^2 13.4 35.7 57.7 80.9 114. 158. 209. 270. 53^ 19.2 371 69.9 84.0 118 163. 216. 278 6 20.0 38.5 62.0 87.0 122. 169. 223. 287: 614 21.5 41.2 66.3 93.2 131. 180. 236. 304.' 7 23.0 43.9 70.5 99 3 139. 191. 250 821. 7/2 24.6 46.6 74.8 106. 147. 202. 264. 888. 8 26.1 49.4 79.0 112. 156. 213. 278. 355. 81/i 27.6 52.1 83.3 118. 164. 223 29E zr. 9 29.2 54.8 876 124. 173. 234. 30i m. 9/2 80.7 57.6 91.8 130. 181 245. 319. 406. 10 32.2 60.3 96.1 136. 189. 256. 333. 423. 10/2 83.8 €3.0 101. 142. 198. 267. 347. 440. 11 35.3 65.7 105. 148. 206. 278. 361. 457. 11^2 86.3 68.5 \m. 155. 214. 289. 375. 474. 12 38.4 71.2 112. 161. 223._^ 300. 388; 491. Heads, 1.8 5.7 10.9 13.4 22.2 88.0 57.6 82;0 205 Weight of CAi?r Iron per Lineal Foot, — Example : What is \veight of a cast iron plate 2" x 14" x one foot long ? Ans. — The thickness multiplied by width equals 28" of sectional area. In the sixth column, we find that 87^ lbs. is the weight of a piece with a sectional area of 28" and one foot long. Area laches. Lbs. Area -r v.. Inches. 1 ^^^• I Area Inches Lbs. {±\ I-b- Area Inches Lbs. iV .20 6 18.75 21^^ 67.19 48 134.38 69 215.63 Vs .39 G'4 ' 19.53 22 68.76 im 135.94 70 218.76 tV .59 6V^ 20.31 223^ 70.31 44 137.5 71 221.88 % .78 62^f 21.09 23 71.88 441^ 139.06 72 225.0 A .98 7 ,21.88 ' 22.66 2sy, 73.44 46 140,63 73 228.13 1 1.17 7'4 24 75.00 45>^ 142.19 74 231.25 1.37 7)^ 23.44 24^ 76.66 46 143.75 75 234.38 V2 1.56 75i 24.22 26 78.13 46^ 145.31 76 237.5 t\ 1.76 8 25.00 2by, 79.69 47 146.87 77 240.63 % 1.95 s% 25.78 26 81.25 47^ 148.44 78 243.75 H 2.15 8^ 26.66 26)^ 82.81 48 150.00 79 249.87 K 2.34 8M 27.34 27 84.38 48J6 151.66 80 260.00 H 2.54 9 28.13 27^ 85.94 49 168.12 81 253.12 ,^ 2.73 0^ 28.91 28 87.6 49^ 164.69 82 256.25 fit 2.93 9\i 29.69 .28V^ 89.06 50 166.26 83 269.88 1 3.125 9?i 80.47 29 90.63 &oyz 167.81 84 262.6 11^ 3.61 10 31.25 29>6 92.19 51 159.38 85 266.68 li^ 3.91 myi 82.03 30 93.75 61K 160.94 86 268.76 IVb 4.30 loy^ 32.81 30>^ 96.31 52 162.5 ^7 271.88 1}^ 4.69 102£ 33.59 81 96.87 62>6 164.06 88 275.00 1% 5.08 11 34.38 81H 98.44 53 166.63 89 278,18 1% 6.47 11^ 85.16 32 100.00 533^ 167.19 90- 281.25 1% 5.86 IVA 35.94 823^ 101.66 64 168.76 91 284.88 V 6.25 n% 36.72 83 103.12 5|>^ 170.31 92 287.6 " 2^H 6.64 12 37.5 3336 104.69 65 171.88 98 290.66 2'^ 7.03 12V^ 39.06 34 106.25 663^ 173.44 ' 94 298.76 2^/^ 7.42 13 40.68 34^ 107.81 56 175.00 95 296.87 2^ 7.81 13>§' 42.19 35 109.38 66^ 176.66 96 300.00 2^ 8.20 14 43.75 35^ 110.94 67 178.13 97 303*18 2^ H.59 14^,4 45.31 36 112.6 57}^ 179.69 98 806.26 2% 8.98 15 46.87 36>6 114.06 58 181.25 99 309.88 3 9.38 l5)/2 48.44 87 115.63 68J6 182.81 100 812.5 3^ 10.16 16 50.00 37)^ 117.19 69 184.38 101 315.63 3H 10.94 IC^i^ 51.56 38 118-75 59}^ 185.94 102 103 104 105 106 818.75 322.88 825.00 328.13 331.26 35i 4 11.72 12 5 17 17^2 63.12 54.69 38>^ 39 120.31 121.88 60 61 187.5 190.63 4^ 13.28 18 56.25 39V^ 123.44 62 193.75 4H 14.06 185^ 67.81 40 125.00 68 196.87 107 384.88 4^4 14.84 19 69.38 40J/2 126.66 64 200.00 108 337.6 ■ 6 ® lo.63 19JA 60.94 41 128.13 65 203.125 109 340.68 &^ 16.41 '20 62.5 4iy. 129.69 6« 206.25 110 343.75 .B^ 17.19 '20y, 6 4.06 4 2 1 131.25 V 209.38 111 346.87 b\ 17.97 21 1 65.63] 42y^| 182.81 6b 1 212.6 112 350.0Q 206 ILIKEAB EXPANSION OP SUBSTANCES BY HEAT. To find the increase in the length of a bar of any material due to an increase of temperature, multiply the number of degrees of increase of temperature by the coefficient for 100 degrees and by the length of the bar, and divide by 100. Name of Substance. Ba)rwood, (in the direction of the grain, dry,) ^ Brass, (cast,) - " (wire,) Brick, (fire,) - Cement, (Roman,) - . , Copper, Deal, (in the direction of the grain dry,) - Glass, (English flint,) - ^ " (French white lead,) Gold, .... Granite, (average,) „ Iron, (cast,) - *' (soft forged,) ^ " (wire,) - Lead, - - - ■":{ ■'•t Marble, (Carrara,) - Mercury, Platinum, •► Sandstone, • Silver, - . » Slate, (Wales,) ,- • _ . - Water, (varies considerably with f the temperature,) - - < Coefficient for 100 " Fahrenheit. Coefficiflntfor 180° Fahrenheit, or 100 Centigrade, .00020 TO .00031 .00046 TO 00057 .00104 .00188 .00107 .00193 .0003 .0005 .0008 .0014 .0009 .0017 .00024 .00044 .00045 .00081 .00048 .00087 .0008 .0015 .00047 .00085 .0006 .0011 .0007 .0012 .0008 .0014 .0016 .0029 .00036 TO .0006 .00066 TO .0011 .0033 .0060 .0005 .0009 .0005 TO .0007 .0009 TO .0012 .0011 .002 .0006 .001 .0086 .0155 207 ^A^eight of Bolts per loo, Including Nuts. c DIAMETER. J — 10.60 11.25 12. ■ r'« \ 22.50 23.82 25.15 i 1 i » H If *2 4. 4.35 4.75 7. 7.60 8. 16 20 16.30 17.40 39.50 41.62 43.75 69. 2i 6.15 8.50 12.75 18.60 26.47 45.88 72. n 6.60 9. 13.50 19.60 27.80 48.' 75. 116.60 • 21 5.75 9.60 14.25 20.70 29.12 60.12 78. 121.75 .. 8 6.^25 10. 15. 21.80 24. 1 30.45 52.25 81. 126. 84 •7. 11. 16.50 33.10 66.60 87. 134.25 . .. 4 7.75 12. 18. ' 26.20 35.76 60 75 93.10 142.50 207 4i 8.50 13. 19.60 28.40 38.40 65. 99.(^ 161. 218 6 9.25 14. 21. 30.60 41.05 69.25 105 20 159.65 229 6i 10. 15. 22.60 32.80 43.70 73.50 111.26 168.- 240 6 K. ;5 16. 24. 35. 46.36 77.75 117.30 176.60 251 6i 26.50 37.20 49. 82. 128.36 185. 262 7 27.'^ 28.60 30. 39.40 41.60 43.80 51.66 54.30 69.60 86.26 00.60 94.75 129.40 185. 141.50 193.66 202. 210.70 27g n 8 •■ ' 284 295 9 ' ■-.., 46. 64.90 103.26 153.60 227.75 317 10 # ' _ 48.20 50.40 70.20 75.60 111.75 1 20.25 166 70 177.80 244.80 261.85 330 * ;' 360 18 -' 52.60 80 80 128.7 5 189.90 278.90 382 la $ .. : . ' 8&10 137 26 202 295 95 404 14 t 1 • - 91.40 115.75 214.10 su. 426 I& . ,. . . 96.70 154 25 226.20 330 05 448 IH r 102. 107.30 162.75 171. 238.30 250.40 347.10 364 15 470 n ' f 492 ■ 8 ■■■:-] •" 112.60 179.50 262.60 381 20 514 19 \ ...'.... 117.90 188. 274.70 398.25 536 >» %..... 1 ■ • I 123.20 206 50 286.80 415.30 66^ 2o8 TENSILE STRENGTH OF COMMON WOODS. Tlie strongest wood which grows within the confines of the United States is that known as "nutmeg" hickory, which grows in the valley of the lower Arkansas river. The most elastic is tamarack. The wood with the least elasticity and lowest specific gravity is the Picus aurea. The wood having the highest specific gravity is the blue wood of Texas and Mexico. The heaviest of foreign woods are the pomegranate and the lignum vitae; the lightest is cork, which, however, is a bark, not solid wood. The tensile strength of the best known woods is set forth in the following schedule: WOOD. POUNDS, Ash 14,000 Beech 11,500 Cedar 11.400 Chestnut 10.500 Cypress 6.000 Elm 13.400 Pir 12.000 Maple 10.500 White Oak 11.500 Pear 9,800 Pitch Pine 12,000 Pour hundred and thirteen different species of trees grow in the various states and territories, and of tiiis number 16, when perfectly seasonable, will sink in water. WOOD. POUNDS. Larch 9,500 Poplar 7,000 Sprace 10,290 Teak 14,000 W?^lnut 7,800 Lance 23,000 Locust 20,500 Mahogany 21.000 Willow 13,000 Lignum Vitae 11,800 TEMPERING STEEL PUNCHES. Heat your steel to cherry-red, dress out the punch, cut off the point the size of a horseshoe nail, then heat to a cherry-red, immerse it a half inch perpendicularly in the water, then take it out and stand it up perpendicular, clean the end with a piece of grinding stone. When you see the first blue pass over the point, dip it in the water the same depth as before. Clean it again with the stone, and on the appearance of the blue again, cool it off. The second blue is to make the punch tough. The reason for keeping the punch perpendicular is to allow the atmosphere and the water to cool all sides equally, and to have it cool straight and true. HOW TO MAKE TRACING PAPER. Take some good thin printing paper, and brush it over on one side with a solution consisting of one part, by measure, of castor oil in two parts of meth. spirit ; blot off and hang up to dry. You can trace by pencil or ink on this. I have tried it and done it. 209 IN THE SHOP — TURNING A BALL. To make a ball as nearly perfect as a billiard ball is made, is not a piece of work that often falls to the lot of the machinist or pattern-maker ; but occasionally arises the necessity for such work. In pumping where chips, sawdust, or dust is very liable to lodge on the seat under the valve, ball valves are sometimes used, because their rolling motion has a tendency to remove the obstruction, and let the valve seat fairly again. Some of the old-style locomotive pumps had ball valves ; and, in tannery work, when small pieces of bark are liable to be ir the liquid, ball valves can be used to advantage. I have some such valves, four or five inches in diameter, for tanner's use. They were of brass, cast hollow, with the core holes in the shell plugged. I have seen some costly ijiachines which were made for the purpose of turning balls ; but I have never seen any better work done by them than can be done in a common lathe. To make the pattern of a ball, first turn the piece on centers, using the calipers to get it approximately near the shape, and then cut off the centers. Next make a chuck- block of hardwood, A, as shown in the cut, Fig. I. Make a cup in the block to receive a small section of the ball, as also indicated. A blunt, wood center is sometimes used instead of the steel center with a concave piece of copper, as represented in cut. Either way will do for making the pattern. Put the work in the chuck so as to take the first cut around it in the direction of its former centers, or axis. Cut lightly, and do not try to make a wide space — let it be only a narrow ribbon or turning — but get it round in the direction of present evolution ; then change ihe chuck so as to make another ribbon at right angles to the first, the first tool marks being the guide for the depth of the second cutting. Next change the work so as to get a ribbon between the other cuts, and continuing this process of changing and turning over the whole surface, thus making the axis of the pattern of equal length in all directions, and then the pattern will be round — it will be a balL At first it might seem as if some laying off were needed to get the " ribbons," 2IO as I iiave called them, at right angles to each other, but there is no need of that ; by the eye is enough. When the machinist comes to finish up the casting, he can bolt the chuck-block to his face plate, and use his steel center and a concave piece of copper as represented in the cut. He will have to use a hand tool, or a scraper, after getting under the scale. If the ball becomes too small for the cup in the block, it is an easy matter to make a new fit by cutting deeper into the chuck-block. THE ACTION OF SEA-WATER ON CAST-IRON PILES. I7idia7ta Engineering notes the results of some observa- tions made by the chief engineer of the B. B. and C. I. Railway on the cast-iron piles forming the piers of the South Bassien bridge. The piles were put down in 1862. Two were found almost as fresh in appearance as when sunk, and showed no corrosions in specimens cut from the metal. The deepest corrosion found on any pile was ^\ inch ; and this corrosion was the greatest near low-water mark. The pile bolts were all in excellent condition. All of these piles have been exposed to the action of sea-water for about twenty- five years, and the examination was made to set aside^ a current suspicion that they were deteriorating under the action of the water. JAPANESE WATER PIPES. The water supply of Tokio, Japan, is by the wooden water pipe system, which has been in existence over two hundred years, furnishing at present a daily supply of from twenty -five to thirty million gallons. There are several types of water pipes in use, the principal class being built up with plank, square, and secured together by frames surrounding them at close intervals. The pipes, less than six inch, consist of bored logs, and somewhat larger ones are made by placing a cap on the top of a log in which a very large groove has been cut. All the connections are made by chamfered joints, and cracks are calked with an inner fibrous bark. Square boxes are used in various places to regulate the uniformity of the flow of the water, which is rather rapid, for the purpose of pre- venting aquatic growth. T!*c water is not delivered to the houses, but into reservoirs on the sides of the streets, nearly 11;, 000 in number. 211 THE HEATING POWER OF FUEL. The heating power of fuel is ascertained by tjie follow dng process, which consists in burning one gramme of the co&l or fuel in a small platinum crucible, supported on the bow! pf a tobacco pipe, and cov'ered by an inverted glass test^ivbe, through Avhich is passed a stream of oxygen, while the i/I.ole is placed under water in a glass vessel. The oxygen i fed into the test tube by a movable copper tube, which ma.^ ^e pushed into the test tube so as to come immediately over tW crucible. The coals burn away in a few minutes with very intense heat, and the hot gases escape through the water, the bubbles being broken up by passing through sheets of wire gauze which stretch between the test tube and the walls of the vessel containing the water in which it is placed. The temperature of the water is taken before and after the experiment, and, from the figures thus obtained, the heating power of the coal is calculated. HOW STEEL RULES ARE MADE. There are few branches of tne engineering trades that require the exactness and precision requisite in the manufact- ure of steel rules, standards, and measuring instruments. Accuracy and reliability are the two absolute essentials. In the general practice the steel blades, after being prepared by being ground, glazed, and tempered, are coated by an acid- resisting varnish, specially made to suit the requirements of the trade, for upon this depends, in a great measure, the clearness of the divisions when etched. The varnish being dry, the blades are placed upon the table of a pentagraph, which might well be termed a copying machine, as its work is to transfer to the steel blades, in a diminished size, any markSj letters, or figures that may be traced ftom the copy. The latter is a plate of thin zinc, or any suitable metal, usually four times larger than the rules to be made, the divisions, figures, and letters all being made four times larger than they are required to be when engraved upon the steel blades; the object of this increased size being to diminish any imperfec- tion that may exist upon the copy. There is a tracer con- nected by a system of steel bands and pulleys to the table so constructed as to move in two opposite directions at right angles to each other, \bove the table are fixed two rows of holders, each having a diamond point; these holders are raised and lowered at the will of the operator by a treadle, so that both divisions, figures, and letters are traced from the copy 212 and transferred in a diminished proportion, to the steel blades. The dianwnd points being required only to cut through the varnish, the blades are taken from the machine and etched, the acid burning away the steel wherever the diamond point has been traced. A WATER CURTAIN. A fire in a large spice mill adjoining the Chicago Public Library gave the first opportunity for testing the water cur- tain, the apparatus for producing which forms a part of the building. Tubes are arranged on the outside of the build- ing on the top through which water can be turned, and the arrangement proved thoroughly satisfactory. Streams of water ponred out of the tubes, covering the walls, and owing to the temperature they were coated with ice in a few minutes. It looked like a closely woven curtain through which the flames and even the heat could not penetrate. Not a pane of glass was injured and the paint of the window frames did not crack. CHEMICAL OR PHYSICAL TESTS FOR STEEL. Captain Jones, of the Edgar Thomson Steel Works, Pittsburg, was in Edinburgh at the meeting of the Union and Steel Institute, and, when invited to speak, said he could not let what Mr. Clark had said about the practice of punching steel plates in America pass without comment. Punching steel plates was a relic of barbarism, and there was an appro- priateness about the president's suggestion, to *' punch a man who punched a plate." As to the relative cost of punching and drilling, he had long since made up his mind about that, for many years ago, in constructing a roof, he had drilled all the holes and found it cheaper than punching. With regard to the use of steel in America, they found boiler-makers, bridge-makers and many others using it largely. ^ They had started with physical tests, not chemical analysis, but they had come to the conclusion that physical tests could be met, and yet the metal not be what it should be. The test for boil«r plates at the Edgar Thomson Works -was higher than that demanded for the boiler plates of the United States cruisers, the limit for phosphorus being .035, and manganese, .350 per cent. He bad seen steel made in America, where the heat had been blown for eight minutes, the manganese being put in cold, and he was of opinion that the reaction had not taken place up to the time of speaking. With regard »«2l to steel for bridge construction, he considered that not moif than .065 per cent, of phosphorus should be present, and th« manganese should be kept low, as that was the great oxidiz- ing agent. He would like to see these conditions enforced by law. In conclusion he wished to impress on his hearers the necessity for judging steel by chemical tests first, and let* ting the physical tests be subsidiary to them. SUGGESTIONS TO STEEL WORKERS. Messrs. Miller, Metcalf & Parkin, of Pittsburgh, have issued a pamphlet on this subject. They draw attention to the following points : Annealing — There is nothing gained by heating a piece of steel hotter than a bright cherry -red heat ; on the contrary, a higher heat may render the steel harder on cooling than would be the case with the heat just mentioned. Besides this, the scale formed would be granular, and would spoil the tools to be used in working the metal, and the metal itself would change its structure, and become brittle. Steel should never be left in a hot furnace over night, af^ the metal becomes too hot, and is spoilt for after treatment. Forge Steel — The difficulty experienced in the forge fire is usually due more to uneven heat than to a high temperature. If heated too rapidly^ the outside of the bar becomes soft, while the inside is still hard, and at too low a temperature for treatment. In some cases a high heat is more desirable to save heavy labor ; but in every case where a fine steel is to be used for cutting purposes, it must be borne in mind that every heavy forging refines the bars as they slowly cool, and, if the smith heats such refined bars until they are soft, he raises the grain, makes them coarse, and he cannot get them fine again, unless he has a very heavy steam hammer at command, and knows how to use it well. When the ^steel is hot through, it should be taken from the fire immediately, and forged as quickly as possible. "Soaking" in the fire causes steel to become "dry" and brittle, and does it very great injury. Tei7iper — The word " temper," as used by the steelmaker^ indicates the amount of carbon in steel ; thus, steel of high l<;inper, is steel containing much carbon ; steel of low temper^ is steel containing little carbon ; steel of medium temper is steel containing carbon between these limits. Between the highest and the lowest, there are some twenty divisions, each representing a definite Dercentage of carbon. The act of tempering steei is the act of giving to a piece 214 of steel, after it has been shaped, the hardness necessary for the work it has to do. This is done by first hardening the piece — generally a good deal harder than is necessary — and then toughening it by slow heating and gradual softening until it is just right for work. A piece of steel, properly tempered, should always be finer in grain than the bar from which it is made. If it is necessary, in order to make the piece as hard as is required, to heat it so hot that after being hardened it will be as coarse or coarser in grain than the bar, then the steel itself is of too low a temper for the desired purpose. In a case of this kind, the steelmaker should at once be notified of the fact, and could immediately correct the trouble by furnishing higher steel. Heating — -There are three distinct stages or times of heating : First, for forging ; second, for hardening ; third, for tempering. The first requisite for a good heat for forging is a clean fire, and plenty of fuel, so that jets of hot air will not strike the corners of the piece ; next, the fire should be regular, and give a good uniform heat to the whole part to be forged. It should be keen enough to heat the piece as rapidly as possible, and allow it to be thoroughly heated through, without being so fierce as to overheat the corners. Steel should not bi left in fire any longer than is necessary to heat it through ; and, on the other hand, it is necessary that it should be hot through to prevent surface cracks, which are caused by the reduced cohesion of the overheated parts which overlie the colder central portion of an irregularly heated piece. By observing these precautions, a piece of steel may always be heated safely up to even a bright yellow heat when there is much forging to be done on it, and at this heat it will weld well. The best and most economical of welding fluxes is clean, crude borax, which should be first throughly melted, and then ground to fine powder. Borax, prepared in this wa.y, will not froth on the steel, and one-half of the usual quantity will do the work as well as the whole quantity un melted. After the steel is properly heated, it should be forged to shape as quickly as possible ; and, just as the red heat is leaving the parts intended for cutting edges, these parts should be refined by rapid, light blows, continued until the red disappears. For the second stage o\ heating, for hardenincr, great care should be used, first, to protect the cuttincr ed-jes and 215 working parts from heating more rapidly than the body of the piece ; next, that the whole part to be hardened be heated uniformly through without any part becoming visibly hotter than the other. A uniform heat, as low as will give the required hardness, is the best for hardening. For every variation of heat which is great enough to be seen, there will result a variation in grain, which may be seen by breaking the piece ; and for every variation in temperature, a crack is likely to be produced. Many a costly ^ool is ruined by inattention to this point. The effect of too high a heat is to open the grain — to make the steel coarse. The effect of an irregular heat is to cause irregular grain, irregular strains and cracks. As soon as the piece is properly heated for hardenmg, it should be promptly and thoroughly quenched in plenty of the cooling medium — water, brine, or oil, as the case maybe. An abundance of the cooling bath, lo do the work quickly and uniformly all over, is very necessary to good and satt> work ; and to harden a large piece safely, a running stream should be used. Much uneven hardening is caused by the use of too small baths. For the third stage of heating, to temper, the first important requisite is again uniformity ; the next is time. The more slowly a piece is brought down to its temper, the better and safer is the operation. When expensive tools, such as taps, rose cutters, etc., are to be made, it is a wise precaution, and one easily taken, to try small pieces of the steel at different temperatures, so as to find out how low a heat will give the necessary hardness. The lowest heat is the best for any steel ; the test costs nothing, takes very little time, and very often saves considerable loss. A NEW BREATHING APPARATUS. A new breathing apparatus has been invented by an Austrian. It is for use as a rescue apparatus for coal mines It consists of an India rubber cloth receptacle made in the form of a collar which closely surrounds the wearer's neck> serving as a breathing bag, and at the same time to hold a store of quickline for absorbing the carbonic acid and water vapor. A mask tightly enclosing the face is also employed, and oxygen can be breathed from an accompanying con- tainer, so that a man wearing these appliances can remain in a locality filled with irrespirable gases. It will be pre- cious for firemen descending in cellars filled with carbonic acid gas, or for well-diggers having to fight sewer gas. 2l6 LIQUID HYDROGEN. In the spring of 1898, Prof. Dewar, of the British Royal Institution, succeeded in liquefying the most volatile of all gases, hydrogen. Liquid hydrogen is colorless, transparent, and of only one-fourteenth of the density of water. It is so cold that it freezes and solidifies air and oxygen instantly. In a closed tube brought in contact with it, the air freezes into a small lump, leaving the tube a vacuum. LARGEST BELT. It is said that the largest belt ever made was turned out by a Canadian concern. It measures 3,529 feet long and is of rubber, its weight being 9 tons. It is made for the grain elevator of the Intercolonial Railway at St. Johns, N. B. WATCH AND LEARN. This is an excellent motto for every young man to adopt, and, by a close observance of it, it will prove of great value, even after he becomes grown up and starts out in business for himself. There is no surer way of gaining knowledge than by a careful and understanding watchfulness of others in the same line of business as yourself. As an apprentice, you cannot expect to know everything, and the best way to gain information from others is to show a willingness to learn ; then they will take an interest in teaching. But if, as is too often the case, a young man, after he has been a few months in a place, pretends to know as much, and sometiraes more, than those much older and more experienced than him- self, he will not get much information from his fellow work- men ; neither will he retain their good will for any length of time, and may expect to have all manner of practical jokes played upon him. As a journeyman, if you are intelligent, you will very often have occasion to believe that you do not know it all, and, in fact, the longer you live and the more you learn, the more you will find that there is to be learned. The egotistical and loud man is seldom a perfect man, and is generally very far from being as near perfection as he would have others think him. The person who, on a first acquaint- ance, is anxious to tell you what he knows, and is very free in giving advice and information without the asking, generally exhausts the supply before very long. He who is willing to listen is generally the one whose source of information is ilroader and of a more durable, valuable and substantial ki>?d An example may prove the idea to be conveyed more 217 cleatly. An employer was in want of a good, practical and experienced man for a certain class of work. A yotmg man applied for the position, who was very certain that he " knew all about the machine," and he was engaged. It was not long before every man in the shop knew all that he did, and one very valuable thing that he did not, and that was that he did not know all that he pretended to. His manner and braggadacio very soon got most of the men down on him. They were not disappointed. The new machine arrived, and was set up ready for operation. The young man was given a job to be worked off, and began operations with that self-conscious air of superiority that is generally apparent in characters of this description. One whole day he worked at the job, and it was not then in a condition to be run. Not only that, but he had shown to the men, who, of course, were secretly watching him, that he knew practically nothing of the machine. Then he bega-n to lay the blame for the trouble upon others, and asked assistance and " points " from some of the other workmen. This of course he did not get, and finally another man was put on the job, and he was discharged amid the taunts and ridicule of the others. If the young man had shown good sense when he first came into the shop ; not been quite so free to tell all he knew, and had shown a willingness to learn, there was not a man in the place that would not have gladly assisted him, and he might have remained in a good position. It sometimes pays to be ignorant, at least a little modesty is a good thing to take with you on going to a new place. If you know more than you pretend, it will soon be found out, and you will be the gainer; but, if you fail to make good your pretensions, not only your employer but all your fellow workmen will be "down on you," and things will be correspondingly unpleasant. DEOXIDIZED COPPER. The advantages to be obtair«ed by the '"^e of copper as nearly chemically pure as possib'% r»re generally admitted, whether the metal be used as coppcj; or in the form of brass, bronze, or the many other alloys into which it enters. The Deoxidized Metal Company, of Bridgeport, Conn., claims that the desired result is secured by the process which is used in its works. The castings of brass, bronze, etc. , made under this process, are most excellent, while the sheet copper and brass, and the wire made, when submitted to careful tests, show an unusually high degree of strength, copper wire hav- ing been tested up to 70,000 lbs. per square inch, tensile 2l8 p&rength. The deoxidized metal also possesses the property [)f great resistance to acids, so that it can be used for many purposes where ordinary metal is soon destroyed by the j;hemical action. Journal-bearings made from this metal have also been tested with very favorable results, while for bells it is claimed that the tone and quality is much superior to ordinary brass. MAKING JAPANNED LEATHEB. Japanned leather, generally called patent leather, was first made in America. A smooth, glazed surface is first given to calfskin in France. The leather is curried expressly for this purpose, and par oicular care is taken to keep as free as pos- sible from grease; the skins are then tacked on frames and coated with a composition of linseed oil and umber— in the proportion of 18 gallons of oil to 5 of umber— boiled until nearly solid, and then mixed with spirits of turpentine to its proper consistency. Lampblack is also added when the com- position is applied, in order to give color and body. From three to four coats are necessary to form a substance to re- ceive the varnish. They are laid on with a knife or scraper. To render the goods soft and pliant each coat must be very light and thoroughly dried after each application. A. thin coat is afterward applied of the same composition, of proper consistency, to be put on with a brush, and with sufacient lampblack boiled in it to make a perfect black. When thoroughly dry it is cut down with a scraper having turned edges. It is then ready to varnish. The principal varnish used is made of linseed oil and Russian blue boiled to the thickness of printers' ink. It is reduced with spirits of turpentine to a suitable consistency to work with a brush and then applied m two or three separate coats, which are scraped and pumiced until the leather is perfectly filled and smooth. The finishing coat is put on with special care in a room kept closed and with the floor wet to prevent dust. The frames are then run into an oven heated to about 175 de- gress. In preparing this kind of leather the manufacturer must give the skin as high a heat as it can bear, in order to dry the composition on the surface as rapidly as possible without absorption, and cautiously, so as not to injure the fibre of the leather. It is well nigh impossible to guarantee the permanency of patent leather, no matter how expensive or how careful be the preparation, for it has a sad trick of cracking without any justifiable provocation. HOW TO LACQUER BRASS. It is strange that not one druggist out of ten knows how ro compound and put up a first-class lacquer, but depends entirely on the manufacturer, who, owing to the general lack of knowledge regarding the matter, often imposes upon their customers, sending a vastly inferior article. Again, not one customer in ten knows how to apply lacquer, and the drug- gist is blamed, w^hen the user's ignorance is the cause of failure. Let both the dealer and the consumer keep the fol- lowing constantly in mind when sellixig or using lacquer : Remove the last vestige of oil or grease from the goods to be lacquered, and do not touch the work with the fingers. A pair of spring tongs or a taper stick in some of the holes is the best way of holding. Heat the work sufficiently hot to cause the brush to smoke when applied, but do not make hot enough to harm the lacquer. Fasten a small wire across the lacquer cup from side to side to scrape the brush on ; the latter should have the ends of the hairs trimmed exactly even with a pair of sharp scissors. Scrape the brush as dry a^ r>cssible on the wire, making a flat, smooth point at the same time. Use the very tip of the brush to lacquer with, go very slow, and carry a steady hand. Put on two coats at least. Li order to make a very dura- ble coat, blaze off with a spirit lamp or Bunsen burner, taking special pains not to burn the lacquer. I f the work looks gummy, the lacquer is too thick ; if prisaiatic colors show themselves, the lacquer is too thin. In the former case, add a little alcohol ; in the latter, place over the lamp, and evaporate to the desired consistency. If the work is cheap, like lamp-burners, curtain fixtures, etc., the goods may be dipped. For this purpose use a bath of nitric acid, equal parts, plunge the goods in, hung ou wire, for a moment, take out and rinse in cold water thoroughly,^ dip inhot water, the hotter the better, removeaud put in alco- hol, rinse thoroughly, and dip in lacquer, leaving in but a few minutes; shake vigorously to throw off all surplus lacquer, and lay in a warm place ; a warm metal plate is the best to dry. Do not touch till cool, and the job is done. Lac- quered work should not be touched till cold; it spoils the polish. Sometimes drops will stand on tlie work, leaving a spot. 220 These drops are merely little globules of air, and can be avoided by shaking when taken out. The best lacquer for brass is bleached shellac and alco- hol ; simply this, and nothing more. In the preparation of goods for lacquering, care should be taken to polish gradually, /. ^., carefully graduate the fine- ness of materials until the last or finest finish. Then, when the final surface is attained, there will be no deep scratches, for, of all things to be avoided in fine work, are deep scratches beneath a high polish. THE REAL INVENTOR OF THE BESSEMER PRO- CESS. The late William C. Kelly, the world-famed inventor of the improved Bessemer process of making steel, was years ago, the proprietor of the Suanee Iron Works and Union Forge, in Lyon County, Ky. The metal produced at these works was taken from the furnace to the forge, where it was converted into charcoal blooms. These blooms had a great reputation for durability and quality, and were used principally for boiler plates and metal. It was while making the blooms at this place that Mr. Kelly made his great inven- tion of converting iron into Bessemer steel, which Judge Kelly of Pennsylvania, at the Masonic Temple Theater last fall, termed the greatest invention of the age. The old pro- cess of making blooms was very expensive, owing to the great amount of charcoal required in its transformation, and Mr. Kelly conceived the idea of converting the metal into char- coal blooms without the use of fuel, by simply forcing powerful blasts of atmosphere up through the molten metal. His idea was that the oxygen of the air would unite with the carbon in the metal and thus produce combustion, refine the metal, and, by eliminating the carbon, wrought-iron or steel would be produced. When he announced his theory to his friends and to skilled iron workers, they scoffed, and were struck with astonishment that a man of Mr. Kelly's learning and practica iron-making knowledge would suggest such an idea as boiling metal without the use of fuel, and by simply blowing air through it. His friends thought him demented, and discouraged him from wasting his time and money upon any such visionary scheme. Mr. Kelly was confident that his idea was a good one, and began making experiments, which he kept up with varying success for ten years, but the blooms were manufac* tuYQd without the aid of fuel. It was generally known as 221 " Kelly's air boiling process," and was in daily use convert* ing iron into blooms at his forge. Mr. Kelly's customers learned finally of the process, and, not understanding it, they advised him that they would not buy blooms made by any but the old and established method. This was the first diffi- culty placed in Mr. Kelly's way, and he was consequently compelled to carry on his work secretly, which subjected him to many disadvantages. Some English skilled workmen in Mr. Kelly's employ were familiar with his non-fuel process, and went back to England, taking the secret with them. Shortly after their arrival in Liverpool, Kenry Bessemer, an English ironmaster, startled the iron world by announcing the discovery of the same process as Mr. Kelly's, and applied for patents in Great Britain and in the United States. Mr. Kelly at once made his application for a patent, and was granted one over Bessemer, the decision being that he was the first inventor and was entitled to the patent by priority. The history of this remarkable invention is a lengthy one, and it is generally admitted by persons cognizant of the facts in the case that Bessemer' s idea was secured from the English ironworkers employed by Mr. Kelly. Certain it is, however, that Mr. Kelly's invention and patents have heaped honors and w^ealth upon Bessemer, and he has been regarded as the greatest inventor of the nineteenth century, and the proper credit was always accorded him. Mr. Kelly's process was but barely successful until after it was perfected by Rob- ert Musshult, a prominent English iron worker. Concern- ing the claims of the different persons, a prominent iron and steel manufacturer, the late James Park, of Pittsburg, once said: " The world will some day learn the truth, and in ages to come a wreath of fame will crown William Kelly, the true inventor, and that truth will never be effaced by time." A NOVEL PLANING MACHINE. A iiiachine for planing the curved surfaces of propeller blades, so as to render them of uniform thickness and pitch, has been invented in England, and is herewith described. The principal feature is guiding and controlling the tool to travel on the curved surfaces, by a cast-iron former. The machine is provided with two tables, which can be rotated through a given range by a worm-wheel and worm, so that the inclinations of both tables can be simultaneously varied, and to an equal degree. One of the tables carries a cast-iron copy of the back or front of the blade it is desired to produce, while on the other table the actuall propeller is 222 secured, one of its blades occupying a similar position on thist table ta that of the copy on the other. Toin-sure the rigidity of the work, the table on which the propelLir is fixed has its iipper surface shaped to correspond with thh form of the blade on it, and is finally brought to the exact sh'ipe necessary by a coating of Portland cement.- A cut ^ ii(i„ deep can be taken without springing the blade. The proptiller is also held by being mounted on a duplicate of tha propeller shaft, which is secured to the table. The cutting io done by a tool of the ordinary type, work being commend!?^! at the top of the blade, and a self-acting traverse i/ \sed to feed the tool toward the boss. The tool-holder is connected by a system of levers with a similar holder at the other end of the slide, carrying a follower, which moves over the copy, and thus guides the cutting tool. As the boss is approached, the inclination of the two tables to the horizontal is altered by the worm gear, <-o as to limit the necessary vertical motion of the tool. In this way all the blades of the propeller may be successfully machined, back and front, and will then be of identical form and thickness, and set at the same angle to the propeller bha't. One of the propellers lately turned out by this machine ^^•as 6 ft. r. diameter, with an increasing pitch, the mean of which was / ft. 9 in., the thickness in the center of the blades varying from yg in. at the top to i in. at the boss. The breadth was 21 in., and the widest part and the cross section showed a regular taper from the center line to a knife-edge. The importance of accuracy and uniformity in the shape of .the blades of propellers for high-speed vessels is now generally acknowledged, and the machine we have described promises to form a very useful addition to the plant of a modern marine engineering establishment. HOW TO REMOVE RUST FROM IRON. A method of removing rust from iron consists in im- mersing the articles in a bath consisting of a nearly saturated solution of chloride of tin. The length of time during which the objects are allowed to remain in the batk depends on the thickness of the coating of rust ; but in ordinary cases twelve to twenty-four hours is sufficient. The solution ought not to contain a great excess of acid if the iron itself is not to be attacked. On taking them from the bath, thf articles are rinsed in water and afterward in ammonia. The iron, when thus treated, has the appearance of dull silver; but a simple polishing will give it its normal appearance. HOW TO ANNEAL STEEL. Owing to the fact that the operations of rolling or ham* mering steel make it very hard, it is frequently necessary that the steel should be annealed before it can be conven- iently cut into the required shapes for tools. Annealing or softening is accomplished by heating steel to a red heat, and then cooling it very slowly, to prevent it from getting hard again The higher the degree of heat the more will steel be softened, until the limit of softness is reached, when the steel is melted. It does not follow that the higher a piece of steel is heated the softer it will be when cooled, no matter how slowly it may be cooled ; this is proved by the fact that an ingot is always harder than a rolled or hammered bar made from it. Therefore, there is nothing gained by heating a piece of steel hotter than a good bright cherry red ; on the contrary, a higher heat has several disadvantages : if carried too far, it may leave the steel actually harder than a good red heat would leave it. If a scale is raised on the steel, this scale will be harsh, granular oxide of iron, and will spoil the tools used to cut it. It often occurs that steel is scaled inthisway, and then, because it does not cut well, it is customary to heat it again, and hotter still, to overcome the trouble, while the fact is, that the more this operation is repeated, the harder the steel will work, because of the hard scale and the harsh grain underneath. A high scaling heat, continued for a little time, changes the structure of the steel, destroys its crystalline property, makes it brittle, liable to crack in hard- ening, and impossible to refine. Again, it is a common practice to put steel into a hot fur- nace at the close of a day's work, and leave it there all night. This method always gets the steel too hot, always raises a scale on it, and, worse than either, it leaves it soaking in the fire too long, and this is more injurious to steel than any other operation to ^^hich it can be subjected. A good illustration of the destruction of crystalline struc- ture by long-continued heating may be had by operating on chilled cast-iron. If a chill be heated red hot and removed from the fuc as soon as it is hot, it will, when cold, retain its |)eculiar crystal- line structure; if now it be heated red hot, and left at a moderate red for several hours; in short, if it be treated as St.eel often is, and be left in a furnace over night, it will be found, when cold, to have a perfect amorphous structure, every trace of chill crystals will be gone, and the whole piece be non-crystalline gray cast-iron. If this is the effect upon coarse cast-irons, what better is to be expected from fine cast- steel ? A piece of fine tap steel, after having been in a furnace over night, will act as follows: It will be harsh in the lathe and spoil the cutting tools. When hardened, it will almost certainly crack; if it does not crack, it will have been a remarkably good steel to begin with. When the temper is drawn to the proper color and the tap is put into use, the teeth will either crumble off or crush down like so much lead. Upon breaking the tap, the grain will be coarse and the steel brittle. To anneal any piece of steel, heat it red hot; heat it uni> formly and heat it through, taking care not to let the ends and corners get too hot. As soon as it is hot, take it out of the fire, the sooner the better, and cool it as slowly as possible. A good rule for heating is to heat it at so low a red that, when the piece is cold, it will still show the blue gloss of the oxide that was put there by the hammer or rolls. Steel annealed in this way will cut very soft; it will harden very hard, without cracking, and, when tempered, it will be very strong, nicely refined, and will hold a keen, strong edge. THE BURSTING AND COLLAPSING PRESSURE OF SOLID DRAWN TUBES. The following table gives the bursting and collapsing fMressure of solid drawn tubes: Bursting Collapsing Diameter. Pressure. Pressure. Difference. jX • 4800 3300 1500 S'/s 4500 3150 1350 3 4500 3500 1000 2^ 5200 3500 1700 2 j2 5000 3600 1400 2X 5900 4500 1400 2 5900 4900 1000 i)^^ 5600 40CO 1600 In this table it will be noticed that the bursting strength exceeds the collapsing strength, and that the diftVrence in- creases with the diameter, as shown in the last column. MINERAL WOOL. Mineral wool is the name of an artificial product view used for a great variety of pui-poses, chiefly, however, as a non-conductor for covering steam surfaces of whatever char- acter. It is largely used for this, and the underground steam pipes of the New York Steam Company are insulated with it. Mineral wool is made by converting vitreous substu.ices into a fibrous state. The slag of blast furnaces affords a large supply of material suitable for this purpose. The product thus obtained is known as slag wool. For the reason that slag is seldom free from compounds of sulphur, which are objectionable in the fiber, a cinder is prepared from which is made rock wool. These products comprise the two kinds of mineral wool; they are noc to be dis- tinguished from it, but from each other. The resemblance of the fibers to those of wool and cotton has given the names of mineral wool and silicate cotton to the material, but the similarity in looks is as far as the comparison can be followed. The hollow and joined structure of the organic fiber, which gives it flexibility and capillary properties, is wanting in the mineral fibre. The latter is simply finely-spun glass of irregular thickness, without elasticity or any such appendages as spicules, which would be necessary for weaving purposes. The rough sur- faces and markings of the fiber can only be detected under a strong magnifying glass. Aside from its uses as covering for hot surfaces, it is also largely employed for buildings. A filling of mineral wool in the ground floor, say two inches thick, protects against the dampness of cellar ; in the outside walls, from foundation to peak, between the studding, it will prevent the radiation of the warmth of interior, and will destroy the force of winds, which penetrate and cause draughts ; in the roof it will re- tain the heat which rises through stair-wells, bringing about regularity of temperature in cold weather ; the upper rooms will not receive the heat of the summer sun, and store it up for the occupants during the night, but remain as cool as those on the floor below ; the water fixtures in bath-rooms, closets and pantries will not be exposed to extremes of heat and cold. Analysis of mineral wool shows it to be a silicate of magnesia, lime, alumina, potash and soda. The slag-wool contains also some sulphur compounds. There is nothing organic in the material to decay or to furnish food and com* fort to insects and vermin ; on the other hand, the fine fibers 220 -ipf glass are irritating to anything which attempts to bu.row in them. New houses lined with mineral wool will not be- come infested with animal life, and old walls may be ridden of tbeir tenants by the introduction of it. Mineral wool is largely used for car linings, in which service it reduces the noise of travel greatly. Aside from those mentioned, it can be applied generally in the arts for all purposes where a non-conductor or a shield is required, and :he experience of several years show that it is both serviceable and cheap. NICKEL PLATING SOLUTION, , According to the Bulletin InternatioJtale de V Electricite^, the following solution is employed for nickel plating by sev» eral firms in Hainault. It is said to give a thick coating ol nickel firmly and rapidly deposited. The composition of the bath is as follows; Sulphate of nickel .,, « ....••,•. *». i lb. Neutral tartrate of ammonia 1 1 , 6 oz. Tannic acid with ether ., , » 08 oz. Water ,.......«.., 16 pints. The natural tartrate of ammonia is obtained by saturat- ing tartaric acid solution with ammonia. The nickel sul- phate to be added must be carefully neutralized. I'his hav- ing been done, the whole is dissolved in rather more than three pints of water, and boiled for about a quarter of an hour. Sufficient water is then added to make about sixteen pints of solution, and the whole is finally filtered. The deposit obtained is said to be white, soft and homogeneous. It has no roughness of surface, pnd will not scale off, pro- vided the plates have been thoroughly cleaned. By this method good nickel deposits can be obtained on either the rough or prepared casting, and at a net cost which, we are told, barely exceeds that of copper plating. HOW GAMBOGE IS PREPARED. Gamboge is a gum, and an average gamboge tree is said to yield annually sufficient to fill three bamboo cylinders, each about 18 to 20 inches long and i J^^ inches in diameter. It takes about a month to fill a cylinder. When full the bamboo is rotated over a fire to allow the moisture to escape and the gum to harden sufficiently to admit of being removed. PROOF OF THE EARTH'S MOTIOlxi. Any one can prove the rotary motion of the earth on its axis by a simple experiment. Take a good-sized bowl, fill it nearly full of water and place it upon the floor of a room which is not exposed to shaking or jarring from the street. Sprinkle over the surface of the water a coating of lyco- podium powder, a white substance which is sometimes used for the purposes of the toilet, and which can be obtained at almost any apothecary's. Then, upon the surface of this coating of powder, make with powdered charcoal a straight black line, say an inch or two inches in length. Having made this little black mark with the charcoal powder on the surface of the contents of the bowl, lay down upon the floor, close to the bowl, a stick or some other straight object, so that it shall be exactly parallel with a crack in the floor, or with any stationary object in the room that will serve as well. Leave the bowl undisturbed for a iew li ours, and then observe the position of the black mark with reference to the object it was parallel with. It will be found to have moved about, and tohavemoved from east to west, that is to say, in that direction opposite to that of the movement of the earth on its axis. The earth, in simply revolving, has carried the water and everything else in the bowl around with it, but the powder on the surface has been left behind a little. The line will always be found to have moved from east to west, which is perfectly good proof that everything else has moved the other way, WHY THE COMPASS VARIES. The compass, upon which the sailor has to depend, is subject to many eirors, the chief of which are variation and deviation ; that is, the magnetic needle rarely points to the true north, but in a direction to the right or left of north, according to its error at the time and place. The deviation of the compass comprises those errors which are local in their character ; that is, due to the effect of immediately surrounding objects, such as the magnetism of the ship itself; this is sometimes very great in an iron ship. The variation of the compass varies with the position of the ship, as shown by these curves of variation. Thus, from Cape Race to New York the variation of the compass changes from 30^ W. to less than 10^ W. ; and from Cape Raceto J^ew Orleans from 30° W. to more than 5^ E., the line of no variation being indicated by the heavier doub'e line stretchnig from the coast near Charleston down throui^h Puerto Rico and the Windward Islands to the northeastern coa'^t of South America. To illustrate these variation curves more clearly, a chart has been made upon which variation curves are plotted for each degree. This illustrates very strikingly the positions of the magnetic poles of the earth, which do not by any means coincide with the geographic poles. On the contrary, there are two northern magnetic poles and two southern; up ';iorth of Hudson's Bay, at the point where these curves converge, there is one magnetic pole, and another to the northward of Siberia. Similarly, there are two in the south- ern hemisphere, and these four poles of this great magnet, the earth, are constantly but slowly shifting their positions, and just so constantly and surely does the magnetic needle obey these varying, but ever-present forces, seldom pointing toward the pole which man has marked off on his artificial globe, but always true to the great natural laws to which alone it owes allegiance. The small figures with plus and minus signs at various places on this chart indicate the yearly rate of change of variation, and this rate varies at different positions on the chart. Thus, near the Cape Verde Islands it is plus -^% ; here the variation increases ^j^ of a minute a year; farther to the southward, near the South American coast, it is plus 7^"^, and to the northward, near the Irish Channel, it is minus 7,-0. Fortunately, however, the^e changes are small and comparatively regu'ar, and iheir cumulative effect can be allowed for, when la.g3 enough to make it necessary to do so THE BANK OF ENGLAND DOORS. The Bank of England doors are now so finely balanced that a clerk, by pressing a knob under his desk, can close the outer doors instantly, and they cannot be opened again except by special process. This is done to prevent the daring and ingenious unemployed of the metropolis from robbing the bank. The bullion department of this and other banks are nightly submerged several feet in water by the action of machinery. In some banks the bullion department is connected with the manager's sleeping room, and an entrance cannot be effected without shooting a bolt in the dormitory. 229 KEEPING TOOLS. Keep your tools handy and in good condition. This applies everywhere and in every place, from the smallest shop to the greatest mechanical establishment in the world. Every tool should have its exact place, and should always be kept there when not in use. Having a chest or any receptacle with a lot of tools thrown into it promiscuously, is just as bad as putting the notes into an organ without regard to their proper place. If a man wants a wrench, chisel or hammer, it's somewhere in the box or chest, or somewhere else, and the search begins. Some- times it is found — -perhaps sharp, perhaps dull, maybe broken; and by the time it is found he has spent time enough to pay for several tools of the kind wanted. The habit of throwing every tool down, anyhow, and in any way, or any place, is one of the most detestable habits a man can possibly get into. It is only a matter of habit to correct this. Make an inflexible end of your life to " have a place for everything and everything in its place." It may take a moment more to lay a tool up carefully after using, but the time is more than equalized when you want to use it again, and so it is time saved. Habits, either good or bad, go a long ways in their influence on men's lives, and it is far better to establish and firmly maintain a good habit, even though that haoit has no special bearing on the moral character, yet all habits have their influence. Keeping tool? in good order, and ready to use, is as neces- sary as keeping them in the proper place. To take up a dull 3aw, or a dull chisel, and try to do any kind of work with it, is w^orse than pulling a boat with a broom, and it all comes from just the same source as throwing down tools carelessly — habit, nothing more or less. To say you have no time to sharpen is worse than outright lying, for, if you have time to use a dull tool, you have time to put it in good order. AN IMPROVED SCREW-DRIVER. A screw-driver has been made in Philadelphia with th^ handle in two parts, said parts being capable of rotating one upon the other. A sto]:)-pin and pawl limit the movement of the shank in one direction, while the top of the handle will move backward without turning the shank. The mechanism appears to be very similar to the principle of a stem-winding watch. 230 THE EFFECT OF MAGNETISM ON WATCHES. At a meeting of the Western Railway Club, Mr. E. M. Herr, superintendent of telegraph of the Chicago, Burling- ton & Quincy Railroad, read the following paper : A magnet is a body, usually of steel, having the property, when delicately poised and free to turn, of pointing toward the north, and of attracting and causing to adhere to its ends or poles, pieces of iron, steel, and some other substances. Materials which are attracted by a magnet are called mag- netic, and it is because the rapidly moving parts of a watch are in general, made, in part at least, of magnetic material, that these timepieces are affected by that peculiar force magnetism. Were magnetic substances only affected while a magnet is near them, there would be little difficulty as far as watches are concerned. Such, unfortunately, is not the case, as certain materials, steel more than any other, are not only attracted by a magnet, but become themselves per- manent magnets when brought into contact with or even in the vicinity of a magnetized body. It is to the latter prop- erty of steel, namely, becoming permanently magnetized by the approach of a magnet without coming in contact in any way with it, that causes trouble with watches. Again, a small piece of steel is much more easily mag- netized than a large one; consequently, the small and deli- cate parts of a watch are most likely to be affected. These are found in the balance wheel and staff, hair spring, fork and escape wheel, and are the very ones in which magnetism causes trouble on account of the extreme accuracy and reg- ularity with which they must perform their movements. It is, in fact, upon the uniformity in the motion of the balance wheel, that the timekeeping qualities of the watch depend. In a magnetized watch this wheel, as well as all other steel parts, become permanent magnets, each tending to place itself in a north and south line, and also to attract and to be attracted by the others; all of which, it is hardly necessary to add, tends to affect its reliability as a timepiece. How small a variation in each vibration of the balance wheel will cause a serious error in the daily rate of a watch, is easily realized when attention is given for a moment to the number of double vibrations this wheel makes in 24 hours. This varies in different watches from 174,000 to 216,000, and the variation of a single vibration in this number will cause a greater error than is sometimes found in the best watch movements. It is therefore true that the variation in 231 each vibration of the balance wheel of 1-200,000 part of thetimeof such vibration^ or in actual time about the 1-500,- 000 part of a second, will prevent the watch rating as a strictly first-class time piece. I wish to state, however, that there are very few watches made of ordinary materials which are absolutely free from magnetism. This may seem like a sweeping statement, but, after taking considerable pains to verify or disprove of it, I am convinced that it is substantially correct. Why this should be so becomes evident when we consider that a few sharp blows upon a piece of steel held in the di- rection of a dipping needle suffice to sensibly magnetize it, and then think of the numerous mechanical operations that have to be performed upon each small piece of steel in the moving parts of a watch before it becomes a finished product. In order to determine, if possible, to what extent magnetism prevails in watches, I have examined and tested for magnetism 28 watches carried by persons other than train or engineer men, with the following result : Three were very seriously magnetized ; one to such an extent that it could not be regulated closely ; twenty barely perceptil^ly affected, possibly, but the normal amount due to the process of manufacture, and in but four could no magnetism be detected. On account of the steel parts of a locomotive being magnetized during the process of construction, and by severe usage in a similar manner to those of a watch, it has been claimed that the watches of engineers are constantly subjected to the action of the magnetic forces, and cannot therefore keep as good time as other watches. I have examined for magnetism the different parts of a number of locomotives in actual service, and, although they were in general found to be magnetic, they are so slightly charged as to render it almost certain they could have no influence upon the rate of a watch, and would surely produce less effect upon it than the originally slightly magnetized parts of the watch itself. That this amounts to practically nothing, is proven by the large number of finely rated watches now in use in which magnetism is apparent. As proof of the statement that engine-men's watches are not, as a rule, more highly charged with magnetism than those of men engaged in other occupations, the watches of twenty locomotive engineers were tested. Of these none were found heavily charged with magnetism; but *^^wo more than normal; twelve with a barely perceptible charge, and in six none could be detected, showing actpally less magnet- 232 ism in these than in the twenty-eight watches previously examined, none of which were carried on a locomotive, a result probably due to the fact that engineers, as a rule, are very careful of their watches, and are less apt to bring them in dangerous proximity to a dynaiiio than those not con- cerned in running trains, and in whom a well-regulated watch is less important. This, I take it, w^ould surely be the case did they all understand that a watch is likely to be entirely disabled by bringing it near a dynamo or motor in opera- tion. It therefore seems important that all to whom accu- rate time is a necessity, should be carefully instructed as to where the danger lies. So much has recently been written about the magnetiz- ing of watches that many persons approach any kind of elec- trical apparatus with caution. Even a battery of ordinary gravity, or LeClanche cells, is regarded with suspicion, while a storage battery is thought almost as dangerous as a dynamo. Others, on the other hand, do not even know that a dynamo is dangerous to watches. It should be borne in mind that it is not electricity which affects watches, but magnetism, and that magnets are the seats of danger. It is the powerful electro-magnets in dynamos and motors that magnetize watches, and not the strong currents of electricity generated or consumed by them. True, there is a mag- netic field about every current of electricity, but it is so very slight that no effect is produced on watches worn in the pocket. Having spoken of the evils of magnetism in watches, it is, perhaps, proper to add a few words regarding its preven- tion. The best and most certain way to prevent a watch becoming magnetized is to never allow it to come near a magnet, Unfortunately, in the present age, this is a diffi- cult matter, as no one can say how soon they may find it necessary to be in the vicinity of a dynamo in operation or be seated in a car propelled by an electro-motor. The only practical protection to watches from magnetism of which I have been able to learn consists essentially of a cup-like casing of very pure soft iron surrounding the works of the watch, which is known as the anti-magnetic shield. That this device is a protection from the effects of magnet- ism upon watches, there can be no doubt, but that it pre- vents magnetizing under all circumstances, even its inventor, I believe, does not claim. ^■) It therefore becomes important to know how far our watches are safe when supplied with this protection, and 233 where to draw the danger line for the protected, as well as the unprotected watch. In order to throw some light upon this question, the following tests were made: First, to discover to what extent magnetic bodies placed within the shield were protected from external magnetic forces ; second, in how strong a magnetic field it was neces- sary to place a watch protected by this device to effect its rate by magnetization. While no pretense of scientific accuracy or precision was made in these tests, it is believed they are sufficiently accu- rate for scientific purposes. The first test was made by filling an inverted shield half full of water, on the surface of which a very light magnetized steel needle was caused to float. In a similarly shaped cup, made of porcelain, another needle, in all respects like the first, was also floated. A horseshoe magnet was then brought near each, and found to affect each needle equally, at the following distances : in shield, 6 in. ; in porcelain cup, l^yz in. Distance below a ^-m. wooden board, upon which shield and cup were placed, at which needles could be just reversed by magnet — in shield, 33^ in. ; in porcelain cup, SX in. With just enough water to cover the bottom of shield, the following distances for equal effects were observed : first exposure in shield, 8 in. : first exposure in porcelain cup, 20 in. ; second exposure in shield, 12 in. : second exposure in porcelain cup, 30 inches. Since the intensity' of a magnetic force varies inversely as the square of the distance, the above results indicate that to produce like effects, at equal distances, magnetic forces from five to six times as strong would be required, with bodies inclosed within the shield, than with those not so protected. |The second test was made with watches of different makes, all furnished with the shield. Space will not permit my going into the details of these tests, which extended over several months. I will only say that they in general con- sisted in obtaining the rating and performance of the watch before and after it was exposed to magnetic influences, The exposure consisted in placing it nearer and nearer to the pole pieces of a powerful arc light dynamo and observing the rate before and after each exposure. After many tests of this kind, the conclusion was reached that a watch carefully and properly shielded could be safely placed not nearer than 4 in. to the pole pieces of a 20 arc light Ball dynamo. When brought nearer they were without exception magnet- 234 ized to a greater or less degree, the amount depending largely upon the time of such exposure. Watches are now being made, however, which it is claimed are entirely non-magnetic and unaffected by the strongest magnetic fields met with in practice. Several such watches were also examined and tested. They were furnished with a balance-wheel, hair-spring, fork and escape wheel made of an alloy of non-magnetic metals in which palladium is the principal component. The first of these watches tested was furnished only with a non-magnetic bal- ance and hair-spring, and had a steel fork and escape wheel. This watch is instantly stopped when brought near a power- ful dynamo. Olher movements were then tried, in which all of the rapidly moving parts were of non-magnetic material. These could not be stopped by the field magnets of the most powerful arc light dynamos, although when placed in actual contact with the pole piece the balance-wbeel was seen to vibrate less freely, probably due to the attraction of the staff and pivots, vvhich were of steel. The rate of the watch was not, however, altered by this test. A hair-spring made of this non-magnetic alloy was also drUcately suspended in still air and subjected to the action of a powerful horseshoe magnet without developing the slightest observable magnetic effect. One of our best-known American watch manufacturing firms is now making a non-magnetic watch on a plan similar to that just described ; others will probably soon follow, hastening the day when a watch thoroughly protected or inherently insensible to magnetism will be as common, and considered as necessary to the successful keeping of correct time as "he adjustment for temperature and position is already. HOW BARRELS ARE MADE. Barrels are now being made of hard and soft wood, each alternate stave being of the soft variety, and slightly thicker than the hard-wood stave. The edges of the staves are cut square, and, when placed together to form the barrel, the out- sides are even, and there is a V-shaped crack between each stave from top to bottom. In this arrangement the operation of driving the hoops forces the edges of the hard stave into the soft ones, until the cracks are closed, and the extra thick- ness of the latter causes the inner edges to lap over those of of the hard-wood staves, thus making the joints doubly secure. 235 FACTS ABOUT IRON CASTINGS. Some experience of the changes of shape which castings undergo by reason of shrinkage strains is necessary, in order to proportion them correctly. I have seen numerous massive and very strong looking castings fracture during cooling, or a long time afterward while lying in the yard untouched, or while being machined ; the reason being that excessive con- traction in one portion had put adjacent parts into a condition of great tension. By putting an excess of metal into some vulnerable point of a casting, is introduced an element of weakness, and almost a certamty of its breaking by reason of the internal shrinkage strains. It is not the excess of metal in itself which gives rise to these strains, but the position in which it is placed relatively to other sections. Thus a lump of metal cast in juxtaposition to a thinner portion will not break the latter, so long as it is able to shrink freely upon itself. Bat if placed between two thinner portions, it may fracture them by its shrinkage. Hence the great aim is to so design castings that all portions thereof thall cool down with approximate uniformity. A founder learns much from the behavior of case-iron pulleys and light wheels. As they are so light and weak, proportioning must be correctly observed, and when customers ask for a " good, strong boss " or " strong arms," the request is one which, if complied with in the manner described ; that is, by unduly increasing the metal, will either fracture the pulley or wheel, or bring it near to breaking limit. In all castings "strong" is a relative term, that form or size being strongest which harmonizes as regards general proportions. In a light pulley, three different conditions may exist: i. All parts may cool down alike, or nearly so ; 2. The rim may cool long before the arms and boss; 3. The arms and boss inay cool before the rim. ±n the first case, the pulley will be strong and safe. In the second, the rim, in cooling, will set rigidly, but the arms and boss will continue shrinking, each arm exerting an inward pull on the rim, and various results may follow. First, the strain may simply cause the arm to straighten; or, in less favorable conditions, and especially if straight arms, or arms but slightly curved, be used, the arms may fracture near the rim, but seldom near the boss. Or, if the rim be weaker than the arm, fracture will take place, or the pulley may be turned, and then break. ^ In the thinl cas;:, the arms and boss cooling before the rim, they are compresse 1 by the shrinkage of the latter, and the arms may then b HM»me fractured, if curved; or, if straight, may prevent the rim from 236 coming inward, and so break it. In most cases, fracture occurs from the mass of metal in the boss. As a single instruct- tive example out of many, I may quote that of a pair of 2 ft. 6 in. pulleys, fast and loose, which had been running for several years, the fast pulley had a boss 6 in. in diameter, the loose pulley one of 5 in. only, and both were bored to 3 in. By the accidental falling of a bar of iron, both were broken. The rim of the fast pulley was at once pulled in, while the loose pulley rem.ained level at the point of fracture. This illustrates the presence of tension in the rim, due to the larger boss, and this tension had been present since the pulley was made. The pulley with the 5 in. boss wa^ probably much stronger than that with the six in. boss. In fast pul- leys, and in wheels keyed on, the necessary strength around the key way may be obtained by the use of key way bosses, without increasing the entire diameter Where large bosses are unavoidable, as in some deep, double-armed pulleys, or in spur wheels keyed onto large shafts, shrinkage is assisted by opening out the mold around the bosses, and removing the central core, thereby accelerating the radiation of heat, and further by cooling them with water from a swab brush when at a low red or black heat. Many a casting is saved in this way Another method is to split the boss with plates, and bond or bolt it together afterward. When casting fly- wheels with wrought-iron arms, the rim is first cast around the arms and allowed to cool nearly down before the boss is poured. If the latter were cast at the same time as the rim, it would set first, and, by preventing the arms from coming inward, would put tension upon the rim. Whe^e aggregations of metal occur in castings, they may, if the castings be too strong to fracture, cause an evil of a secondary character, known as " drawing;" in other words, the metal is put into a condition of internal stress, and becomes open and spongy in consequence. " Feeding " tends to diminish this evil; but m.uch can often be done by light- ening the metal with cores, chambering out, or reducing the metal massed in certain places by other means. There is a difference in the behavior of cast-iron and of gun metal, of which advantage may be taken in small, light castings. Designs which will not stand in cast-iron or steel will stand n gun metal, hence the latter may be useful in cases of diffi- culty. Sharp angles very often lead to fracture. When brackets, ribs, slugs, etc. , are cast on work, the corners should never be left square or angular, for, if there be much disproportion 237 of metal, fracture will almost certainly commence in the angles. I have already alluded to the " straining " which large plated and heavy castings undergo, so that the sides and faces increase in dimensions, becoming more or less rounded. The main reason is, I think, that the metal round the central portions does not cool so rapidly as that at the sides. The outsidss radiate heat quickly, and shrink to their full extent; but the middle rib or ribs, and the cen- tral portions of the plate, retain their heat longer, and hold the sides in a condition of tension, thus forcing them to bulge or become round. When the central portions cool, the outsides are too rigid to yield to the inward pull. This refers to framed hollow work. When plates " gather " or increase in thickness, it is due mainly to the lifting of the cope, from insufficient weighting. When a cubical mass of metal shows no shrinkage, this is due to the pressure of the entire mass compressing the sand on every side. Briefly stated, then, in deciding the proper contraction allowance for a pattern, I should take into consideration its mass, the manner in which it is molded and cast, the Dresence or absence of cores, and the nature of the same, its general outline, and the character of the metal. For a heavy solia casting in iron, I should allow considerably less than t'? normal contraction for iron ; for a similar casting in steel, more than the normal contraction for steel; for a heavy casting in gun metal, less than the normal contraction foi gun metal. The precise allowance in any case must be regulated by circumstances. For the vertical depth of a shallow casting, very little shrinkage, if any, should be allowed; for a deep casting, the full amount. Then, again, a mold, with dry sand cores of moderate or large size, will not allow the casting to shrink so much as if the cores were of green sand, or were altogether absent. For hard and chilled iron, the shrinkage will be at its maximum ; for strong mottled iron, at its maximum ; and for common gray metal, at about the average. FLEXIBLE GLASS. An article called flexible glass is now made by soaking paper of proper thickness in copal varnish, thus making it transparent, polishing it when dry, and rubbing it wilh pumice stone. A layer of soluble glass is then njipl-ed nndiubbfd with salt. The surface tiius produced is said lo be as perfect r planed Straight. If gear patterns are made accurate and true. ^4^ and the face of the cogs perfectly smooth, there will be no difficulty in molding them if they are nearly or quite Straight. All patterns before being used should be well covered with at least two coats of pure shellac varnish. After applying the first coat, and when it is perfectly dry, the surface should be well rubbed down with fine sandpaper, and all imperfections, such as nail holes and sharp corners, not already provided for, should be carefully filled with bees- wax and rubbed off smooth before the second coat of var- nish is applied. After a pattern has once been used, it is good practice to again rub it off with very fine sandpaper, and apply another coat of varnish. Many well-made pat- terns are ruined in the foundry by not being provided with the proper facilities for rapping and drawing. The molder must have some means for attaching his appliances for lift- ing it out, and, if suitable provision is not made for this pur- pose, he will screw his lifter in any part of the pattern tha^ is most convenient, and the chances are, that it will split the first time it is used, or badly marred up. Iron plates should be let into all patterns with holes threaded to suit his lifters, and well secured either by screws or rivets, and, if a sufficient number are attached, the molder will respect the pattern and use them. Wood patterns should never be allowed tc remain in the foundry; as soon as they are used, they should be taken to the pattern-room, brushed off ana placed in such a position for future use that they will not become warped or sprung. ELECTRIC HAND LANTERN. A German patent has been granted to A. Friedlander for an electric hand lantern. This consists of a box of hard rubber carrying a small three-candle power incandescent light, together with a reflector and glass protector. The elements in the box, carbon and zinc, produce the current necessary to feed the light. The box is divided into five compartments holding the liquid, and the electrodes are placed in such position that no decomposition occurs when the lantern is not in use. The circuit is closed when the electrodes are dipped in the liquid ; the current is stronger and the liq;ht brighter if the electrodes are dipped deeper in the liquid ; this depth and consequentlv the brightness of the light can be regulated by means of a button on the outside. The liquid is a combined solution of chloride of zinc, bichro- mate of soda in water and acid, and the lantern can hold a sufficient supply of lli.s solution to last for about three hours. ^43 rABLES OF GEARS FOR CUTTING STANDaRI^ SCREW-THREADS. INTRODUCTION. It may, perhaps, be necessary to state that these tables are the fruit of much experience, and a deep-seated convic« tion that their want is sorely felt by many. Notwithstanding the vast improvements of modern screw-cuttini^ machinery, much time is still wasted by the most experienced workmen in endeavoring to find wheels to but any particular pitch o. screw, or broken number, in consequence of the various changes to be obtained from the usual set of screw-cutting wheels, most of which begin with a 20-teeth, 25, 30, 35, 40, 45» 5O' 55» 60, 65, 70, 75, 80, 85, 90, 95, 100, no, 120, 130, 140 and 150. This may be considered a full set, inasmuch as any screw may be cut with it, Supposing the 20-wheel to be put on the mandrel, for single changes, without the pinion, the first figure up to 95 will give the number of threads to the inch. A 20 and A 25 will cut 2J4 ; 20 and 30, 3 to the inch, and so on in like ratio. When three figures are on the wheels, however, the first two will indicate the number to the inch ; as, 20 and 100 will cut 10 ; 20 and 1 10 will cut 11; etc. For many common numbers this will save the trouble of looking to the tables, if a ^, ^, or other coarse pitch. If the. book be referred to for the decimal of the ratios required, against it will be found the wheels that will cat it. If the number be required to the foot, then multiply by twelve. These tables are calculated on the assumption that a pin- ion of twenty teeth is used, and a driving-screw of two threads to the inch. Wheels, when affixed to the mandrel, are r ^.hod maadrel* wheels ; those on the screw, screw-wheels ; aj d those inter- vening, intermediate-wheels. When the ma/ drel and screw- wheels are connected by one or more whe is directly, they are termed simple wheels. When attach/? i by means of a pinion joined to the intermediate wheel iwey are calledcom- pound-wheels. '^o. I, is a table of sirwpi*; wiieels. The mandrel- wheels are in the first perpendicular column; and the screw-wheels in the top horizontal column. In the spaces where the per- pendicular intersects the horizontal, will be fovmd the pitch of the thread which any two wheels will cut. The remaining tables are of compound wheels. The mandrel-whee's will be fojnd in the first ]:)erpendicular column, the intermediate-wheels in the top horizontal column, and the screw-wheels in the bottom column. The pitch of thread 244 to be cut having been found in the tables, on the left hand the mandrel- wheel will be found, on the top the intermediate wheel, and at the bottom the screw-wheel. All lathes have not a twenty-teeth pinion, in which case, the following rule will be of use as applying to any other pinion : Multiply the pitch of thread intended to be cut, by the new pinion, and divide by twenty. Find the wheels in the tables corresponding with the quotient, and use the new pin- ion instead of the twenty. In some lathes the mandrel-w^heel is a fixture. In these instances, suppose the mandrel-wheel to be the pinion, and attach the mandrel- wheel found in the t;',ble to the interme- diate-wheel. To ascertain the ratio of any series of wheels, multiply the whole of the driven wheels togetner, which will give the total number of teeth in the series. Then divide the result by the driving wheels multiplied into each other. The quo- tient will be the number of times the first wheel will revolve to the last. Suppose a wheel of twentv teeth to be driving a wheel of loo teeth, to which is attached a wheel of thirty teeth driving a wheel of 150 teeth, and the ratio be reoiured — 100 X 150 ■ =25 revolutions. 20 X 30 To find the number of threads a set of wheels will cut, multiply the ratio of the wheels by the pitch of the driving-screw. To cut double or more threads, divide the mandrel-wheel in as many parts as you require threads, and, as you cut the screw, shift the mandrel-wheel a division, while the screw-wheel remains stationary. This plan will insure equal division and regularity of cutting. In all lathes where the leading screw is two to the inch, and an equal number of threads being cut, if the saddled clutch be thrown out of gear, it will always fall into the right place. If an odd number of threads are bemg cut, it will fall right every other one. By rittending to this rule, run- nmg the latrie backward will be avoided, and a screw cut in about half the time. A difficulty frequently arises in finding the number of threads to the ik-ch or foot when a particular pitch or fractional number has to be matched. This can easily be ascertained by measuring onward, for, if it do not come right in one Inch, notice how msny there are betweei: any division of rule. In measuring a screw, you discover there are twenty-eight threads in three Inches. Consequently, If twenty-eight be divided by three, it gives 9.333 as the pitch. Against that number in the table will be found the wheels to cut it. Suppose a coarse pitch be required, say one thread In i;^ inch, the wheels may be found thus: when there is less than one thread to the Inch, see how many there are in twelve inches; as, 1.615 In. pitch into 12 in. Is 7.384 to the foot. If divided by twelve, we have the dec, 615, against which in the tabic will be found the wheels. 245 u 00 lo ro N O ■<*• ^N 10 ro M xfi rhvo a\ f^ fO M t^vO *0 t>. 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J8 N M N m 10 O VO mvo 10 VO NO t^ 10 ^ _-^iOM t^rOH t^>o t^ r^ IT) ro M o 00 lt/> VOMt^M WOOVO lOvo 00 H IT) ir;vo ^J^ ro C>i *ft|»»»» •• 1 ■'l-COCONNNMMMMHM iH o O Onoo t^ t^vo 2 fOVO 10 N »n ro LO CN w N 00 00 00 tH CM 0\ VO VO 00 (N N -<1- w •^ O 0^ On O N vO 00 00 -^ tn O rovo -^ 10 t>. O '^ (>» two -(I- ro m N M O Onoo 00 t^ 10 On VO m 10 fooo t^ (N 00 -^^ VO fOOO 10 H VO U-) CO N CM r^VO ro 0\ N VO VO ■<^ Tj- m ID t^ H CM t>. tnoo CN 00 to N 10 -^ rO CO M M CM s ON h^vo 10 -^ ro N (MHO <7\00 00 VO ■^^ 10 ■* Th m ir> VO 00 r^ ■<*• 1000 t^T*-M MOO -^txTl-lo M VO 1^00 N "■J-VO ro CM (N VO ■* Tl- ID t^ tN, H M in cs Oi P) ro cs (N loco fO 10 H VO w CO IT) 10 00 VO VO ID P) ro W IDVO H H rj- f«-, ID t>. t^ t^vo VO t^ H CD O OnOO ro CO O O N 10 VO CD ThcXD CD OnvO -^ c^ O OS t^vo iDM--<4-rocq m O 0\ VOlDTfCDrOCM(NC4CM01MHHIHI-lMMMMM ■<^ IDvO 00 N t^ •I CM VO O ID CJ ID ID r^vo VO ID On t^ O ro W rh m -^ ID H CO M VO CD ID ID r^vo t^ 00 t^OO W OiOO 0\ H VO 00 ■<1- m ro Thvo W CJ 00 VO „ t>. ?> VO N Tt- m w M VO ID --J- (M t^ VO VO ID H VO "^ ID ■. CM ID M ■«J-00 w ID ThVO M r^ Tf <*• (D C^ CM M M C7N00 t~* M ID "<*■ CD . W »D s IH 00 -^ VO VO -^ Tj- CO CD P) •>!^ M 00 tvvo ID -<*• CO pj (M CMMMHMMMMMMHMH CTvOO ro pj 00 CD r^ 00 CO H 1DCX3 VO VO H CO -* rhOO 00 CO co'O f^ CO ID On -^oo h CO VO VO ID CO CM P> •. cv) 00 VO ID ■<*• CD CO W VO CO M 00 t^VO ID ^ CO CO H ON H WPIPJPIMM MM "^ coco CO O '^^ t^vo On IDCOCO CO t-^iDCO pjvovo ■"^COlD VOlD-» t>.VO t>. Ow^OV)OmOv>Ow^Oino»nOviO O O N CJ CO ro -^ T^ ID iDVO VO C>. t^OO OOONONQMPJCOrJ- C/3 133HAV 'laHQNVIM 249 PINION 20. 00 (N Vp 10 M H ■<:*■ 10 VO LOVO t^ CO t^ N VO 10 ro ro t^ -^00 ro t^ w w 1000 (N M w rt- Omd N >o Tj- ro N t>.00 t^ H 1000 M r^ ro m -"i- 0\ . OVOO M M H M 00 t^ ro M „ IT) tJ- (N Lo ro 00 in w H m -"J-oo ro w C4 VO M VO >-i in t^ t^ VO (N in On N O M ij- t-^ mvo 00 w a CO in in CM ^s. t^ CM in -^ ro m ro ■<*■ t^oo -^ m in M 00 m w in (N M CM -^vo CM mvo t^ in t^ N t-^ m 10 t>. H m M m ON w "^00 Tj- M 0, t^ in ■"il-rOtNCMCMMWH Tf ro N w jH H H H 0^ O\oo tr^ t^vo vo & tN. ID ro VO ro VO t^ 00 00 00 moo M m 00 H rooo VO 00 CM CM T(- M m ov Tt- 8 invo in (N CO VO ■"^-rorocMCMNHH >n ro (N CM H O^ C>00 t^vo VO M & 00 in invo IN t^ CO 00 M ro T(- in CM Hi p) m tr>. rovo H c^^ M CM m w t>, ■n 'd- ro CM H 11 H M On OVOO t^ C^ H M a m « 00 VO ro VO VO moo in H N VO rf Thm t-> ro CO t>. rh VO M i-i rooo 00 ro t>. s ■«!l- rovo ^^ "* m rf CO ro w cm w cDvoo VO m -t- ro « CM M cy.00 tx *^ 8- CO CM in inoo s- (N CM '^ CM ■<*• in -<4- H (N VO in t^vo VO t^ m VO t>. M ro m m ro t>^vo t^ ro % 00 VO Oi ro o^vo m "i- ro CO CM m ro M CM N Cj\oo VO m M M »-: M -* ro ro CM H as a^oo M H H W a -* m OS M OS 00 ro 00 ro m (N t^oo M^O ■<*- mvo mo CM VO - 00 VO m ■<4- ro m CM in CM CM CN H« OVOO VO m T^ '^ ro CM M C^ C3\ *^ 8v m in (>• in in 0\ in VO 00 in t^ N m CM t^oo 00 00 CM Th CM M t^ moo Tf CM m CM CM rovo t> Ti- inoo ro t^ "* VO lOTi-rororocM cm CM c^oo VO lnlnT^ro^^ h 0\ CM (M H H ------ ••"•***' * * ..••• • Oinomoinom CM CM coroTt-.i-inin Q m in in VO VO t^ t^oo 00 §^^82gg,|' 03 'SiaaHAv aaHQNVK PINION 20. <7J 5 h vo t>> t*» 10 m t^oo vo HOOH wvo^OT^> vom tv "^foONVo Hoocj t^vo U-) M j vo 00 IS ^ 10 CO CO TfVO -^00 rf N vo H t^ C/ I vd ci 6 t^^ -^ 'O N M d 6 ONOO 00 00 t' ^d vd IT) I M CO On ID rovo 00 •H O On 0\00 00 t>.vO vo 00 rovo 00 vo vo fO 00 ■^ rcvo N VO Ti- On c^ Ti- r^ O CO ro H M rovO cS •^ 00 CM cn Th On Tj- ro m vo H CO w -<*■ c- t^oo -^vo in t^ -^ t^ ONVO CM 00 »0 CM vo M vo t^ rooo CM 00 00 ^ CJnvo n 0) 10 On ■<*- -"i-vO -^ N H "^ OnVO 10 <^ m (N N MOOO t^VO -"i-rOfON VO lO'jH00O\ ONOO 00 t^ vo m ID rOCOCMWHMMMHHHH 10 c» 10 VOHt-^Tj-OMOO rovo voro N id(NC?nmoo t^ H r^OO -^ IDOO ID eg rOVO 0, t^ C-^ Tf- (N « vo CO CO 0^.0 H ONHVO -^-^iDt^O IDONIDO rOO,(N t^ ID CM vo fD t^VO Tj- CO CM M ONOO CO C30 t^vO VO ID ^fOCNCMMHWWMHHMM ID cx> fO ID ■D iDvo t^-^rocM ^t1- CMOoror^ ID rOC^CJOO ri- M 1-^ CDVO 'i" ON ID t-^ '-O 8 N 'i-oo TfMoo t^iDThcoM M ON.oo 00 t^ r>.vo vo M-COWCMCMWI-IHWMHHHH 10 00 VO-<*-lDt^ mTft^VOf->OOM MCMOO ID vow-f^r^ OOOOiDVOOO CO-^iD, ONO\t-«, t^TTMt^rot^t-, m m en -^vo o-;0C ro id c>^ m vo M vo t-MVO COOOO t^lD^m(>) w H ON ONOO t^ C*»vo TtrOrOCNNWMHHHMHMHM 0lD0lD0»D0lDC)lD0lD0»O0lD0 C 00 CM M CO ro -"^ -"^ ID IDVO vo t> CxOO 00ONO^0HCM^OT^ siaaHAV i.'^^^cK^r FINION 20. in in N •"^ N t^ H N VO in CM in 00 t-^ t^ in CO T(- ro ^ in in ro (N On tx in CN 00 in M w rovo ■^OMnn t^MVO M a m t^ N O\>o in CO w M o> 0\.vo r^ VO 00 H cs r^ rooo ir, -o in c^ roco 00 (N 0,00 ON in OiroOMOM rhOi-^ m 0. in 00 m t^ in -^ (N - n 000 00 fx t^ t^vb m in ! ro M 0) (N W H M M M 1 00 vo VO t^ Tf in ro ro '^ 00 00 N invo ro ro r^ 0) ro On m mvo m in '^ t-svo VO m in tx rooc rooo moo ci t~>. rx 1 M tx m H 00 VD 10 ro M M ONCO 00 t>> t>.vo vO m ro en • (N ro in o\oo H mvo 00 in (^ •'ij- 5.0 w in mvo n"; m t^VO tx ro c^ H VO N moo ro H Cx fH H mt^mooovo in ro (N H M On 0.00 00 t^vo VO ■* CO (N N N M M M M M '"' "^ •^ ^ CN vn r^ 00 M M ro M VO m moo t^ 00 (N ir, t^ ir. CO 00 00 >. 00 t-^ m CO ro "^ m -^ in t^vO N IT) r>j 00 t^ rovo mvo (N in t-^ moo rovo in f^ N C7n H ^00 (N t^oo w m ro r^ M 00 Cy» N t^ Tj- M Oi t^vo in ro n- N M Onoo 00 tx ■"^ fO m N (N 0) H M H H •^ •^ m N VO N m vo N mvo m ■. M rovo o m m t>N o ro rt- ro H ■* ro tx 00 VO (N tx ro H M VO On m ro T^ 00 Noovovooo M moi On rovo O "^ ■* vo On moo Onvo m ro W O O ONOO 00 00 t^vo VO m mo mo mo mO m^ m mvo VO tx t^oo 00 On On I m tx CN m m T)- (N M m H H T^ t^ H CN m m m t^ VO ro m -<*• rx ro w N t>v in ro ■^ m N t-^ m moo N CM rovo a VO m tx (N 00 m m Tf CO ro . VO r-> M N in Tj- ■^00 M- VO CO t^ M 00 8. w in H 00 CO N W H 10 Ti- N M 0^ O^oo t^ t^ t>.vo VO in in -"i- ^ 1 to vo W VO H lOVO W CO t^ N t^ o^oo CO VO f^ CO M VO in 00 N COOO m H 00 M M 00 m -^ ■'J- M cooo CO VO m M to ON f^-VO W 0^^0 ■'t CO (N H mOCMMHHHMMH OnOO 00 t>- C^ t^vo VO to 10 ^ CO ro CO to t^vo 0^ 10 « vo VO to 10 t^vo r^ in t^oo CO CO ■<*■ w in CO t^vo VO cooo CO tr^ W t-» CO cooo CO 8 H moo CO CO N CN M t^ m Tl- N M onoo 00 t>. t^ t^vo m to g. 1000 VO H CO -^ IT) H CO H W M -* 00 t^ VO moo in 01 VO t^ VO (N in m in m m (N vo m H t>. -<^oo H M 00 0,m N CO CO M M ON t^ 10 '<*• CJ M H H M H h-l H 1^ On onoo 00 t^ E^vo in ^ VO VO « CO VO t^ CJ VO 00 W ON N c^ CO N vo M 00 CO -<*• CO VO l/NOO cooo Tl-VO Tj- H CJ coco -^ -^ CO w w H 00 VO 10 Tj- (N W M M M M 1-1 M M On Onoo 00 t^ t^vo R. lO •^*- CO N lOVO 10 « Tj-vo t^ W N 10 w CO inoo H 00 w CO CO t^ m H t^ t^oo Hcotv.MinHc^in ^ invo VO '"i- CO CO N N OOOVO lO-«:hCOM CgCNHMMMMM H On Onoo t^ t^ a VO N VO t^ vo cr.yC t>. M CO c-^ 10 t^-VO 00 CO 1 M 00 N 00 VO 00 rnvo 00 11 VO CO M moo cooo On H m % o> o^ N 00 "<*• CO CO (N ■«*■ H On r^vo 10 Th CO 01 w Onoo 00 c^ ^ g. to CO CO 10 CO ON 10 01 CO 10 M m « VO (N m VO M mvo m T^ in c^ M rovo in m c-~ « « 10 m -^ CO CO VO CO M ON t^VO in ■.COON m 00 M to H 00 CO N W M 10 Ti- N H On OnOO c^ c^ t^vo VO m m ■<*• (/3 Omot^otootoQtootootoOioo 000 c» « CO CO -"J- ■<*• m mvo VO ^^ t^oo 00 o^ On o m n co 'saaaHAY ^la^aNVH PINION 20. CO in t^ W N t^ 00 10 m H 00 IT) 10 H t^ moo moo 10 M 00 rooo to C^i M 0^\0 -<*- fO H O O O^00 !>• t^M3 vO vo lO u-j tj- -.^ m ONt^N t^H M rooo '^ H t^ oo-^ro(NincNO\ oroMVOvo 00 t^ 10*0 - t-^vo vo vo 10 10 -^J- vo H •* 00 CO vo t~^ 10 -^ H ro lO vo 10 M ^ 00 00 lOVO 10 t^ N (N OnVO OOVOM-^tN-^ O" NVO MVO >oo w c^sO 00 -^00 00 m a. Tj- m t^ H T^vo 00 HmmHTt-cNvo 10 M lOOV^ONlOH 100.10 2 u^oo m m M (N (N t>^ 10 '^ m H H H 000 00 t>. t^ c^vo 10 to M 10 VO 10 m M m 00 10 mvo H (M vo vo 10 ■<*• 10 t^vo M 0\ H M-t^i-iVO CNOO to H Q\ H vo N m ro w N o\ t>. 10 -^ m N M On Onoo 00 C^ t-.vo vo M M v^ NOO H H 10 t>^ mm N c^ vo 00 M t^ ov m HVO(NH00Th HM txVO vo -:J-00 O\lO00 ^ (N 10 On moo T^vo »o m (M moo -"^ -^ m -vo to vo m to "^ m N lOVO 10 (N "^vo t^ N N 10 H m looo H 00 N m m t^ 10 M t>, t^oo Hmt^HlOHNlO ^ K xovo vo ■<1- m m . lOVO t^ 10 10 r^vo (N 10 t>. 1000 mvo 10 c^ (N 00 rv 10 m m m u-) N 00 t^ mvo lOVO (N ON M TfOO N f^OO M 10 10 00 On M t^ "■i- m m N Tt w 0\ t^VO 10 m m, (N H onoo 00 t^ N W M M M lOVO 10 VO w vo Th 10 c^ 10 MVOlOlOt^QlO « vo mvo N if 00 vo c-^mcN lot^^fo lOHoo ION r-^mo O Onoo 00 t^ t^vo vo 10 vo 10 ^ -^ '^ I «^ vo vo -^vo H m 10 00 m M M mvo 00 0) '^ O vo t~-> 00 W ON ONVO o 10 ?j 00 vo o vo m O Onoo 00 t^ r^vo vo 10 10 10 ■* ■0 ON -<*• M m Onoo vo M vo 10 O m r^ vo (N On ■<*- On 10 ONmONt^TfmH On onoo t> t^ c^vo vo 10 10 'i- ■<*- OiooioOtoo*oQioovoO*ooioOOOO w w m ro "<*• -^ 10 »ovo vo t>s t^oo 00 On ON O M N m •S133HAV aHHQNVH 254 PINION 20. 00 vo 10 Tj- LOVO H IT) 10 O 'O 00 -"i- O C7^00 CX5 C- C--^ VO ^O lO XT) tJ- t>. vo rooo -*• m t^ vo rj- cj invo N w '^OO 04 t>. ro Oi^ 10 O m^ Noovo -+roc* h o Oicx) 00 t^ t-N.vo vo vo 10 10 fOOJNMMMIHHHH H Mvom mooiooo r^ On 0.00 t^ r^ -r ro CO U-) ^O :)(N>0 T^ u-)(NU-) IT) vooo Thooovo ^m(N H o 0\ o\oo 00 r^ i^^vo vo 10 rOWWPJMMHHMHW T^^OM (N vovotoON 00 00 00 T^ Lo r^vo « o\ N CN 10 mvo >H MTf-I-^MVOCNOOOU^ OnmvO CS- OC->i-OTl-roCN r-i O On C^OO OO O^ t>«vO vo rOC^eNOlMI-IMI-IMIHHM vO(Nm CNo-;csvOH vo t^CM ooro^rovo vo vo 00 (N Ov N 1000 rooo ■nf(N N M o ON Onoo 00 t-^ t^O rrrOCJ(N(N-(P-tMMMI-l(HlH T^ rovot^ oofOMcn M vo ■"d-i'^iOOO t^OO W t^io rooooo win -<*• wioON invo QiJ^CSOOOVCmrO'^lNMOOON O^.OO O-'O ^rOrONWCNMMMMHMMMH vo 10 M ojro vor^omoN vow in vo t^ HI r^oo vo 00 m moo m moo t^NH fOHHWU-) mOvOrOOt^iDMD^u-) CN 00 U-) m M o Onoo t^ f^vo vo iriir:m-^^-^cncn M t-l M H M M m oot--.ro com rh ro r^vo m i/i m oj t^ m (N 00 ro rnvo o vo on m m ro t^ rovo m ro ID M On M 00 t^oo w toONioo r^'^Hoo -^ O t~~ Tf onvo ro n O onoo 00 tr-^vo vovo Lou-jio-^-^^ro CN M M M M M 0-, c^ m Ti-vo oom t^t^ro t^m ro in in invo n ro m c^ r^ oj ro 09 rooo in r^ Tfvo Ti-CNinw t> ^w t^ro vo o r^ -i- m H o onoo 00 ^^vo vovd in m ir, ^ -o mvo vo t^ t^c» 00 o^ On O m n co •s^a3HAv qaHaNviM >8 255 PINION 20. 10 ^>vo woo Tj-rot> vo rj- 00 »OVO N M Tf C30 W t^ ro ON^ lO COVO CNOOVO "^fON M COWNHMMHHMM ovoo 00 t^ t^vo vo vo »o in ^ fooo IOCX3 vo t^vo 00 -"t-oo 00 ro 0\ 'i^- ro t^ M rt-^ 00 HrorowTi-cMin in « inovrt-osiOH inovm looo mo t^inTt-rOM m O^oo 00 !>. t^ t^vo m in K vo M fO>0 vo IT) M ro "^ 1000 vo « M T^ 00 00 vo inoo m (N vo ro vo N in m m h (n (MVO0"~>Ht>N •t>«»O-<*-N HI COCOWCJMMMWMM H Ov Ovoo 00 t^ C^vo u> H M »0 t^ CM ro in ovoo m mvo 00 to t^ Tt- N in mvo ro in t-^vo r>. ro c^ h vo w moo ro M M cot^roOoovO inroN w M Oi OVOO 00 t^vo VO W M H vS N vo H M inoo ro N in ^ invo c\ t^ t^oo ro m -<*- m mvo H t^vo ooQio mwoomcoHOvmN OMn ro H o^oo «>. t^O v© ^o^o•<4••*"««•T^fOcococo M M H Ht vS* -8 rovo w mvOmoo ro ro vo in -^vo c^ >-> m CO ^ .*?^'t'^ -^ vo « ONVO <«1- « 00 in M HI vd ""4- W Ovod C^ t^vO vo mu>Tj-Thr5-Tj-cOCOCO W W tH !H M a 5 in i^ H rooo m -^ vo H w mm 00 WW wONroov mvo ooM nmoN-^ vow t^mot^"* m w 00 in (N M O^oo t^vo vovo miow»Tj-'^Tfroco . vo vo t^ rooo Th vo ro 00 CO vo vo vo ro m w m t^ CO w m 00 mo t^ t}- (N H o^oo t^ t^vo vovo ininin-<4-->4-ro « M H H H M M , 00 OOrO-<*- tM'<*-ONVO - -- O -- . , vo Tj-in 0000 ror^wc>.ro vo-^ovmHO I ov ; ^^H00mro^)0O^ o^oo >• t^vo vo vo m m •<*• -^ " W W M M M H H moo m vo ro ov 0) moo ro jh T^ 00 mvo vo vo Tj- (N m ro 00 moo wwvoT^romt^MVOHt^ro t^Mt^co ^ ^S o>vo rj- w w Ovoo 00 t>« txvo vo vo m m '^^ -^ gs'^i^e^s.Mv^a^^c^as^s 2 ii •siaaH^A i-^aaMviY 256 PINION 20. ]^ 00 CO « 10 CO 10 « -vj- w rovo to ■^ to N vO CO t^ t^w NOOVOt^ toco toot^-^woovo-^co t<»to 3 CO M o\oo t^vd v6 sn»0'<*-'«i--^rococorocoN ci M M M 0. H M CO t:^ 10 00 CO a. W Ov On H 00 t>sVO 00 to CJ CO to On 10 vo vo t~^vo t^ to C^ to tOOVtOM C^Tt-N OVt^tOW ONt>« ^' t^ •* H 00 t> t^vo >o»o»o-<4-'ilOlO QVO •^cmomoo tow 000 tow o\ g. OMO N w OnOO C^ t^VO »OiOlO^'4-COfOCOC« ss to 10 « vo CJ tOOO H VO lO vo to t^ t^ CO H « lOVO 0) vovorOMiO t^fO t^ -^ ON in c^oo -s t>, vo vo to t^OO CO On lovo vo 00 m vo '^ covo 00 vo c^oo CO vo 00 COt^WOOlOMOOVO-* . 00 1000 ooto o^o^^^»^OT^ ChcNt^ioChO CO C^ vo fOVO COCOtOt^MVO NOO ton 0\V0 N 00 to to 00 COOO to CO M ONCO C^ C>»V0 vo lOlOlO'^-^'4-COCO N M W M M M 10 10 N to to Tj- C^ ^N0O to M CO On to H 10 fO to to t^ lOiHC^ ooc) Mtn NO NVO QVO MOO tON OnIOwOO 8n rf onvo tJ- cm h on Onoo t>. t^vo vo toto»o-<4-Tt-Ti-ro W l-l M 1-1 H M 10 to vo 00 0) M 00 00 -^-vo M tv. 10 to ■<*- o^ N M (N vo M to COVO VOrOT^O NIOVOM ■tl OV-^OVQVO Tj-tOt>.0 "^ONIOMOO tOM t^COO ^ vo t^ -^ ro H CJ W H M M M M ONOO 00 t^VO VOVO tOiOto-*''!-''*- I^ CO M 10 N in CO c^ c^ 01 VOHt-^COlOlOMON coo VOVOlOCOt^t>.H00 ooco M Ti-00 COOO Tj- w c^ to 10 w § t^ oj 00 to CO e4 H C* W ft It M M M ONOO t^ t^VO vo vo to to to ><*■ "<«- S^ vo t/> Y> Th 10 vo 00 N Tj- CI « M W M Tj- M covo NVONC^NOO MOO 00 C^ "^VO vo H (N vo to Tt-OO covo lOM t^roo toovo M "^ t^ to CO N CO W « H W IH M H ONOO 00 t^ t^vo vo vo to to ■* M M Ow>0»oO«OOiOOtOO>'>OtoOtoOOOO e» « ro CO "^ •«<■ to lOvo vo t^ t^oo 00 On O^ O •-• N CO •H M M M •- ^ ^ 5 H 257 PINION 20, 8, e«» »r> t^ CO ro moo wc^ro vo-*HO\t^-*woo »-• H H M a fO CN 00 i>.vO lOHfO tOTfM rorot>* eg CO CO w 00 00 t>.>o vo iou-)io^Ti-rh-<*-cnfOco N M H H H a vo CM vo Th t^ rooo MoocN NfO roHON JO vo-*(N**- M0orot>.-OM (N t^invo --tvo ©) Mi-iVO-^lOt>.0"^OVOCO t^'<^(N00lO(N CO M t^ Tt- (N 0"00 t^ t^vo vo iomir>-^rt--<^romm « M M H W H rooo u-) Tj- vo H M CC (N (N (N On fO On u-jVO hioON'^ vOC^ C^iDQt^Tt- N 00 »o N H o Onoo t^vo VO VO in m m a roMirjiO vovovou-jroc^oot^ ro t>> t>» ID ro M t~«.oo ro rooo c^ 00 1000 m lovo ON ro c^ ro ON ID c^ 00 00 00 in H inoo t>. ro ONvo I in vo in IH ^ ro N 0) vo 04 in ro rnvo vo vo 00 ON ro On Tfvo inoo invo Tl-^ Tj- 2, VO M in H rovo M vo (N 00 in 01 in M 00 8 in vo ^ rj M On 00 t>. t-^vo VO m in in m T^ ^ ro (N (N H H M fO -<*• N vo i_i r^ ro in LO H <3n ro ro M in 0) vo vo 10 ro r^ C^ M X) CO ro in ro c-^ t^ W ^00 rooo ^ H tr^ in m 01 in t^ N 00 in ro r>) M On 00 t^ t-^vo >o vo in in in Ti- Tf M w (N H '^ •^ ^ rg ro On t^ „ 00 vo in Tt- 00 Tt- ro n ro C^ irjVO in H ro ON CM in m VO ro -^ vo in OJ ^ t^ I'l ro C^ aoo 00 C^ C~>vo vo vo in m ■<*• H 04 (N H i-i •-1 11 73 invoint^NN (3^. t^ OOVOOl-^C^-^ QtH NVO ihVO OICX) inON-'T 00 vo -tf ro H o O O^co 00 t^ t^vo vo in m m ro 'D t^vo (3". ro in t^cx) ro rri ^j- ro i»- cMvovo romroc^vo vo rooo ro \r) If) i^Ot^ ror>.CMt^ro rooo ro 00 vo 0) invo T^ tN.'0 vo 00 ■>!■ ro ro M vo in m c^ in ro ro Th 00 0^ t^ 04 ro C3n m mvo rooo rooo moo w t^ oovoinroo4HOO onoo 00 t^ tN.vo vo »/» mOmOinOmQinOinoinoinoo CJ ro ro ""J- "^ m mvO vO t> t>iOO <» O* a» w i •siaaHiW laHQNVH PINION 20. 5 to 00 W H 00 in -4- vo H 00 (N w M a> fo o\ invo HinoN-^ vow t^inot^-* § WOO 10 W w M M H M M *n vi ^ "t -^ ffi tfi ^ N in in H t^ cA m in t*i inHt^ ooCT Min NO OS Mvoo'OHooinNOMniHoe 2 s-s^^i^ss a> ONGO K^ c^vo vd »o«nio4"«i-4«n ^ NO %^ 00 NO sh w ^ 0^ 00 w t^M inmoo 000 0000 mt^H t^vd '<>^ ic in ^ 4- 4^ VO t>. vo in t^ fo m T}- vo rooo rr.oo ro vo in r^oo ^ H vo N VOt^'HOOOO OOmOn vo m M 00 VO m H onvo t^ ""i- w o 00 t^ t^*o mmiO'^Tt-'^mmcooN w momomomo mo mo mo mo w ro fo ^ Tf m mvo vo t^ c^oo 00 o\ Os o % ^ rhm vo ^s0^l« t>»c6m 10 HW com mHHoo mmHt^ M rt- V) ts.vo t^vo t>. CO c«» rooo in M 00 cooo m gs o^ fo ovvo ^ CO H a> ovoo t^ ts.vo vo vo m m r^ Ti- ^ 10 w "^ N m H H t^ VO m mo> r^M mrom-^ e*. vo ■<*• mvo ■. t>.vo vo m m -* N M M H M W M ^ mm N -^N N.H N vomcj 00 t>i tv. moo ""^ roTf- mvomoos m w 00 m w w mvo --j-osmM t^nvo m m t>. w Osvo m CO N H OS Ovoo t^ tv t^vo vo m m rOMWMWHHMMH a m vo ^< m H rooo oovoh^mmTj- MO^ vomt^H oorowvoforomovm ovh H 00 00 w m m N ovvo TfN 000 ^^meg w m m CO H M H OS i>.vo vommTj-ri-fococococow 01 w w n a M vo rt- mm 0^^0fO t^ t^ t^ vo m H 00 m N rovo CM m mvo -^ von t>«mrooi t^ioro v8 m w M M 00 t^vo vomm-^rj-Tj-fococofOfocM n w p. m (T) in m N 0\vo « ro N m h n -^oo rooo w CM iH -^ rovo 04 m m m m q CX3CMlHC^^r)O^T^ vorOOvO'<^NOsC>.in m vo vo r"i O\oo C--VO mmm^'^'^coromcoN ^vo -^0 t^mcoN ONOo 00 t^ j>sVO vo *o in in Tf NWMHMHHM xr 00m H HT*-Nt^00 CN(N 0. mvOH H-^ vo m-^vo rnoc^^N oovomr^ mmo m -<^ tN. ro (N 00 t^ s. 0. c>>vo inm-rfTi-rororofOW N m w CM CM H H in in t^oo in cMOm c^iMino CM H incjNmHoo mmo 0\ t-^^o m CM ro t^ mvo Tj- (N ON m m 00 t^vo m^'^'^rorororoc^ 04 w CM CM C^ M in ID m M 00 rt C7> rovo in'O CM win inm t^t-^ tj- t^r^ -^ONmMcx^vorow 00 m m t~>. t^ '>*• CM S M C^vo "O inrt-Tj-ri-rororororotN M . m ro moo rooo m h onvo tj- cm O Os"^ ■*• cm m vo C/2 H O^oo t^vo mm'^^^rororororo 01 M CM CM W W 10 10 m t^ vo t>>oo m r>N M m ^ mm h m 00 roo^cMoomcMONC^mro ro m ro mvo (N CM M 00 ^ T^ a in N c>i t^ t^vo mm-^'^-^rororom ro CM (M OJ in 00 in CMt^ vomoiM 00 vo m-^ro mr<"0)ON(N HC^mt^ Nvo Thmc^Hvo McxD incM c>>t^m ro 00 m 1 m Pi u C/3 ^ M o^oo r^^vo mm-^^'i-rororororocM cn to Tl- m mvO(N mONOo 00 Tj-ro-^ rocor^^ CM cMm mHOomcj t~^vD n 00 00 CM 0.00 t^vo \0 mm'^-^'^'^rorororoCM ■<4- «n oo(N T^ln'^-^ M >oinc^t^(N in (N MD in in t^oo vo 00 m c^ cm t-^oo -^ ro t^ C^i m mvo 0. rooo tj-h o^mw 000 -^m 0\ m 00 o^ in (N Choo t>Nvo vo ininm^^^'i--"*- ro ro ro W 10 in CM M m ro t^m nti- ro t^ N vo m rooo vo vo ^o mmw Hrot^CMC^'<*-ot^mcM M moo moo r-« M ^ ro H. 8n g^ ro H Onoo t^^ ^ m m m -* Tf xi- ■^ ro ro ro"" IT) in m H Tf r> CM mvo t^ ro On mMoo mt^NrxO -"S-wm CM CMVO mmr^M mtn t^roo t-^m \r)\C CM 00 t^OO VO 00 CM 00 m CM m ON M t^ T^ CM Onoo t^t>.ovo mmm->*-'Tj- H H tH TT ro ro ro •'•'•'"•■•*•■•*•*• •'••*'*'•'•**•••**** ....,.,•. • •'•• ••• ..•.,.. . . '..',,'.'.'.... •*•••■•." *', 8 mo "^0 mo mo mo mo mom w m m Tf -^ in mvO vo t^ t>.c» 00 on On 82g^ M W M M i 'siaaHAV qaHQNViM 26o PINION 20. r M VO -* in IT) On CO r^ t% «^ t^vo m Hioo lowrou-) n O »o 10^ ■* VOM t^ioroM t^ioro »n M 00 t^vO vd»o»r>'*'i--o -* inoo ovo >cr;N n w H M H % roTj- m wvot>.t^ro t^oo m moo fOH IT) ooMDmmfom t^t^ o\ rr-, m VO CO t^ U-) 1000 mvomoou-).vo ^ CN win inMooma c^vo » VO tv. t>» VO VO in c^oo CO 0\ invo VO 00 M cove CO VO r>.oo CO coc^woo inHoovo VO T^ VO 00 VO CO H ovoo 00 t^vo VO m m m "i- •^ VO t^ M VO C) t>. VO VO t>i 00 in cooo -"i- t^ CO in CO N -<*• CO in VO o^ VO CO O 00 CO VO CO t^ in rhvo ro in m mvo 00 cooo in ->*■ -N t>. CO f^ ro CO H c>. t^ 0) ro VO VO ri-VO w ro in 00 CO M M C0"0 VO 00 01 ^ H VO rsi VO 00 w Ov o^vo O ->*• incNOOVOQvoro ioO»nO»nO"~'Qino»noino»nooOO N CO CO ■«*■ '^ m inv5 vo t>, t^oo 00 0\ 0> O m m c*> % •siaaHAV aa^QNViAi 26l PINION 20. 10 10 ■u-)iHoo incN OOu LocM On OMT) N M O^oo £■«= tN,vo iOLoiO^^^Tt-rororo(N Ti- 0) O ONOO !>. i>.vO O u-)in-<*-^'^^rnro M ro f^oo "Ot^Nino\o^ON vo 00 10 1000 un m^ O ro ro m>o CO 00 ONVO 00 rOiOTfTht^ -*(-oOn lOOO- O^ro ro(N^-:^LO mcX3VD (NOOOOONMIO lOMt^TfuON-^l-OC^ 01 M H Tf (N ONOO CO C^ t^VO "O LOLOlO^^^rO l^ 10 CO 10 (N 10 LOVO iJ^ VO CJ VO rovo C^ lOOC MVO -"^Lor^ vot-^roNior^t^ro r-tvoinrnt^-oio ii">HOO>ocNf^roO H >0 H I>» (N (N M LO ro w ONOO 00 !>. C^VO VO 10 U-> LO Tj- -^ Ti- N (N (N On H t>i Th VO ■<*- rv.vor>. ioc>. On rooo in vo(N c^io-^cSiH oooovoLoro 10 0\ t^"0 io-.vo 0) 01 10 VO CO rh ror<~, t^iovo lOdO oovoro ^ voroOoo.voiorO(N»H HVOio i. ?. <»^0 miO-<^-*rororO(NC^M(NCM(N(N -MM i ro LO CO rooo CO 00 ro N 1000 ■* VO -:!- (N 0-. VO 00 T^ ro VO ro H 0- 00 Tt- t^ LOOO T(- H t-^ 10 -^ ro IN ro N ro On »n 10 H 00 C^vo LO -"d- rj- ■^ ro ro ro (N (N N N CN (N CM M M S- LO VO 00 ro ro rooo ro (N 00 VO On (N ro VO Th (N rovo VO (N VO Tt--^Tj-rorororoN H M CI N W (N OLOO>nO«nO»nQioOtoOLno "O (N N CO ro -"J- Tl- LO iOv5 VO t^ t^OO 00 ON 0> 8 2§S.! C/3 w w \^ •^IHHHAV. aaHQNVW 202 PINION 20. in 10 \0 Nr^ OOOOm vovo -^oo vo «M Ht-»inM0"O 100 "O fO (N \0 tv Th 1000 Noc row ost^u->^N M 'i§$% s OS l^VO lO-^-*-mmfO(N N N N N 04 (N H M H M ^ vo 00 M tr> fo Vi Tt (NVONOOiON OOVOTTfOOJ M 8sKlO £ 00 t^vO »Or(--*^f<->corOfON N N N N Hi N H M ti^ CO tn ro tv vn vo M en ro>0 l>. ■* 1000 »n t^ CO ooinioroos ir>ro^r^(.>0 u-)1^r^^^O'^^O^OCM (N e4 W O 05 \r» N ro N looo w 00 >o m irjo ^^ os N 10 VOOOlO!>.t^(^in CX300MVO(M00C»H H 10 t*. 10 1000 w c>.roo t^i^.cN O OS r^MD co m O r^i O 00 t^VO lOiO'^-^rfromc^roW N N N N N fo N M VO t^ (N OSO O N vO O VO ro CO On M -^ ><^ CO 10 r>. 10 N - osoo in ro w Osoo t>.vo vmoTj-Ti-Tj-rororofOC* w cm n n 10 vo r^ H • o\oo t^ vc 00 ir> w in ^ c?^oo c^ M fOMioomt^ invo »h o co t^ O f^oo 00 Os OS in -^so Os^omN os^slnroH o>t^'^oj c>oo t>.vo m m ro ro fo CO CO m tN vo t^oo in ro in fn m c^ (MinTh fOLOH invo cm n t>.vo in 00 fot^wooinojosc^inmwoovo-"*- in 0) o OS t^ rs,vo inin'^'<4-';»■ m o>vc m co o t^ •'^ '^ vd ro w Osoo f^vd vd in in -^ -^ ^cncn(v>rofnN « vo t^ vo in t>. vo ir^ t>. rn en ^ vo moo moo m vo in r>«oo rf H vo N VOI>.H0000 COhhOS vo m w 00 vo in H osvo t^ -* M o 00 t^ t^^ mmm-^'^'^cncnroc^ca c« 0»oo»r>Oti^OV)OTnOi/^0>J^O»jOOOa. « N m m -"^ -"^ m mvo vo c^ N.00 00 o^ os o h w en 8. •siaaHAv aa"aaNVK 253 PINION 20 i ^ OS ■<:^ r^ tnvo N ■* t^ lO to t^ l^ -i- tfS in t^ ^ IT) 00 ts, t^ •"^ OMO 00 VO CO M 00 t^ ■^ M Bs (D 6 OM>.vO VO lO Tj- ■* ■^ CO CO CO CO CO (N N 0) c^ CN) " !N lO 0"j l_ ^ N covO o tn in 1 in ^ w m 00 to CO t^ VO in so Lf'j OS t^ M N -«*• IT M M CO t^ M C^ «vd VO VO lO -^ ■^ ^ CO CO CO CO CO CN (N 01 H '^ H 00 ro r-- Th lO M VO CO 00 0) u~j ro t^ (N OO VO r^ in CO o U-) N -^ (N cnvo lo t^ Tl- » VO ■^ CO Os to ro • l-l VO C H a>oo t^vo VO u- lO -<4- rf -^ O") CO CO cr CO 01 N H ■^ ^ Th lO 00 o in OS M OS DO -^ CO CO X) t^ VO o -^ c^ N lO lO w X) lO ,vd VO lO in •^ ^ ■^ Tt- CO co c; cr 01 IH H H l-l M VO l_l M lOOO co lo tn -^ lovo On t^ r^oo CO o rh tn o u-iVO H t^vo 00 u- m M 00 m CO OS lO 01 CO CO • . H- OS lo c; M ON 00 t^ t^vo VO tr> to -*• ^ ■Tf ^ CO CO CO CO •^ M H ^ CO VO „ M vn „ CO o CO CO VO lO Tt-vO (N M CO o >0 lO CO -^vo Tl- VO w OSVO -^ N 00 tn 01 Tj- CD l-l M VO ■^ (N OnOO t> t>.vo VO in to Tf rt- ^ ^=1- CO CO CO (N H •^ M I^ ^ cooo lO r^ f^ M H lO lo 00 N r>) (N OS CO OS tnvD U-) DO (M H >0 On '^ VO C>) t^ lO t^ ^ in ro N 00 lO w H w 1-1 OS 00 t^ VO VO VO lO lO lO ■^ -^ ■^ CO CO VO H lO CO CO VO t^ in CO (N VO VO VO ■<*■ n- to VO lO Tt- in t^ t^VO r^ CO VO VO lO M 00 lO co 00 tvvO lO -^ M- OJ IH % t^ lO ■"I- ■<*■ CO CO . CO lO CO 00 OS r-N „ t>. VO CO lOVO 0) 0) m VO fx to lO r^ CO 1?^ 00 CO 0» U-) OMO H 00 VO '^ c^ H OS 00 t^vo lO ■"ii- CO 0) ID •>4- t^vO lo '^ cr fo CO N N « N « '-' M H ^ H " H ^ CO lOOO H o N CO tvOO rr CJ 00 VO m en t^OO 00 OS CO 00 lO 3; T^ in ctn m CO f^ 00 coco m H CvVO »o CO H 00 t^ to Tl- CO a 00 t^min-^cororON w M 01 M (N M H " M H ^ i to f5 lo 6 in d "^ d to d lo d in i lO 8 d d d / w CO ro ■^ "^ lO m o VO t^ r.VO 10 •^ fO * in Ti- r^oo 1^00 M t^ irjoo 10 lOt-s loiOt>-(N 00 00 MlOWMCa t^ -* moo ro t^ ^ w o CJ>oo vo ir)io->^fniM Mf> vOio- in CO oj o iH covo in o\ Th ro fO in ^NVO Oioo r^vo in CO cj 00^ in-<^'<*-cococoN OJ (N . vo t^ in 1-1 ^N Hin vo(N c^iO'^j-WK o^ t^vo in^^cococooi N c5 ci ci ■^ vo -^ C>i ro 00 00 00 vo in CO w -n CO in in t^ c^ ro '^ in t-^00 in moo CO o^ m (N in t-^ Tj-vo (N N in c» ^ CO o^vo in in t>. CN t^vo -^ 0) M o o^. t^vo in On t^vo mTf^rocorocoN n (N cn w w* m 00 in vo invo M CO N vo cj 00 in (N l^ CO o On in ^.Jjt^coM omM 00 vo T^ CO (M H ON r^vo O 00 tvvo in-<^-.vo in m Ti- Ti- fo fo ro CO (N c^ -'-'-•-' ' * ' *^ N 0) N M H vo CO CO CO vo cooo CO o 00 On 0) vo '^l- N covo vo CM 'O 0) 00 vo LO Tj- N ONOO vovo in-'^'^TfrococorocN M vo 30 ^ M 00 CJ CN W (N N H in 00 t^vo CO in (N ^ 00 COOO in H nvo t>« c^ in w covo M vo (N ONvo Tj- M TO S in f^ M o^ N o 00 c-^vo inm-^^cocococococi c^ m ci eg m Qw^OmcmomomoinoinOmOO |«c>jcoco- c>»oo 00 on on o m S7a3HA\ Tf^THaNVK 265 /ABLE FOR MAKING THE UNIVERSAL TAPS, WITH THE MOST SUITABLE PROPORTIONS REQUISITE FOR GOOD WORKING TAPS USED BY HAND. From X ^^ A ^^^ head is turned the same size as the screw; the ^, and all above, to pass through, the holes screwed. As the same table shows the size of tap and bot- tom of screw, the workman will be enabled to make the tapping holes a size that will insure a full thread. The bot- tom of screw will give the size for drills, bits, etc. c3 X 1^ Vs. iX o o lb % and 3 2 and and 5/ T^ and 6, }i and -3^3 I and §-^ 2X 23/ 3^/ 4 4X 4/2 5 5X 6 6^ 7 1/8 I ^- 2 2>^ 2X 2^ 2>^ 2^ 3X 3^ 3^' 4X ffi 7 . ] 6 i! 1« X and j-ig- -g Wheels for cutting the screws. ^-^ I 20 18 16 14 12 12 II II 10 9 8 7 7 6 ^ ^ 40 40 45 i . S ii E! 53.2 ^0 ■^-^ c: >— 1 Ph 80 20 80 20 80 20 c/2 100 90 90 Simple wheels. ?o 20 ?o 70 ?o ?o '^n ?,o ?o ?o ?o 140 12a 120 no no 100 90 80 70 70 60 266 Table for Making the Universal Taps- -« (Continued.) Q. 5 "2-^ gi •0 ^ G Wheels for cutting th^ ^ ■5 ^ ^ ^ S screws. o ^_ c •£3 Head lengt square. ^ a. 1 s Bottom o or tappi 1 St.. 13 I'A *32 7^ 43/ iH 6 20 60 iH 9 S'A iVi 5 20 50 13/ iVB and e^i 9% s% iH 5 20 50 I?^8 ijl 10 b% I'A 4J^ 40 90 2 i|^ andi,% 11 63/ i^ A% 40 90 2>i 1 34: and 3^ 11;^ 7X 1% A% 40 ^ 2X i^and-i-L 12 P4 in 4 40 80 zH 26\- 12% «K iH 4 40 80 2% 2-,% n I03/ iH 4 40 80 zH 2-4 13 QX 13/ 4 40 80 2 3/ 2^ 13;^ 9^ lU ■3^2 40 70 zVi 2/3 13/2 10 1% 3/5 40 70 3 2>^ 14 10 2 3K 40 70 UNIVERSAL GAS-PIPE THREADS. Diameter. Wheels for Cuttinc, Etc. Man- drel. Interme- diate. Pinion. Screw. Pitch. t%, and all above I K M Small brass tube . . 85 20 20 30 30 80 20 60 20 20 120 140 140 85 120 11.294 14. 14. 18.412 24. HOW PUMICE STONE IS MADE. Pumice stone is now prepared b)/- molding and baking a mixture of white feldspar and fire-clay. This product is said to have superseded the natural stone in Germany and Austria. 267 NOTES ON THE WORKING OF STEEL. 1. Good soft heat is safe to use if steel be immediately and thoroughly worked. It is a fact that good steel will endure more pounding than any iron. 2. If steel be left long in the fire it will lose its steely na- ture and grain, and partake of the nature of cast iron. Steel should never be kept hot any longer than is necessary to the work to be done. 3. Steel is entirely mercurial under the action of heat, and a careful study of the tables will show that there must of necessity *"»e an injurious internal strain created, whenever two or m(y^e parts of the same piece are subjected to dif- ferent temperatures. 4. It follows that when steel has been subjected to heat not absolutely uniform over the whole mass, careful anneal- ing should be resorted to. 5. As the change of volume due to a degree of heat in- creases directly and rapidly with the quantity of carbon present, therefore high steel is more liable to dangerous in- ternal strain than low steel, and great care should bo exer- cised in the use of high steel. 6. Hot steel should always be put in a perfectly dry jJace of even temperature while cooling. A wet place in the floor might be sufficient to cause serious injury. 7. Never let any one fool you with the statement that his Steel possesses a peculiar property which enables it to be ** restored " after being " burned; " no more should you waste any money on nostrums for restoring burned steel. We have shown how to restore " overheated " steel. For " burned '* steel, which is oxidized steel, there is only one way of restoration, and that is through the knobbling fire or the blast furnace. " Overheating '* and " restoring " should only be allowable for purposes of experiment. The process is one of disintegra- tion, and is always injurious. 8. Be careful not to overdo the annealing process; if car- ried too far it does great harm, and it is one of the commonest modes of destruction which the steelmaker meets in his daily troubles. It is hard to induce the average worker in steel to believe that very little annealing is necessary, and that a very little is really more efficacious than a great deal. 268 WEIGHT AND NUMBER OF SQUARE NUTS IN A BOX OR KEG OF 200 POUNDS. AMOUNT OF HEAT REQUIRED WROUGHT IRON. Width. Thick- Hole. Size of No. in Weight ness. Bolt. 200 lbs. of Nut. % X 7-3-^ X 14,844 lbs. 'A S-16 9-32 5-16 7,880 K rs^ 11-32 V, 4,440 % 7-16 13-32 7-16 2,732 % A A 7-16 7-16 \y. 2,450 1,816 \% % % 9-16 1,390 lYs A 9-16 [ A 1,174 .17 1% H 9-16 898 •23 ifi U 21-32 \A 662 •3 1% U 21-32 538 •37 1% A 25-32 i yA 392 .51 lU A 25-32 i /' 326 .61 iK I ^ r I 304 .66 2 I ^ 224 .89 2 lA 15-16 ^>^ 214 •93 2X iV, 15-16 152 1.32 2X iX I 1-16 -iX 143 1.4 ^'A iX I 1-16 108 1.85 2% I A I 3-16 I^ 83 2.41 3 lA I 5-16 I>^ 65 31 3X lA I 7-16 I>^ 51 4- 3A iV I 9-16 iX 42 4.8 z% lA I 11-16 lA 32 6.3 4 2 I 13-16 2 27 7-4 4 2% lyk 2M 7H 4X 2% 2 2X 8X 4X m . 2y% 2>^ 8X ^A 2y2 2% 2>^ lOK 4'A 2^ 2 7-16 2^ 13X 5 3 2 11-16 3 14 TO MELT The temperature necessary to melt Nvrought iron lies between 4,000^ and 5,000^ F., and even ai that tremendous heat, wrought iron is only rendered fluid by ihe addition of a small amount of aluminum. 269 WEIGHT AND NUMBER OF HEXAGON NUTS IK A KEG OR BOX OF 200 POUNDS. Width. Thick- Hole. Size of No. in Weight ness. Bolt. 200 lbs. of Nut ^ y* . 7-32 ^. 17,332 lbs. Vi 5-16 9-32 5-16 8,964 H n ^ 11-32 /8^ 5,016 'A 7-16 13-32 7-16 2,988 Vs 'A 7-16 ^- 1/ 2,674 I A 7-16 ( 72 2,160 1% 9.16 A 9-16 1,445 1% A (^-16 f >^ 1,310 "Vii 1% V% 9-16 1,028 .2 iX 'i 9-16 ) 920 .22 iVi i 21-32 \ 3/ 752 % VA 21-32 f ^ 510 1% A 25-32 [ % 450 .44 1% I 25-32 428 .47 i^ I % r K ■ 372 •54 iK lA Vs P , 336 .6 2 iX 15-16 I>^ 211 •95 2'/ I A I 1-16 IX 259 1.26 2/2 iK I 3-16 1/8 119 1.68 2% lA I 5-16 ^y^ 88 2.27 3 iK I 7-16 IH 69 2.9 3X lA I 9-16 I^ 56 3.6 3>^ 2 I II-16 I^ 44 4-6 1% 2 i 13-16 u 43 4.7 4 2 I 13-16 (^ 29 6.9 Z% 2>^ I^ 2>^ S% 3X 2^ 2 2X ^% 4 2/8 2}i 2^8 6X aV. 2;^ 2X 2X 1% AV2 2^ 2 7-16 2H 9% aK 3 2 II-16 3 ii/i HOW TO PREVENT GEAR TEETH FROM BREAKING. Gear teeth generally have one corner broken off first, after which they rapidly go to pieces. This may be avoided and the teeth made much stronger by thinning down the edges with a file, thereby briiic:mg the whole strain along the centre of the tooth. jear teeth fixed this way will not break uuleSf the strain be sufficient to br ^ak off the v/Jiole tootlu 270 NUMBER OF LIGHTS OF WINDOW GLASS IN A BOX OF 50 FEET. Size. No. Lights. Size. No. Lights. Size. No. Lights, 6x 8 150 28 16 5? 5 7x9 115 30 15 30x38 7 8x10 90 18x22 18 40 6 II 82 24 17 42 6 12 75 26 16 44 6 13 ^9 1 28 14 ^^ 5 14 64 30 14 48 5 9x12 67 32 13 50 5 13 62 20x26 14 52 5 14 57 28 13 54 4 15 53 30 12 32x40 6 10x13 56 32 II 42 6 14 5? 34 II 32x44 5 IS 48 36 10 4^ 5 16 45 22x28 12 48 5 11x14 47 30 II 50 5 15 44 32 10 52 4 16 41 34 10 5^ 4 18 39 36 9 56 4 12x15 40 38 9 34x44 5 16 3S 24x30 10 4^ 5 18 34 32 10 48 5 20 30 24x34 9 50 4 13x16 35 36 9 52 4 18 31 38 8 54 4 20 28 40 8 5^ 4 22 25 26x32 9 g 4 14x18 29 34 8 4 20 26 3^ 8 36x46 4 22 24 38 7 48 4 24 22 40 7 50 4 15x18 27 42 7 52 4 20 24 44 6 54 4 12 22 28x36 7 '•6 4 24 20 38 7 58 3 26 19 40 7 36x60 3 16x20 23 42 6 62 3 22 21 44 6 64 3 24 19 46 6 38x46 4 a6 17 48 «; 48 4. ^y i NUMBER OF LIGHTS OF WINDOW GLASS IN A BOX OF 50 FEET Continued. Size. No. Lights. Size. No. Lights. Size. Now Lights 50 4 60 3 66 3 52 4 40x62 3 68 3 54 4 64 3 70 2 56 3 66 3 44x54 3 5^ 3 40x68 3 5^ 3 60 3 70 3 5^ 3 62 3 42x50 3 60 3 64 3 52 3 62 3 66 3 54 3 64 3 40x48 4 5^ 3 66 2 50 4 58 3 68 2 52 3 60 3 70 2 54 3 62 3 72 2 56 3 64 3 COMBUSTIBILITY OF IRON PROVED. Combustion is not generally considered one of the prop- erties of iron, yet that metal will, under proper conditions, burn readily. The late Professor Magnus, of Berlin, Ger- many, devised the following method of showing the combus- tibility of iron : A mass of iron filings is approached by a magnet of considerable power, and a quantity thereof is per- mitted to adhere to it. This loose, spongy tuft of iron pow der contains a large quantity of air imprisoned between its particles, and is, therefore, and because of its extremely com- minuted condition, well adapted to manifest its combustibil- ity. The flame of an ordinary spirit lamp or Bunsen burner readily sets fire to the finely divided iron, which continues to burn briUiantly and freely. By waving the magnet to and fro, the showers of sparks sent off produce a striking and brilliant effect. The assertion that iron is more combustible than gun- powder, has its origin in the following experiment, which 19 also a very striking one: A little alcohol is poured into a saucer and ignited. A mixture of gunpowder and iron filings is allowed to fall in small quantities at a time into the flame of the burning alcohol, when it will be observed that the iron will take fire in its passage through the flame, while the gun* 272 powder will fall through it and collect beneath the liquid alcohol below nnconsumed. This, however, is a scientific trick, and the experiment hardly justifies the sweeping asser- tion that iron is more combustible than gunpowder. The ignition of the iron under the foregoing circumstances is due to the fact that the metal particles being admirable con- ductors of heat, are able to absorb sufficient heat in their passage through the flame — brief as this is — and they are consequently raised to the ignition point. The particles of the gunpowder, however, are very poor conductors of heat, comparatively speaking, and, during the exceedingly brief tmie consumed in their passage through the flame, they do not become heated appreciably, or certainly not to their point of ignition. Under ordinary circumstances, gunpowder is vastly more inflammable than iron. Another method of exhibiting the combustibility of iron, which would appear to justify the assertion that it is really more combustible than gunpovvder, is the following: Place in a refractory tube of Bohemian glass a quantity of dry, freshly-precipitated ferric exide. Heat this oxide to bright redness, and pass a current of hydrogen through the tube. The hydrogen will deprive the oxidt of its oxygen, and reduce the mass to the metallic state. If, when the reduction appears to be finished, the tube is removed from the flame, and its contents permitted to fall out into the air it will take fire spontaneously and burn to oxide again. This experiment indicates that pure iron, in a state of the ex- tremest subdivision, is one of the most combustible sub- stances known — more so, even, than gunpowder and otrier explosive substances which require the application of con- sideraole heat, <^r a spark, to ignite them. HOW IRON BREAKS. Hundreds of existing railway bridges which carry twenty trains a day with perfect safety would break down quickly with under twenty trains an hour, writes a British civil en- gineer. This fact was forced on my attention nearly twenty years ago, by the fracture of a number of iron girders of ordinary strength under a five-minute train service. Simi- larly, when in New York last year, I noticed, in the case of some hundreds of girders on the elevated railway, that the alternate thrust and pull on the central diagonals from trains passing every two or three minutes had developed a weak- ness which necessitated the bars being replaced by stronger ones, after a verv .'^hort service. Somewhat the same thing 273 I -. iv be done r'^cently witha hridije ovt-i th^ river Trent, but, the tiaiii service being sn^all, the life of I he bars was measured by years instea I of months. If ships v^'ere ahvays among great waves the number going to the bottom would be largely increased. It appears natural enough to every one thr.t a ]^iece, even of the toughest wire, should be quickly broken if bent back and forward to a sharp angle; but, per- haps, only to locomotive and marine engineers does this ap- pe^nr equally natural that the .same results would follow in ti:re if the bending were so small as to be quite imperceptible to the eye. A locomotive crank axle bends but one eighty- fourih of an inch, a straight driving-axle a still sn aller amount, under the heaviest bending stresses to which they a: e subject, and yet their life is limited. During the year I CS-^ one iron axle broke in running, and one in fifteen was renewed in consequence of defects. Taking iron and steel axles together, the number then in use on the railways of the United Kingdom was 14,847, and of these 911 required renewal during the year. Similarly, during the . past three years, no less than 228 ocean steamers were disabled by broken shafts, the average safe life of which is said to be about three or four years. Experience has proved that a very moderate stress, alternating from tension to compres- sion, if repeated about 100,000,000 times, will cause a frac- ture as surely as bending to an angle only ten times. VALUE OF EMERY WHEELS. The increased quantity and quality of work that goes out of the modern machine shop is due to the skillful use of solid emery wheels. A grain of sand from the common grind- stone, magnified, would look like a cobble stone, a fracture of which shows an obtuse angle, w^nereas a grain of ( orun- dum or emery would look like a rhomboid, always l)reak- ing with a square or concave fracture. No matter how much it is worn down in use, it does not lose its sharpness ; hence it is evident that the grindstone rubs or grinds and heats the work brought in contact with it, while the corundum, or emery wheel, -"ith its sharp, angular grit, cuts like a fde or angular saw. There are two general classes of emery wheels in the market — one class of wheels has the grains of emery joined and consolidated by a pitchy material, as rubber, linseed oil, shellac, etc. These must run at a high speed to burn out the cementing material by friction, loosening the worn*out grains, and thus revealing new cutting angles. These are "tni-porous an wheels. Truing up this class of wheels is done with a dia« mond tool. The other class consists of two kinds, one made by mix- ing the emery with a mineral cement and water into a paste, which will harden and bind the grains together ; the other kmd, by mixing the emery with a mineral flux or clay, mold- ing into shape, and burning in a muffle at a high tempera- ture. These are porous wheels, in which the grains of emery are held together by matter having affinity therefor. This class of wheels, unlike the grindstone, has sharp grains of emery bedded together among matter which, in some cases, is as hard and sharp as the emery itself. Such wheels cut very greedily, and do not need to be run at any particular speed. The dresser, made of hardened steel picks, is the proper tool for truing up this class of wheels. Manufacturers in metal goods aiming at reducing the cost of production, would do well to look into the adaptability of the solid emery wheels or rotary file, and other labor-saving machinery, before deciding on reducing labor wages. THE SECRET OF CAST STEEL. The history of cast steel, remarks a contemporary, pre- sents a curious instance of a manufacturing secret stealthily obtained under the cloak of an appeal to philanthropy. The main distinction between iron and steel, as most people know, is that the latter contains carbon. The one is converted into the other by being heated for a considerable time in contact with powdered charcoal in an iron box. Now, steel thus made is unequal. The middle of a bar is more carbonized than the ends, and the surface more than the center. It is, therefore, unreliable. Nevertheless, before the invention of cast steel, there was nothing better. In 1760 there lived at Attercliffe, near Sheffield, a watchmaker named Huntsman. He became dissa!tisfied with the watch-spring in use, and set himself to the task of making them homogeneous. "If," thought he, "I can melt a piece of steel and cast it into an ingot, its composition should be the same throughout." He succeeded. His steel sooii became famous. Himtsman's ingots for fine work were in universal demand. He did not call them cast steel. That was his secret. About 1780a large manufactory of this peculiar steel was established a^ Attercliffe. The process was wrapped in secrecy by ever* means within reach. One midwinter night, as the tall chim, *»eys of the Attercliffe steel works belchSi forth their smoke H traveler Smocked at the gate. It was bitterly cold, and the snow fell fast, and the wmd howled across the moat. The stranger, apparently a plowman or agricultural laborer seek- ing shelter from the storm, awakened no suspicion. Scan- ning the wayfarer closely, and moved by motives of humanity, the foreman granted his request, and let him in. Feigning to be worn out with cold and fatigue, the old fellow sank upon the floor, and soon appeared to sleep. That, however, was far from his intention. He closed his eyes apparently only. He saw workmen cut bars of steel into bits, place them in crucibles, and thrust the crucibles into a furnace. The fire was urged to its extreme power until the steel was melted. Clothed in wet rags to protect themselves from the heat, the workmen drew out the glowing crucibles and poured their contents into a mold. Mr. Huntsman's factory hsid notiiing more to disclose. The secret of making cast Jteel had been discovered. IRON AND STEEL MAKING IN INDIA. Indian Engineerings in a recent issue, gives a most interesting account of the manufacture of iron and steel in India, which we reproduce below: Notwithstanding the simplicity of their processes, the iron turned out by the natives is of superior quality, and is selling very cheaply; so, for instance, a mound of horseshoes sells at Rs. seven, and of clamp iron Rs. six-eighths. These low prices are accounted for by cheap fuel, the rich ores, the miserably cheap labor, and the absence of managing expense.. There are reasons to believe that " Wootz " (Indian cast steel) has been exported to Asia Minor more than 2,000 years ago; how long, however, its manufacture has been commenced, cannot be traced. The following is a description of the method for making " Wootz " employed by the natives at Hyderabad. The minute grains or ' scales of iron are diffused in a sandstone-like gneiss or mica schist, passing into a horn- blende slate. These rocks are excavated with crowbars, and then crushed between stones; if hard, this is done after prelim- inary roasting. The ore is then separated from the powdered rock by washing. This was at a village called Dundurti, but the pro- cess of manufacture was the same as that at Kona Samun- drum, twelve miles south of the Godavari, and twenty-five from Nirmal, which has been described by Dr. Voysey. The furnace was made of a refractory clay, derived from decern- 276 posed granite and the crucibles are made of the same, ground t# a powdei together with fragments of old furnace and broken crucibles kneaded up with rice, chaff and oil. He states that no charcoal was put into the crucible, but some fragments of old glass slag were. A perforation was made sn the luted cover. Two kinds of iron, one from Mirtapalli and the other from Kondapore, were used in the manufacture of the steel. The former was made from magnetic sand, and the latter from an ore found in the iron clay (? laterite) rlwenty miles distant; the proportions used of each were This mixture being put into the crucible in small pieces, the fire was kept up at a very high heat for twenty-four hours by means of four bellows, and was then allowed to cool down. Cakes of steel of great hardness, and weighing on the average i% lbs., were taken from each crucible. They were then covered with clay and annealed in the furnace for twelve to dxteen hours; then cooled, and, if necessary, the annealing was repeated till the requisite degree of malleability had been obtained. The Telinga name for this steel was " Wootz," and " Kurs" or cake of it, weighing no rupees, was sold on the spot for eight annas. The daily produce of a furnace was 50 seers, or in value Rs. 37. Also Mysore is a country where the manufacture of iron and steel by the natives was of great importance owing to the excellent quality of its produce. ^The iron was made from black sand, which the torrents, formed in the rainy season, brought down from the rocks. The furnaces in the Chin-Narayan Durga taluk were on a small scale, the charge of ore being 42^ pounds, from which about 47 per cent, of the metal was obtained. Work was carried on for only four months, the smelters taking to culti- vation during the remainder of the year. The stone ore was smelted in the same way as the iron sand, but the latter, it is said, "was alone fit for manufacturing into steel. There were in this vicinity five steel forges, four in the above taluk, and OUe at Devaraya, Durga. The furnace, of which a figure is given by Buchanan, con- sisted of a horizontal ash-pit and a vertical fire-place, both sunk below the level of the ground. The ash-pi': was about three-fourths of a cubit in width and height, and was con- nected with a refuse pit into which the ashes could be drawn. The fire-place was a circular pit, a cubit in width, which was connected v/ith the ash-pit, being from the surface of the ground to the bottom two cubits in depth, A screen or mud- wall five feet high, protected the beliows-man from heat and sparks. The bellows were of the ordinary form, a conical leather sack with a ring at the top, through which the opera- tor pasr^ed his arm. 'The crucibles, made of unbaked clay, were conical in form, and of about one pint capacity. Into each a wedge of iron and three rupees' weight of the stem of the Cassia Auricii- lata and two green leaves of a species of convolvulus or Ipo- maia were put. The mouths of the crucibles were then covered with round caps of unbaked clay, and the junctures well luted. They were then dried near the fire, and were ready for the furnace. A row of them was first laid round the sloping mouth of the furnace; within these another row was placed, and the center of the dome, so formed, was occupied by a; single crucible, makmg nfteef. ii: :-!i The crucible opposite the bellows was then withdrawn, and its place occupied by an empty one, which couid be withdrawn in order to supply fuel below. The furnace, being filled with charcoal, and the crucibles covered with the same, the bellows were plied for four hours, after which the opera- tion was completed. When the crucibles were opened, the steel was found melted into a button with a sort of crystalline structure on its surface, which showed that complete fusion had taken place. These buttons weighed about twenty-four rupees. There were thirteen men to each furnace, a head man to i^nake and fill the crucibles, and four relays of three men each, one to attend the furnace, and two for the bel- lows. P2ach furnace manufactured forty-five pagodas' worth of X, 800 wedges of iron into steel. The net profit was stated to be 1,253 fanams, but into the further details as to cost it is not, perhaps, lecessary to enter. The total production of steel in this vicinity was estimated to be 152 cwt. , or about ;^300 per annum. The principal sources of the ores were the magnetic sand found in rivers, and the richer portion of the laterite. THE FLASH-POINT OF VARIOUS HYDRO- CARBONS. The following table gives the temperature at which various hydrocarbons give off inflammable vapors: Flajih Fire Open Test. Point. Point. Brandy, as usually sold retail 69 F. 92 P\ Whisky, *' '* 72 96 Gin, ** " 72 loi 278 ^^ Flash File Fire Test. Point. Point. Petroleum (ordinary American lamp oil) 73 104 Saxoline no 150 Ordinary high-test Petroleum iic-120 140-160 Crystal Oil 150 180 Downer's Oil , 270 310 Mineral Sperm 310 330 HOW BREAKS IN SUBMARINE CABLES AR?: DETECTED AND REPAIRED. The following is an account of how submarine cables art found and repaired at an immense depth: The break, which the " Minia " was sent to repair, occurred early last summer. The officers of the company first located the distance of the break from the stations on shore, on each side of t'^e ocean. The details of the instru- ment by which this is done are not easily described, though easily understood in principle. The machine consists of a series of coils of wire, which offe a known resistance to the electric current. Enough of tho coils are connected to make a resistance equal to the resistance offered by the entire cable " when it is in working order, and thus, when the machine and the cable are connected, a balance is effected. But, if the cable should break, the balance is destroyed, because that portion of the cable between the shore station and the break, wherever it may be, will offer less resistance to the electric current than the entire cable would do. Enough coils of wire are therefore disconnected from the machine to restore the balance. The resistance of the part of the cable that remains intact is thus accurately determined by the number of coils remaining connected with the machine. Having, when the cable w^as intact, learned the resistance which a mile of the cable offers, by dividing the entire resistance by the number of miles of cable, it is easy to find how many miles of cable are still in good order, by dividing the entire resistance of the piece by the known resistance of one mile Having determined how many miles from the shore station the break is, orders are sent to go to the place, pick up the ends, and splice them to new piece. Having received such an order and acted on it, Captain Trott found himself and his ship, on July 25th last, in latitude 42^ 30' north, and longitude 46° 30' west, or just to the eastward of the Grand Banks ''of Newfoundland, with one of the hardest jobs before him that he h^^ ^ad in some time, for sounding 279 showed that the wate*- was about 13,000 feet, or a good deal more than two miles deep. He knew he was somewhere aear the break in the cable, but he did not know absolutely within about three or four miles, because, while he had been able to determine his own position by repeated observations of the sun and stars, he could not tell how accurate the observations of the officers of the ship laying the cable had been. The first work done was to get a series of soundings over a patch of the sea aggregating twenty-five or thirty square miles. The sounding apparatus consisted of an oblong shot of iron, weighing about thirty-two pounds, attached to a pianoforte wire in such a way that, when lowered to the bottom^ the shot would jab a small steel tube into the mud down there, and would then release itself from the wire, and allow the sailors to draw up the tube with the mud in it. The moment the weight was released, the men on deck stopped paying out the wire, and thus, knowing how much wire had been run out, they were able to tell the depth. It is a fact that it took twenty-four minutes and ten seconds for the weight of the oounding apparatus to reach bottom in 2,097 fathoms of water. The ship was now ready to begin the search proper for the cabl?. She was run off at right angles to the line of the cable for n distance of five miles, and a buoy got down to mark the limits of thi> territory to be grappled over in that direction. Buoy 3 were afterward r:et elsewhere to mark the other limits of the territory. The grappling iron was low- ered over :he bows, the rope attached to it passing over one of the three big grooved wheels that revolve where the bow- sprit of an ordinary vessel stands. The grappling iron used is the invention of Captain Trott. It looks something like a four-pronged anchor. It has a shaft four feet long, and four arms about a foot long, that are set at right angles to each other at the bottom of the shaft. Right in each crotch formed by the arms is a little button that has a spring behind it that may be regulated in strength. The button projects a third of an inch into the crotch. The angle of the arms with the shaft is so small that a rock could not get down in so far as to reach the button ; but, when the cable is caught by the hooks, it presses down against the but- ton, and thus closes an electrical circuit through a copper wire running through the grapnel's rope and the grapnel itself, and a bell is set ringing upon deck. But the experi- enced m' n in charge of the grappling are generally able to telJ wha i: the hook has hold of without the aid of the bell. They judge by the strain on the rope, which is indicated by a dynamometer on deck. The ordmary strain on the dyna- mometer is from 3 to 3X tons when the grapnel is dragging ^reely over a smooth bottom as the vessel forges slowly ahead. :)metimes a rock catches on the hooks. This frequently breaks off an arm, but sometimes it fetches clear, the strain indicated by the dynamometer informmg the old sailor man m charge wheiner an accident has happened or not. It took two hours and twenty minutes to get the grap- pling iron from the bow of the ship down to the bottom of the sea, 13,000 feet below. The cable used to drag it with is the patent wire and hemp invention of the captain. The drag- ging began on July 25th, the day of arrival, but they swept backward and forward over the territory for ten days without finding the broken telegraph cable. A good part of the time they were steaming back and forth day and night, and the only time when they were not doing so was when the weather was too bad. On such occasions they went to the buoy at the supposed end of the broken cable, and hove to till the gale was ended. Finally, on August 5th, the bell rang, indicating that the grs-pnel had caught the cable. The grapnel drag rope was tnereupon fastened to a buoy and thrown overboard. Then the steamer went off two miles toward the end of the broken cable and got out a cutting grapnel. This is like the other one, except that there are knives in the crotches. When these crotches catch the cable and strain comes on them, th^ ' cut the cable off clean. " Why did you cut off the cable there? " was asked. " Because, if we had tried to get up the bight of the cable where we first found it, the cable might have broken under the strain. That cable was laid in 1869, and is getting pretty well along in years. It would have been as apt to break on the shore side as the other, but, when we had only an end of two miles to deal with, we were sure of being abk» to get up without damage. We grappled European end first." Having cut off the cable, the vessel returned to the buoy on the grappling rope, and, getting the rope inboard again, led it to £. drum six feet in diameter located on the uppei deck andr^^ '^ated by a steam engine. Then they began to wind in the grapnel rope and hoist the old cable to the bows. They started the drum at i :2o in the afternoon of August 5, and at 7:51 had the bight of it at the bow of the ship. Then the two miles and odd of end that was hanging down from the bow was fished up and stretched in lengths along the deck until the end was reached iliis was connected with » •/8l very complete cable telegraph office located amidships, and a second later the operators who had been on watch for days in the British station awaiting this event saw the flashes on a mirror in their ffice that told them all about it. Sometimes it happens that, when an end of the cable is picked up in this way, and an attempt is made to communi- cate with the shore, it is found that there is another break, and that they have only the end of an odd section lying loose. Then they have to drop that over, after testing it to see how long it is, and go on toward the shore and begin over again. In this case, however, they found that they had hold of a sound wire to Great Britain. Without any delay, the end of a new cable was spliced to the old end brought from the bottom. Two experts, one who is trained in splicing cores, and one who is trained in spHcing the outside or sheathing, are employed in this work. When the splice was completed and tested, and found perfect, the cable was started, running out around drums and grooved wheels controlled by brakes, and over the stern, the Old end having been led fair through these sheaves before the splicing was done. Then the ship headed for shoal water, and ran away at from three to four knots an hour until over a part of the banks where w^ork could be done more easily than where the water was more than two miles deep. Of course this involved the abandonment of a good many miles of old cable, but the old cable wasn't of very much impor- tance anyliow. Arrivmg in shoal water, the end of the new piece was attached to a buoy and put overboard. Then the old cable was grappled and cut as before, and a new piece spliced to it. Then the ends of the two new pieces were spliced to- gether and the job was complete. It had taken nearly two months to do it, although in the meantime two easier jobs were attended to, and a trip to Halifax for provisions was made, not to mention the encountering of the storm that damaged the rudder. The " Minia " has a crew of ninety, all told, including the explain, three deck officers, a navigator, three expert elec- Inciar.s, four engineers, a purser and a surgeon. A. black* smitti and a boiler maker, with their tools, are carried. There are three big, round tanks to hold the 600 miles of cable cariied, which includes sizes to fit all the old cables under the charge of this ship. - There is a cell-room where the electricity ibr telegraphing is generated, and two dynamos with their engines, one to furnish electricity for a system of arc lights used when at work at night, and the other for the incande** 282. cent system that lights the ship below decks. The main saloon is large, and is comfortably and handsomely fitted. The captain has a cabin under the turtle-back aft, as fine as any captain could wish for, and the other officers have rooms below that are as well fitted as those usually occupied by naval officers. The crew are all expert men, and get pay that averages a good deal better than the pay in the packet service between New York and Liverpool. The entire crew is kept under pay the year round, the ship making her head- quarters at Halifax when not engaged in repairing cables. They are as comfortable a lot of sailor men as one could find anywhere. THE USELESSNESS OF LIGHTNING RODS. The uselessness of the lightning rod is becoming so generally understood that the agents find their vocation a a trying one. Fewer and fewer rods are manufactured each year, and the day will come when a lightning rod on a house will be regarded in the same light as a horseshoe over a man's door. The breaking strain on various metals is shown in the following table, the size of the rod tested being in each case one inch square, and the number of pounds the actual break- ing strain ; Pounds. Hard Steel 150,000 Soft Steel 120,000 Best Swedish iron 84,000 Ordinary bar iron 70,000 Silver. 41,000 Copper 35^000 Gold 22,000 Tin 5.500 Zinc 2,600 Lead 860 To make varnish adhere to metal, add five-hundredths per cent, of boracic acid to the varnish. Machinery will do almost anything, and what machinery can't do a woman can with a hairpin. To find the weight of a cast-iron ball, Haswellsays — Mul« tiply the cube of the diameter in inches by 1365, and tha orodu t is the weight i)i pounds. 283 NUMBER OF REVOLUTIONS OF WATCH WHEELS. Very few who carry a watch ever think of the unceasing labor it performs under what would be considered shabby treatment for any other machinery. There are many who think a watch ought to run for years without cleaning, or a drop of oil. Read this and judge for yourself: The main wheel in an ordinary American watch makes 4 revolutions a day of 24 hours, or 1,460 in a year. Next, the center wheel, 24 revolutions in a day, or 8,760 in a year. The third wheel 192 in a day, or 59,080 in a year. The fourth wheel, 2,440 in a day, or 545,600 in a year. The fifth, or 'scape wheel, 12,960 in a day, or 4, 728,200 in a year. The ticks or beats are 388,800 in a day, or 141,882,000 in a year. A VALUABLE POINT FOR HOLDERS. It is claimed that a saving, as well as a better job, can be effected by the substitution of the following for the coal dust and charcoal used with green sand : Take one part common tar, and mix with 20 parts of green sand ; use the same as ordinary facing. The castings are smooth and bright, as tar prevents metal from adhering lo the sand, prevents formation of blisters, and helps tlie production of large castings by absorbing the humidity of the sand. METRICAL EQUIVALENTS. As in much of the scientific literature of the. steam engine the metrical system of weights and measures is used, we publish the following equivalents, which may be of use to our readers in readily reducing them to British units: 1 kilogrammetre 7,23^ foot pounds. I foot pound 188 kilogrammetre. I French horse power (chevelvapeur) 75 kilo- gramme tres per second 9863 horse power. I British horse power 1.0139 chevaux. I kilogramme per cheval 2,239 pounds H. P. I pound per horse power. 447 kilo, per cheval. 1 caloric, or French heat unit 3968 British units. I British thermal unit 252 caloric. French mechanical equivalent, 423.55 (usually called 424) kilogrammetres 3063. 5 ft. pounds. English mechanical equivalent, 772 footpounds 10.76 kilogrammetres. A NEW ALLOY. An alloy, the electrical resistance of -which diminishes with increase of temperature, has recently been discovered. It is composed of copper, manganese and nickel. Another alloy, due to the same investigator, the resistance of which is practically independent of the temperature, consists of 70 parts of copper combined with 30 of ferro-manganese USE OF NATURAL GAS IN CUPOLAS. At Pittsburgh, Pa., natural gas has been utilized in cupolas for ordinary castings. The apparatus consists of a series of pipes, covered with fire-clay tiles, and, at the same time, ventilating the pipes with a current of air. A combus- tion chamber is necessarily connected with the furnace, to insure the required heat and prevent the chilling of the fur- nace. A NEW CEMENT. A cement called magnesium oxychloride, or white cement, has been discovered, and is now manufactured in California, as we learn from an exchange. It is composed of one-half (}4) magnesium oxide, which is obtained from the magnesite deposits in the Coast Range, and one-half (J4) magnesium chloride, obtained from various sea-salt manufactories uiioughout the State. It may be used for sidewalks, and for intexior decorating, and in appearance resembles pure white marble. It has a natural polish, and, above all, is much cheaper than any of the other substances now in use. KOW TO CAST A FACE. The person whose face is to be "taken" is ])!aced flat upon his back, his hair smoothed back by pomatum to pre- vent it covering any part of the face, and a conical piece of paper or a straw, or a quill put in each nostril to breathe through. The eyes and mouth are then closed and the entire face completely and carefully covered with salad oil. 'Ihe plaster, mixed to the proper consistency, is then poured in large spoonfuls to the thickness of one-quarter or one-hair inch. In a few minutes this can be taken off as if it were a film. When a cast of the entire head or of the whole human figure is required, either a cast of the face is added to a mass of clay, which is to be modeled to the required figure, or the whole figure is modeled from drawings prepared for th-'' purpose Tl::s is the work of the sculntor- 285 When the clay model is finished, a mold is made from it as in the former cases. If the model be a bust, a thin ridge of clay is laid along the figure from the head to the base, and the front is first completed up to the ridge by filling up the depressions two or three inches deep. The ridge of clay is now removed, the edges of the plaster are o'^led, and the other half is done in a similar way. The tw^d htilves are like- wise tied together with cords, and the plaster is poured in. In complicated figures, say a " Laoccon," the statue is oiled and covered with gelatine, which is cut off in section?: by means of a thin, sharp knife, each piece serving as a iviold for its own part of the new statue. ' MELTING POINTS OF METALS. Metals. Aluminum. . . . Antimony . . . Arsenic , Bismuth . . . . , Cadmium .... Cobalt Copper Gold Indium Iron, wrought Iron, cast . . . . Iron, steel . . . Lead Magnesium. . . Mercury Nickel Potassium. . . . Platinum .... Silver Sodium , Tin.. , Zinc Centigrade. Fahrenheit. degrees 700 degrees 1,292 425 (( 797 66 i«5 a 365 a 264 it 507.2 a 320 « 608 ti i,200 (C 2,192 6i 1,091 (( 1,995.8 466. 59 Uranium 434.88 Gold 299.72 Titanium (fused) 239.80 Tellurium " 196.20 Chromium " 196.20 Platinum " 122.31 Manganese " 108. 72 Molydenum. 54. 34 Magnesium (wire and tube) 45-30 Potassium (globules) 22.65 Silver 18.60 Aluminum (bar) 16.30 Cobalt (cubes) [ 12.68 Nickel 3.80 Cadmium , 5.26 Sodium 3.26 Bismuth (crude) 1.95 Mercury. 1. 00 Antimony .36 Tin... .25 Copper .22 Arsenic , o.,,. .15 Zinc , , .. .10 Lead .06 Irom. ^ .13^ 288 LENGTH PER COIL AND WEIGHT OF ROPE PER HUNDRED FATHOMS. Tarred Manila and Sisal R ope. 1 C( Le'gth Drdage. Diameter in Cir. in Le'gth Lbs. Lbs. inches. inches in feet. per 100 Fa in feet. per 100 Fa X or 6th. % 1,300 12 840 18 5-16 or 9th. 15-16 1,300 17 840 29 Ys or I2th. iy% 1,200 23 840 40 15 thread. 15 thread. 1,200 31 840 47 18 thread. 18 thread. 1,100 45 840 ^^8 21 thread. 21 thread. 1,100 50 840 68 y^ . iK 990 52 960 64 9-16 iYa, 990 70 960 79 '6 2 990 83 960 94 u 2^ 990 105 960 130 % 2K 990 125 960 140 15-16 2I4: 990 155 960 170 I 3 , 990 175 960 207 1 1-16 3^ 990 205 960 238 1 3-16 3>^ 990 255 960 272 iX 3l< 990 280 960 300 1 5-16 4 , 960 310 960 332 in 4^ 960 355 960 31^ 1% aVz 960 410 960 440 iVs ^ aU 960 450 960 505 I 11-16 5 , 960 500 960 573 lU 5^ 960 550 960 610 1% sK 960 610 960 654 I 15-16 SI4: 960 690 960 797 2 6 960 750 960 900 2 3-16 6>^ 960 845 960 1.057 2% 7 , 960 1,000 960 1,163 2% 1/2 960 1,100 960 1.356 2% 8 960 1,270 960 1,613 3 9 960 1^595 960 2,013 HOW TO MAKE BRONZE MALLEABLE. Domier has discovered that bronze is, rendered malleable by adding to it from one-half to two per cent, of mercury 2,Sg WHEN A DAY'S WORK BEGINS. The decision of the Supreme Court that a workman who has agreed to do work at a specified sum per hour, is not entitled to charge for the time spent in gomg to or returning trom work, is one that equitably applies to some kinds of business, but not to others. Where house-building mechan- ics have several days' work to do at a building, and their tools and materials are on the spot, they are expected to re- port at the building in time to do a full day's work. Where they are doing odd jobs and are obliged to start from the shop in the morning, they do so at the regular hoar for beginning work, thus reducing the hours of actual labor But they must be paid for the whole day, and the person for whom the vvork is done must be charged for the time occu- pied in going to and from the job; otherwise, the " boss" A'ould have to pay his journeymen, for say ten hoiu-s' work, though accounting for only six hours work' in his bill to cus- tomers. In some of the small trades a journeyman will go to half a dozen houses in a day, doing an hour's wo^k in each, and spending the other four hours in passing from one job to another. In one way cr another he is bound to be paid for the whole time. If he can charge only for the actual work- ing time, then his rates will be increased so as to compensate him for the time spent in service that is not to be paid for. The decision shows the importance of making agreements of this kind specific, both as to the rate of wages and the hours and kmd of service. CAMEL'S-HAIR BELTING. Camel' s-hair belting has been recently the subject of experiments at the Polytechnic school, at Mul\ ?ch, from which it aopears that the strength of camel's-hair belting reaches 6,315 pounds per square mch, whilst that of ordinary belting ranges between 2,230 pounds and 5,260 pounds per square inch. A contemporary says the camel's-hair belt is said to work smoothly and well, and it is unaffected by acids, TO PERFORATE GLASS. In drilling glass, stick a piece of stiff clay or putty on tlie part where you wish to make the hole. Make a hole in the putty the size you want the hole, reaching to the glass, of course. Into this hole pour a little molten lead, when, unless it is very thick glass, the piece will immediately drop out. 290 HIGH SPEED GEARING. During the last few years, and particularly since the adoption of double-heliacal teeth, a great increase has been made in speed at which gearing is run, and, in many cases, there are now successfully adopted speeds which in former days would have been regarded as utterly impracticable. The most striking instances of this which we have come across, is in the case of a pair of double-heliacal wheels at the works of Messrs. R. Johnson & Nephew, the well-known wire-drawers of Manchester. These wheels, which were cast by Messrs. Sharpies & Co., of Ramsbottom, Lancashire, are 12 in. wide on the face, by 6 ft. 3 in. diameter, and they have now been running for over a year at 220 revolutions per minute, the pitch-line speed being thus 4,319 ft. per minute. Notwithstanding this enormous speed, the wheels run with scarcely ^ny noise, and their working has been most satis- factory. This is the highest speed we have heard of for geared wheels, running iron to iron, and the fact that it haa been adopted with success, is a most interesting one. The large gear on the Corliss engine at the Centennial Exhibition was 30 feet in diameter, outside, and run at 36 revolutions per minute. It had a 24-in. face, and the speed of the pitch-line is about 3,360 ft. per minute. This speed is exceeded by a similar gear, also made by Mr. Corliss, which is now running in a mill in Massachusetts. It is 30 ft. in outside diameter, and has a 30-in. face. It makes 50 revolu- tions per minute, and the speed of the pitch-line is not far from .4,670 ft. per minute. This is probably the highest speed at which any gear has yet been run continuously. The Corliss gears are all accurately shaped by a revolving cutter; but it is probable that Messrs. Sharpies & Co.'s gears are not cut, but cast, and then finished up by hand. If that is the case, their performance is much more remarkable than that of the Corliss gears. THE WATCH AS A COMPASS. Due south can be readily ascertained if one possesses a fairly correct watch and the position of the sun is distin- guishable. Point the hour hand to the sun, and the south is exactly half-way between the hour and the figure XII on the watch. For instance suppose that it is 4 o'clock. Point the hand indicating IV to the sun and II on the watch is exactly south. Suppose that it is 8 o'clock, point the hand indicating VIII to the sun, and the figure X on the watch is due south. ^9* LIABLE TO SPONTANEOUS COMBUSTION. Cotton-seed oil will take fire even when mixed with cwenty-five per cent, of petroleum oil ; but ten per cent, of mineral oil mixed with animal or vegetable oil, will go far to prevent combustion. Olive oiJ is combustible, and, mixed with rags, hay or sawdust, will produce spontaneous combustion. Coal dust, flour-dust, starch (especially rye flour), are all explosive when with certain proportions of air. New starch is highly explosive in its comminuted state, also sawdust in a very fine state, when confined in a close shute, and water directed on it. Sawdust should never be used in oil shops or warehouses to collect drippings or leak- ages from cask«. Dry vegetable or animal oi4 inevitably takes fire, when saturating cotton waste, at 1 80° F. Spontaneous combustion occurs most quickly when the cotton is soaked with its own weight of oil. The addition of forty per cent, of mineral oil (density .890) of great viscosity, and emitting no inflammable vapors, even in contact with an ignited body at any point below 338° F. , is sufficient to prevent spontaneous combustion, and the addition of twenty per cent, of the same mineral oil doubles time necessary to produce spontaneous combustion. Greasy rags from butter, and greasy ham bags. Bituminous coal in large heaps, refuse heaps of pit coal, hastened by wet, and especially when pyrites are present in the coal ; the larger the heaps the more liable. Timber dried by steam pipes or hot water, or hot air heating apparatus, owing to fine iron dust being thrown off, in close wood-casings, or boxings round the pipes, from the mere expansion and contraction of the pipes. Patent dryers from leakages into sawdust, etc., ©ily waste of any kind, or waste cloths of silk or cotton, saturated with oil, varnish, turpentine. HOW COMBUSTION IN COAL IS PFODUCED. In a ton of anthracite coal, there is about 1,830 lbs. of car- bon, 70 lbs. of hydrogen and 52 lbs. of oxygen; while a toa of good bituminous coal is composed of 1,600 lbs. of carbon, 108 lbs. of hydrogen and 32 lbs. of oxygen. The combus- tion of coal proceeds from its combination with oxygen gas, and, when fuel of any kind combines with oxygen, heat is pro- duced. All bodies, substances, gases and liquids, are com- posed of separate particles, often of molecules of inconceiv- •^ble sma.llness. These particles, it is scientifically conceded. 292 are m motion among themselves, and this motion constitutes heat, for heat is only a kind of motion. This internal vibra- tion of infinitesimal particles may be transmuted into a per- ceptible mechanical movement, or the mechanical movement may be converted into the invisible motion called heat. The oxygen combined with coal has a very considerable range of internal motion, and the combining process produces carbonic acid gas; and, the particles of this gas having a much smaller range of motion than the particles of the oxygen have, the difference appears in the form of heat. " CAPACITY OF CYLINDRICAL CISTERNS. The following table shows the capacity in gallons for each foot in depth of cylindrical cisterns of any diameter: Diameter. Gallons. Diameter. Gallons. 25 ft. 3.059 7 ft. 239 20 ft. 1,958 6/2 ft. 206 15 ft. I,IOI 6 ft. 176 14 ft. 959 5 ft. 122 13 ft. 827 4Kft. 99 12 ft. 705 4 ft. 78 II ft. 3 ft. 44 10 ft. 489 2>^ft. 30 9 ft. 396 2 ft. 19 8 ft. 313 HOW TO SELECT A HAND SAW. A saw-maker has this advice to give to carpenters In the selection of a saw: "See that it 'hangs' right. Grasp it by the handle and hold it in position for working to see if the handle fits the hand properly. A handle should be symmetrical, and the lines perfect. Many handles are made of the green wood; they soon shrink and become loose, the screws standing above the wood. An unseasoned handle is liable to warp and throw the saw out of shape. Try the blade by springing it, seeing that it bends evenly from point to butt in proportion as the width and gauge of the sav/ vary. The bl'ide should not be too heavy in comparison to the teeth, Jis it will require more labor to iise it. The thinner you can get a stiff saw the bet- ter; it makes less "kerf and takes less muscle to drive it. *'See that the saw is well set and has a good crowning breast. Place it at a distance from you; .^et a proper light on it, and you can see if there has been any imperfections in grinding or hammering." 293 FROM ONE TON OF COAL. Prom one ton of ordinary gas coal may be produced 1,500 pounds of coke. 20 gallons of ammonia water and 140 pounds of coal tar. By destructive distillation the coal tar will yield 69.5 pounds of pitch, 17 pounds of creosote, 14 pounds of heavy oils, 9.5 pounds of naphtha yellow, 6.3 pounds of naphthaline. 4.75 pounds of naphthol, 2.25 pounds of solvent naphtha, 1.5 pounds of phenol, 1.2 pounds of aurine, 1.1 pounds of benzine, 1.1 pounds of analine, 0.77 of a pound of toludine, 0.46 of a pound of anthracine and 0.9 of a pound of toulene. From the latter is obtained the new substance known as saccharine, which is 530 times as sweet as the best cane sugar, one part of it giving a very sweet taste to a thou- sand parts of water. HOW TO SELECT ROPE. A German paper, in an article on the present methods of rope manufacture from hemp, and the determination of the different qualities and the probable strength simply from the appearance, lays down the following rules : A good hemp rope is hard but pliant, yellowish and greenish gray in color, with a certain silvery or pearly luster. A dark or blackish color indicates that the hemp has suffered from fermentation in the process of curing, and brown spots show that the rope was spun while the fibers were damp, and is consequently weak and soft in those places. Again, sometimes a rope is made with inferior hemp on the inside, covered with yarns of good material — a fraud, however, which may be detected by dissecting a portion of the rope, or, in practical hands, by its behavior in use ; other inferior ropes are made with short fibers, or with strands of unequal strength or unevenly spun — the rope in the first case appearing wooly, on account of the number of ends of fil.)er projecting, and, in the latter case, the irregularity of manufacture is evident on inspection by any good judge. THINGS THAT WILL NEVER BE SETTLED. Whether a long screw-driver is better than a short one of the same family. Whether water-wheels run faster at night than they do in the day time. The best way to harden steel. Which side of the l)elt should run next to the pulley. The proper speed of line shafts. The right way to lace belts. Whether cojupression is economical or the reverse. Th'^ ])rincip!e of the sleara injectoi-. 294 THINGS WORTH KNOWING. Dominer has discovered that bronze is rendered malleable by adding to it from one-half to two per cent, of mercury. An " inch of rain " means a gallon of water spread over a surface of nearly two square feet, or a fall of about loo tons on an acre of ground. A steam power plant is divided into five fundamental ■parts by a French author — the boiler, motor, condenser, distributing mechanism, and mechanism of transmission. Turpentine and black varnish, put with any good stove polish, is the blackening used by hardware dealers for polish- ing heating stoves. If properly put on, it will last throughout the season. A workman in the Carson mint has discovered that drill points, heated to a cherry-red and tempered by being driven into a bar of lead, will bore through the hardest steel or plate glass without perceptibly blunting. To harden copper, melt together, and stir till thoroughly incorporated, copper and from one to six per cent, of mand- ganese oxide. The other ingredients for bronze and other alloys may then be added. The copper becomes homogene- ous, harder and tougher. SIMPLE TESTS FOR WATER. Boiler-users who desire simple tests for the water they are using will find the following compilation of tests both useful and valuable : Test for Hard or Soft ^-6.4 17.6 21 16.8 —7 -5.6 19.4 22 17.6 —6 -4.8 21.2 23 18.4 —5 —4.0 23.0 24 19.2 —4 —3-2 24.8 25 20.0 —3 —2.4 26.6 26 20.8 - 2 —1.6 28.4 27 21.6 304 C. R- F. C. R. F. 28 22.4 82.4 65 52.0 149.0 29 23.2 81.2 66 52.8 150.8 30 24.0 86.0 67 53.6 152.6 31 24.8 87.8 68 54.4 154.4 32 25.6 89.6 69 55.2 156.2 33 26.4 91.4 70 56.0 158.0 34 27.2 93.2 71 56.8 159.8 35 28.0 95.0 72 57.6 161 6 36 28.8 96.8 73 58.4 163-4 37 29.6 98.6 74 59.2 165.2 38 30.4 100.4 75 60.0 167.0 39 31.2 102.2 76 60.8 168.8 40 32.0 104.0 77 61.6 170.6 41 32.8 105.8 78 62.4 172.4 42 33.6 107.6 79 63.2 174.2 43 34-4 109.4 80 64.0 176.0 A4 35.2 III. 2 81 64.8 177.8 45 36.0 1 13.0 82 65.6 179.6 46 36.8 1 14.8 83 66.4 181. 4 22.4 82.4 23.2 81.2 24.0 86.0 24.8 87.8 25.6 89.6 26.4 91.4 27.2 93-2 28.0 950 28.8 96.8 29.6 98.6 30.4 100.4 31.2 102.2 32.0 104.0 32.8 105.8 33-6 107.6 34-4 109.4 35.2 III. 2 36.0 113.0 36.8 114.8 37-6 116.6 38.4 1 18.4 39-2 120.2 40.0 122.0 40.8 123.8 41.6 125.6 42.4 127.4 43-2 129.2 44.0 131.0 44.8 132.8 45-6 134.6 46.4 136.4 47.2 138.2 48.0 140.0 48.8 141. 8 49.6 143.6 50-4 145-4 51.2 147.2 47 37.6 II6.6 84 67.2 183.2 48 38.4 1 18.4 85 68.0 185.0 49 39.2 120.2 86 68.8 186.8 ^o 40.0 122.0 87 69.6 188.6 51 40.8 123.8 88 70.4 190.4 52 41.6 125.6 89 71.2 192.2 53 42.4 127.4 90 72.0 194.0 54 43.2 129.2 91 72.8 195.8 55 44.0 131.0 92 73.6 197.6 56 44.8 132.8 93 74.4 199.4 5,7 45.6 134.6 94 75.2 201.2 58 46.4 136.4 95 76.0 203.0 59 47.2 138.2 96 76.8 204. S 60 48.0 140.0 97 77.D 206.6 61 48.8 141. 8 98 78.4 208.4 62 49.6 143.6 98 79.2 210.2 63 50.4 145.4 100 80.0 212.0 64 WHY STEEL IS HARD TO WELD. A metallurgist gives, as a reason why steel will not weld as readily as wrought iron, that it is not partially composed of cinder, as seems to be the case with wrought iron, which assists in forming a fusible alloy with the scale of oxidation on the surface of the iron in the furnace. 305 DIFFERENT COLORS OF IRON, CAUSED Bl? HEAT. Deg. Cen. Deg. Fah. 261 370 502 680 500 932 525 700 800 900 1000 977 1292 1472 1657 1832 1 100 2012 1200 .2192 1300 1400 1500 1600 2372 2552 2732 2912 / Violet, purple and dull blue. Between 261'^ C. to 370*^ C. it passes to bright blue sea 1^ green, and then disappears, f Commences lo be covered with a light coating of ox- ■{ ide ; becomes a deal more I impressible to the hammer, i and can be twisted with ease. Becomes a nascent red. Somber red. Nascent cherry. Cherry. Bright cherry. Dull orange. Bright orange. White. Brilliant white-welding heat. ] Dazzling white. TO DRAW FERRULES. A useful tool for drawing thimbles or ferrules out of loco- motive boiler tubes is here shown. It is an English inven- tion, and it is not stated that it is pat- ented. The tube ^/ is split in quarters on the end so that it can be easily slipped in. The rest of the device explains itself, as does the second figure also, which is another device f^^ the same purpose. 3o6 BELTING SHAFTING AT RIGHT ANGLES jn Fig. 1 of the illustration, A is the driver. The toelx, leaves the pulley at C, goes to the driven pulley, and then aown to the driver at h. In Fig. 2 this movement is re- 19 M If u r m 9 Fig. I. Fig. 2. •ersed. Fig. 3 is a side view of tlie driven pulley B, and Fig. 4. shows the driving pulley A, with the driven pulley B in- side, so as to run in the one direction, while the dotted linesi B outside, so as to run the opposite way. Figs, t ands •how that centers of the faces of both pulleys must be in liao 3^7 with each other, and if this point is attended to the pulleys will run well together, although they may be of different diameter. AN EASY WAY TO LEVEL SHAFTING- The device here Illustrated for leveling shafting I have found to be very handy. The hangers A. are made of wood and are cut at an angle of 45 o at the top end, so that they will fit different sized shafts, and a slot is cut at (a) to receive the straight edge C. The hangers are placed on the shaft to loe tried, at any convenient place as near the bearings as possi- ble, and the straight edge placed in the slots, in which it should fit tight. Then by placing the spirit level D on the parallel part of the straight edge, it will be seen whether the shaft is level or not. It is best if the hangers be made of hard wood. A SELF-WINDING CLOCK MOVEMENT. A self-winding clock is now on the market and we present herewith an engraving of one. It is made by the American Manufacturing and Supply Co., Limited, lo and 12 Dey street, New York. Objection may be made to the employ- ment of a battery as an auxiliary, and therefore that the clock 308 fcnot self-winding, but the office of the battery is secondarf^ the operation of the clock opening the circuit while the bat- tery is used only to interrupt it. Appended is a descriptioc «f the movement: The wheels and arbors below the center are removed frt>m the clock. In their place a small electric motor is substituted. This motor connects Vv'ith a spring barrel on the center arbor, which incloses a spring six feet long, three-sixteenths of an inch in widtn and six-one-thousandths of an inch in (hicksiess. This sprinj^, at its innej' end, is attached 309 to the arbor, and at the ouver end to the periphery of the ppring barrel. The spring is coiled around the arbor many toes, but not so close as to produce friction between the coils; and being attached to the center arbor it follows that the inner end will unwind one turn every hour. "By a sim- jple attachment the electric circuit is made to pass into the motor already referred to, which quickly carries the spring barrel around once (being free on the arbor), and the outer 'ud of the spring attached to its periphery with it. Upon he completion of one revolution of the spring barrel, as de- scribed, the electric circuit is broken and the motor stops. By this arrangement it will be observed that the inner end ot the spring always has a m.otion from left to right, or in the direction the hands are moving, and the outer end of the spring a motion in the same direction when the clock 19 being wound. Now, since the winding is done in the same direction as the imwinding of the inner end, and the spring is SO wound originally as to avoid friction between the coils, it follows that the tension upon the train is absolutely uniform at all times whether the outer end of the spring is at a point of tem- porary rest or is being carried around the arbor at the tinae of winding, as above described. By actual experiment it is found that to obtain a given force at the escape wheel it is only necessary to apply a power in this manner at the center arbor equal to less than one- forty-sixth part of that used in the ordinary clock. The train work is not only shortened one-half, but the friction on the remainder is reduced in the proportion stated. The invention lies in bringing a motor and clock-wor"k gogether in a time piece, and is not limited to any particular levice. Experiments prove that a motor as constructed for this purpose cnn be run for one year at an expense of less than twenty-five cents; hence a clock may be sealed up and left to itself for a period of at lea^t one year with a certainty of closer time during tliat period than can be secured by any- other known method of giving time. In short, a common clock constructed on this principle has been found to keep as accurate time as one of the higher grades with gravity escapements, etc., run by the old methods. The electric motor is normally out of circuit, but at stated intervals, by the operation of the clock itself, the circuit is completed and the motor is thus set in motion. To be more exact we wili give a general description of the mechanism employed in the clock. Upon the center arbor there is placed a loose " arm ** between the hour wheel and the wheel carrying the spr 3»o box. At one side of one of the " train plates " is secured an insulated spring connector, the free end of which extends to, and is within reach of, the " arm," when the same has been brought to a perpendicular position, which is done by means of a pin projecting from the hour wheel. When the hour wheel has thus brought the " arm " to an upright position and in contact with the insulated spnng connector, the circuit is completed through the motor, which at once commences to rotate the spring box one revolulion from left to right, or in the direction that the hpnds move. The spring box wheel also carries a projecting pm, but set at a less distance from the axis than the other pin. Now, as the motor continues to rotate, the spring box wheel, while the spring connector is resting upon the "arm," it follows that as soon as there has been one revolution of the spring box wheel the projecting pin upon this wheel will press the "arm" forward and out from under the spring connector, thereby breaking the circuit and stopping the motor. This arrangement prevents the possibility of the clock running beyond the regular limit for winding, and prevents the motor wnen once set IJQ operation from performing more than the work required, TESTS OF STEEL PIPE. The Riverside Iron Works, of Wheeling, W. Va., has carried out a series of interesting experiments to ascertain the relative corrosive action of water acidulated with nitric acid upon iron and steel plates cut from pipe. The Avater was acidulated with one part of strong nitric acid in ninety parts, the plates being of the same dimensions, free from scale and grease and polished bright. In each case the pieces cut from iron and steel pipe were hung side by side in the same acidulated water, the loss of weight being deter- mined at the end of twenty-four and of forty-eight hours. One test was made by exposing both surfaces and edges to the action of dilute acid, the result being that the loss in gi-ains after twenty-four hours was 3.6 in the case of iron from standard iron pipe, and 1. 15, or less than half, with steel pipe. In forty-eight hours the figures stood 6.53 and 2.21 gx'ains, respectively. In a second test the edges of the pieces were protected from the action of the acid and the t wo oppo- site sides only exposed. In this test the loss of iron after twenty-four hours was 1.89 grains, against 0.49 grains with ^'he steel, and after forty-eight hours 4.28 and 1.24, respect- yely. The dimensions' of the test-pieces were i}4 'nches 3»i square by 3-16-inch thick. A series of comparative tests have also been made to ascertain the relative strength of the weld of Riverside steel and standard iron pipe. Two test- pieces were cut from Riverside pipe, mechanically lap-weld, with the weld at the middle, and in a similar way from mechanical lap-welded iron pipe, in each case with the weld in the middle. Not one of the tests broke at the weld, the steel showing a tensile strength of 52,400 and 66,330 pounds, with an elongation of 18.75 and 17.25 per cent, in 8 inches, while the iron pipe samples showed 62,480 and 35,240 pounds per square inch, and an elongation of 2.25 and 0.50 per cent Two samples from a sheet of Riverside steel lap-welded by hand, with the weld in the middle, showed a tensile strength of 51,860 pounds, and an elongation of 7 per cent, in 8 inches, the fracture occurring at the weld. A second sample had an ultimate strength of 56,090 pounds, elongation 13 per cent, and did not break at the weld. Iron plates cut with the grain and hand-welded have a tensile strength of 44,630 and 43,500 pounds, respectively, with an elongation of 5- and 4.25 per cent., both breaking at the weld. TOOL FOR COUNTER-BORING. The above is a sketcii of a tool that will be found very con- venient on many occasions, when counter-boring work in the drill press; usually such work is done with a cutter of the same shape as it is desired to have the finished work, when if there is any scale, as in cast iron, it is very difficult to get the cut- ter started. The tool in the sketch entirely obviates that difficulty, as only the points come in contact with the scale at first and are easily forced through it. Referring to the sketch, A is the end of a cutter-bar, B, the cutter, and C, the wedge for keeping the cutter in place. It will b* noticed that the teeth Z>, on one sid« of the bar will, as it is revolved, cover the space left by the part of the cutter on the other side of the bar, and thus rapidly remove the scale and metal, when the work may be finished by the ordinary flat cutter. 312 HOW TO MAKE A SMALL STORAGE BATTERY. A storage battery, or accumulator, to light an incandes- cent lamp of 4 candle-power, would not |go in an ordinary sized pocket, because one would require at least four cells, nd if the plates were made too small, the charge put into ■ ^em would last scarcely a few seconds. The following di- ..ections will enable any person to construct a storage bat- tery, which, when charged, will light a 4-volt lamp. The first thing to do is to procure of some dealer in elec- trical apparatus and material a hard rubber cell, about 3^ inches by 5 inches by i inch, having two compartments of equal dimensions. Such a cell can be purchased for about fifty cents. Next, cut four plates from one-sixteenth inch sheet lead, 4 J^ inches by i X inch, having an ear to each ; punch as many holes in each plate as you can to within ^ inch from the ear or top end. Then fill up the holes, and also smear the plates with a thick paste of red lead (minimum) and di- luted sulphuric acid. • Cut out a piece from thin — -Y^ of an inch — hard wood, 3^ inches long and i inch wide ; pierce it with four slits large enough to allow the ears of the plates to come through (two to each cell), and, also, where con- venient, two holes should be made and fitted with glass tubes for the purpose of filling the cells. As soon as the red lead paste has become hard, plac thee four plates in their positions, and solder the ear of one plate to the ear piece of the next cell. This will leave one free end from each cell ; to these a wire or terminal should be sol« dered. Now cement on the top and cover all over, except the glass tubes, with a composition of one part melted- pitch and tw^o parts of gutta-percha. Having filled the cells three-quarters full with a 10 per cent, solution of sulphuric acid, connect the wires on ^ primary battery or small dynamo. Charge, discharge and reverse every three hours, and let the last charge remain in all night. Do this till you find your storage battery will ring a bell, with fifteen minutes' charging, for about ten. Then only charge one way, and mark the ends in some way so as to know where to connect one next time for chargmg. This battery, when completed, will light a 3 or 4 volt /amp well during intervals for about two hours. A similar cell, having four compartments instead of two, would suffice to operate an 8 or 9 volt lamp, or one of about 6 candle- Dower. Such a battery r '-^as just been described may be 313 veniently be formed by a ten-cell Daniel telegraph battery in about a fortnight's time. A storage battery of this size should never be charged until within an hour or so of its being wanted for use, as it will run down a little by short circuiting, owing to the damp- ness of the inside. Finally, it should be stated, that, before putting the plates in the cells for good, a piece of india rubber ought to be placed between the plates, as well as a piece on the two out- sides, and held by a piece of asbestos fiber. This prevents the plates from touching each other, and also keeps them from shaking from side to side. LUBRICATING WITPIOUT OIL. Several interesting facts in regard to cylinder lubrication were brought out at the recent meeting of the American Society of Mechanical Engineers, a'. Philadelphia. Among other things Mr. Denton stated as b.:s opinion that the fric- tion of an engine was independen" of the lead, and, among other things, presented the subjoined interesting table: Indicated H. P. 84 Unloaded 23 Unloaded 347. . . . 185 181 137 Kind of engine. Westinghouse, 12X11 inches, 300 revolut's. Buckeye, 7x14 inches, 280 re- volutions. Compound con- densing throt- tled. Compound con- d e n s i n g ex' pansion. This table, it will be observed, shows that the friction is actually less in all cases but one when the load is greatest, Mr. Denton thought that the friction of a piston in a cyl- inder was slight, and that lubrication did not bring about any noticeable result so far as this particular part was concerned. In support of these statements he cited first the case of an engine in which the steam of the same pressure was admitted to both cylinder ends at the same time The difference in area between the two faces of the piston^ owing to the pres ence of the piston-rod, and the consequ^.ntly greater effective 314 pressure on the back, as compared with the front face, caused the piston to move slowly to the front end of the cylinder. The friction, therefore, could not have been appreciable. As regards lubrication Mr. Denton gave an account of his experience with engines which had been cleaned out with ether, and in which no oil whatever had been used for months. The records obtained under such conditions, when compared with data from the same engines using oil in the cylinders, showed no difference worthy of special note. The fact that engines showed less friction under the heavier loads than under the lighter ones Mr. Denton explained by the assump- tion that the various journals, through the reversal of motia.?. of the reciprocating parts of the engines, developed a suc- tion-pump action, drawing in the lubricating oil, and that this action was more vigorous when the engines were fully loaded. CALKING. Calking is something that is not always -done as it should be. In fact, in some sections of the country it is done as it shouldn't be, about as emphatically as it is possible to do any- thing. The thing most particularly referred to in this con« nection, and the practice of which should bankrupt any boilermaker, is known as "split calking." To do calk- ing in the best manner, and as it should be done, the edges of the plates should be planed. They are planed in all first- class shops, and trouble caused by bad calking is something very rare with such work. But of course this refers to new work. Repair jobs, and boiler work turned out of the shops in remote sections of the country where planers are unknown, afford the demon of split calking a chance to get in his most effective work. He rarely neglects a chance that is offered him, Some one may inquire, what is split calking? To which we would reply, split calking consists in driving a thin caulking tool, scarcely one-sixteenth of an inch thick, against the edge of a sheet so that a thin section of the plate is driven in between the two plates, with the idea of making a joint tight. The result generally is that the plates are sepa- rated from the edge of the lap back to the line of rivets, some- times as much as one-thirty-second of an inch, the only bear- ing surface outside of the rivets being the portion split oft from the plate and driven in by the calking tool. This bearing surface may be an eighth of an inch wide, but it is apt to be much less, and no patent medicine yet discovered will keep the seam tight for any lengtli of time. When a boiler thus calked gets to leaking so badly that it can't be 3IS fun, the boiler-maker is sent for, and he usually proceeds td do more split calking, and in a short time the boiler leaks worse than ever. In one instance one of our inspectors examined a boiler and found one of the girth seams leaking badly. It had repeatedly been calked in the above manner; so many times, in fact, had the process been repeated, that there was not enough of the lap to perform another opera- tion on. . He, therefore, gave instructions for putting on a patch, with a special caution to the owner, to whom he ex- plained the cause of the trouble, to allow no split calking to be done on it. On his next visit he examined the patch, and he declares that the boiler-maker had put in on it the worst iob of split calking he ever saw in his life. USEFUL NUMBERS. 3.i4i5926=ratio of diameter to circumference of circle, .7854=ratio of area of circle to square of its diameter. 33,000 minute foot pounds =1 HP. 396,000 minute inch pounds— i HP. 396,000 cubic inches piston displacement per minute of engine wheel would develop i HP. with i Tb. mean effective pressure on the piston. 23,760,000 cubic inches piston displacement per hour of engine developing i HP. with i lb. mean effective pressure on the piston. 859,375 pounds of water per hour at i Tb. pressure per square inch to give i HP. 55 lbs. mean effective pressure at 600 feet piston speed gives I HP. for each square inch of piston area. 0.30i030=natural logarithm 2. 0.477I2I (t 0.602060 <( 0.698970 a 0.778I5I tt 0.845098 u O.Q03090 a 0.954243 a 1. 000000 (C <( 3- i( 4- a 5- <( 6. tt tf /• «< 8. M 9- (( 10. 2.3025851 times natural logarithm gives hyperbolic log ^ arithm. .5000000= sine of 30^ with radius I. .7071068 ^' 45Q " I. .8660254 " 6oC> « I. 9,Goo to 13,000 feet per minute velocity of circular saw him. 27,000 tbs. pcv scjuare inch tensile strength of cast ii'on. 3^^ $0,s. per lineal foot of i incti round wrought iron. 3.368 lbs. per lineal foot of i inch square wrought iron. 40 lbs. per square foot of i Lnch plate wrought iron. 2.45 lbs. per lineal foot of i inch round cast iron. 12 times weight of pine pattern = iron casting. 13 times weight of pine pattern = brass casting. 19 times weight of pine pattern =lead casting. 12.2 times weight of pine pattern = tin .casting. 1 1.4 times weight of pine pattern =zinc casting. .06363 times square of inches diameter, times thickness in liches= weight of grindstone in pounds. .8862 times diam. of circle = side of a square equaling. ,7071 times diam. of circle =side of inscribed square. 1. 1283 times square root of area of circle =diam. of circle. 57^ 2958 in. arc having length = radius .01 745 3 X radius=length of arc i deg. 9.8696044=3. 141 5926'^ = n 2, 1.7724538= v^ (3. 1415926)= vn. 0.497i5=nat. log. 3.1415926. r .3l83i=reciprocal of 3. 1415926=— fi .cxD2778=i^36o=i-36o. II4.59=36o-^3.I4I5926. 3i83Xcircumf.=diam. of circle. 2786^ F. =melting point of iron. :-ioi6° F.=melting point of gold. 1873° F.=melting point of silver. 2160° F. =melting point of copper 3^/ 740^ F.=melting point of zinc. 620^ F, =melting point of lead. 475^ F.=melting point of tin. 537 lbs. per cu. ft. =weiglit of copper. 450 lbs. per cu. ft.=\veight of cast iron. 485 lbs. per cu. ft. =:vveight of wrought iroil. 708 lbs. per cu. ft.=weight of cast lead. 490 lbs. per cu. ft.=weight of steel. 27.684 cubic inches of water per pound at 32° F 27.759 cu. in. water per lb. at 70^ 036 lbs. per cu. in. water at 60^ F. 62.355 lbs per cu. ft. water at 62 ^ F. 59.64 lbs per cu. ft. water at 212 ^ F. .54 lbs. anthracite per cu. ft. 40 to 43 cu. ft. anthracite per ton 49 cu. ft. bituminous coal per ton. 39.3635 inches = I meter. 3.2807 feet = I meter. 1.0936 yards = i meter. 61.02 cubic inches = I meter. 2.113 pints = I liter. 1.057 quarts r== I liter. BUYING OIL AND COAL. There are many establishments which, when buying oil, u'Oal, and such supplies, consider merely the question of first cost irrespective of their economic value. The best is not necessarily the cheapest, nor is it necessarily the dearest. The true economic value is due to the service it will per- form, divided by the price. We will take the case of coal. Some coal will evaporate ten pounds of water per pound of coal under certain condi- tions, and others only seven. In the one case there will be 2240X10=^22,400 pounds of water evaporated, and in the other only 2240X7 = 15,680 pounds, under the same condi- tions. If the first lot sold at $5.25 per ton, and the second at only $5 the first would be the cheapest, for in the one case (including freight and labor in stoking and cost of remov- mg ashes) we would get 22,400-^5.25=4,266.66 ;^ounds of steam per dollar's worth of coal, and in the other only 1 5,680-^5 -=3, 136 pounds of steam per dollar's worth of coal. Not allowing for freight and the cost of removing ashes, and not considering the capacity of the boiler with good coal as compared with its capacity with poor, the first coal would be a scheap at $6.80 per ton as the second at $5 ; or, to put 3i& it tlie other way, the poorer coal ought to be S'' ^^ hjj.SJ per ton to make it as cheap as the better material at $5.25. vVhen the other expenses are taken into consideration, the economy of buying the better coal becomes greater. In the matter of oils : these vary in their lubricating powers, in their coolness of running, and in their durability. We will consider two oils, one at 25 cents per gallon and the other at 30, having the same lubricating power and running equally cool under free feed, but one requiring 100 gallons to keep the friction down to a minimum and the other taking only 75 gallons to effect the same object. The relative economy of these two oils is not as 30 to 25, or as 120 to 100^ but as 30X75=2,250 to 25X100=2,500, or as 100 to 90; that is, the cost of the high-priced oil to effect a given desired condition is only .90 the cost of the poor oil to do the same thing ; then the economy is as 100 to 90. At this rate the better grade of oil would be as cheap at 10X30 ^^33/i cents per gallon, as the cheaper at 25 cents ; or the lower grade would have* to be sold at 9X25 — 22 j^ cents per gallon, to bring its economy down to that of the better grade ; and this without counting freight, which, in many cases, should be added to the invoice price, or time in oiling, which is time lost. NOTES ON PATTERN-MAKING. Never work with a dull tool. Take time to sharpen and put your tools in good order; it saves time in the end. Above all, never use a dull or badly " set " saw. It will ruin your v/ork, sour your temper, and make you disgusted with the whole world. If you are varnishing or polishing a piece of work, have the room or shop Avarm, exclude draught and dust, and don't be in too big a hurry. If you are polishing in the lathe, see to it that ah dust and dirt are removed from the lathe-bed before you com- mence work. ( It is better, when possible, to polish all turned work in the lathe. It always has a better appearance for it. In making patterns for castings, if you have no experience 3^9 you had better consult some person who has had experience. Patterns are difficult things for amateurs to make if they do not understand the principles of molding and founding. White pine or mahogany makes the best work for pat- terns. Lead, brass, copper and sometimes plaster of Paris are used for making patterns; especially is this so for small fine castings. Shellac varnish is the best material for coatijiq; pat- terns. Beeswax may be used for stopping up holes or to cover defects in patterns if it is coated with shellac varnish after- ward. The beeswax will " take " the varnish readily, and will not cling to the -'sand," like ordinary putty. Shellac varnish may be mixed with a little lampblack to give it body and make a black pattern. Sometimes pattern-makers use stove polish or "black lead," as it is called, to finish their patterns. It is applied nearly dry, then polished with a brush. Wood used for patterns must be of the very best finish, straight grained, free from knots or shakes, and well sea- soned. A clean pattern gives a clean casting, and much labor may be saved by making the pattern the right size, and smooth and clean. After patterns have been used they should be kept in a dry plfice, as damp will distort and otherwise injure them. Always make a drawing of patterns before making. Much time and labor will be saved. Where patterns part in the center they should be made to separate easily. Put on your best workmanship when pattern making. AN INTERESTING EXPERIMENT. You think you stand pretty straight, don't you? Well, just back up against the wall of a room and bear against it all over ; you will find there more buckles, short bends an4 offsets between your head and your heels than you had any idea of. While you have your heels against the baseboard, keep them there, and reach over forward and touch your fingers to the floor, if you want a specimen of upset gravity. A steel wire nail mill has just begun work at Hamilton, Ont, The output at present is a ton a day. 320 THINGS TO REMEMBER ABOUT SHAFTING. Don't buy light hangers, and think that they will do well enough, when your own judgment tells you that they will spring. Remember that shafting is turned one-sixteenth inch smaller than the nominal size. Cold-rolied and hot-rolled shafting can be obtained ihe full size. The sizes of shafting vary by quarter inches up to i.iree- and-a-half inches. The ordinary run of shafting is not manufactured longer than from 1 8 to 20 feet. For line shafts, never use any that is smaller than one- and-eieven-sixteenth inches in diameter, as the smallest diameters are not strong enough to withstand the strain of the belts without springing. ) The economical speed of shafting for machine shops has been found to be from 125 to 150 revolutions per minute, and for woodworking shops froni 200 to 300 revolutions. A jack-shaft is a shaft that is used to receive the entire power direct from the engine or other motor, which it delivers to the various main shafts. Keep the shafting well lined up at all times, as this will ward off a breakdown, and avoid a waste of power. Know that the pulleys are well balanced before they are put in position, as a pulley much out of balance is quite a sure method to throw shafting out of line. Look to the pulleys, and see that they have been bored to the size of the shaft, for unless this is done the pulley may be out of center on the shaft and prevent smooth running. If possible, apply the power to a line of shafting at or near the center of its length, as this will enable you to use the lightest possible weight of shafting. Hangers with adjustable boxes will be found to be the most convenient for keeping the shafting in line. Keep your drip-cups cleaned, and Jo not allow them to overflow or get loose. Have a supply of tallow in the boxes ; ni case of acciden- tal heating it will melt and prevent cutting ; this rule, while good for general use, applies particularly to special cases wbeie there is a supposed liability to heating. Never lay tools or other things on belts that are standing Still, for they may be forgotten and cause a breakdown when the machinery is started. Don't attempt to run a shaft in a box that is too large or 32X too small, as you wiU waste time and fail to secure good re* suits. A loose collar held by a set screw will cause the collai to stand askew, and it will cut and wear the box against whick it runs. In erecting a line of shafting, the largest sections should be placed at the point where the power is applied. The diameter can then be gradually decreased toward the extrem- ities remote from this point. Don't put loose bolts in plate couplings, as this will give no end of trouble in cutting, shearing and the wearing away of the bolt holes. Don't think that because your shafting has been weli erected and you oil it regularly, that it will never need any inspection or repairs. Don't try to economize in first cost by having long dis- tances between hangers, for a well supported shaft will always do the best work ; short shafts are the surest to be straight and to remain so. ''^ The length usually adopted for shafting bearings is twice to four tniies the diameter of the shaft, varying with the diameters of '.haft, kind of bearings and the material used in them. Large shafts in the gun-metal or bronze boxes may have bearings only twice their diameter in length. Cast iron bearings up to and including three inch shafts are often made four diameters of the shaft in length, particularly for self- adjusting hangers. If Babbit is used for the boxes, use onlv a good metal; do not adopt the common mixture of tin, antimony and lead. Insist upon having good iron in your shafting, as the bearings will take a finer polish, and you will nut be subject to sudden ruptures. If the strain on a pulley is so great that the set-screws already in will not hold it, do not let them score into the shaft, but put in an extra screw, or cut a key-way and put in a key. The width of a key-v/ay should be one-quarter of an inch for each inch of diameter of the shaft. 'I'he depth of a key-way is one-half its width. 322 WORKSHOP JOTTINGS. To P7'epai'e Zinc for Painting — Apply sulphuric acid and water for a quarter of an hour ; then wash off clean with water and dry. Moisture-Resisting Glue — A glue which is proof againsj moisture may be made by dissolving i6 ounces of glue in 3 pinfes of skim milk. If a stronger glue be wanted, add powdered lime. A Good Lubricator — It may not be generally known that tallow and plumbago thoroughly mixed make the best lubri. cator for surfaces when one is w^ood or when both are wood. Oil is not so good as tallow to mix with plumbago for the lubrication of wooden surfaces, because oil penetrates and saturates the wood to a greater degree than tallow, causing it to swell more. To Prevent Metals Rusting — The following is said to be a good application to prevent metals rusting: Melt i oz. of resin in a gill of linseed oil, and while hot mix with it two quarts of kerosene oil. This can be kept ready to apply at any time with a brush or rag to any tools or implements required to lay by for a time, preventing any rust, and saving much vexation when the tool is to be used again. 7In order that we may better understand the •stupendous amount of labor performed by these tiny works, let us make a pertinent comparison. Take, for instance, a locomotive with six-foot driving wheels. Let its wheels be run until they have given the same number of revolutions that a watch does in one j^ear, and they will have covered a dis- tance equal to 28 complete circuits of the earth. All this a watch does without other attention than winding once every 14: hours. 326 METAL-WORKING DIES AND THEIR QSES. BY HENRY LONG. In the following pages, which have been specially prepared for this work, will be found a condensed description of the commoner kinds of dies now in use for sheet-metal w^ork. There being several kinds of punching presses, I will specify the variety m which each die can be used as I describe it. The commonest in use is the simple cutting-die, and I will describe it first. It can either be made by welding a steel ring of the shape desired on a wrought iron plate, and then dressing the hole out roughly to pattern while hot, or by drilling out a hole of the shape required through a piece of flat steel of proper dimensions, and then dressing it out with files, etc. , to exact size. ^While the former plan is most expen- sive, it is the best in regard to wear and quality of work. Fig. i represents a die of this kind. The forging for this die would be made as I explained above; that is, by welding a steel ring of the shape of tt.e pattern on an iron plate, and cutting the hole through the iron afterward. The punch for this would be made similarly, only that the ring is the shape of pattern outside, and after welding to the iron plate it is trimmed off outside. There is also a shank to be welded on the other side of plate, as nearly central as possible, and large enough to finish up easily to size required. In making this die the two faces are planed off clean, and then the pattern is laid on top face and the die is marked from it. When this is done, it is put in the shaper and planed out to the marks, care being taken to throw the work forward in the chuck to ^ive about 16 in. clearance to the inch, in depth. It is now filed out and champfered off on face, as shown, tffeface being hollowed out 3V' on three or four sides after- ward to give it a shearing edge. It is now ready for tempering. As the tempering requires great care it is very necessary to watch your heat closely, and while making it even, do not heat any higher than necessary, and plunge it carefully into cold soft water with one edge down, keeping it in there until perfectly cold. '^ Now take it out and polish the face and inside well, and reheat very evenly as before until you observe 327 inside the marks and a dark straw color, when you can cool it off, at th«.: is. con- sidered a good temper, and one that will stand wear without breakmg. The punch is pared off on both sides and shank turned up to size, and then the die is laid on it face to face and the shape marked out. Now it is shaped off to the lines and fitted closely in the die, the inside edge of punch being afterward champfered off as shown. This die can be used in any press, and is particularly designed for light metals such as zinc, tin, etc. A flat-cutting die would be made by taking a piece cut from the bar at least i}{" longer and wider than your pattern, and, after planing it, lay your pattern on and mark the hole. Then drill around file out in same way as you do the other. The punch would be made same as last, but without champfering off the edge. This die can be used in any press, and is designed for heavy work, such as hard brass, steel, etc. Sometimes there may be some narrow or weak part in the die which is likely to break out in time, in which case it is economical to insert a plug as shown in Fig. 2. Of course these plugs can be renewed as often as necessary without disturbing the form of the die. For round holes of small size, a steel plug is fitted in a soft steel plate, and the hole drilled and reamed through it, after which the plug is tempered. The punch is simply a socket with a set screw in which round steel of the right size is used, in this way saving any turning or fitting. Sometimes a gang of punches is used, as is shown in Fig. 3, for which a special punch is designed. In this, the shank is a separate piece, and has a dove-tailed groove planed through it. This groove should be from ^^' to }4'^ larger in every way than the dimen- sions you wish to punch. It should also have 3^7,'' draft, or taper endwise to allow of a driving bit on the plate fitted in. This plate should be }4" thick at least. You first drill all the holes in your die in the right position, and after reaming Fig. 3. them out, harden and temper it. You now place this plate, which you have fitted in the shank, on the face of the die in its true position and fasten it securely there. The next thing is to run the drill you used on the Fig. 2. 328 die, through tne die holes, and mark their exact position on this plate. When this is done, remove the die and drill the holes through from these marks, and countersink them from behind. Now, the stripper or guide, which should be about ^" thick, is fastened on in the position you wish it, and marked and drilled in the same way. The wire punches are made by riveting over a head on one end and then driving them in from the back, afterward filing off any superfluous metal which extends above the back. When you have made a gauge and placed it under the stripper, fastening securely, the die will be finished. The punches should be filed to an even face, and then hol- lowed out a little to give more ease in cutting. All the dies mentioned thus far can be used in any ordinary press. V7e will now take up the different kinds of form- ing dies. 1 nere are only two kinds, half- round and square; all others are modifica- tions of these-. The depth of a half-round forming die should be two-thirds of the diameter to give the best results,. and the punch should go down into the groove as shown in Fig. 4. A mandril is necessary to form the work over in the die. A square or box-forming die is simply a square hole of the right size, cut through the die, per- fectly parallel, and with the upper corners rounded a little. If a smooth flat bottom is required it is usual to make thedieofthinest steel, and put a plate under it as in Fig. 5, with a pad and spring, to throw it out. The punch is size of the inside of box, and a close fit. A die for formmg a shape at any angle is simply a groove planed thro' the block and having a punch to fit it. Fig. 6 is a view of a common form of drawing die for deep work. They are used for making caps, cart- ridge cases, etc. It consists of a round disk of steel about J^"deep with a hole the size of shell required bored in it . This hole is well rounded off at the corner, and counter- oored from the bottom with a square, sharp shoulder for stripping the work off the punch after it has passed through the die. A cast-iron holder with set screw is generally used with these dies for convenience in changing. The punch is Fig. 4. Fig. 5. Fig. 6. 329 fitted into a socket in the shank and held by a set screw. It is rounded on the corners to give the metal a better chance to turn up around it. When the punch and die are set the blank is laid on the die, and the punch should be tight enough to carry it through without a wrinkle. If the shell is not long enough after this operation, make a die a little smaller and a punch the same, and after annealing the shells pass them through it. By repeating this operation you can produce shells of almost any length. Sometimes it is necessary to make a die to perform some operation on the edge of a box which has already betxi formed In this case the die is m.ade in such a way that the box can be put on it, thus placing the die on the inside. A hub is made the shape of the box, and with the die dovetailed into its upper side, a hole being bored down through the hub to allow the cuttings to fall through. This hub is fitted into a special holder as shown. The punch is made in the same way as others.^ These dies can be used for any operation that a flat die performs, such as cutting, form- ing, etc. As I have given a description of the different forms of simple dies, I will now explain some double and combination dies. A double die is two distinct dies in one plate, and it may be extended to include three or four, although the work gets complicated in this case, and the economy is doubtful. This xdie may be composed of two cutting dies, or one cut- ting and one forming die, or, in fact, any combination which may seem desirable. It is gen- erally used for cutting dies, such as washers, etc. Fig. 8 shows the plan of one of these dies designed to make a washer. The first punch is the size of the hole in the washer and the second cuts out the washer it- self. The punches are set in a long, flat socket, fastened with screws. The main point in these Fig. 8. a — if-H — 330 dies is to get them correctly spaced so as to cut out all the stock. They can be used in a power or foot press. A com- bination die is one which performs two or more operations in one die. Fig. 9 is one of these, designed to make a black- ing-box cover. In this die the punch comes down and cuts out the blank which is immediately gripped be- tween the two face a and ^, and held firmly enough to prevent wrinkling, but still to allow of its being drawn through and over the form which is in the center of the die. When tne press is on the return stroke, the ring d follows the punch up and pushes the cover off again, w^iile the pad in the punch does the same there, thus having the cover loose on the top of the die. These dies tig. 9. must be operated in a power press, or one specially de- signed for the purpose, and they are more conveniently worked in an inclined than a horizontal press, as the work will then fall off by the force of its own gravity. -t Fig. 10 is a die of the J same class, but with another operation added. It is de- S'igned to make a pepper-box cover, and perforates four holes in it after it is drawn. The punch, as you will per- ceive, is entirely different in its construction. The die is the same, excepting that four cutting holes or dies are drilled in the top of the form LI^fflE '^^ ri :j Fig. 10. 331 or plug, and the inside is bored out to allow the cuttings to fall through. The stub is also bored out for the same reason. In the punch a is the shank, bored out as shown, b is the cutting edge or punch proper ; it is bored or chambered out for the pad c to work in it. ^ is a plate that screws into the top of the punch b^ to act as a back for the pad c to press against, and also as a holder for the four small punches. It has three holes in it, through which short pins work to com- municate the power of spring E to the pad c. i^ is a washer under the spring, and 6^ is a plug or pin that screws in the top of shank, and extends down to the plate z9% il it 12X 126 DX DXX 147 DXXX a a a 168 DXXXX ii il (( 189 5 l^C i DX . DXX. i DXXX 2Q» 15 II 1 63 A a a 189 11 u a 210 a (( a 231 \ DXXXX... frw 6( (( li 252 225 I nU 10 112 The following tai:>ic^ showing the number of pomids pei fe»t m various woo(^, in different stages of dryness : Green. White ash 4^ Gray ash „ . . . 4}^ Birch 5X 3asswood 'X}/ Cottonwood 3^ Cherry ^ Chestnut 4^ Soft elm 4 Rock elm 5 Hickory 5^ Plard maple 5X Bird's-eye maple .... 5^ Curly maple 43^ White oak 6" Red oak K%, ^amwT* J VValnuli. . .^^.^ ^^ .. .. 6 VVhitewoed ^% ipping Thoroughly Kiln dry. air dried. dried. 4 z% 2 4-5 31^ J 2K 4K 4 , 3^, 3 2}4 2>i 3 2K 2/8 4>^ 3H 3 ^ J>^ 2% 2^ 3J^ 3 , ^Yz 4X 3^ A 45^ 4 3J^, 4J^ 31^ 3 4X 3^ 3 ^ 4 3.^ 2^ s 4>^ 4 4^ Z% 3 4 3 23^ 5 4 , 3U 3,'^ 2^ 2% 334 CALIBER AND WEIGHTS OF LEAD PIPES. WEIGHT 1 WEIGHT CALIBER. PER 1 CALIBER. PER FOOT. FOOT. LBS. oz. LBS. oz. 14^ in. tubing 6 1 iX in. aqueduct. . . ^ in. aqueduct .... « ! ex. hght 3 8 light 12 ; light 4 medium I medium 5 strong I 8 strong 6 ex. strong. . . 2 ex. strong, . . 7 8 1/2. in. aqueduct .... 10 134; in. light 3 12 ex. light 12 light 4 8 light I medium 5 8 medium I 4 strong 6 8 strong I 12 ex. strong... . 8 ex. strong. . . 2 8 2 in. waste 3 ^ in. aqueduct. .... 12 2 in. ex. light 4 ex. light I 4 i light 5 light I 12 medium 7 8 medium 2 strong 8 strong 2 8 ex. strong. . . 9 ex. strong. . . 3 2^ in. 3-16 thick. . 8 ^ in. aqueduct. . . . I X thick II ex. light I 8 5-16 thick. . . 14 light 2 y% thick 17 medium 2 4 3 in. waste S strong 3 3-16 thick.. . 9 ex. strong. . . 3 8 X thick 12 ^ in. aqueduct .... I 8 5-16 thick. . . 16 ex. light 2 ^ thick 20 light 2 8 3/^ in. X thick. . . . 15 I in. aqueduct I 8 5-16 thick... 18 ex. light 2 y% thick 21 lignt 2 8 4 m. waste S 1 medium 3 4 X thick 16 1 strong 4 5-16 thick. . . 21 1 ex. strong. . . 4 12 ^ thick 2S 1 iX in- aqueduct 2 7-16 thick.. . 30 1 ex. light 2 8 4X in. waste 6 I %ht 3 5 Tn. waste 8 1 medium 3 12 1 Strong 4 12 1 ex. strong, . . 6 -M 335 WEIGHT OF CIRCULAR BOILER HEADS. Diam. in Thickness of Iron. — Inches. inches. 3-16 . X 5-16 n 7-16 y^ 9-16 i6 II 14 18 21 25 28 32 i8 13 18 22 27 31 36 40 20 17 22 27 Z2> 38 44 50 22 20 27 33 40 47 54 60 24 24 32 40 47 55 64 71 26 28 37 46 S^ 64 75 84 28 32 43 53 65 75 86 97 30 2>7 50 62 74 ^7 100 112 32 42 56 70 84 99 112 127 34 48 64 79 96 III 128 143 36 54 71 89 108 125 142 161 38 60 79 99 120 139 158 179 40 66 88 no 132 154 176 198 42 73 97 121 146 170 194 220 44 80 107 nz 160 187 214 -40 46 88 117 HS .76 204 234 ^62 48 95 127 158 190 222 254 286 50 103 138 172 206 241 276 310 52 112 149 186 224 260 298 335 54 121 160 200 242 281 320 362 5^ 130 172 214 260 302 344 389 58 139 1^5 231 278 324 370 417 60 149 198 247 298 336 396 446 HOW TO CALCULATE THE CAPACITY OF TANKS. In circi^ar tanks, every foot of depth, five feet diameter, ^ves 4^ barrels of 31^ gallons each; six feet diameter, 6^ ►arrels ; seven feet diameter, 9 barrels ; eight feet diameter, 2 barrels; nine feet diameter, 15 barrels; ten feet diameter, 83^ barrels. In the case of square tanks, for every foot of epth 5 feet by 5 feet gives 6 barrels; 6 by 6 feet, 8^1^ bar- ils; 7 by 7 feet, 11)4, barrels; 8 by 8 feet, 15^ barrels ; 9 y Q feet, I9J^ barrels: 10 hy lo feet, 23^4^ barrels. 336 NUMBER OF BOILER RIVETS IN A loo POUND KEG. Length. ^2 9-16 % 11-16 % ^ Inch. Inch. Inch. Inch. Inch. Inch. 990 760 56'^ 450 \ys 875 725 530 415 iX 800 690 490 389 356 228 1/8 760 650 460 370 329 211 l}j 730 625 425 357 290 180 i/s 710 595 505 340 271 174 I'X 690 550 390 325 264 169 Iji 665 530 375 312 257 165 2 630 510 360 297 248 156 2y8 590 500 354 289 237 152 2X 555 490 347 280 232 149 2% 525 475 ZZS 260 219 141 2% 500 440 312 242 211 133 3 460 AIO 290 224 203 127 3X 430 380 267 212 190 115 3X 410 350 248 201 180 108 3^ 395 335 241 192 162 102 4 326 230 184 ' 158 99 4X 312 220 177 150 96 A}2 298 210 171 146 94 aYa 284 200 166 138 !^ 5 270 190 161 135 ^1 5X 256 180 156 130 84 5^, 244 172 151 124 80 5?^ 233 164 145 120 n 6 223 157 140 115 74 6X 213 150 137 III 71 6 207 146 134 107 . 69 6 203 143 129 104 67 7 n8 140 125 100 64 To Bronze Iron Castings. — After havmg thoroughly cleaned the castings, immerse them in a solution of sulphate .A Lopper. The castings will then take on a coa<-ing of cop- •p'-r Then wash thoroughly in water. Copper is said to lose 18 per cent, of its tenacity upoi Deing raised f r om 60^ to 360*^- 337 NUMBER OF "AMERICAN" NAILS AND CUT SPIKES IN A POUND. •l-H _• G bi) i gth ches W) .S2 a^ fl « OJ C *w5 X (—1 .,_, 53 1— < N ^ 3 F 860 1 2 900 iJ4 3 500 650 670 iX 4 300 480 450 500 ^H 5 212 350 300 370 2 6 160 85 240 212 260 2H 7 135 65 190 160 210 2% 8 95 50 135 120 155 2U 9 75 40 3 lO 60 35 115 100 135 i6 3X 12 48 30 100 120 3/^ i6 34 25 80 100 14 4 , 20 24 20 65 85 12 4>^ 30 18 50 70 10 5 40 15 40 60 9 5X 50 12 8 6 60 10 6 7 4;^ 8 4 Clinch-nails weigh about the same as common. Box-nails are made ^ inch shorter than common nails of same sizes. 5 lbs. of 4d or 3^ lbs. of 3d will lay 1,000 shingles. 5^ lbs. of 3d fine will put on 1,000 laths, four nails to the lath. Bricks made from the refuse of slate quarries arc stronger than stone; they stand 7,200 lbs. compression against 6,000 for stone, and 3,200 lbs. for common brick. The cost is from $12 to $20 per thousand. In London 20,000 men earn their living at carpenter work* 4,000 in Paris, and 4,000 in Berhn. Hours in London are 52 j^ per week. 338 WAXING FLOORS. Take a pound of the best beeswax, cut it up into very small pieces, and let it thoroughly dissolve in three pints of turpen- tine, stirring occasionally if necessary. The mixture should be only a trifle thicker than the clear turpentine. Apply it with z. rag to the surface of the floor, which should be smooth and perfectly clean. This is the difficult part of the work, forj if you put on either too much or too little, a good polish will be impossible. The right amount varies, less being required for hard, close-grained wood, and more if the wood is soft and open-grained. Even professional " waxers " are sometimes obliged to experiment, and novices should always try a square foot or two first. Put on what you think will be enough, and leave the place untouched and unstepped on for twenty-four hours, or longer if needful. When it is thor- oughly dry, rub it with a hard brush until it shines. ^ If it polishes well, repeat the process over the entire floor, vj. If it does not, remove the wax with fine sandpaper and try again, using more or less than before, as may be necessary, and con- tinuing your experimenting until you secure the desired result. If the mixture is slow in drying, add a little of any of the common " dryers" sold by paint dealers, japan for instance, in the proportion of one part of the drier to six parts of tur- pentine. )When the floor is a large one, you may agreeably vary the tedious work of polishing by strapping a brush to each foot and skating over it. HOW TO MAKE AN IVORY GLOSS ON WOOD. A most attractive ivory gloss is now imparted to wood surfaces by means of a simple process with varnish, the latter being of two kinds, namely, one a solution of colorless resin in turpentine, the other in alcohol. P^or the first, the purest copal is taken, while for the second sixteen parts of sandarac are dissolved in sufficient strong alcohol, to which are added three parts of camphor, and finally, when all these are dis- solved, they are combined with hve parts of well-shaken Venice turpentine. In order to insure the color remaining a pure white, particular care is essential that the oil be not mixed with the white paint previously put on. The best French zinc paint, mixed with turpentine, is employed, and, when dry, this is rubbed down with sandpaper, following which the varnish described is applied. CARE OF OAK LUMBER. Throughout the civilized world, except in extremely hot countries, one or more species of the oak is found. In this country oak forests abound in almost all the Southern and Central States. In species there are so many that even experienced lumbermen are frequently perplexed to correctly designate to which class a samp'e piece of wood belongs. Ordinarily in the yard trade but two kinds are known- white and red. Among shipbuilders, carriage-makers and machinists may be found live oak, a species of wood that is peculiarly adapted to purposes where immense strength is necessary. The average lumberman, when he talkb about white oak or red oak, is influenced solely by the color of the wood when it becomes partially seasoned. Again and again veterans in the wood-working business have been known to select red oak for white, and vice vej-sa in fact, from a dozen specimens of six different species of oak, they have been unable to correctly name a single sample. Oak is a wood* which calls for unusual and unceasing care ,in its manufacture. The tendency of oak, from the moment an ax is planted in the side of the tree, is to split, crack, and play all sorts of mean tricks on the owner. Such tendencies can be held in hand, and almost absolutely ■)bviatecl, by following certain rules. A thick coat of water- :)ioof paint applied to the ends of the logs is a wise expendi- ure ; it prevents the absorption of moisture. Oak, when piled, should have the ends protected so as to prevent absorp tion of rain and moisture, followed by the baking process of a hot sun Alternate moisture and heat is the prime cause of checks and cracks, and when such defects begui in oak they are bound to increase and ruin otherwise perfect stock. Oak should be stuck as fast as sawed. It is a mistake to permit it to lie in a dead pile even for a single day. Jt is a wood that contains a large amount of acitl, which oozes to the surface as fast as the lumber is sawed, and, if the stock i.s allowed to remain piled solid, it is apt, evcu in a few hours, to cause stain on the surface. The lumber should be stuck in piles not over six feet in width.* The bottom course should be raised two feet from the ground, and a space of five inches left between tlie pieces. It is advisable to follow this rule up to about t?:^ nfth course, when tne space can be gradually diminished to two inches, and continued to the top >f the pile. In this v/ay air has free circulation through the le, and the lumber will dry readily. The pde should ca«H ward the back, so that rain will fallow the iiclination. ;4^ Board sticks not over three inches wide should be used, the front stick placed so as to project a half inch beyond the lumber. This plan permits moisture to gather in the stick, not the lumber. Other sticks should be placed not over foui feet apart, and in building the pile the sticks should be exactly over one another. By this plan, warps, twists and sags are avoided. It is advisable to pile every length by itself. This rule permits more systematic piling, and, in shipping, consign- ments can be made of lengths precisely as wanted. Thick- nesses in piling should never be mixed. Twisted stock is certain to be the result if this advice is ignored. The sap should be placed downward. The draft is up- ward, and any practical lumberman can readily observe the advantage of this advice. Every pile should be well covered ^ith sound culls, the covering so placed as to project beyond all sides of the pile. Raise it a foot from the top course. The piles should not be nearer than twenty inches^apart; twenty-four inches is better. HOW TO SHARPEN A PLANE-IRON. The simple art of sharpening a plane-iron is supposed to De understood by every mechanic, remarks a writer in a contemporary, but there are hundreds of men who cannot do a creditable job in this respect. The common tendency is to round off the edge of the tool until it gets so stunted that under a part of the cutting the tool strikes the work back of the cutting edge. To do the job correctly we will begin at the beginning, and grind the tool properly. First, the kind of wood to be cut must be taken into consideration. Com- mon white pine can best be worked with a very thin tool, ground down even to an angle of 30 degrees, provided the make of the tool will allow it. Some planes will not, for the iron stands so " stunt," or nearly perpendicular, that its grind- ing causes a severe scraping action, which soon wears away the tool. In such cases, from 45 to 60 degrees is the proper angle for plane-iro»% and this, too, is about right for hard- wood planing. < Determine the angle you want on the plane-iron and thea grind to that angle, taking care to grind one flat bevel, and not work up a dozen facets. If the stone be small, say 12 to 18 inches in diameter, the bevel will be slightly concave like the side of a razor, and this is a quality highly prized by many good workmen. In grinding, take care to avoid a "feather edge." If the tool aheady possesses the ri^t ^rilape, grind carefully right up to thi? edge, but not grinding it entirely off. The time to stop grinding a tool is just before the old bevel is ground off. Should the tool need any change of shape, such as the grinding out of a nick or a broken place, then put the edge of the tool against the stone and bring the tool to the de- sired shap^ before touching the bevel. Let the iron lay perfectly flat upon the stone, with a tendency only to bear harder upon the edge of the bevel than U'^on the heel. Move the iron back and forth on the stone as fast as your skill will allow, taking care that the heel of the bevel is not lifted from the stone. As you be- come proficient in whetting an iron, the heel may be lifted from the stone about the thickness of a sheet of paper, or just enough to prevent it from touching. The reason why many carpenters cannot set an edge is because they raise their hand too much, and perhaps rock the tool, thus forming a rounding bevel, the sure mark of a poor edge-setter. The proper way to oil-stone a tool is to continue the grinding by rubbing on the oil-stone until the bevel left by the grindstone is entirely moved and the edge keen and sharp. If this be properly done the tool need not be touched upon its face to the stone, but among a dozen good edge- setters not more than one can do it. It is a delicate opera- tion, and can only be acquired by long practice. Nine times out of ten the average workman is obliged to turn the plane- iron over and wet the face thereof, and here is where many men fail who have done the other things well. By raising the back of the tool only a very little the edge is "dubbed off," and regrinding of the face becomes an immediate necessity. A good stone should " set " an edge on a tool wh» jh will shave off the hair on a person's wrist without cutting the skin ci missing a single hair. VALUE OF MAHOGANY, As is known to every woodworker, mahogany has nc flqnalfor durability, brilliancy, and intrinsic value for any work which requires nicety of detail and elegance of finish. Cherry, which is a pretty wood for effect, and extremely pleasing when first finished, soon grows dull and grimy- looking. Oak, which has been so much used of late, is attractive when first finished, but experience teaches that it does not take many months to change all this, and instead of i^ light, fresh looking interior, one tliat has a dusty appear- •^JOiC^ is presented, which no amount of scraping and re- 34^ caking will restore to its original beauty. What applies lo in this yet more applicable to ash. Mahogany, however, seems to thrive best under the condi- tions which are detrimental to these other woods. At first of a light tone, it grows deeper and more beautiful m color with age, and although its first cost is more than these other woods, yet its price is much less than is popularly supposed ; and the only objection urged against it has been cost. What is more valuable, however, and what makes mahogany in reahty a less costly wood, is the fact that, unlike cherry, oak or ash, it is easily cleaned, because it is impervious to dust or dirt, while it does not show wear, and instead of growing duller, grows brighter and more pleasing in appearance. While first cost is more than that of cherry, oak or ash, it is nevertheless true that the judgment of many men has led them to regard mahogany as the cheaper wood when its dura- bility and cleanly qualities are considered, and to-day it takes |bnt rank in first-class material. POLISHING GRANITE. The form is given to the stone by the hands of skilled masons in much the same way as is done with other stone of softer nature. Of course, the time required is considerably preater in the case of granite as compared with other stones. If the surface is not to be polished, but only fine-axed, as it IS called, that is done by the use of a hammer composed of a number of slips of steel of about a sixteenth of an inch thick, which are tightly bound together, the edges being placed on the same plane. With this tool the workman smooths the surface of the stone by a series of taps or blows given at a right angle to the surface operated upon. By this means the marks of the blows as given obliquely on the surface of the stone are obliterated, and a smooth face produced. Polishing is performed by rubbing, in the first place, with an iron tool and with sand and water. Emery is next applied, then putty with flannel. All plain surface and molding can be done by machinery, but all carvings, or sur- faces broken into small portions of various elevations, are done by the hands of the patient hand-polishers. The operation of sawing a block of granite into slabs tor panels, tables or chimney-pieces is a very slow process, the late of progress being about half an inch per day of ten hours. The machines employed are few and simple; they are tech- nically called lathes, wagons and pendulums or rubbers. The lathes are employed for the polishing of columns, the wagons 343 for flat surfaces, and the pendulums for molding and such flat work as is not suitable for the wagon. In the lathe the column is placed and supported at each end by points upon which it revolves. On the upper surface of the column there are laid pieces of iron segments of the circumference of the column. The weight of these pieces of iron lying upon the column, and the constant supply of the lathe-attendant of sand and water, emery or putty, according to the state of finish to which the column has been brought, constitute the whole operation. While sand is used during the rougher state of the process these irons are bare, but when using emery and putty, the surface of the iron next to the stone is covered with thick flannel. The wagon is a carriage running upon rails, in which the pieces of stone to be polished are fixed, having uppermost the surface to be operated upon. Above this surface there are shafts placed perpendicularly, on the lower end of which are fixed rings of iron. These rings rest upon the stone, and , -when the shaft revolves they rub the surface of the stone. At the same time the wagon travels backward and forward upon the rails, so as to expose the whole surface of the stone to the action of the rings. The pendulum is a frame hung upon hinges from the roof of the workshop. To this frame are attached iron rods, moving in a Horizontal direction. In the line upon which these rods move, and under them, the stone is firmly placed upon the floor. Pieces of iron are then loosely attached to the rods, and allowed to rest upon the sur- face of the stone. When the wdiole is set in motion, these irons are dragged backward and forward over the surface of the stone, and so it is polished. When polishing plain sur- faces, such as the needle of an obelisk, the pieces of iron are flat ; but when we have to polish a molding, we make an extra pattern of its form, an«d the irons are cast from that pattern. IN FAVOR OF SMALL TIMBER. The statement that a 12x12 inch beam, built up of 2x12 planks spiked together, is stronger than a 12x12 inch solid tim- ber, will strike anovice as exceedingly absurd. An authority on the subject says every millwright and carpenter knows that it is so, whether he ever tested it by actual experience or not. The inexperienced will fail to see why a timber will be stronger simply because the adjacent vertical longitudinal portions of the wood have been separated by a saw, and if this were the only thing about it, it would not be stronger. 344 but the old principle that a chain is no stionger that its weakest link comes into consideration. Most timbers have knots in them, or are sawed at an angle to the grain, so that they will split diagonally under a comparatively light load. In a built-up timber no large knots can weaken the beam except so much of it as is compc3ed of one plank, and planks whose grain runs diagonally will be strengthened by the other pieces spiked to them. VALUABLE ARTESIAN WELLS. Two artesian wells recently sunk in Sonoma Valley, Cal., are considered to be worth not less than $10,000 each. One of them flows 90,000 gallons of water per day, and the other 100,000. The cement by which many stone buildings in Paris have been renovated is likely to prove useful in preparing the foundations for machinery. The powder which forms the basis of the cement is composed of two parts of oxide of zinc, two of crushed limestone and one of pulverized grit, together with a certain proportion of ochre, as a coloring agent. The liquid with which this powder is to be mixed consists of a saturated solution of six parts of zinc in com- mercial muriatic acid, to which is added one part of sal-ammo- niac. This solution is diluted with two-thirds of its volume of water. A rnixture of one pound of the powder to two and a half pints of the liquid forms a cement which hardens quickly, and is of great strength. Large cylinders of window-glass are now cut by encircling the cylinder with a fine wire, which is then heated to redness by an electric current, and a drop of water being allowed to fall upon the hot glass a perfectly clean cut is obtained. The old method was to draw out a fiber of white-hot semi- molten glass from the furnace by means of tongs, and to wrap it round the cylinder. The Hudson Bay Company, which was incorporated 225 years ago, is the oldest incorporated company. The grindstone quarries along the shores of the Bay of Fundy are developed when the tide is down. The best ma- terial is down low in the bay. Some fine pearls were recently discovered in Tyrone (Ire- land) rivei'S. 345 \A^OODEN BEAMS. Safe Load. Uniformly Distributed, for Rectan* gular White or Yellow Pine Beams one inctl thick, allowing 1,200 lbs. per square inch fibre strain. To obtain the safe load for any thickness, multiply the safe load given in table by the thickness of beam. To obtain the required thickness for any load, divide by the safe load for i inch given in table. If DEPTH OF BEAM. 6" Lbs. 7" 1 8" 0" Lbe. 10^' Lbs. 11" Lbs. 12"! 13'' 14// 15" 16" r«6t Lb^ Lbs. Lbs. lbs. Lbs. Lbs. ■Lbs. ^ 960 1310 1710 2160 2670 3230 3840 4510 5230 6000 6830 6 800 1090 1420 1800 2220 2690 8200 3760 4360 5000 5690 7 690 930 1220 1540 1900 2300 2740 3220 8730 4290 4880 8 600 820 1070 1350 1670 2020 2400 2820 3270 8750 4270 9 530 720 950 1200 1480 1790 2130 2500 2900 3330 3790 10 480 650 850 1080 1330 1610 1920 2250 2610 zm 3410 11 440 590 780 980 1210 1470 1750 2050 2380 2730 3100 12 400 540 710 900 1110 1340 1600 18S0 2180 2500 2840 13 370 500 660 8^0 1030 1240 1480 1 1730 £010 2310 2630 14 340 470 610 m 950 1150 1370 • 1610 1870 2140 2440 16 320 440 570 720 890 rd80 1280 ! 1500 1740 2000 22S0 16 300 410 530 680 830 1010 1200 1410 1630 1880 2130 17 280 880 500 640 780 950 1130 1330 1540 1760 2010 18 270 860 470 600 740 900 1070 11250 1450 1670 1900 19 250 340 450 570 700 850 1010 1190 1380 1680 1800 20 240 830 430 540 670 810 960 1130 1310 1500 1710 21 230 .310 410 510 630 770 910 1070 1240 1430 1630 22 220 300 390 490 610 730 870 1020 1190 1360 1550 23 210 280 370 470 580 700 830 980 1140 1300 1480 24 200, .^70 360 450 560 670 800 940 1090 1250 ^200 1420 25 190 260 340 430 530 650 770 900 1050 1370 26 180 260 830 420 510 620 740 870 1010 1150 1310 27 180 240 320 400 500 600 710 830 970 1110 1260 28 170 230 800 890 480- 680 690 800 930 1070 1220 29 170 230 290 870 460 660 660 780 900 1030 1180 34^ WEIGHT OF A CUBIC FOOT OF SUBSTANCE. Average Names of- Substances. 'Weight. ■ Its. Anthracite) solid, of Pennsylvania, - - * - 93 " broken, loose, - - . - # 54 *• • *• moderately shaken, - . - 58 ** heaped bushel, loose, . - - ^ (80) Ash, American white, dry, --» * ^ - 38 Asphaltum, ....*-,•- 87 Brass, (Copper and Zinc,) castt * « • * • 604 « rolled, - - - .' • *^ " - 624 Brick, best pressed,^ - - • •? -» -s - 160 *' common hard, - - - * • •» 126 *' soft, inferior, .---..- 100 Brickwork, pressed brick, - - • - ' 140 ordinary, - - - - ^ -' : - 112 Cement, hydraulic, ground, loose, American, Rosendale, 66 *l « " . " ** Louisville, 60 •* " « " English, Portland, - 90 Qherry, dry, * -- - -x- -^^42 Chestnut, dry, - . - - - - - .- » 41 Coal, bituminous, solid, - 7 - * - - 84 " " broken, loose, ^ - % - * .49 " ** heaped bushel, loose, ^- - - (74) Coke, loose, of good coal, - .'- ■? -. * 27 '• ** heaped bushel, -■, - * / * " * (SSj Copper, cast, - ^ - . , - ,^ ^ - , * 642 rolled, . - .. - ^ • 543 Earth, common loam, dry, loose, - - • "^ * 76 *' " " *' moderately rammed, 95 " as a soft flowing mud, - ' * • 108 ^bony, dry,» .*•.♦« 76 Eim, dry, • * ^ * •, • • 35 Flint, -^ -- - . ^ «' 162 Glas!;, common window^ *j ^ w ' 157i 347 WEIGHT OF SUBSTANCE. (CONTINUED.) Names of Substances. . wei.gbt Lba Gneiss, common, - 168 Gold, cast, pure, or 24 carar. 1204 " pure, hammered, . « . - . -1217 Granite, 170 Gravel, about the same as sand, which see. Hemlock, dry, . . - • - • • - 25 Hickory, dry, - . ^ 53 Hornblende, black, - . - . - , - 203 Ice. , - . - 58.7 (ron, cast. - - - 450 " wrought, purest, - . - - - - 485 " " average, - - - - - - 480 Ivory. 114 Lead, . - - 711 Lignum Vitae, dry, .--.--- 83 Lime, quick, ground, loose, or in small lumps, - «• 53 " " " thoroughly shaken, - - 75 " " •• " per struck bushel, - - (66! Limestones and Marbles, ------ 108 " " loose^ in irregular fragments, - 96 Mahogany, Spanish, dry, - - - - - '' 53 Honduras, dry, - - . - - - 35 Maple, dry, •- 49 Marbles, see Limestones. Masonry, of granite or limestone, well dressed, - 165 •' mortar rubble, ----•. 154 " dry •• (well scabbled,) - * 138 " sandstone, well dressed, .... I44 Mercury, at 32° Fahrenheit, - . , ► . 849 Mica, 183 Morlar, hardened, •<..... 103 Mud, dry, close. - 80 to 110 " wet, fluid, maximum, --...- 120 Oak, live, dry, - - - ^ , • - , ♦ 59 348 WEIGHT OF SUBSTANCES. (CONTINUED.) Names of Substances. Weight Lte. Oak, white, dry, -----.. 52 *♦ other kinds,- 32 to 45 Petroleum, ---.--.-- ,55 Fine, white, dry, --.-..-25 " yellow. Northern, -...-. 34 ** " Southern, - - . . . - 45 Platinum, - -- - - • . - 1342 Quartz, common, pure, ---.-.. I65 Rosin, --_---. .-69 Salt, coarse, Syracuse, N. Y- ... . - - 45 " Liverpool, fine, for table use,\ - - - i. 49 Sand, of pure quartz, dry, loose, - - - 90 to 106 '* well shaken, 99 to 117 *' perfectly wet, ----- 120 to 140 Sandstones, fit for building, - - - - - 15X Shales, red jor black, '-.---. 102 Silver, --- 655 Slate, - . . - ." - . - - 175 Snow, freshly fallen, - - - - ^ 6 to 12 " moistened and compacted by rain, - - 15 to 50 Spruce, dry, -^- - - > - -- 25 Steel. -------..- 490 Sulphur, -,- -- - ^ - . 125 Sycamore, dry, - - - -- - ^ -, 37 Tar, - - - _ - - - ... 62 Tm, cast, -^* - ^ - 459 Turf or Peai, dry, unpressed, - - - - 20 to 30 Walnut, black, dry, - - - - - - .- 33 Water, pure rain or distilled, at 60° Fahrenheit, - 62>^ '• sea, -- r. - - - - -64 Wax, bees, - - ,. - . . . . 60.5 Zinc or Spelter, '--- 437 Green timbers usually weigh from one-fifth to one-half more than dry. 349 ROUND CAST IRON COLUMNS.—Safe Load in Tons of 2,000 pounds ; safety, 6. — These tables are based on columns made of the best iron, perfectly molded and with both ends turned. « * Oltisill B Diameter, 3 in. J^in. 5iin. lin. 44,070 69,890 71,190 »H,»94 53,535 63,636 34,579 46,992 55,859 «0,i!31 41,083 48,835 26,26S 35,698 42.433 22,812 31,001 36,851 19,844 26,967 32,056 17,339 23,564 28.010 15,147 20,694 24,630 13,402 18,213 21,650 11,785 16,123 19,223 10,469 14,335 17,097 9,453 12,84 7 15,271 Ontsidf ) Diameter r, 6 in. J^in. Uin. lin. ' 79,100 141,250 113,000 74,118 132,353 105,833 68,99« 123,207 98,566 63,886 114,082 91,266 68,951 105,270 84,216 64,261 96,895 7 7,516 49,875 89,062 71,250 45,826 81,832 65,466 42,105 7 5,187 60,150 88,710 69.125 55,300 85,618 63,603 50,833 32,830 58,625 46,900 30,298 54.I(K{ 43,283 28,003 50,006 40,005 25,931 46,306 37,04 5 24,056 42,957 34,366 Ontsid B Diamete r, 7 in. 5i in. lin. V4 in. 166,110 212,440 255,380 158,664 202.917 24 3.933 151,086 193,226 232,282 143,283 183,37 5 220,4 40 135,769 17 3,636 208,783 128,198 163.954 197,094 120,936 154,667 185.930 113,948 145,730 175,186 107,824 137,258 165.002 101,062 129,250 1 55,3 7 5 95,123 121,654 146,24 4 89,567 114,548 137,701 84,27 5 107,780 129,565 79,380 101,520 122.040 74,798 96,660 114,995 70,589 .90,27 7 108,525 66,635 85,220 1(^2,458 02,930 80.4 82 W6,750 6 7 8 9 10 11 12 13 14 1 5 16 17 18 19 20 21 22 23 8 9 10 11 12 18 14 15 16 17 18 19 20 21 22 23 24 2.^ Outside Diameter, i in. l^ in: 61,02(H 56,140 51,246 46,552 41,858 37,912 33,885 30,701 27,476 25.000 22.464 20,511 18,557 U in. 1 in. 85,880 106,220 79.202 98,020 7 2,124 89,206 65,968 82,035 58,912 7 2,865 53,303 65,925 4 7,690 58,985 42,681 53,011 3S,K7 1 4 7,830 34,794 43.167 31.616 39,104 28,567 ;{5,504 26,1 !8 32,304 Outside Diameter,^ in. 2£in. lin. 140,120 177,410 132,782 168,120 125,253 158,587 117,676 148,993 109,945 139,205 103,021 130.438 96,119 121,700 89,612 1 13,448 83,514 105.7 39 77,810 98,517 72,532 91,835 67,633 85.632 63,094 79,886 58,962 7 4,653 55.131 69,803 51,684 65,312 48,348 61,21 5 45,365 57,4 38 V4 in. 210,180 199,174 187.880 176,514 164.908 154.532 144,179 134.403 125,271 1 l(>.715 IOS,79S 101.449 94.(142 88.443 82,69 7 77,376 7 2,523 68.048 Outside Diameter, 8 in. K in. 193,230 185,6 71 177,942 170,110 162,279 154,359 146,700 139,655 132,552 125,787 119.323 1 13,15(» 107.3(^2 101,796 96,580 -91.656 /87.009 82.695 I in. 248,600 238,876 228.t»32 218,856 208,780 198,(;38 188,738 179.674 170,535 161.832 153.516 145,574 138.050 130,966 124.252 /4 in. 299,450 287,73 7 2 7 5,759 263.622 251.485 2 3 '.1.2 6 S 227.343 2I(>.42.. 205.4 17 194,U34 1S4.9i: 17 5,350 166,487 15 7.754 14 9.672 14 2.040 I34.s:{'» I2s.l.i» 350 BOUND CAST IRON COLUMNS — (Continued). i Oatside Diaftieter, 16 in. t a •9' OnUide Diameter, 16 in. 5 liD ly^in. ,;2in., 134 m. 2 in. 2)6 in. )15 496,974 718,793 922.584 16 772,129 9ft3,648il,198,139 IIS 486,727 703,97 2 903,958 17 757.143 974,78511,175,918 17 476,259 688,833 884.513 18 741,996 955.168 1,161,880 18 465,654 673,666 864.910 19 726,521 985,897 1,127,623 J% 464,978 658,045 84 4.980 20 711,042 916,3121,103,848 20 444,242 642,625 825,050 21 695,394 895,149 1.079,067 21 433,467 626,940 805.038 22 679,610 874.750 1,064,674 22 422,736 611,419 785.108 23 664,031 854.795 1,030,400 23 412,005 695,898 764,178 24 648,452 834.740 1,006.226 24 401,405 680.568 7 4 5,493 25 632.941 814.778 982,156 25 800,938 565,429 726,054 26 617,667 7 94,982 958.299 26 880,559 550.417 706,777 27 602,329 775,867 984,657 27 870,400 635,733 687,909 28 587,296 756,016 911,328 2H 360.240 521,220 669,286 29 572,637 737,017 888.366 29 850,565 507,035 651.071 80 557,983 548,702 718,281 866,841 SO 840,933 493.106 633,183 31 699.918 843,681 «S1 880.921 479,492 615,704 32 529.694 681,866 822,34 6 664,186^ 800,033 82 822.329 466.198 596,633 33 26 516,960 Outside Diameter, 17 in. Outside Diameter, 17 in. IHin. 825,852 1 2in: 2Km. 1)6 in. 686.503 2 in. 2}i in. J'' ,065.026 1,286,84 4 885,856 1,070,368 1h 809,752 1 ,046,798 1.263,012 27 671,018 865,876 1,046,216 iu 795,333 1 ,026.l98|l,240.039 28 665,753 846,176 1.022,416 20 7 79,994 1 .006,495 1.216,125 29 640,634 826,667 998,841 21 764,610 986.515:1,101,982 30 626,661 807,846 976,496 22 748,952 966.439,1.167.726 31 610.907 788,807 962,492 28 788,832 946,27 9,1,1 43,355 32 596.4 55 769,645 929,944 24 717.618 22<(,006|K1 18,871 33 582.132 7 44,267 907.787 26 702,060 90a,98i;i.094,615 84 566.206 730.626 882.798 NEW STEEL .RAILS USED AS LINTELS GR GIRDERS. 6afc load in tons of 2000 lbs. =^ Length [ 2 52 lb. rail, per yardjl0.7oj 7.00 60 )b rail, ycr yard'l2. 8.00 5 65 4 75 Deflection in inches'o.045|o O'lOO 07 5 0.090 5.0O! 1.2. 3.50 3. 2.7- 4.O0I 3 50, 8. 125 170 Dctlectioniu Inches 0.47 6^ 4 5u 0.226 2.60 2.70 OSOO 536 O.Om'0. 7300.830 0.93a' j5i AREAS OF CIRCLES. Advancing by Eighths. AREAS. .0 .7854 3.141C 7.068 12.56 19.63 28.27 38.48 50.26 63.61 78.54 95,03 113,0 132,7 153.9 176.7 201.0 226.9 254.4 283.5 314.1 « ] i 346 3 380.1 415.4 452.3 490.8 530.9 572.5 615.7 660.5 706,8 754.8 804,3 8.55.3 907. 9 962.1 1017.9 1075.2 1134.1 1194.6 1256. f-\ 1320. A 1385.1 J452.2 1520.5 1590.4 .0122 .9940 3.546 7.669 13.36 20.62 29.46 39.87 51.84 65.39 80.51 97.20 115.4 135.2 156.6 179.6 204 . 2 230 3 258.0 287.2 318.1 350.4 384.4 420.0 457 1 495.7 536.0 577.8 621.2 666.2 712.7 760.9 810.6 861.8 914.7 969.0 1025.0 1082.5 1141.6 1202.3 1264.5 1328.3 1393. 7 1460.7 1529.2 1599.3 .0490 1.227 3 . 976 8.295 14.18 21.64 30.67 41.28 53.45 67.20 82.51 99.40 117.8 137.8 159. i 182.6 207.3 23 J. 7 261.5 291.0 322.0 354.6 388.8 424.5 461.8 500.7 541.1 583.2 626.7 671.9 718.6 767.0 816.9 868.3 921.3 975.9 1032.1 1089.8 1149.1 1210.0 1272.4 1336.4 1402.0 1469.1 1537.9 1608.2 .1104 1.484 4.430 8.946 15.03 22.69 31.91 42.7; 55 . 08 69 . 02 84.54 101 6 120.2 140.5 162.2 185.6 210.5 237.1 265.1 294.8 326.0 358.8 393.2 429. 1 466. 6 505. 7 546.8 588.5 632.3 677.7 724.6 773.1 823.2 874.9 928.1 982.8 1039.2 1097.1 1156.6 1217.7 1280.3 1344.5 1410.3 1477.6 1546.6 1617.0 .1963 1.767 4.908 9.621 15.90 23.75 33.18 44.17 56.74 70.^8 86.59 103.8 122.7 143.1 165 1 188.6 213.8 240.5 268.8 298.6 330. 363.0 397 6 433.7 471.4 510.7 551.5 593.9 637.9 683.4 730.6 779,3 829.6 881.4 934.8 989 8 1046.3 1104.5 1164.2 1225.4 1288.2 1352. 1418. 1486. 1555. 1626.0 .3068 2.073 5.411 10.32 16.80 24,85 34.47 45.66 58.42 72.75 88.66 106.1 125,1 145.8 167.9 191.7 217.0 243,9 272:4 302.4 334.1 367.2 402.0 438.3 476.2 515.7 556.7 599.3 G43.5 689.2 736.6 785.5 836.0 888.0 941,6 996,8 1053.5 1111,8 1171,7 1283.2 1296.2 1360.8 1427.0 1494,7 1564.0 1634 . 9 'H .441; 2,405 5.939 11,04 17,72 25.96 85, 78 47.17 60. J3 74.66 90.76 108.4 127.6 148.4 170.8 194.8 220.3 247.4 276.1 306.3 338.1 371.5 406.4 443.0 481.1 520.7 562.0 604.8 649.1 695.1 742.6 791.7 842.4 894.6 948.4 1003.8 1 060. 7 1119.2^ 1179.3 1241.0 1304.2 1369.0 1435.4 1503.3 1572.8 1643.9 •% .6013 2.7(il 6.491 11.79 18.06 27.10 37,12 48.70- 61.86 76 58 92. 8« lie, 130. 151. 173. 19-7. 223,6 250.9 279.8 310.2 342.2 375.8 410.9 447.6 485.9 525.8 567.2 610,2 654.8 700.9 748.6 798.0 848,8 901.3 955,3 1010.8 1068.0 1126,7 1186,9 1248.8 1312,3 1377.2 1443.8 1511.9 1581.6 1652.9, 352 CIRCUMFERENCES OF CIRCLES. Advancing by Eighths. CIRCUMFERENCES CO ' .0 .^ ■hi .H ■M .56 .H .T^ € .0 -3927 .7854 1.178 1.570 1.963 2.356 2.748 1 3.141 3.534 3.927 4.319 4.712 5.105 5.497 5.890 2 6.283 6.675 7.068 7.461 7.854 8.246 8.639 9.032 8 9.424 9.817 10.21 10.60 iO.99 11.38 11.78 12. )7 4 12. 5*5 12.95 13.85 13.74 14.13 14.52 14.92 15.31 6 15.70 16.10 16.49 16.8.S 17.27 17.67 18.06 18.45 6 18.84 19.24 19.68 20.02 20.42 20.81 21.20 • 35.73 86.12 36.52 36.91 37.30. 12 3r.69 38.09 38.48 38.87 39.27 39.66 40.05 40.44 13 40.84 41.28 41.62 42.01 42.41 42.80 43.19 43.. 58 14 43.98 44.37 44.76 45.16 45.55 45.94 45.33 46.73 15 47.12 47.51 47.90 48.30 48.69 49.08 49.48 49.87- 16 50.26 50.65 51.05 51.44 51.83 52.22 52.62 53.01 17 53.40 53.79 54.19 54.58 54.97 55.37 55.76 56.15 18 56.54 56.94 57.33 57.72 58.11 58.51 58.90 59.29 19 59.69 60.08 60.47 60.86 61.26 61.65 62.04 62.43 SO 62.83 63.22. 66.80 ' 68.61 64.01 64.40 64.79^ 65.18 65.58' 21 65.97 66.75 67.15 67.54 67.93 68.82 68.72 22 69.11 69.50 69.90 70.29 70.68 71.07 71.47 71.86 23 72.25 72.64 73.04 73.43 73.82 74.22 74.61 75.00 24 75.39 75.79 76.18 76.57 76.96 77.86 77.75 78.14 25 78.54 78.93 79.32 79.71 80.10 80.50 80.89 81.28 26 81.68 82.07 82.46 82.85 83.25 83.64 • 84.03 84.43 27 84.82 85.21 85.60 86.00 86.39 86.78 87.17 87.57 28 87.96 88.35 88.75 89.14 89.53 89.92 90.82 90.71 29 91.10 91.49 91.89 92.28 92.67 93.06 93.46 93.85 SO 94.24 94.64 95.03 95.42 95.81 96.21 96.60 96.99. 81 97.89 97.78 98.17 98.57 98.96 99.35 99.75 100.14 82 100.53 100.92 101.32 101.71 102.10 102.49 102.89 108.29 88 103.67 104.07 104.46 104.85 105.24 105.64 106.03 106.42 84 106.81 107.21 107.60 107.99 108.89 108.78 109.17 109.56 85 109.96 110.35 110.74 111.18 111.53 111.92 112.31 112.7V 86 113.10 113.49 113.88 114.28 114.67 115.06 115 45 lis. 85 87 116.24 116.63 117.02 117.42 117.81 118.20 118.61 118.99 88 119.88 119.77 120.17 120.56 120.95 121.34 121.74 122.13 89 122.52 122.92 123.31 123.70 124.09 124.49 124.88 125.27 40 125.66 . i 126.06. 126.45 126.84 127.24 127.63 128-02 128.41 41 128.81 129.20 127.59 129.98 130.88 130.77 [Si.f^^ m.70 42 181.<95 132.34 182.78 133.13 133.52 133.91 134.30 43 135.0ft . 138.25. 135.48 135.87 136.27 136.66 137.05 137.45 137.84' 44 138.62 189.02 139.41 139.80 140.19 140.59 140.98 4*> 141.87 141.76 142.16 14?. 55 142.94 143.34 143.73 \M.y9 353 WEIGHT OF CAST IRON COLUMN PER LINEAL FOOT OF PLAIN SHAFT. 2 3 4 4H8 6 6)6 I 8 9 > 10 10'/^ 11 llj^ 12 12H 13 13»^ 14 15 16 i: 18-. ly 20 THICKNESS OF METAL. 'Ain. 4.8 55 9.2 10.4 11.7 12.9 14.1 15 3 16 6 17 8 19 20.2 21 5 22 7 23 9 25.2 28 4 27 6 28 8 %in, V^in. 1 18 91 24 5 7 4 12 3 14 17,2 19.fi 22 1 8 4 9.2 11 5 12 9 27.8 29 5 31 9 29.9 39 1 in. %in. lin 16.6 20.3 23. 9j 27.6 31 3 35 38 7 42 3 46 34 4 42 2 49 36 8 45 39 3; 4>^ 41 7' 51 44.2: fA 46 61 51 49 l! 60 51 6 54 8 56 5 58 9 63 53 4 60 '64 4 14.71 19 6 24.6 29.5 34 4 39 3 44 2 49 1 54 61 58 9 9 63 8; IHin. V4in. '8 71 81 82 75 5 79 2 82.8 72 9 88.5 46 5' 61 4 75 9 90 2 _.^ I 63 8 79 93 9 3 82 .7 85 II 97 6 2il01 2 61 2 65 5 104 108 112 117 71 21 88 21104 9 121 76 1 94 3112 3 129 81 O'lOO 5ill9 7 86 9)J06 6!l27 90 81112 95 7 118 81134 4 91141 'i 155 164. 78 5 83 5 88 4 93 3 98 2 103 1 108 112 9 117 8 122 7 127 6 132 5 137 5 147 3 1.57 1 166.9 178 7 186.5 37.3 42.6 48^3 53.9 69. 4! 64 9 70.4 75 9 81.5 87 oi 92 51 08 103 5 100 1 114 6j 120 1' 126 6i 131.21 138 7 142 2 147 7 153 2 164 6 175 3! 186 i 197 4' 208 01 39 9 VAlD. 46.0 58.3 64.4 70.6 76 7 82.8 89 a5 1 101 2 107 4! 113..ii no 125 8 131 9 138 1 144 2 15(J 3 156.5 162 6 168 18) 01 1V>3 3 205 6 217 8 230 1 l%in. 2 In 81 -. 88 4|.. 95 7I . 10» 1 110.5 ir 125 2 132 5 139 9 147 3 1.5i:6 162.0 133. 2f. 141 150 167 176 184 71 1.^7 t 3. 166 y 9; 176 T 5 J8C.5 1! 196 3 7; 20«i 2 169 41 193 3: 216 9i 225 8 176 184 1 191 4 198 8 213 5 238 3 243 t^l 7 274 4 201 210 219 ;V 2a5 6 ll 245 4 6 2.V) •* 2tt? 279 296 313 274 VI 'OH 5 314 1 IfWi 4 Increase IN Weiubt foa 'A »N Increase in Diameter «1D. J 8 2.5 3 7 '/i in. 1 in ) I. '-8 in. ix.iin. 1 l>iin. U4ln 2 in. >a 2 4 9 5^ 6 1 7 4 8 6 9.8 354 Weight of Square or Rectangular Cast Iron Col* umn Shafts Per Lineal Foot. Example : Column 6" X lo'' X i' 6"X \o" ~ i6" X 2 = 32. Following out line on which 32 is found in left hand column to column headed i'\ we find the weight per foot to be 87.5 pounds, which, multiplied by 10' i" == 875 pounds. A ivi e:ta L.. < 1 1 V lUh %•• 2i" Vb!' 1" irs" !%•■ \w IM" 2" 12 18.6 22.5 26.4 21.1 25.8 30.5 23.3 28.7 84.2 25.0 31.3 37.5 26.4 33.4 40.4 27.3 35.1 43.0 28.1 37.5 46.9 14 16 49.2 60.0 18 30.3 35.2 39.7 43.8 47.4 50.8 66.3 60.2 62.5 20 34.2 39.8 45.1 50.0 64.6 68.6 65.6 71.1 76.0 22 38.1 44.5 60.6 66.3 61.6 66.4 75.0 82.0 87.5 24 42.0 49.2 56.1 62.5 68.6 74.2 84.4 98.0 100.0 26 45.9 53.9 61.6 68.8 75.6 82.0 93.8 103.9 112.5 28 49.8 68.6 67.0 76.0 82.6 89.8 103.7 114.8 125.0 30 53.7 63.3 72.5 81.3 89.6 97.7 112.6 126.8 187.6 32 57.6 68.0 77.9 87.6 96.7 106.5 121.9 187.7 160.0 84 61.5 72.7 83.4 93.8 103.7 113.3 131.3 147.7 162.5 86 65.4 77.3 88.9 100.0 110.7 121.1 140.6 168.6 176.0 88 69.8 82.0 94.3 106.3 117.8 128.9 150.0 169.5, ; 187.5 40 73.2 86.7 99.8 112.6 124.8 186.7 169.4 180.6 200.0 42 77.1 91.4 105.3 118.8 131.8 144.6 168.8 191.4 212.6 44 81.0 96.1 110.8 125.0 138.8 162.3 178.1 202.3 226.0 46 84.9 100.8 116.2 131.3 146.9 160.2 187.5 213.3 287.5 48 88.8 105.5 121.7 137.6 152.9 168.0 196.9 224.2 260.0 60 92.8 110.2 127.2 148.8 159.9 175.8 206.3 235.2 S62.6 62 96.7 114.8 132.6 160.0 167.0 188.6 215.6 246.8 276.0 64 100.6 119.6 138.1 166.8 174.0 141.4 225.0 267.0 287.6 66 104.5 124.2 148.6 162.5 181.0 199.2 234.4 268.0 300.0 68 ?08.4 128.9 149.0 168.8 188.1 207.0 243.8 278.9 812.6 60 112.3 138.6 154.6 176.0 195.1 214.9 253.2 289.8 826.0 62 116.2 138.3 160.0 181.3 202.1 222.7 262.6 800.8 887.6 64 120.1 143.0 165.4 187.6 209.2 230.5 271.9 811.7 360.0 66 124.0 147.7 170.9 193.8 216.2 238.3 281.8 822.7 362.5 68 127.9 152.3 176.4 200.0 223.2 246.1 290.6 836.6 876.0 70 131.8 157.0 181.8 206:3 230.3 253.9 300.0 844.6 887.6 72 135.7 161.7 187.7 212.6 237.8 261.7 309.4 366.6 400.0 74 139.5 166,4 192.8 218.8 244.8 269.6 818.8 866.4 412.6 76 143.5 171.1 198.3 226.0 261.8 277.3 828.1, 877.8 ^888.8 426.0 78 147.4 175.8 203.7 231.3 258.4 286.2 837.6 487.6 .80 J 151.3 180.5 209.2 287.6 265.4 293.0 840.9 899.2 460.0 CUBIC MEASURE. ( Inches. 1. 1728. 4^656. Foet Yard. =t 0005788 = .000002144 = 1. .03704 27, 1- Cubir Metreii .000016386 .028315 764513 A CUBIC FOOT IS EQUAL TO 1728 cubic inche.^ gallons A cubic inch of water ai 62^ Fahr weighs 252.458 grains. A cubic foot of water ai 62 Fahr weighs 1002.7 ounces. A cubic yard of water at 62'' Fahr. weighs 1692 pounds FRENCH CUBIC OR SOLID MEASURE. Centilitre . Decilitre Litre j Decalitre ] Hectolitre ^ ] Kilolitre ot \ Cubic Metre / MyrioHtre •! Dry .. Liquid Dry . . Liquid Dry .. Liquid Dry Liquid 21 13 Dry Liquid 211 3 Dry Liquid Dry . Liquid Pint Quart. .0181 .0211 .1816 .2113 1,816 2.113 0908 1056 .908 1.056 9 08 10 56 90.8 105 6 1056 5 10565. Bush. 2887 2.837 28.37 283.7 Cubic Inch. I 61016 I 6.1016 61.016 610.16 6101 6 61016. Cu Ft .0363 .3531 3.53J 35.31 353.1 35^) AVOIRDUPOIS WEIGHT. The standard avoirdupois pound is the weight of 27.7015 cubic inches of distilled water, weighed in the air, at 39.83 degrees Fahr. , barometer at thirty inches. Ounces. Pounds. Quarters, Cwt.8. Ton. 1. = .0635 = .00223 = = .000558 =: .000028 t6. 1. .0357 .00893 .000447 44t8. 28. 1. .25 .0125 1792. 112. 4. 1. .05 35840, 2240. 80. 20. 1. 7000 grains 5760 grains A drachm = 27.343 grainsi A stone = 14 pomids; A quintal = 100 kilogrammes^ = 1 avoir, pound — 1.21528 troy = 1 troy pound — .82285 avoir. Kilos p. sq. centim. Pounds p. sq. inch pounds; pound. 14.22 = Pounds p. sq. inch. .0703 := Kilos p. sq. centim. FRENCH WEIGHTS. EQUIVALENT^TO AVOIRDUPOIS. Milligramme Centigramme Decigramme . , _ . _ . Gramme Decagramme .. Hectogramme Kilogramme ..-, _. Myriogramme Quintal Millier or Tonae. . .015433 .154331 1.54331 15.4331 154.331 1543.31 15433.1 Ounces. f»J0352 .003527 .035275 352758 3.52758 35.2758 352.758 3527 58 85275.8 Pounds, .000022) .000220) .002204 .022047 .220473 2.20473 22.0473 220.473 2204.73 357 SQUARE MEASURE. 1 144. 1296. 39204. 6272640. Inches Feet. Yard I'erche.s. Acre. C00772 - .0000255 - .000000159 111 .00367 .000023 .0331 .0002066 1. .00625 160 1 = 1 square. - I acre. = 8 acres per mile. - 2.471143 acres. = 27,878.400 square feet. = 3,097.600 square yards. ( - 640 acres. Acres x 0015625 — square milei Square yard x 000000323=: square miles Acres x 4840= square yards Square yards X 0002066 nacres. A section of land is 1 mile square, and contains 640 acres, A square acre is 208 71 ft at each side; or, ; 20 k 198 ft. A .square ^ acre is 147 58 ft at each side, or, 110 x 198 ft. A square i acre is 104.855 ft. at each side. or. 55 x 198 ft. A circular acre is 235 504 ft in diameter. A circular ^ acre is 166 527 ft, in diameter. A circular i- acre is 117.752 ft m diameter Feet. .00694 1. 9. 1. 2721. 30i 43560. 4840. 100 square feet 10 square chains 1 chain wide 1 hectare 1 square mile FRENCH SQUARE MEASURE. Square Square locliea Square Feet Square Vftrds Millimetre. 00154 0000107 000001 Centimetre 15498 .0010763 .000119 Decimetre 15 498 107630O 011958 Met cr Ccn 1549 8 10 76305 1 19589 Decametre 154988 1076 305 119.589 Hectare 107630 53 10763058 1195S 9:. Kilometre . '.38607 amis 1195895. Myriamei. . 38.607 . . . ^ 358 SURVEYING MEASURE. Inches, 1. 12. 792. Feet. 1. 3. 66. 5280. (LINEAL.) Yards. Chains. Mile. = .0278 = .00126 = .0000153 .333 .01515 .000189 1. .04545 .000568 22. 1. . .0125 1760.> 80. , 1. .07 feet = 1855.11 One knot or geographical mile = metres = 1.1526 statute mile. One admiralty knot = 1.1515 statute miles 6080 feet. LONG MEASURE. Inches. 1. 12. 36. 198. 7920. Feet. Yards. Poles. Furl. = .083 = .02778 1. .333 3. 1. 16i. 5i. 660. 220. : .005 = .000126 .0606 .00151 .182 .00454 1. .025 63360. 5280. 1 40. 320. Mlie. .0000158 .0001894 .000568 .003125 .125 1- A palm = 3 inches. A hand = 4 inches. A span = 9 inches. A cable's length = 120 fathoms.^ FRENCH LONG MEASURE. Inches. Feet. Yards. Mflos. Milliinclre .03937 .39368 3.9368 39.368 393.68 .0083 .0828 .3280 3.2807 32.807 328 07 3280.7 328C7. Centimetre Decimetre Metre Decametre Hectometre .10936 1 09357 10.9357 109 357 1093 h'-f 10935.7 " 062134 Kilometre 621346 Mvr'M metre 6 2l3'tt)6 359 STRENGTH OF MATERIALS. ULTIMATE RESISTANCE TO TENSlOS IN LBS. PER SQUARE INCH. METALS. ATer>. Brass, cast, • - 18000 " wire. . - 49000 Bronze or jnn metal, - . ^ - . . 36000 Copper, cast. - - 19000 sheet, - 30000 bolts, - *- 36000 wire, . * . . . . 60000 Iron. cast. 13400 to 29000, - . - - - . 16500 ** wrought, round or square bars of 1 to 2 inch diameter, double refined, - 60000 to 54000 •• wrought, specimens yi >nch square, cut from large bars of double rehned iron, - 50000 to 63000 •• wrought, double refined, m large bars of abouf 7 square inches section, - - 46000 to 47000 wrought, plates, angles and other shapes. 48000 to 61000 plates over 36" wide. - 46000 to 60000 Wrought iron, suitable Inr the tension members of bridges, should be double refined, -ind show a permanent elongation of 20 per ct-nr in fi", when broken m small specimens, and a re- duction of area of 25 per cent at point of fracture The modulus of elasticity of Union Iron Mills' double refined bar ,ron ei »» r^'w sj— ceoceooieo oicsaioc^ ei-aDissisi ©c» — (N (N» ej©S"*'<»««5 W«»«»CO» »0»«t>iX» «« •saqooi OS® [>.« VD.S6,.99 ©lec-*^* X3srie^*i *05 •*«c CO «>oo©i>(N «at>.xxp. ©»o5»95ie» ^^w ift r." fJ © X 04 «^ tC t»' (m' •«•* « X t> 3S — *" X X WW — ,-.^^« ^^.^MlM «> .« (M (£4 (M 9* f-ffi S ^ i , ^1 QD • ©X : • • • : ; i 2t 1 : • • : : : ,© — (NW •*/©.x©(yi^ ©ec 5 ©1 (» ' : : : : ••^M"**-®: '©C3 — ©S.Ot", ©J© ;,ii,Mi-M »--n©l(N(M©J (MOl © ©X r^ ©J aa©i ^lO «3>© — ©» — M«er^Ci ©'si^^eosw ■*©. ^^rm ^^..p.,* •-• (M (M 9) (M CO (MOI QC J ©ie« iO» i>.'»-(Nec^ «;cx©ei5 (N»i5X»-^t>. osm — — — — F-^»-(M(M We« XM'* c c X ©35 — •*!>. ififfiM©©** *SX p. — — (N©1©I (NCJWWSC* WW •♦ CO c «>(X r-. .0 (N ©»3»ftC5lM OS^XOliftX C^W ei — (N(J»©J©S dStM**"* «•» Z u ti 06 1 1-4 . 1 «x* ©.» lij-Nifflxej «P-Ltr:««. asift-to — » ot© QC CD c «. 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OD OS © © — CO CO ©1 — OS r- CO •^ 00 © © O — CO .(0 .© so © y; © © OS© — ©ICO .©1- © —CO 1 '* C ao r- .rt (N © TC SO r- OO © © — — 'M © © © © © X' © 00 © © — -^ ©1 •'J" ©1 -f I© .© so -.0 © O — ©icC-;0 /•- — ©1 •^ i<> ssau>i IM ^^i^^^S :i^Nr^^^':'.-^ -f^ •saqoin i j| © o - ©1 ;oiaiUTJ!(jap!S'ino 3H TABLE OF SAFETY LOAD OF CAST IRON COLUMNS. (continued.) Oi — lOr- lO^QCOOQCiC or:'^?000— e-i-.-*r,|>.^ .-■"^^ ^ — ^^^^^1 ^^^^^-Mri ..- — — — ^OJl, OC;«»-* t^ r* — S5 «o ©a cs t>.— « O CXJeOC-Jr- «c; — — — _QtO OlkO — ifflODMCO 0«-©3io;5> •^-r>eo ec-^'TiO'OOO -*"*»ffl»o»oor>. ■» ■«!»■ >c «e » r» o r- oc o Oi 1 *' o ©' c^ OD ©©JGf3-*©^©5 .© ;» CO r- 00 © © »© ©1 © r- <* €>• Oi>.r-ac ©© 00 " eoooco I— GO ■»?« © r- r- CD U2 »0 CC f ^ o. QO Ci ♦1 CO ^ »- r» © )-< ©©i^aoac©^ — oO'*cc©i«o CO C CO CO © CC »-C iC US »o CC 1^ !>. OC O © © CO © r>. "* r>. © ©r-OCOOO©©* O i© CO ©1 © • 1- 00 © © ^ ©1 en a or- COO ^ C5 t^ -!>"5^ ■<»« « e <© r- GC Si © »-i ©J © X lO ce 00 ©1 c»aoac©©T-o3 CO OS ©I •-©r- oc©©P-©ios z ii ©J 00 o r'. ./2 -<(■ CO I-"* © CO I- GC Oi © ^ (M oo r* .o ■«»• ©1 ac CO c>.aD©©^©ii!f ©©©©©GD ©©—©!«(■»♦< ©laesr. V ) r-GC©©^(NCO lO ■*••»■ ec OJ © tv--' t- cc ©© ^ © • O S'. Of) c CD c »-< 1-1 l-« »-t 1— !>• (M OD Oi © T-i (M 99 iO ©J CO eo M M ©1 « © © i-< ©1 CO 1© r- *©ao©*^»a © -« ©1 1»< Iffl l>- E OS X eo ©.-KM ©I 09^00 Oi © ^ (N w »o ce — ©1 CO -»> U2 © CS ©F^©ISO-*©QO ©lOOD'-OS© »-©IO?»©©© -i* a ©35t-»0 r- © »^ ©5 lO '(t- ffit»© ©ccao»-»o©i ©IOSi^©t»© O z llj o* 00 a © 1-1 OS •* »o t>» © t-©a«©oD©J© 1-- as 1J- »o © © — ^ « ^ ^ „ « (5, CC05r.©I©0l ©1 •«*■ ifS t>- 00 1-1 o OQ c (MCOiOr- -^©©-^QO©© i^ej-^usooo^ ^ iM *« i>i< .M <-« «i .O © OS I- © © « O109^©CC©00 ;« fiN ^ t-« *« ©1 ©1 ©©lr.©lt5iO ©SUOOODOSOI iM *i« *« w *M OI ■ 00 C ■^iOr-© -^ce-*©*^©©! M^^^M©i©i ^iC©-*©©01 5C©iu3.Ml-.C0 ^»oc-©oco « a, C co»cc:m i'.(NaO'«»<©'#r>. •C«aC-- O»iO »-l — ^1^fM©l®l ©t>.^^r..QD us©ao© — >* JO p^;^*;^ ::?e:i?^:f?^ ^S2^3S2 •eaqooi ui | 36s Crushing and Tensile Strength, in lbs., per square inch of Natum' and Artificial Stones- DBSCRTPTION. Aberdeen Blue Granite Qaincy Granite — Freestone, Belleville Freestone, Caen .. Freestone, Connecticut Sandstone, Acqula Creek, used for Capitol Wash Ington Limestone, Magneslan, Grafton. Ill Marble. Hastings, N. Y ... Marble, Italian Marble, Stockbrldge, City Hall, N. Y . . Marble, Statuary Marble, Veined Slate Brick, Red .• ^ Brick, Pale Red Brick, Common Brick, Machine Pressed Brick. Stock Brick-work, set In Cement, brlcka not very hard Brick, Masonry, Common Cement, Portland Cement, Portland, Cement 1, Sand 1 . Cement, Roman Mortar Crown GIa«8 Portland Cement Portland Cement, with Sand Glass, Plate Mortar Plaster of Paris SlHie Weight per Cubicft in lbs 164 166 165 135.5 130.3 Crushing Force. Lbs, per Square inch. 5.400 to 10,914 15,300 3,522 1,088 3,319 5,340 17,000 18,941 12,624 10,382 8,216 9,681 9,300 808 ■ 562 800 to i,000 5,222 to 14,^1* 2,177 - 521 500 to 80O 1,000 to S.SQO 1,280 S42 120 to 240 31,000 TKN910N. 427 to 711 92 to 284 9.420 50 72 11,000 Capacity of Cylindrical Cisterns.' FOB KACn FOOT OF DEPTH. Diameter Diameter In Feet. Gallons. Pounds. In feet. Gallons. Poundth 2.0 23.5 196 9.0 475.9 3^968 2.5 36.7 806 9.5 580.2 4,421 8.0 52.9 441 10.0 587.5 4,899 3.5 72.0 600 11.0 710.9 5,928 4.0 94.0 784 12.0 846.0 7,054 4.5 119.0 992 13.0 992.9 ' 8,280 5.0 146.9 1.225 14.0 1,151.5 9,602 5.5 177.7 1,482 15.0 . 1.821.9 11.023 «.o 211.5 1,764 20.0 2,350. 1 19>596 6.5 248.2 2 070 25.0 8,072.0 80.620 7.0 287.9 2,401 30.0 5,287.7 44,098 7.5 330.5 2.756 35.0 7,197.1 60,016 8.0 376.0 3,135 40.0 9.400.3 78,f 38 8.5 424.5 3,540 .... PROPERTIES OF TIMBER. a^>l 1 1 i. 1 1 11 m 2 ' ; i ; ; i i i 2 1 3 s 1 % 1 I § i 1 if 2^23 § i s i 5 12 ? ! S fi . t" o> ^ ■♦ 00 1^2 3 $ : 2 2 ■; fi^ S '# i i i g CM ; £ s go > fii g^ii 2 S CO £1 2 S c- g g 1 ^Is - «o — * c* « c» •- •-■ 5 2 g 2 S B 2 2 2 i 2 ! 11^. i 1 S " S £ S ^ i i s ■" ^ s i 33^ • e<9 1 i i 11 Si i i i:^ of » « 1 » -« S S ! fi s °. i 3 § 3 i 1 OS i^ g * 1 11 i i i " tf. ^ 00' «c c 1 f- ■* n m* ' in « o» •* ifl 10 in n a ' 1 S, ; 5 f 1 ; i : 1 g § § 10 c ^--• t^ * rf ' So 00 r( s. • c oT C5> <£ — c -^5 2 2 : ^ 3 § a f > 2 \ "- o 2 5 Su5 I 00 : 2 * ei 5 ^' i c - 1 g S c* 2 o>' H '^ »» F r — ^ a « . •» 1 ^- — : c^ ^ ^ CO 9 t* : • "11 ! ^1. 00 T» 00 t- 6in. 2 in. lin. IJ^in. 2 m. 4^ 12 616,846 7 40,029 989,720 414,986 594,184 754,520 18 606,383 7 25,048 920,696 22 403,458 57 7,678 733,560 14 495,550 709,537 901,000 23 392,093 561,406 712,896 15 *484,418 693,598 880,765 24 380,864 645,328 692,480 16 473,057 677,332 860,104 25 369,829 529,527 672.416 17 461,579 660,888 839,160 26 359,005; 514.030 652,736 18 449,913 644,194 818,024 27 348,401; 498.847 633,456 10 438,253 627,499 796,824 28 337.731) 483.569 614,050 ^5) 426,593 610,804 775,624 29 329,941 469.552 696.256 COST OF LIVING IN CHINA. Land in China is divided into more holdings l!^n any other land in the world. It takes but a very small piece of land to support a Chinese family. The Chinese a*e the closest and most thorough cultivators in the world. Field hands in China are paid $I2 per annum. The food is cooked by the employer. With his food he is furnished straw, shoes and free shaving — the last a matter which a Chinaman never neglects for any great length of time where it is possible to secure the luxury. It costs about $4 a year to clothe a Chinaman. Much of the land in China is divided up into gardens of areas as small as one-sixth of an acre. 368 NOTES ON HOT WATER SYSTEMS. Let your " risers " not be less than i }^" , for smaller pipes soon become coated, if the water used contains lime or other matters in solution or suspension. Galvanized pipe is best; it does not become rusty and dis- color the water. In ordinary pipe be sure to get "galvanized steam," and 0(Ot " galvanized gas. " Let your draw-off services be for bath i'\ to lavatories I", for hot water >^". Do not make the " draw- offs " too small, it takes too long to drain a pipe of cold water. The larger the pipes the freer the circulation, and, if you have hard water, they will remain in good order longer. Be sure that all joints are secure and free from leaks, and always look through a pipe before fitting it in place, to see that there is no dirt or impediment to the flow of the water through it. Avoid the use of elbows in circulating pipes, use only bends; if you cannot avoid using an elbow, see that it is a round one. TO SOLDER ALUMINUM. M. Bourbouze has formed an alloy of 45 parts of tin and 55 parts of aluminum, which answers for soldering aluminum. This alloy possesses almost the same lightness as the pure aluminum, and can be easily soldered. M. Bourbouze has invented another containing only ten per cent, of tin. This second alloy, which can replace aluminum in all its applica- tions, can be soldered to tin, while it preserves all the prin- cipal qualities of the pure metal. A new and curious alloy is produced by placing in a clean crucible an ounce of copper and an ounce of antimony, and fusing them by a strong heat. The compound will be hard, and of a beautiful violet hue. This alloy has not yet been applied to any useful purpose, but its excellent qualities, independent of its color, entitle it to consideration. A CHEAP FILTER. A cheap filter which any tinner can make is 12x6 inches m size, and 8 inches high. The water flows in near the top, and on the top is a door through which to get into it to clean it. The outlet pipe at the bottom projects two inches up on the inside to hold the dirt back. A large sponge is placed inside, which forms the filtering medium, which, of course, can Dr cleaned as often as desired. 3^9 COMPOSITION OF BABBITT METAL. Genuine Babbitt metal, according to the formula of the inventor, is 9 of tin, i of copper. Antimony has been added since, so that the proportions by hundreds will stand So tin., 5 copper, 15 antimony. For high speeds the metals should be cooler, giving a larger proportion of tin ; for weight the metal should be harder, giving a larger proportion of antimony. THE HEATING SURFACE OF A STEAM RADIA- TOR. For instance, the radiator contains 300 feet of one-inch pipe; what will be its heating surface in square feet? A. 300. feet =3,600 inches. The outside circumference of one- inch piper=4 inches. And 3,600 X 4 = 14,400 square inches of heating surface. Lastly, 14,400 = 100 144 square feet of heatmg surface. The way you have calculated the heating surface is not correct, because you did not multi- ply the length of the pipe by the circumference. A CHIMNEY THAT WILL DRAW. To build a chimney that will draw forever, and not fill up with soot, you must build it large enough, sixteen inches square; use good brick, and clay instead of lime up to the comb; plaster it inside with clay mixed with salt; for chimney tops use the very best of brick, wet them and lay them in cement mortar. The chimney should not be built tight to beams and rafters; there is where the cracks in your chimney comes, and where most of the fires originate, as the chimney sometimes get red hot. A chimney built from the cellar up is better and less dangerous than one hung on the wall. ANCIENT USE OF LEAD. The ancients, like the moderns, used lead to fasten iron into stone, to give a glaze to pottery, and as a help to the manufacture of glass. Very singular were the " imprecation tablets, surrentitiously deposited in tombs, and sometimes even in the cotfin of the deceased, that a curse might follow him to the other world," which seem " to have been more frequently deposited by women than by men." VitruviuJ describes elaborately a vast aqueduct, the lead mi whicj 370 would cost to-day two millions. The leaden bullets of the ancient slingers often bore an inscription in relief such as « Appear," " Show yourself," "Desist," " Take this,"' " Strike Rome. " The Greeks were especially fond of bullets with Such mottoes, and they have been found upon Marathon and many other famous fields. A RUSSIAN WELDING PROCESS. The process of welding, invented by Mr. De Benardox, of Russia, is now applied industrially by the Society for the Electrical Working of Metals. The pieces to be welded are placed upon a cast-iron plate supported by an insulated table, and connected with the negative pole of a source of electricity. The positive pole communicates with an electric carbon in- serted in an insulating handle. On drawing the point of the carbon along the edges of the metal to be welded, the oper- ator closes the circuit. He has then merely to raise the point sligntly to produce a voltaic arc, whose high temperature melts the two pieces of metal and causes them to unite. The intensity of the current naturally varies with the work to be done. For regulating it, a battery of accumulators is used, and the number of the latter is increased or diminished as need be. This process of welding is largely employed in the manufacture of metallic tanks and reservoirs. COLD SOLDER. La Metallurgie gives the following receipt for cold solder: Precipitate copper in a state of fine division from a solution of sulphate of copper by the aid of metallic zinc. Twenty or thirty parts of the copper are mixed in a mortar with con- centrated sulphuric acid, to which is afterward added seventy parts of mercury, and the whole triturated with the pestle. The amalgam produced is copiously washed with water to re- move the sulphuric acid, and is then left for twelve hours. When it is required for soldering, it is warmed until it is about the consistency of wax, and in this state it is applied to the joint, to which it adheres on cooling. TO TIN MALLEABLE IRON. W. M. writes : I tin malleable iron, which comes from the bath nice and bright, but although I keep it covered, after few days it gets red, copper colored in spots, and this color gradually spreads all over the work. Can you tell n;c the cause ? A — The red color is probably derived from oxida^ 37^ tioi? of the iron by the acid left in the pores of the iron. The acid rusts the iron and oozes out through the pores of :he tin by the pressure due to increase of bulk by the action ?f the acid upon the iron ; possibly also moisture may be hsorbed by the acid through the tin, which is porous, Rinse the work immediately after tinning in boiling water, holding 2 oz. sal soda to the gallon in solution. OLD TINS NO LONGER USELESS A number of people recently gathered at the Colurrxbli "oiling mill, Fourteenth street and Jersey avenue, Jersey City, at the formal opening of the mill. The industry is a novel one, being the manufacture of taggers' iron from old tin cans, and other waste sheet metal. This iron has heretofore been manufactured almost exclusively in Europe, and the Columbia Rolling Mill Company is the only American company which turns out the product in large quantities. The process is simple. The tin cans are first heated in an oven raised to a temperature of about i,ooo^, which melts off the tin and lead. The sheet iron which remains is passed first under rubber- coated rollers, and then chilled iron rollers, which leaves the sheet smooth and flat. After annealing and trimming, they are ready for shipment. The tin and lead which is melted from the cans is run into bars, and is also placed upon the market. All the raw material used is waste, but the sheet iron turned out is said to be of good quality. It is used for buttons, tags, and objects of a like nature. The material used costing little, and the demand for taggers^ iron being consider- able, it is thought that this is a good opportunity to build up another American industry. LEAD ON ROOFS AND IN SINKS. Tenacity is very slight in some of the metals. An in- stance may be seen where roofs are covered with lead. The heat of the sun will expand them, and, of course, it is easier for the sheets to expand down-hill than up; then, when they get cold, their own weight will be too great for them, and they will sooner stretch than creep back up hill; so, in fact, unless properly laid, the lead roof will to some extent crawl off its frame-work. The same thing will be seen in kitchen sinks of lead, where very hot water is run into them. The lining gets wrinkled, because, after buckling by reasor '^f the expansion, it will sooner pull thinnei than come bach co the •^*dinary position and conditicn of surface. 372 THE USE OF THE STEEL SQUARE. The standard steel square has a blade 24 inches long and 2 inches v»ide, and a tongue from 14 to 18 inches long and \% inches wid<" The blade is exactly at right angles with the tongue, and the angx;; formed by them an exact right angle, or square corner. A proper square should have the ordinary divisions of inches, half inches, quarters and eighths, and often sixteer.ths and thirty-seconds. Another portion of the square is divided into twelfths of an inch; this portion is simply a scale of 12 feet to an inch, used for any pur- pose, as measuring scale drawings, etc. 'I'he diagonal scale on the tongue near the blade, often found on squares, is thus termed from its diagonal lines. However, the proper term is centesimal scale, for the reason that by it a unit may be divided into 100 equal parts, ond therefore any number to the looth part of a unit may he expressed. 3ii this scale A B is one inch; then, if it be required to take off 73-100 kiches, set one foot of the compasses in the third parallel under i at j&, extend the other foot to the seventh diagonal in that parallel at G, and the distance between E G is that required, for E F is one inch and F G 73 parts of an inch. Upon cne side of the blade of the square, running parallel with the length, will be found nine lines, divided at intervals of one inch into sections or spaces by cross lines. This in the plank, board and scantling measure. On each side of the cross lines referred to are figures, sometimes on one side of the cross line, and often spread over the line, thus, i ] 4 — 9 | — We will suppose we have a board 12 feet long and 6 inches wide. Looking on the outer edge of the blade we find 12; between the fifth and sixth lines, under 12, will be found 12 again; this is the length of the board. Now follow the space along toward the tongue till we come to the cross line under 6 (on the edge of the blade), this being the width of the board; in this space will be found the figure 6 again, which is the answer in board measu^-e, viz., six feet. ^ ^- . On some squares will be found on one side of the blade^g lines, and crossing these lines diagonally to the right are rows of figures, as seven is, seven 2s, seven 3s, etc. This is another style of board measure and gives the feet in a board according to its length and width. In the center of the tongue will generally be found two parallel Jines, half an inch apart, with figures between them; this is termed the Brace Rule. Near the extreme end of the tongue will be found 24-24 and to the right of these 33-95- The 24-24 indicate the two sides of a right-angle-triangle, while the length of the brace is indi- cated by 33.95. This will explain the use of any of the figures in the brace rule. On the opposite side of the tongue from the brace rule will generally be found the octagon scale, situated between two central parallel lines. This space is divided into intervals and numbered thus : 10, 20, 30, 40, 50, 60. Suppose it becomes neces- sary to describe an octagon ten inches square; draw a square ten inches each way and bisect the square with a horizontal and per- pendicular center line. To find the length of the octagon line, place one point of the compasses on any of the main divisions of the scale and the other leg or point on the tenth subdivision. 3/3 ENDLESS TIN PLATES. A patent has been recently granted for a novel process of manufacturing continuous tin plates. The plates are made of steel, and the process consists of producing a sheet of st>eel of any continuous length and of required width, by first rolling the metal hot and afterward rolling it cold, until a proper thickness and perfectly smooth surface is obtained. Next, the surface of the sheet is scoured, and then it is afterward passed through a bath of molten tin, thus receiving its coating. Finally the sheet is subjected to a rolling operation, under heavy pressure, between highly polished rolls, by which the tin and steel are condensed and consolidated together, and the surface hardened and pol- ished. The inventor states that, by this method, the tin will be found to be so hardened upon and incorporated with the steel, as to produce a tin plate which is superior, in most respects, to any tin plate, wherever produced. ORIGIN OF PORCELAIN. The Chinese, the pioneers in the art of porcelain manu- facture, began to make it nearly two centuries before the Christian era, and so careful were they to guard the secret of the art that nearly fifteen centuries lapsed before their neighbors, the Japanese, got any inkling of it. But once in their possession, the wily Japanese lost no time to profit by their knowledge. The few intrepid navigators of those days brought samples of both Chinese and Japanese ware to Europe, but not until early in the sixteenth century did a trade in it of any extent take place. Among the early im- porters were Portuguese traders, and to them, we owe the word porcelain, derived from the Portuguese porcellana, or sucking pig. When the Portuguese traders first saw pieces of Japanese ware they were struck w^ith its translucence, which somewhat resembled that of the cowry shell. The cowry shell resembled a small sucking pig, hence our "porcelain." CRYSTALLIZED TIN [PLATE. Crystallized tin plate has a variegated primrose appear- ance, produced upon the surface by applying to it, in a heated state, some dilute nitro-muriatic acid for a few sec ends, then washing it with water, drying, and coating it with lacquer. The figures are more or less diversified, ac. cording to the degree of heat and relative dilution of the acid. 1 Place the tin plate, slightly heated, over a tub of 374 water, and rub its surface with a sponge dipped in a liquid composed of four parts of aquafortis and two of distilled water, holding one common salt or sal-ammoniac in solution. When the crystalline spangles seem to be thoroughly brought out, the plate must be immersed in water, washed either with a feather or a little cotton, taking care not to rub off the film of tin thc^- forms the feathering, forthwith dried with a low heat, ana ccsted with a lacquer varnish, otherwise it loses its luster in the air. If the whole surface is not plunged at once in cold water, but is partially cooled by sprinklins water on it, the crystallization will be obtained by blowing cold air through a pipe on the tinned surface, while it is just passing from the fused to the solid state. USEFUL EECIPES. Tinning Acid for Zinc or Brass.— Zinc. 3 oz.; muriatic acid, 1 pt. Dissolve, and add 1 pt. water and 1 oz. sal-ammoniac. To Solder Brass Easily.— Cut out a piece of tin foil the size of the surface to be soldered. Then apply to the surface a solution of sal-ammoniac for a flux. Place the tin foil between the pieces, and apply a hot soldering-iron until the tin foil is melted. To Solder Without Heat.—meel filings, 2 oz. ; brass filings, 2oz.; fiuoric acid, Ij^ oz. Dissolve the filings in the acid, and apply to the parts to be soldered, having first thoroughly cleaned the parts to be connected. Keep the fluoric acid in earthen or lead vessels only. To Tin Brass and Copper.— Mafke a mixture of 3 lbs. cream of tartar, 4 lbs. tin shavings, and 2 gallons water, and boil. After the mixture has boiled sufficiently, put in the articles to be tinned, and continue the boiling. The tin will be pre- cipitated on the articles. TO POLISH NIOKEL-PLATE. To brighten and polish nickel-plating and prevent rust, apply rouge with a little fresh lard or lard oil on a wash- leather or piece of buckskin. Rub the bright parts, using as little of the rouge and oil as possible: wipe off with a clean rag slightly oiled. Repeat the wiping every day and the polishing as often as necessary. 375 PATTERN FGK FLARING OVAL ARTICLES. Of all the great, variety of patterns with which the tin man has to deal, there is probably none that seems more difficult and causes mere troub'e and perplexity to make thana flaring oval pan. By following the annexed diagrams and explana- tions, the deve-Opment of this pattern will be seen to be sim- ple, easy and quickly per- formtcl First, always describe the oval from two centers — thus making the bottom of the dish — parts of two diameters or circles. Separate the circles when they intersect each other, and proceed the same as in any round, flaring article. In Fig. I the compasses are set at a a, and the large circles described as A A B B, then set the compasses 'd.\. b b and describe the smaller circles, thus completing the oval or bottom of pan. To make the pattern for the body : In Fig. 2 mark A B tlie size of large diameter. Then draw the depth of vessel and flare desired, as A B C D. Extend the lines C A anc J z^b D B until they cross at £?, set the compasses at ^^ and describto the curved lines C D and A B, Make the length A F equal to A A in Fig. i. Add the locks r.s shown in dotted lines; this will be the ] attern for side of dish. In Fig. 3, make a a equal to the small diameter and pro- ceed the same as in Fig. 2, this will be the end pattern. It takes two pieces of the large pattern and two of the small to Fig 4. make the dish. Should it be found desirable to mcike the body of pan in only two pieces, then cut the smaller or end pattern in two and place it upon each side of the large pattern, as shown m Fig. 4. An oval can be made from three or more centers upon the same plan when desirea. FLARING ARTICLES WITH f A . V J \ A / p \ X " ( / me se£:ments of thecircles a b; ROUND CORNERS. First, to cut the pat- tern of an oblong "^ar. ing dish with square- cornered bottom and round cornered top, in two pieces, of which Fig. I IS the grouna plan, and Fig. 2 the side elevation. The height of side A, Fig. 2, is from a to by which is also the radius for the corners. First mark off the side A, Fig. 3 ; then strike this gives the comer. Then 6n murk off £)ne-half of end on each side oi a h [c and K. spring wire clamp, 1^^ y/^^^^^ ^^^^x^ ^"^ ^^ ^^ used at VCT I /// \\ ^^^^ seam of the "J /// V\\- trough. The dark IJ III y^l line on outside of the '~ - il __ ^ i smaller diagram rep- resents a small clamp used to hold the head down at the ends of the loii. The 3^o large diagram shows the log with tb^ trough clamped to it. It will be seen that a 3^-inch piece is secured to the flat side of the log, which piece projects 3^ o'^ an inch beyond one edge of the log. A rocker may also be placed under the log. The log IS secured to the bench by hooks or staples with a long shank fastened to the bench and hooking onto spikes driven into the eids of the log. TABLE OF HEIGHT OF ELBOW ANGLEo. The following table gives the height of pitch of miter lines for elbows from one inch to twenty-five inches in diameter. It will be found of great assist- ance in describing el- bow patterns quickly and accurately, by do- ing away with draw- ings and geometrical calculations, which would otherwise be necessary to get the correct pitch of elbows. The accompanying dia- gram indicates the po- sition of base and miter lines. The height of pitch, that is, the length from O to W, IS shown by the table for all elbows from one inch to twenty-five inches in diameter, and of from two to ten pieces. In two-piece elbows the height of pitch is the diam- eter of the elbow, and this column is added to make the table complete. No matter how large the sweep of an el- bow, the angle of pitch remains the same, and the only dif- ference to be made in cutting the pattern is to add space as desired, as indicated at X in the diagram. Locks and seams are to be addedo ^x, \\ ' \ \ ; \U / Mi^:-^''"'"'^ ,^ /\^ ^^^^jj^ ' v-^y B»» hit. >• 3»i 7 8 9 lo II 12 13 14 15 i6 17 i8 19 20 21 22 23 24 25 NO. OF PIECES IN ELBOW. 2 3 4 5 6 7 - 8 1-8 I 7-i6 9-32 7-32 6-32 5-32 2 27-32 18-32 13-32 11-32 9-32 1-4 3 I 1-4 13-16 5-8 1-2 7-16 11-32 4 I 21-32 I 1-16 13-16 21-32 9-16 15-32 5 2 i-i6|i 5-16 13-16 11-16 9-16 6 2 1-2 I 5-8 3-16 31-32 13-16 11-16 7 2 29-32 I 7-8 3-8 1-8 15-16 13-16 8 3 5-i6;2 1-8 9-16 1-4 I 1-16 29-32 9 3 23-32 2 13-32 13-16 7-16 1 3-16,1 lO 4 1-8 2 11-16 2 9-16 5-16 I 1-8 I II 4 1-2 2 15-162 3-16 3-4 7-16,1 1-4 1 12 4 15-16 3 3-162 3-S 7-8 9-16 1 3-8 I 13 5 3-8 3 7-8 2 9-16 2 1-16 23-32 15-32 I 14 5 3-4 3 23-322 3-4 2 7-32 7-8 9-16 I 15 6 5-32 4 2 31-32 2 3-8 2 11-16 13-16 i6 6 19-32 4 1-4 3 5-322 17-32 2 1-8 I? 7 4 7-32 3 6-16 2 11-16 2 1-4 15-16 i8 7 3-8 4 25-32 3 9-16 2 27-32 2 3-8 2 1-32 19 7 13-16 5 1-16 3 3-4 3 2 1-2 2 1-8 20 8 1-4 5 5-16 3 31-32 3 3-16 2 21-32 2 1-4 2 21 8 5-8 5 19-32 4 5-32 3 11-32 2 13-162 3-8 2 22 9 '-'^J. 27-32 4 3-8 3 1-2 2 15-162 1-2 2 23 9 7-166 3-32 4 9-163 21-32 3 1-16 2 19-32 2 24 9 7-8 \6 3-8 4 3-4 I3 13-16 3 3-162 11-16 2 25 lO 9-32 6 5-8 4 15-16 3 15-16 3 5-.6 2 13-16 2 1-8 7-32 5-16 13-32 1-2 5-8 9-16 13-16 29-32 3-32 3-16 5-16 3-8 1-2 19-32 11-16 25-32 7-8 1-16 3-16,1 9-322 3-8 |2 7-162 10 3-32 6-32 9-32 3-8 7-16 9-16 5-8 23-32 13-16 29-32 1-16 5-32 1-4 11-32 7-16 1-2 19-32 11-16 25-32 7-8 15-16 1-32 1-8 3-16 The table is adapted to right-angled elbows only. The line of figures at the top of the table indicate the number of pieces of which elbows are to be made. All other figures are in inches, the first or left hand column being the diameter of elbows, the remaining column being the height of pitch required. ZINC AS A FIRE EXTINGUISHER. Zinc, placed upon the stove, in fire or in grate, is said to have proved itself an effective extinguisher of chimney fires. To a member of the Boston Fire Department is reported to be due the credit of successfully introducing this simple scheme. When afire starts inside a chimney, from whatever cause, a piece of tin sheet zinc, about four inches square, is merely put into the stove or grate connecting with the chim- ney. The zinc fuses and liberates acidulous fumes, which, passing up the flue, are said to almost instantly put out what- ever fire may be there. It certainly sounds simple enougli. ^ 3^2 HOME-MADE ASH SIFTER. An Iowa correspondent sent Good Housekeeping the fol- lowing diagram and description of a home-made ash-sifter, any tinner or other person may construct : " I got my idea of it from seeing sand sifted by throwing it on a sieve that stood slanting. The wire sieve (already wove) can be bought at a hard- ware store for twenty cents a running foot, and it is two or two and a half feet wide, and this can be tacked to a frame made to fit the sifter, one end just reaching over the box for coal, and the other end ex- tending nearly to the top of the sifter. There is no shaking, nor any dust. Ashes are emptied in the top of the sifter, the coal being carried over the sieve to the coal box, while the ashes go through into the ash box. The sieve should be two and a half feet long. Can use a sliding or swinging cover." TO DESCRIBE A MITER. As there seems to be some interest manifested in regard to tb3 miter question, and nothing definite as to the desired miter has been given, I wish to submit the following rule: Let a in diagram be the size of the article upon which the miter is to be cut ; strike a circle full size, or from edge to edge as shown at e and b of the diagram ; draw a line as shown by d^ from e to b^ which divides the circle equally. If s c t \ \^ ^ \ a »4\ d. ) , . ■ ■ . you wish a square miter set compass at e and obtain one- fourth of the circle as shown at figure 2, and draw line by intersecting the circle where the point of the compass shows one-fourtii of circle. Cuttmg this hne you have a square miter. Should you wish your work to form six squares, take the sixth of a circle as shown at figure i by line c h ; or, if eight squares, one-eighth ^ f circle, and intersect the circle at point designated by compass. A miter may be cut for any angle desired by the same rule ; divide the circle into the number of squares wanted, and proceed as shown above. This rule does not apply to forming a miter for gutters. TO DESCRIBE A PATTERN FOR A FOUR-PIECE ELBOW. Three and four piece elbows have very largely taken the plr?xe of the old right-angled elbow, on accounf of their bet- ter appearance, and also ft .r . , i" — ,.-- , ■' r ? becaase they lessen ob- struction to draft. The machine-made article is k pt in stock for all common sizes, but the 'inner is liable to be called upon at any time to make such an elbow, on account of stock be- ing sold out or of un- usual size, or other cause. Herewith are given diagrams and ex- planations which will enable any tinner to construct a pattern for any desired size. Let ABE D,Fig. i, A98 7 6 » A aaia ^e the given elbow; draw the line F C ; make F M equal in length to one-half the diameter of the elbow, with F as a center; describe the arcKL; divide the arc K L into three equal parts; draw theknes F II and F I ; also the line I II ; divide the section H K into two equal pn rts, and draw the line F G ; draw the lin3 A B at right angles to B C ; describe the semi-circle A N B ; div^'-'^ *he semi-circle into any number of equal parts ; from me points draw lines parallel to B C^ as I, 2, 3, etr,. 3H Set off the line A B C, Fig. 2, equal in length to the cir- cumference of elbow A B ; erect the lines A F, B D and 1 2 3 4 5 6 T C E ; set off on each side of the line B D the same number of equal distances as in the semi-circle AN B ; from the points draw lines parallel to B D, as i, i, 2, 2, etc. ; make B D equal to B G ; make A F and C E equal to A J ; also each of the parallel lines, bearing the same number as 1,1, 2, 2, 3, 3, etc. ; then a line traced through the points will form the first section ; make F G and E J equal to H I ; re- verse section No. i ; place E at G and F at J ; trace a line from G to J ; make G H and J I equal to P O, Fig. 6*]^ or to D K, Fig. 68; take Sec. No. i, place F at H and E at I, and trace a line from H to I ; this forms_Sec. No. 3 and 4. Edges to be allowed. In the West Indies the work of coaling ships is performed by negresses. Like ants going to and fro, each of these women, with a load of coal weighing about forty pounds, carried in a ba^iket on top of the head, climbs the gang-plank, and the bunkers are filled in a wonderfully short time. For this arduous work, a cent a basket is the general price, but night work and emergencies double the rate. A penn)' is given to each woman as she fills her basket, and the number given out forms a check on the tally kept by the parties receiving the coal. The name of the firm owning the coal pile is stamped on the coins, which are current throughout the slands 3»5 A WIRE FLOWER STAND. Tinners are ingenious, and can generally make anything from sheet metal, wire, or other light material, which they take a fancy to try their hands at. Many have made orna- mental articles at odd moments with which to beautify their own home, or possibly that of some young lady. By their skill in this direction they are frequently able to make presents of arti- cles of their own make, which are not merely or- namental, but also usefuL This is commendable, and such skill and enter- prise is worthy of encour* agement. We here present an illustration of a new round flower-stand con- structed in three parts^ which can be taken asun- der so as to convert the stand at will into a rustic table. The cut is taken from the London Ironmonger^ which says that the originator of the flower-stand is doing well with it. TO STRIKE AN OVAL OF ANY LENGTH OR WIDTH In a recent number of the American Ar'isan, which I have mislaid, some one asks for a rule to strike an oval of any desired width and length. There are several different ways of striking an oval or ellipse, but I find the one I en- close you the most practical. Let A B and C D equal width and length. On the line CD lay off the width of oval as CC. Divide the distance from E to D into thr e equal parts, and lay off two of the parts thus formed on either side of the center F, as G and H. Span the dividers from H to G, and, with F as a center, check the line A B, as at M and K. Draw line intersecting the points H M G K, and, with the radius G D and K B strike the ends and sides of oval. 32^0 AN ORNAMENTAL PAPER HOLDER. Tinners with leisure who desire to use their handiwork in Sialsing something for Christmas, will be interested in the accompanying illustration which we reproduce from a European journal. It is intended for a holder for paper, magazines, or sheet music. HEATING AND VENTILATION. Much continues to be said and written about heating and ventilation, and some may consider it a worn-out subject ; but so long as millions of people continue to be poisoned by impure air, jagitation to secure reform cannot be overdone. It will do no harm, therefore, to again name some of the evi- dences and consequences of a lack of ventilation : Head- ache ; dull pressure on the lungs ; lungs become parched, pro- ducing irritation; dryness of the throat, producing sore throat ; a fevensh condition of the whole system; These are «ome of the immediate consequences, but by no means embraa :PT all the ultimate evil effects. It should be the duty of aB f:imacemen to call the attention of their patrons to these c c , matters. Furnaces are often blamed for the quality of air supplied, while the fault lies solely with the operators in not making provision for the supply of pure air to the furnace, and proper ventilation. This subject will not take care of itself We must first feel that fresh air is worth taking some trouble to obtain, and then we must study how to obtain it without the body's becoming either chilled or overheated in summer or winter, in the daytime or in the night. At night more care needs to be taken to secure ventilation, because there are no doors being opened ; no stirring about to promote circulation. Especially should pure air be supplied to the sick room, and the vitiated air removed. In summer we depend on the natural movement of the air for ventilation, windows and doors being open more or less. In winter, with the liouse closed up, it requires thought and effort to provide for a change of air in apartments. It must be remembered that, under natural conditions, air moves hor- izontally, according to the direction of the wind. Heat causes air to move in a perpendicular direction. In dry weather, heated air and smoke will rise until the same density of atmos- phere is reached, which soon results from loss of heat. When the atmos]:)here contains a great deal of moisture, smoke \vill descend, on account of quick condensation and loss of heat. This principle, understood by all must be kept in view in any plan for ventilation. Suppose we wish to ventilate a loom in the morning when the air outside has become a little warmer than the air inside. The upper part of a window being opened the warmer air outside would blow ncross the top of the room, leaving the air below undisturbed, Now, if we open the v/indow at the bottom we shall secure a cir- culation of air in the room. While the outside air is warmer we do^not notice the draft. Suppose we now go i.ito the kitchen, where the windows are only opened at the bottom and raised halfway up; we shall feel the lower part is cool. 388 while the air in the upper part is undisturbed. Now, if we open the top of the window and divide the difference so as to have the top and Dottom open, we shall have a circulation. Or if we open a door and hold a candle at the top and then at the bottom, we will see the same circulation illustrated by the cold air flowing in at the bottom and the hot air out at the top. These experiments furnish the natural laws which should govern ventilation. Carbonic acid gas from respiration and other exhalations of the body, as well as gases caused by decayed vegetation in cellars, or from garbage, sewer emanations or any kind of ^1^ lU \ V. Fig. 2 ■filthy are all poisonous, and, being heavier than pure air, sink to the bottom of a room by gravitation. It is a gross error to suppose, as many do, that the foul air rises to the ceiling and remains there. The sickness and death of children, often attributed to other causes, arises from blood-poisoning from the foul air near the floor to which children are much more exposed than grown persons. The illustrations given herewith will show where the foul air is and how it is confined unless drawn off by some superior force. In Fig. i, A represents a cellar, DD the walls, CC the surface of the ground outside of the house. . Foul air seeks the lowest space by gravitation, therefore all below CC is foul air because there is no ventila- tion to draw it away. So long as it remains stagnant, pure air will not take the place of the foul. Now, if we place a furnace in the cellar, as shown in Fig. 2, and take the air from the same, it would amount to almost the same thing as living in the cellar, for you breathe the same air. Opening ^e windows furnishes an outlet for the warm air and thus lools off the furnace; but the same foul air, dust and ashes are brought up from the furnace for inhalation. Again, if the rooms are closed, the air from the furnace will rise to the ceiling, then pass to the windows, where the 3»9 temperature will be reduced, and will then descend to the floor and down the sides of the hot-air flue to the furnace to be reheated and sent up again. This has been proven by ex- periment. The children will be the first to be aft'ected by this reheated foul air. How can we obtain pure air? By ventilation. How can ventilation be secured? In various ways. The principal method used is the ventilating shaft. One shaft is generally sufficient for one dwelling, and is usually in the form of a large chimney, as shown in Fig. 3. A is the chimney; B is a heavy sheet-iron pipe, with air space around the pipe for ventilation; 6" is an opening into tne pipe B for connection with the furnace; Z>is a place for cleaning out just below the furnace opening; these two openings should be in the cellar where the furnace is; C is the place for the kitchen stove, which will supply sufficient heat for ventilating the house dur- ing the summer season. Fig. 3. We will next consider how to supply the furnace with pure air. It should be taken from the side from which come the pre- vailing winds. Of course, care should be taken that it is not polluted by a sewage hopper, water closet or other source of con- taination. The opening into the air-duct should be two feet or more above the ground, and should be covered with fine wire gauze. The air-duct should be carried along the ceiling of the cellar until it reaches the fur- nace, as shown by dotted lines in Fig. 2, then drop down at the side of the furnace to the bottom. The space around the furnace should be made air-tight. Any foul air in the cellar will be drawn into the fire-box of the furnace to promote the combustion of the fuel. The area of the cold-air duct should, in no case, be less than half the area of the hot-air pipes. In setting a furnace, particular care snould be taken to see that the chimney has a good draught. There should be sufficient height betweer the top of the furnace and the ceiling of the cellar to permil a good rise for all the hot-air pipes from the furnace. If there is not' sufficient height in the collar to admit of this, the furnace should be set into ? pit dug out below the cellar floor and bricked up. Ample room should be allowed in front of the furnace for cleaning out ashes. All the pipes should be kept as close to the furnace as possible. If any hot-air pipe is extended more than fifteen feet from it, it should be encased witl] about half an inch space around, with both ends of casing entirely closed, to prevent the loss of heat. The location of the furnace should be so that the length of hot-air pipes shall be about equal. The smoke-pipe should be run directly to the chimney. Dampers should be placed in all the hot-air pipes close to the furnace, and, when the pipes are not in use, the dampers should be closed. The vapor-pan should be placed where the water will not boil. In some cases, if set on the top of the furnace, the water will boil over and crack the furnace. A proper place must be provided for it. In a brick- set furnace, the vapor-pan should be automatic in action, being connected with an outside pan with a ball and cock. Without this arrangement it is hard to keep up a regular supply of vapor, as this is a point generally neglected. In order to distribute the heat through the rooms, the ventilating registers must be located in the proper places. They should be placed in the floor near the windows or in the coldest part of each room, so as to draw the heat to that part. Never run a hot-air pipe up an outside wall if you wish success with your work. If ventilators are put iato a side wall, be sure that they extend down entirely to the floor, otherwise there will be a cold stratum of air next the floor, causing cold feet. A failure to do this, causes children to have cold feet at school. People frequently suffer in a simi- lar way at church. LIQUID AIR, THE COMING FORCE. Water freezes at 32*^ above zero. Mercury in a ther- mometer freezes solid at 40-42^ below zero. The alcohol in a spirit thermometer freezes at 200^ below. Air becomes liquid at 312^ below zero. Eight hundred cubic feet of free air are condensed into one cubic foot of liquid air. One pint weighs one pound, like water. By the aid of a 50-horse power steam air-pump, ordinary air is compressed until it becomes red hot. Then it is cooled in submerged pipes, and is further compressed until the pressure is registered at thousands of pounds to the square inch. More cooling is done, more pressure applied, until finally the air liquifies. It oozes through the steel of 391 the pipe in the shape of a milky white vapor and trickles down into the receptacle below. As there is a difference of 344^ between the tempera- tures of ice and liquid air, it will be understood why liquid air boils furiously even when placed on a block of ice. A hand thrust in this liquid, in appearance' like water, would be destroyed in 10 seconds, but if drawn out in- stantly, the moisture of the skin freezing to ice would be protection enough. The feeling at touching the liquid is like that of iron at white heat. Like quicksilver, liquid air does not adhere. If poured over silk, it will leave no stain. When boiling, the vapor of liquid air, being nothing but highly-compressed air, sinks to the ground. If water is poured into liquid air it turns to ice instantly, and of such a low temperature that it will not melt near a red-hot stove for a long time. A stick of arc light carbon, heated to 2,000 degrees above zero, thrust into liquid air, causes the oxygen in it to burn with a dazzling bright flame. A teaspoonful of liquid air in a close vessel, if lighted, explodes with tremendous force, jarring the ground like an earthquake. The expansive power of liquid air is about 20 times greater than that of steam. •iTen years ago it cost about $2,000 to produce a gallon of liquid air. To-day, so Prof. Chas. E. Tripler, of New York, states, it can be manufactured at a cost of 3 or 4 cents per gallon, at the rate of 40 or 50 gallons a day* A steam engine horse-power is now figured at $36.00 a year expense; by the use of liquid air it should not be more than $7.00. A pocket flask full of liquid air will furnish free air for a submarine apparatus for hours. EXPLOSION OF A DOMESTIC HOT WATER BOILER. Explosions of domestic hot water boilers attachea to cooking ranges, water-backs in ranges, etc., through freezing up of the pipes in cold weather, are becoming so frequent that it may not be out of place to give an account of one ot* the most destructive ones that has occurred recently, and point out its cause. The boiler in question was used in an hotel in a large cit^ 392 in one of the Northwestern States, where the temperature is very low at times. It was connected to the kitchen range, the range was a very large one, and the heating surface was furnished by a coil of j j^ inch pipe, placed near the top, mstead of the cast-iron front or back, such as is commonly used in the smaller ranges in private dwellings. The con- nections to the boiler were made in the usual manner ; the accompanying cut shows its essential features. The operation of all boilers of this sort is as follows : The connections being made, as shown in cut, the water is turned on from thv: main supply, and the entire system is fil. 1 with water. When it is filled, and all outlets are clobjtl, it is evident that no more water can run in, although the l)oiler is in free connection with, and is subjected to, the full pressure of the source of supply. When a fire is started in the range, and the water in the circulating pipes, or water-back, is heated, the water expands, is consequently lighter, nnd flows out through the pipe into the boiler at A, ns tliis C()niiecti;)n is ]ilaced higher up than the one at B; iliis siarts the circulation, and the water, as it becomes :i93 heated, constantly flows into the boiler at A, and rises to the upper part of the holler, while the cooler water at the bot- tom of the boiler flows out into the circulating pipes at B, and, if no water is drawn, a slow circulation goes on, as heat is radiated from the boiler, in the direction indicated by the arrows, the water at the top of the boiler always being much hotter than at the bottom. When the hot cock is opened, cold water instantly begins to flow into the boiler at D, by reason of the pressure on the city main, and forces hot water out of the boiler at C. Thus it will be seen that hot water cannot be drawn unless the cold water inlet is free, and it is equally evident that cold water cannot enter the boiler unless the hot water cock or some other outlet is open. The above points being understood, we are in a position to investigate the cause of the explosion referred to, which killed one person and badly injured twelve or thirteen others, besides badly damaging the building. ':|On the morning of the explosion Are was started as usual in the range about four o'clock a. m- It was found, on try- ing to draw water, that none could be had from either cold or hot water pipes; it was rightly judged that the pipes were frozen. The fire was continued in the range, however, and the breakfast prepared as best it could be, and a plumber sent for to thaw out the pipes. He arrived on the premises about seven o'clock, as would naturally be the case. He opened both hot and cold water cocks, and, getting neither steam nor water, concluded there was no danger, and proceeded to thaw out some pipes in the laundry department first. About an hour afterward the explosion occurred. The lower head of the boiler let go, and the main portion of the boiler shot upward like a rocket through the four stories of the hotel and out through the roof. ^ J The coroner held an inquest on the remains of the person killed, and some of the testimony given, as reported in a local paper, would be amusing were it not for the tragic nature of the affair which called it out. The usual expert, with the usual vast and unlimited years of experience, was there, and swore positively to statements which a ten-year- old boy who had been a week in the business ought to be ashamed to make. He had examined the wreck with a view to solving the mystery (?) The matter was as much of a mystery now as oh the day of the explosion. His theories were exploded as fast as he presented them. The boiler must have been empty. If it had been full of water, it could not possibly have exploded, etc., etc. And then a lot more nonsense about the "peculiar" construction of the boiler 394 AS a matter of fact, there was 7.iothiiig peciiliar about tlie boiler or its connections. Everything was precisely like all boilers of its class, of which there are probably hundreds of thousands in daily operation throughout the country, and, moreover, they were all right. Now let us inquire what caused the explosion. Every- thing was all right at eight o'clock the previous evening, for water was drawn at that time. The fire was built in the range at four o'clock a. m. It is admitted that the cold water supply pipes were frozen, for no water could be had for kitchen use. It is also proved absolutely that the hot water supply was frozen or otherwise stopped up, by the fact that at seven o'clock the plumber who came to thaw out the pipes opened the hot water cock and got "neither water nor steam." Here was his opportunity to prevent any trouble, but he let it pass. Any one who understood his business would have known that there must have been a tremendous pressure in the -boiler at this time, as the range had been fired steadily for three hours; there were about eight square feet heating surface exposed to tne fire by the circulating pipe in the range, and there had been no outlet for the great pressure which must have been generated during this three hours tiring. The blow-off cock should have been tried at once; if this were clear, and th8 probability is, from its proximity "".o the range, that it was clear, the pressure could have been relieved, and disaster averted. If the blow-off proved to be stopped up, then the fire should have been at once taken out of the range. At the time the plumber opened the cocks connecting with the boiler, it probably was under a pressure of 400 or 500 pounds per square inch. An ordinary cast- iron waterback such as is used in small ranges in private houses would have exploded shortly after the fire was built, but it will be noticed that the heating surface in this case was furnished by a coil of 1^-inch pipe; this was very strong, and the boiler was the first thing to give way, simply because it was the weakest part of the system. Accidents of this sort can be easily avoided by exercising a little intelligence and care. The hot water cock should always be opened the first thing on entering the kitchen every morning. If the water flows freely, fire may then be started in the range without danger- If it does not flow freely, don't build a fire until it does. A Cement to Make Joints for Gra-Nite Monuments— Use clean sand, twenty parts; litharge, two parts; quicklime, one part, and linseed oil to form a thin paste. 395 USEFUL SHOP KINKS. Fig. 1. A rule for different angles, or rise of elevations for elbows: The usual rise given to furnace pipe elbows is one incli to the foot. A rule to obtain the desired result is as follows, and is almost identical with the one commonly used to get the height and pitch of miter line of right-angled elbows. It is applicable to any sized throat and any sized el- bow; also, to elbows with any number of pieces or sections. First draw lines a c and c 6, Fig. 1, at right angles to each other. From point c on line c b, measure off 1 foot, and perpendicular from the point thus obtained erect line d to r, which is the desired height you wish the elbow to rise, or angle from a true right-angled elbow, in this case one inch to the foot. From point c as center, draw the arc a to r. From point r draw the line r c for base line. This will give the correct elevation, as proof clearly shows by the dotted lines c to z and r to m; these show the continuation that the elbow leads to, namely, as in this instance, 1 inch to the foot, or 1 foot in 12 feet. The line c to ic is 1 foot, and from xx,o z, 1 inch. |Tf an elbow of four pieces is desired, divide the arc or curve rto a into six equal parts; if an elbow of three pieces or sections is wanted, divide same into four equal parts. From point c for a four-piece elbow, draw line c to s, and from point n, where inner curve of elbow intersects line c s, draw line n lo I parallel to line c i\ and same intersecting linersat^. This much gives the pitch and rise for miter line for a four-piece elbow of the desired elevation. 4. For a three-piece elbow the dotted lines from i)oint k on the inner 396 curve Lo points u and o on outer curve, give the miter de- sired. I have also shown a FiG. "X, smaller-sized elbow in the drawing to show how the rule works, and is applied on same. It is, of course, not necessary to give the same size of throat, as is given in the drawing, nor the same outside sweep. This rule will suit any case or sized elbow as may be desired, and as one becomes fa- miliar with the working of the rule, some of the other lines need not be drawn out, but are here given to make the draw- ing complete. The above is given to get the complete data for side elevation which are necessary to develop the / patterns for the different sections of an elbow. To develop the same I will give a quick snap rule, which comes so near right as to be prac- tically almost correct. I will, however, tirst give a good snap rule for angles. If Fig. 3 is examined, it shows the usual long and tedious geometrical method of obtaining miter lines for both a two- piece, and also a three-piece angle, both of the angles being of the same pitch. The solid lines are for a three-piece angle, and the dotted lines are for a two-piece angle. •^Now, to do away with all this drawing, and to get a quick and very nearly correct method to obtain the desired result, suppose an angle is wanted as is given by the lines a h and a to c. Fig. 3, the diameter to be as full drawing requires, proceed as follows: First measure off the distance which is the size of diameter wanted, from a lo h; do the same frbm a to c, and from points thus obtained, which are c and &, draw the line d from c to h. Then from either line, a c or line a 6, draw at right angles the line a to ic, as shown, the line a x intersecting line d at x. This mucn gives tne re- Quired elevation for miter line of a two-piece angle as called 397 for: line ^from c \.o x is miter line, « to x is height of rise, and a to r, base line, which is size of diameter called for. The line x to a divided into half gives the point r where the miter line intersects., of a three-piece angle ; r to « is height, a to c is base line, and r to r is miter line, as will be seen by- dotted line in drawing. Twice the length of distance of line from points a to is the width of outer curve of center see* tion. You must, ot course, allow for laps or burrs for join- ing same together when cutting pattern. Compare this with the solid line center section of full side elevation, and see how much quicker this method is over the old way. When once accustomed to use this method, you will use no other. This rule is absolutely correct for a two piece angle, and varies so little on a three-piece angle f^-oni Fig. 2 6eing absolutely correct, as that the variation is practically of no moment. To develop the stretch-out, Fig. 2, lay out the full length of circumference, as is shown in Fig. 2 from a to />, and divide this length into six equal parts as in drawing. Make the center line. No. 2, same height as required, as in this case for the two-piece angle of Fig. 3. Next divide the right and left lines nearest to the center line, into four equal parts, and mark of one off these parts nearest to the top of each line ; .QXid do the same as to s]-)acing to the lines nearest to the end 6f stretch-out, as lines No. 4 and ;-, but with the difference that you mark off one space at the bottom of each line as the drawing fully shows. '>^ntinue the center line 39^ indefinitely downward, and with dividers strike the arc i, 2 and 3, cutting lines at points i, 2 and 3. Draw line b in- definitely upward, reverse the dividers, and with line b as center line, draw the arc from point 5 to point 4, cutting points 5 and 4; do the same on the other end. Then draw a straight line from point 3 to 4, and same from i to r. This completes the pattern. Allow for locks or laps on both ends, and miter lines, of course. The method given above is an old one, but not so uni- versally known among tinners as its merits deserve. This method is also applicable to develop the pattern for elbow as given in Fig. i. I use it for all kinds of elbows. TO DRAW ANY OVAL WITH SQUARE AND CIRCLE. '?^ The following is a correct rule to draw any size or oval used in the tin shop, with square and circle : Draw the line from I to 2, which is the length of the ovak Draw line from center to 3, which is one-half the width, and draw a line from i to 3. vSet compass from i to center ; leave one point on i, and mark 4. Set compass from center to 3. Leaveone end (of compass) in cencer and mark 5. Set compass from 4 to 5, and Irom 6 draw head lines of circles 7 and 8, and dot 7 and 8 from points i and 2. Set compass from 7 to 7, and mark 9 from 7 7 and 8 8. Complete oval Crom 9. 399 RAIN WATER STRAINER. I hand you a sketch of a rain water strainer which I have put up and which gives good results. It is eighteen inches high, twelve inches in diameter at the half-circle, five and a half inches length of bottom, and five inches deep. Allow for all seams. A, A^t D^ B'^y By represents the outside of finished strainer. K ^^ a section of circular top hinged at .5^ and fastened with a turn button. The dotted lines at E show the section of circular top, K^ partly open; in is a galvanized strainer with three-eighth inch holes. The strainer rests upon supports at the ends, and may be removed at will. L IS a tin strainer with one-eighth inch holes, and is soldered in place. F and G are three-inch inlet and outlet. 2 2 are straps on back side, by which the strainer is fastened to the building. As wiif be seen, the top strainer catches the refuse whicn IS washed from the roof and gutters, and is easily taken out; the finer particles are C'-ught below and nu^y be removed when the top strainer is out. 4t»o OVAL DAMPER, inclosed please find method of obtaining an oval damper, that when closed in, the pipe will be at an angle of 45°. Let A B C D repre- sent the pipe, and E F the line through the pipe at an angle of 45^, which will be the position of the damper when closed. Divide the semi-circle into any even num- ber of equal parts, as, i, 2, 3, 4, etc. (even numbers, because in doing so you obtain the center line of the short diam- eter of the damper). Carry lines up until they cut the line E F as dotted lines, then draw solid lines across, and at right angles to the line E F, and number them to correspond with spaces in semi-circle, as I, 2, 3, 4, etc. With the dividers step from a to I on dotted line, and with one point of the dividers at a'; cut the solid line I each side of the line E. F. Step ^■"^ • ^ ^ ^ TTTTJu ' fi-oixi b to 2, and with one point of the dividers on b^, cut the solid line to both sides of the line E F, and so on until all the spaces have been trans- ferred. Now set the dividers so as to draw an arc through the points 5, 6, 7, both sides of the line E F, and then set them to draw the two end circles, as 11, 12, ii, and 1,0, I. Draw a' line free hand through the points from I to 5, and from 7 to II, both sides of line E F, and you have the re- quired damper. y The same method is used to obtain the shape of a hole in piece of sheet metal that a pipe is to pass through on an angle. For instance, let A B C D represent a pipe, and E F a roof through which the pipe passes ; we want a piece of iron or tin laid on the roof for the pipe to pass through ; we want to know how to get the shape of the opening. Employ this method and it will give you the required article 4^1 A TAPERING ROUND-CORNERED SQUARE RESERVOIR. ' Not long since, there was an inquiry in your columns for a pattern for a tapering, round-cornered square reservoir. I give herewith diagrams for constructing such a pattern : Fig. I is the size, top and bottom (ACFHDBGEis the top, and I K N P L J O M is the bottom), and Fig. I the upright height. Take the perpendicular height a d, Fig. I, and mark it off from h to k. Fig. 3. Take the radius for the corners d C, Fig. I, and mark it off from h to i, Fig. 3, also the radius dK^ mark off from K to 1, drawing a line from il to cut the line h K, which gives the slanting height and the radius required for striking the corners. Draw the lines IK and AC, Fig. 4, the same length as I K, Fig. 2, and the same distance apart as 1 to i, Fig. 3 ; prolong the lines A I and C K, Fig. 4, till Ac and C d equals to i m, Fig. 3, With radius d C, Fig. 4, using d and c as centers, strike the curves C F and A F, and, with a radius d K, Fig. 4, using the same centers, strike the curves K N and I M. Take the length of the large quar- Eig.. 3. Fig. 4. 9 ter-Lircle D H, Fig. 2, and dot off the same distance from C to F, Fig. 4; make A E equal to C F. and dravi 402 lines from E and F to the centers c and d; draw E G and M O at right angles with E c. Take the dis- tance from A to C, and make the same distance from E to G and M to O, Fig. 3. Draw Ge parallel to E c. From G mark off point e, the same length as E to c, then, using e as center, strike the curves G B and O J, making the curve G B equal to A E ; draw line from B to center c, draw B T and J R at right angles to Be, taking the distance from B to S, Fig. 2, mark off the same distance from B to S and J to R, draw S R parallel with B e, and proceed in the same manner with the other end; addmg on the laps, as shown, will make the pattern complete in one piece, being joined together at R S. PATTERN FOR T JOINTS. The following rule is a short and explicit method of ob- taining a pattern for T joints where different diameters are required. Suppose, for instance, a T is required whose diam- eters are 3 and 8 inches respectively. Divide the stretch-out, a a (which must be the exact length required to form up 3 inches, allowing for locks as shown by dotted lines) in center as shown in the figure. Then divide each half equally between 6-7 and 7-8 as shown by indefinite lines 2 and 3. Now spread the compass to 8 inches, which is the diameter of the large pipe, set one point at 4, and the other <. t 6; strike a circle to 7; then set compass on the other line at 5 and draw circle 7 to 8. Cut out the circles, and you have your pattern. The same rule applies to any diameter by spreading compass to the larger diameter and striking the circle on the stretch- out required for smaller diameter as shown above. Ireland has seventy-six collieries — nine in Ulster, seven in Connaught, thirty-one in Leinster, and twenty-nine in Munster. Very few of these are being worked. ^ ! 1 [ < 2 1 8 ► 403 KOVEL DRAWING INSTRUMENT, A pair of dividers, or compasses, which will de- scribe any figure is shown herewith. It is of Eng- lish origin and very simple. The former, or template A, is affixed to one leg, and beats against the mid- leg B, around which, of course, revolves the work- ing leg. By this means the drawing pen or pencil is moved in and out in an obvious manner. Speci- mens of the work are shown in Fig. 2. ^ The quality of wood is determined by spirals. The best has about thirty " crinkles the number of ' in an inch. 404 TO DESCRIBE A PATTERN FOR A TAPERING SQUARE ARTICLE. Erect the Derpendicular line G E ; draw the line A B at right angle to G E ; make E F equal to the slant height, and draw the line C D par- allel to A B; make AB equal in length to one side of the base; make CD equal in length to one side of the top or smallest end, draw the lines A G and B G, cutting the point s A C and BD, Gas a center with the radii G C and G A. Describe the arcs K M and J I ; set off on the arc J I, J A, B H and H I equal in length to A B, and draw the lines J G, H G, and I G, also the lines J A, B H, H I, and K C, D L, L M. Edges to be allowed. THE PAINTING OF IRON. Cast and wrought iron behave very differently under atmospheric influences, and require somewhat different treat- ment. The decay of iron becomes very marked in certain situations, and weakens the metal in direct proportion to the depth to which it has penetrated, and, although where the metal is in a quantity this is not appreciable, it really becomes so when the metal is under three-fourths of an inch in thick- ness. The natural surface of cast iron is very much harder than the interior, occasioned by its becoming chilled, or by its containing a large quantity of silica, and affords an excel- lent natural jTotection, but, should this surface be broken, rust attacks the metal and soon destroys it. It is very desira- ble that the casting be protected as soon after it leaves the mold as possible, and a priming coat of paint should be applied for this purpose : the other coats thought requisite can be given at leisure. Jn considering the painting of wrought iron, it must be noticed that, when iron is oxidized by contact with the atmosphere, two or three distinct layers of scale fotia on the surface, which, unlike the skin upon cast iron, can be readily detached by bending or hammering the metal. It will be seen that the iron has a tendency to rust from the moment it leaves the hammer or rolls, and the scale above described must come away. One of the plans to ])reserve iron has been to coat it with paint when still hot at the mill, and, although this answers for a while, it is a very trou- blesome method, which iron masters cannot be persuaded to adopt, and the subsequent cutting processes to which it is submitted leave many parts of the iron bare. Besides, a good deal of the scale remains, and, until this has fallen off or been removed, any painting over it will be of little value. The only effectual way of protecting wrought iron is to effect a thorough and chemical cleansing of the surface of the metal upon which the paint is to be applied ; that is, it must be immersed for three or four hours in water containing from one to two per cent, of sulphuric acid. The metal is after* ward rinsed in cold water, and, if necessary, scoured with sand, put again into the pickle, and then well rinsed. - If it is desired to keep iron already cleansed for a short time before painting, it is necessary to preserve it in a bath rendered alka- line by caustic lime, potash, soda, or their carbonates. Treat- ment with caustic lime water is, however, the cheapest and most easy method, and iron which has remained in it some hom-s will not rust by a slight exposure to dampness. Hav- ing obtained a clean surface, the question arises, what paint should be used upon iron ? Bituminous paints, as well as those containing variable quantities of lard, were formerly considered solely available, but their failure was made appar- ent when the structure to which they were applied happened to be of magnitude, subjected to great inclemency of weather or to constant vibration. Recourse has, therefore, been had to iron oxide itself, and with satisfactory results. A pound of iron oxide paint, when mixed ready for use in the propor- tion of two-thirds oxide to one-third linseed oil, with careful work, should cover twenty-one square yards of sheet -iron, which is more than is obtained with lead compound. INVENTOR OF THE SCREW-AUGER. The screw-auger was invented by Thomas Garrett about )lOO yeai-s ago. He lived near Oxford, Chester County, Pa^ The single screw-auger was invented by a Philadelphian, and it is said to be the only one used with any satisfaction in very hard woods, wh'^re the double screw-augers bec(^,me clothed 4.o6 RUST PROOF WRAPPING PAPER. This is made by sifting on the sheet of pulp, in process of tnanufacture, a metallic zinc powder (blue powder), about to the extent of the weight of the dried paper, the pulp sheet Is afterward pressed and dried by running thiough the rolls and over the drying cylinders as usual. The zinc powder adheres to the paper, and is partly incorporated with it, the amount varying with the thickness and wetness of the pulp sheet. The paper may be sized with glue or starch and then dusted with the zinc powder, or the powder may be stirred into the size and then applied to the surface of the paper. If silver, brass or iron articles are wrapped in paper thus pre- pared, the affinity of the zinc for the sulphureted hydrogen (always present in the air), chlorine or acid vapors, will pre- vent those substances from attacking the articles inclosed in the piper. HIP-BATH IN TWO PIECES. Fig. I. Draw the hip-bath full size, as it would look when finished, as in Fig. i . Extend line b, or the front, to same height as c, the highest part of the tub. Draw line d parallel with ^, or bottom of tub, until it intersects c and b. Strike the half-circle f f, and divide into any number of equal parts, as i, 2, 3, 4, etc. (the more lines the better). For the points draAv lines as shown in profile. Set dividers same as when the circles in Fie. I were described, and strike the circles ^ p\ and wdth a T square draw the perpendicular lines hhhh. Draw the line i parallel with the lines h. Take the height same as from d to e, in Fig. I, and mark the line/. Fig. i. Draw lines k k until they intersect at /. Set dividers at /, and strike the 407 circles m m. Draw line n, and, taking it as the center li»«, step each way one-fourth of the circumference, in as mani* parts as in profile, I, 2, 3, 4, etc., and draw lines same as iu Fig. I. Fig. 2. Take a pair of dividers, and from the bottom of tub in profile step on the lines, as from 9 to 9, 8 to 8, etc., making the line in Fig. 2 equal to the hnes in profile, st opining where the curved line a crosses. A line traced through the dots will give the ]Dattern, is the foot, which is drawn tlie same as \he other, with the exception of drawing tl>e lines through. A VERY dural)le black paint for out-of-door work, and for many other purposes, is made by grinding powdered charcoal m linseed oil, with sufficient litharge or drier. Thin for use with boiled linseed oil. 4oS ROjeE TRANSMISSION IN ENGLAND. According to the London Engineer, a fly-rope apparently ft-as first used in England in 1863, by Mr. Ramsbottom, for driving cranes at Crewe. These ropes were ^ inch in diam- eter when new, of cotton, and weighing i^ ounces per foot. They lasted about eight months, and ran at 5,000 per minute. The total lengths of the rope were 800 feet, 320 feet and 56G feet. The grooves in the pulley were V-shaped, at an angle of 30°. The cord was supported every 12 feet or 14 feet by flat pieces of chilled cast iron. The actual power strain on \he rore was about 17 pounds, and the ropes were kept tight by a pull of 109 pounds put on by a jockey pulley. Rope- gearing is now superseding belting and gearing in cotton mills. It has long been used in South Wales for driving helve hammers in tin-plate mills. The ropes are usually about 5^ inches to 6^ inches in circumference, of hemp. The diameter of the pulleys should be at least 30 times that of the rope, and the shafts should not be less than 20 feet apart. A 6^-inch rope is about equivalent to a leather belt 4 inches wide, running at the same speed — 3,000 feet per minute. Such a rope will transmit 25 horse-power. The coefficient of resistance to slipping of a rope in a groove is about four times that of an equivalent belt. HEAT-PROOF PAINTS. Steam pipes, steam chests, boiler fronts, smoke connec- tions and iron cliimneys are often so highly heated that the l^'^'int upon them burns, changes color, blisters and often flukes off. After long protracted use, under varying circum- stances, it has been found that a silica-graphite paint is well adapted to overcome these evils. Nothing but boiled linseed oH'y required to thin the paint to the desired consistency for application, no dryer being necessary. This paint is applied in the usual manner with an ordinary brush. The color, of course, is black. But another paint, which admits of some variety in color, is mixed by making soapstone, in a state of fine powder, with a quick drying varnish of great tenacity and hardness. This will give the painted object a seemingly enameled surface, which is durable, and not aftected by heat, acids, or the action of the atmosphere. When applied tc wood it prevents rotting, and it arrests disintegration when applied to stone. It is well known that the inside of an iron ship is much more severely affected by corrosion than the outside, and this paint has proven itself to be a most efficient protection from inside corrosion. It is lig^ht, of fine grain. 409 can be tinted with suitable pigments, spread' easily, and takes hold of the fiber of the iron or steel quickly and tena- ciously. A cheap and effective battery can be made by dissolving common soap in boiling water and adding to it small amounts of bran and caustic potash or soda. This mixture, while warm, is poured in a jar containing a large carbon pole and an amalgamated zinc rod. When cold the battery "sets " after the manner of a jelly, and consequently will not readily evaporate or spill over. NEW PROCESS FOR WIRE MANUFACTURE. A machine for cheapening and improving steel or iron wire has been invented, which is calculated to make a change in many branches of industry in which iron, steel, copper and brass wire are used. The invention, which has just been patented, consists of a series of rolls in a continuous train, geared with a common driver, each pair of rolls having a greater speed than the pair preceding it, with an intervening friction clutch adapted to graduate the speed of the rolls to the speed of the wire in process of rolling. The entire pro- cess of manufacturing the smallest-sized wires from rods of one-half inch is done cold. The new process obviates the danger of unequal annealing, and of burning in the furnaces, and the wire is claimed to be more flexible and homogeneous than that produced by the common processes, and capable of sustaining greater longitudinal strain. It is, therefore, specially adapted for screws, nails, cables, pianofortes, and many other uses, and copper wire made by this process is claimed to be possessed of greatly increased electrical con- ductivity. SLEEPERS USED BY THE WORLD'S RAILROADS. According to the Moniteitr Indtistriel^ the six principal railways of France use more than 10,000 wooden sleepers pet day, or 3,650,000 per annum. As a tree of ordinary dimen* sions will only yield ten sleepers, it will be necessary to cnt down 1 ,000 trees per day. In the United States the con- sumption is much greater, amounting to about 15,000,000 sleepers per year, which is equivalent to the destruction of 170,000 acres of forest The annual consumption of sleepers by the railways of the world is estimated at 40,000,000. From these figures the rapid progress of disforest at ion will be understood, and it is certain that the natural growth can* not keep pace with it. 4IO WEIGHTS OF CAST IRON PIPES. Weights, per foot, of Cast Iron Pipes in general use, including Socket and Spigot ends. Diameter. Thickness Weijrht per foot. Diameter. Thickness Wcijrht per loot. Staehcs. K+" inch. 6I41I.S. 14 nchcs % inch. 138 lbs. ,« T" % " - «'^ " 1 6 " ^ ~« 85 - :.'« cA ^.6 " 14 . " 16 % - 108 - <»■ & %+ :« 11 ' 16 % " 129 • : '^ «■' % " ISJ^ " 16 H 152 •* '4'. xS> H "" 18 - 16 1 175 • 'Cs\ ^ •^ " 23 " 18 % 114 - i* «- iJ^8 + ■m 16>^ « 18 \ 187 • '* & J6 u 23 - 18 % 161 - * «• % 31- " 20 % 132 • «» 3ff " 26 - 20 H 160 • U «> J6 „ 33 ' - 20 re 197 - hft <« !5^ •«' 4 "21^ " 20 1 216 • ] ■ ■A % 40 r»2 - 24 ■Xs 159 • l« v« % •» 4» 24 % 100 "^ '9 .ur \^ " 4336 " «4 " 30 I 310 * 1 10 u % - 68 - 30 \% 360 *. 10 k ?i a 80 " 36 % 332 "^ 12 '.•1 Jv - 67 - 36 1 881.-^ 12 " 51 M 82 " 36 1^8 429 -J 12 2i • 99 36 VA 470 -1 12 » % " 117 48 1 612 •! 14 " J6 u 74 « 48 1^8 684 *' • M % a 94 48 1^4 686 • M % M 113 « 48 1J6 776 ^- 411 POINIS FOR BUILDERS. BY STEEL SQUARE. Never compete with ^ ' botch " if you know he is favored by the person about to build. He will undercut and beat you every time. Favor the man who employs an architect. Under an honest architect you will have less friction, make more money, be better satisfied v;ith your work, and give greater satisfaction to the owner than in working from plans fur- nished by a nondescript. In tearing down old work, be as careful as putting up new. Old material should never be destroyed simply because it is old. ! When putting away old stuff, see that it is protected from rain and the atmosphere. It costs about fifteen per cent, extra to work up old ma- terial, and this fact should be borne in mind, as I have known several contractors who paid dearly for their " whistle " in estimating on working up second-hand material. These remarks apply to woodwork only. In using old brick, stone, slate and other miscellaneous materials, it is as well to add double price for working up. Workmen do not care to handle old material, and justly so. It is ruinous to tools, painful to handle, and very de- structive to clothing. In my experience I always found it pay to advance the wages of workmen — skilled mechanics — while working up old material. This encouraged the men and spurred them to better efforts. Sash frames, with sash weights, locks and trim complete, may be taken out of old buildings that are being taken down and preserved just as good as new by screwing slats and braces on them, which not only keep the frame square, but prevent the glass from being broken. Doors, frames and trims may also be kept in good order nntil used, by taking the same precautions as in window frames. Old scantlings and joists should have all nails drown oi hammered in before piling away. Counters, shelving, draws and other store-fittings should be ^12 kindly dealt with. They will all be called for sooner or later. Take care of the locks, hinges, bolts, keys, and other hard- ware. Each individual piece represents money in a greater or less sum. *■ Old flooring can seldom be utilized, though I have seen i^ used for temporary purposes, such as fencing, covering of veranda floors, while finishing work on plastering, etc. As a rule, however, it does not pay to take it up carefully and preserve it. Conductor pipes, metallic cornices, and sheet metal work generally can seldom be made available a second time, though all is worth caring for, as some parties may use it in repairs. Sinks, wash-basins, bath-tubs, traps, heating appliances, grates, mantels and hearth-stones should be moved with care. They are always worth money and may be used in many places as substitutes for more inferior fixings. Marble mantels require the most careful handling. Perhaps the most difiicult fixtures about a house to adapt a second time are the stairs. Yet, I have known where a shrewd contractor has so managed to put up new building? that the old stairs taken from another building just suited. This may have been a " favorable accident," but the initiated reader will understand him. Seldom such accidents can occur. Rails, balusters and newels may be utilized much re-adler than stairs, as the rail may be lengthened or shortened to suit variable conditions. Gas fixtures should be cared for and stowed away in some dry place. I'hey can often be made available, and are easily renovated if soiled or tarnished. It is not wise to employ men to take down buildings who who have no other qualities to recommend them than their strength. As a rule they are like bears — have more strength than knowledge, and the lack of the latter is often an ex- pensive desideratum. Employ for taking down the work good, careful mechanics, and do not have the work " rushed through." Rushers of this sort are expensive. Never send old material to a mill to be sawed or planed. No matter how carefully nails, pebbles and sand have been hunted for, the saw or planer knives will most assuredly find some vou overlooked; then there will be trouble at the mill. Have some mercy for tjie workman's tools. If it can be avoided, do not work up old stuff into fine work. If not 413 avoidable, pay the workman something extra because of in» jury to tools. Don't grumble if you do not get as good results from the use of old material as from new. The workman has much to contend with while working up old, nail-speckled, sand* covered material. RULES FOR ESTIMATING COST OF PLASTER- ING AND STUCCO WORK. PLASTERING. Plastering is always measured by the square yard for aB plain work, and by the foot superficial for all cornices of plain members, and by foot lineal for enriched or carved moldings in cornices. By plain work is meant straight surfaces (like ordinary walls and ceilings), without regard to the style or quantity of finish piit upon the job. Any paneled work, whether on walls or ceilings, run with a mold, would be rated by the foot superficial. Different methods of valuing plastering find favor m different portions of the country. The following general rules are believed to be equitable and just to all parties: Rule I. — Measure on walls and ceilings the surface actually plastered without deducting any grounds or any openings of less extent than seven superficial yards. Rule 2. — Returns of chimney breasts, pilasters and all strips of plastering, less than 12 inches in width, measure as 12 inches wide; and where the plastering is finished down upon the wash-board, surbase or wainscoting, add 6 inches to height of wall. Rule J. — In closets, add one-half to the measurement ; or, if shelves are put up before plastering, charge double measurement. Raking ceilings and soffits of stairs, add one- half to the measurement. Circular or elhptical work, charge two prices ; domes or groined ceilings, three prices. Rule 4. — For each 12 feet interior work is done further from the ground than the first 12 feet, add five per cent. For outside work, add one per cent, for each foot the work is done above the first 12 feet. STUCCO WORK. Rule I, — All moldings, less than one foot girt, to be rated as one foot ; over one foot, to be taken superficial. When work requires two molds to run same cornice, add one-fifth. 414 Rule 2. — P'or each internal angle or miter, add one foot to length of cornice ; and each external angle add two feet. All small sections of cornice less than 12 inches long measure as 12 inches. For raking cornices add one-half. Circular or elliptical work, double price ; domes and groins, three prices. Rule j>. — For enrichments of all kinds, charge an agreed price. Rule 4. — For each 12 feet above the first 12 feet from the ground, add five per cent. CHINESE CASH. A large number are engaged in molding, casting and fin- ishing the " cash " used as coin all over China, Mexican dollars and Sycee silver being used in large transactions. The cash are made from an alloy of copper and zinc, nearly the same as the well-known Munn metal, and it takes about 1,000 of them to answer as change for a dollar, so minute and low do prices run in this country, of which I will only give one instance. The fare for crossing the ferry on the Peiho was only two cash, or one-fifth of a cent. DEEP SOUNDINGS NEAR THE FRIENDLY ISLANDS. Her Majesty's surveying ship Egeria, under the com- mand of Captain P. Aldrich, R. N., has, during a long sounding cruise and search for reported banks to the south of the Friendly Islands, obtained two very deep soundings of 4,295 fathoms and 4,430 fathoms, equal to five Eng- lish miles respectively, the latter in latitude 84 deg. 37 min. S., longitude 175 deg. 8 min. W., the other about twelve miles to the southward. These depths are more than 1,000 fathoms greater than any before obtained in the Southern Hemisphere, and are only surpassed, as far as is yet known, in three spots in the the world— one of 4,655 fathoms off the northeast coast of Japan, found by the United States steamship Tuscarora ; one of 4,475 fathoms south of the Ladrone Islands by the Challenger ; and one of 4,561 north of Porto Rico, by the United States ship Blake. Captain Aldrich's soundings were obtained with a Lucas sounding machine and galvan- ized wire. The deeper one occupied three hours, and was obtained in a considerably confused sea, a specimen of the bottom being successfully recovered. Temperature of the bottom, 33.7 deg. Fahr. 423 SIZE AND WEIGHT OF FLAT-TOP CANS. The following table gives the size of the flat top cans and the amount of material required when galvanized iron is used in their construction. The table shows the net weight per can with iron from No. 27 gauge to No. 20 gauge. No al- lowance is made for seams, hoops, or solder. SIZE CANS. WEIGHT PER CAN. N 0. No. No. N 0. No. N 0. N 0. N *rt 27 G. 26 t/3 G. 25 !/5 G. 24 G. 23 t/2 G. 22 G. 21 G.. '«» 4. This same board may have two bent or elbow tubes in it, opening upward and into the room, so that the air coming through does not blow directly in. The inside open- ings may be protected by valves, and thus the amount of in- coming current can be regulated. We thus get a circulating movement of the air, as, the window being raised, there is an opening between the sashes. 'v^. In summer a frame half as big as the lower sash may be made of perforated zinc or wire gauze and placed in so as to keep the window up. There is no draught; and, if kept in position all night, then, as a rule, the inmate will enjoy re- freshing sleep. 6. In addition to these plans, the door of every bed- room should possess, at the top thereof, a ventilating panel, the simplest of all being that formed of wire gauze. In conclusion, let me again beg of you to value fresh air as you value life and health itself; while taking care not 10 sleep directly in an appreciable draught, to abjure curtains all round the bed. A curtained bed is only a stable for nightmares and an hotel for a hundred wonder-ills and ail- ..^^nts. STRENGTH OF ICE. Ice two inches thick will bear men to walk on. Ice four inches thick will bear horses and riders. Ice eight inches ihick will bear teams with very heavy loads. Ice ten inches thick will sustain a pressure of 1,000 pounds per square foot. 423 THE FORESTS OF THE UNITED STATES. The total area of forest lands in the United States and Territories, according to the annual report of the Division of Forestry of the Department of Agriculture, is 465,795,000 acres. The State which has the largest share is Texas, which is credited with 40,000,000 acres. Minnesota comes next with 30,000,000, then Arkansas with 28,000,000; and Florida, Oregon, California and Washington Territory are put down at 20,000,000 each. Georgia and North Carolina have each 18,000,000; Wisconsin and Alabama, each 17,000,000; Tennessee, 16,000,000; Michigan, 14,000,000; and Maine, 12,000,000 acres. Taking the States in groups, the six New England States have, in round numbers, 19,000,000 acres; four Middle States, 18,000,000; nine Western States, 80,000,000; four Pacific States, 53,000,000; seven Territories, 63,000,000; and fourteen Southern States, 233,000,000 acres, or almost precisely half of the whole for- est area of the country. Reviewing the figures given by the department, the Tradesman, of Chattanooga, Tenn., makes the following instructive comment: "These statistics show that, while the process of denudation has been carried on to an unhealthy extreme in the Eastern, Middle and a few of the Western States, the forest area still remaining in this country is a magnificent one. If the estimates of the department are approximately correct, the timber lands of the country, exclusive of Alaska, cover an area equal to fifteen States the size of Pennsylvania. If proper measures are taken to pre- vent the rapid and unnecessary destruction of what is left of our forest domain, it should be equal to all requirements for an indefinite period. It is not yet a case of locking the stable after the horse is stolen, and never should be allowed to become so. With the adoption the policy of judicious tree planting in the prairie States, and a system of State or government reservations in the mountainous districts, which are the sources of the chief rivers of the country, the evil effects which have followed forest denudation in Europe and some portions of Asia would never exist here. " TO FIND THE WEIGHT OF GRINDSTONES. .06363 times square of inches diameter, times thickness In inches =^ weight of grindstone in lbs. ^•1415926 = ratio of diameter to circumference of cirdo 4^4 ALTITUDE ABOVE THE SEA-LEVEL OF V^ARX- OUS PLACES IN THE UNITED STATES. Portland, Me 185 Concord, N. H 375 Cleveland, O 645 Detroit, Mich 595 Mt. Washington 6,293 Ann Arbor, Mich 890 Boston, Mass 82 Albany, N. Y 75 NewYork, N. Y 60 Buffalo, N. Y 580 Philadelphia, Penn 60 Pittsburg, Penn 935 Baltimore, Md 275 Washington, D. C 92 Charleston, S. C 27 Vicksburg, Miss 352 New Orleans, La 10 El Paso, Texas SjSsi Knoxville, Tenn . . » x.-V>', Louisville, Ky ^ /^^g Cincinnati, O 480 Upper portion of cd'-^ 588 San Francisco, Cal 130 Indianapolis, Ind 700 Chicago, 111 581 Milwaukee, Wis 590 St. Anthony Falls, Mmn.. 822 Dubuque, la 1,400 St. Louis, Mo 480 Omaha, Neb 1,300 Lawrence, Kan 803 Fort Phil Kearney, Wy 6,000 Yankton, Dak 1,900 Fort Garland, Colo 8,365 Salt Lake City, Utah 4,322 Sacramento, Cal 22 VALUE OF LEAVES AS PURIFIERS. A single tree, through its leaves, is capable of purifying the air of the carbonic acid which has been exhaled by a dozen individuals, or even a score. A human being exhales, in the course of 24 hours, about 100 gallons of carbonic acid. According to Boussingault's estimate a single square yard of ^leaf surface, countnig both the upper and the under sides of the leaves, can, under favorable circum- stances, decompose at least a gallon of carbonic acid in a day. One hundred square yards of leaf surface then would suthce to keep the air pure for one man. bin the leaves of a tree of moderate size present a surface of many hundred square yards. HOW TO POLISH ZINC. We have been successful in polishing zinc with the follow- ing solution: To 2 quarts of rainwater add 3 oz. powdered rotten stone, 2 oz. pumice stone, and 4 oz. oxalic acid Mix thoroughly, and let it stand a day or two before using. Stir or shake it up when using, and, after using, polish the zinc with a dry woolen cloth or chamois skin. The more thor- oughly the zinc is rubbed the longer it will stay bright. 425 HOW TO MAKE A GOOD FLOOR. Nothing attracts the attention of a person wishing to rent or purchase a dwelling, store or office, so quickly as a hand- some, well-laid floor, and a few suggestions on the eubject, though not new, may not be out of place. The best floor for the least money can be made of yellow pine, if the mateiial is carefully selected and properly laid. First, select edge-grain yellow pine, not too "fat," clear of pitch, knots, sap and splits. See that it is thoroughly seasoned, and that the tongues and grooves exactly match, so that, when laid, the upper surfaces of each board are on a level. Ihis is an important feature often overlooked, and planing-mill operatives frequently get careless in adjusting the tonguing and grooving bits. If the edge of a flooring board, especially the grooved edge, is higher than the edge of the next board, no amount of mechanical ingenuity can make a neat floor of them. The upper part of the groove will continue to curl upward as long as the floor lasts. Supposing, of course, the sleepers, or joists, are properly placed the right distance apart, and their upper edges pre- cisely on a level, and securely braced, the most important part of the job is to "lay" the flooring correctly This part of the work is never, or very rarely ever, done nowa- days. The system in vogue with carpenters of this day, of laying one board at a time, and " blind nailing," is the most glaring fraud practiced in any trade. They drive the tongue of the board into the groove of the preceding one, by pounding on the grooved edge with a naked hammer, mak- ing indentations that let in the cold air or noxious gases, if it is a bottom floor, and then nail it in place by driving a six-penny nail at an angle of about 50^ in the groove. An awkward blow or two chips off the upper part of the groove, and the last blow, designed to sink the nail-head out of the way of the next tongue, splits the lower part of the groove to splinters, leaving an unsightly opening. Such nailing does not fasten the flooring to the sleepers, and the slanting nails very often wedge the board up so that it does not bear on the sleeper. We would rather have our flooring in the tree standing in the woods than put down that way. The proper plan is to begin on one side of the room, lay one course of boards with ilie tongue next to, and neatly fitted to, the wall (cr studding, if a frame house), and be sure the boards are laid perfectly straight from end to end of the room and square with the wall. Then nail tliis coursf: firrpl- <-o the sleeners, through and throuj-k, one nail near 426 each edge of the board on every sleeper, and you are ready to begin to lay a floor. Next, fit the ends and lay down four or six courses of boards (owing to their width). If the boards differ widely in color, as is often the case in pine, do not lay two of a widely different color side by side, but arrange them so that the deep colors will tone off into the lighter ones gradually. Push the tongues into the grooves as close as possible, without pounding with a hammer, or, if pounding is necessary, take a narrow, short piece of flooring, put the tongue in the groove of the outer board, and pound gently on the piece, never on the flooring board. Next, adjust your clamps on every third sleeper and at every end joint, and drive the floor firmly together by means of wedges. IDrive the wedges gently at the start, and each one equally till the joints all fill up snugly, and then stop, for, if driven too tight, the floor will spring up. Never wedge directly against the edge of the flooring board, but have a short strip with a tongue on it between the wedge and the board, so as to leave no bruises. Then fasten the floor to the sleepers by driving a flat- headed steel wire nail of suit- able size, one inch from either edge of every board, straight down into each sleeper. At the end-joints smaller nails may be used, two nails in board near the edges, and as far from the ends as the thickness of the sleeper will permit. Pro- ceed in this manner until the floor is completed, and you will have a floor that will remain tight and look well until worn out. Such minute directions, for so common and simple a job, sound silly, but are justifiable from the fact that there are so many alleged carpenters who either do not know how or are too lazy to lay a floor properly. GLUE FOR DAMP PLACES. For a strong glue, which will hold in a damp place, the following recipe works well : Take of the best and strongest glue enough to make a pint when melted. Soak this until soft. Pour off the water, as in ordinary glue-making, and add a little water if the glue is likely to be too thick. When melted, add three table-spoonfuls of boiled linseed oil. Stir frequently, and keep up the heat till the oil disappears, which may take the whole day, and perhaps more. If necessary, add water to make up for that lost by evaporation. When no more oil is seen, a tablespoonfulof whiting is added and thoroughly incorporated with the glue. 427 MORTAR MAKING. Much depends on having mortar made on correct, if not scientific, principles. The durabiHty, if not the actual safety, of a building is more or less affected by the kind of mortar that is put into it. We have seen brick buildings, and not very old ones either, from which the dry and hardened mor- tar could easily be picked in cakes from between the bricks. The advantage of using such mortar is, that, when the buikling tumbles down, 'there will be no trouble in picking from it the old bricks, preparatory to rebuilding. A brick wall, if put up with the right kind of mortar, will be solid and almost homogeneous, as likely to break through the middle of the bricks as at the joints. Such a building will never tumble down, except under great strain, and will with- stand a pretty severe earthquake shock. An old builder, of nearly forty years' experience in mak- ing mortar, writing upon the subject to a contemporary, very justly says : " The mere matter of slacking lime does not make mortar out of it. Lime and water alone will not make any better mortar than sand and water." He sug- gests the use of plenty of water in slacking the lime, so that, when it is run out of the box into the bed, it will not bake or burn, as it is liable to do, if not well watered. The mortar bed should be large and tignc, so there will be no leakage of the lime water. The proportion should be about fifty yards of good sand to twenty-five barrels of lime, for the first mixing, which should be thoroughly done. The hair should be put into the lime before mixing in the sand. After the mortar has been mixed in the above proportions for ten days or more, if the amount of materials given have been used, twenty-five to fifty loads of sand may be added and worked in. It is said that the water that rises on a bushel of slaked lime, and where plenty of water has been used, if removed and put on a sharp sand, will make better stone than lime and sand mixed, showing that the water should be retained in the sand and lime while it is fresh, and that the mortar should be tempered in its own liquor. Of course, where smaller quantities are used, the proportion should be retained, both at the first mixing and in the sand added subsequently. A pound of ten-penny cut nails will do as much work as two pounds of wire nails. Taking the average of all cut nails, they are worth nearly double as much as wire nails, from tests made at the Watertown Government Arsenal. 428 COST OF EXCAVATING AND HANDLING ROCK. The average weight of a cubic yard of sandstone or con^« glomerate, in place, is given as 1.8 tons, and of compact granite, gneiss, limestone or marble, 2 tons, or an average of 1.9 tons, or 4,256 pounds. A cubic yard, when broken up ready for removal, increases about four-fifths in bulk, and /^ of a cubic yard, 177 pounds, is a wheelbarrow load. Experience shows that, with wages at $1 per day of 10 hours, 45 cents per cubic yard is a sufficient allowance for loosening hard rock. Soft shales and allied rocks may be loosened by pick and plow at a cost of 20 cents to 30 cents per cubic yard. The quarrying of ordinary hard rock re- quires from ]4. pound to ^ pound and sometimes ^ pound of powder per cubic yard. Drilling with a churn driller costs from 12 to 18 cents per foot of hole bored. Upon these data, Mr. Rigly estimates the total cost, per cubic yard of rock in place, for loosening and removing by wheel- barrow (labor assumed at $1 per day of 10 hours), as fol- lows: When distance removed is 25 feet, total cost=$o.537; when 50 feet, $0,549; when 100 feet, $0,573; when 200teet, $0,622; when 500 feet, $0,768; when 1,000 feet, $1,011; and when 1,800 feet, $1,401. This is exclusive of contractor's profit. When labor is $1.25 per day, add 25 per cent, to the cost prices given; when $1.50 per day, add 50 per cent, and so on. In hauling by cart, the cost of loading, which will be about 8 cents per cubic yard of rock in place, and the addi- tional expense of maintaining the road must be added. Allowing, then, 851 pounds as a cart-load, the total cost per I ubic yard is estimated, when removed 25 feet, at $0,596; when 50 feet*, $0,599; when 100 feet, $0,605; when 200 feet, $0,617; when 500 feet, $0,655; when 1,000 feet, $0,717; and when 1,800 feet, $0.94. IRON BRICK. It is reported that the German Government testing labor- atory for building materials has reported favorably on a new paving-block called iron brick. This brick is made by mix- ing ecjual parts of finely-ground day, and adding 5 per cent, of iron ore. This mixture is moistened with a solution of 25 per cent. sul])hate of iron, to which fine iron ore is added until it shows a consistency of 38 degrees Baume. It is ther formed in a press, dried, dipped once more in a nearly con- centrated solution of sul]:)hate of iron and finely ground iron ore, and is baked in an oven for 48 hours in an oxidizing flame, and 24 hours in a reducing flame- 429 DRY ROT IN TIMBER. No wood which is liable to damp, or has at any time absorbed moisture, and is in contact with stagnant air, so that the moisture cannot evaporate, can be considered safe from the attack of dry rot. Any impervious substance applied to wood, which is not thoroughly dry, tends to engender decay ; floors covered with kamptulicon and laid over brick arching before the latter was dry ; cement dado to wood partition, the water expelled from dado in setting, and absorbed by the wood, had no means of evaporation. Woodwork coated with paint or tar before thoroughly dry and well seasoned, is liable to decay, as the moisture is imprisoned. Skirtings and wall paneling very subject to dry rot, and especially window backs, for the space between woodwork and the wall is occupied by stagnant air ; the former absorbs moisture from the wall (especially if it has been fixed before the wall was dry after building), and the paint or varnish prevents the moisture from evaporating into the room. Skirting, etc., thus form excellent channels for the spread of the fungus. Plaster seems to be sufficiently porous to allow the evaporation of water through it ; hence, probably, the space between ceiHng and floor is not so frequently attacked, if also the floor boards do not fit very accurately and no oil cloth covers the floor. Plowed and tongue floors aie disadvantageous in cer- tain circumstances, as when placed over a space occupied by damp air, as they allow no air to pass between the boards, and so dry them. Beams may appear sound externally and be rotten within, for the outside, being in contact with the air, becomes dryer than the interior. It is well, therefore, to saw and reverse all large scantling. The ends. of all timber, and especially of large beapis, should be free (for it is through the ends that moisture chiefly evaporates). They should on no account be imbed- ded in mortar. Inferior and ill-seasoned timber is evidently to be avoided. Whatever insures dampness and lack of evaporation is conducive to dry-rot, that is to say, dampness arising from the soil ; dampness arising from walls, especially if the damp-proof course has been omitted ; dampness arising from use of salt sand ; dampness arising from drying cf mor- tar and cement. Stagnation of air resulting from air grids getting blocked with dirt or being purposely blocked through ignorance. Stagnation may exist under a floor although there are grids in the opposite walJs, for it is difficult to induce the air to move in a horizontal direction without some special means of suction. Corners of stagnant air are to be guarded against. Darkness assists the development of fungus ; whatever increases the temperature of the wood and stagnant air (within limits) also assists. PAINTING FLOORS. Colors containing white lead are injurious to wood floors, rendering them softer, and more liable to be worn away Paints containing mineral colors only, without white lead, such as yellow ochre, sienna or Venetian or Indian red, have no such tendency to act upon the floor, and may be used with safety. This quite agrees with the practice com.mon in this country, of painting floors with yellow ochre or raw umber or sienna. Although these colors have little body^ compared with the white-lead jmint, and need several coats, they form an excellent and very durable covering for the floor. Where a floor is to be varnished, it is found that var nish made by drying lead salts is nearly as injurious as lead paint. Instead of this, the borate of manganese should be used to dispose the varnish to dry, and a recipe for a good floor varnish is given. According to this, two pounds of pure white borate of manganese, pounded very fine, are to be added, little by little, to a saucepan containing ten pounds of linseed oil, which is to be well stirred, and gradually raised to a temperature of three hundred and sixty degrees Fahren- heit. Meanwhile, heat one hundred pounds linseed oil in a boiler until bubbles form ; then add to it slowly the first liquid, increase the fire, and allow the whole to cook for twenty minutes, and finally remove from the fire, and filter while warm through cotton cloth The varnish is then ready, and can be used immediately. Two coats should be used, and a more brilliant surface may be obtained by a final coat of shellac. The railroads consume half of the coal used in this country. 431 COLD WATER SUPPLY PIPES. The following matter, in catechetical form, illustrates the teachings of the New York Trades Schools in this con- nection : I. — What size should the pipe from the street main to the house be ? A. — The supply pipes of New York average about i/4 to I )4 inches in diameter. 2. — What material is used for this pipe in New York ? A. — Mostly lead pipes. 3. — What other materials, besides lead, are used for sup- ply pipes ? A. — Galvanized iron, brass, and tin-lined lead pipes. 4. — How is iron used ? A. — Plain, galvanized, and lined with tin or glass. 5. — What are the advantages and disadvantages of lead pipes ? A. — Advantages are its ductility, strength, and easiness of working, also its durability. Disadvantages are danger of poisoning the water, and of being eaten by rats. 6. — What are the advantages and disadvantages of plain iron pipe ? A. — Advantages are cheapness, easiness of putting to- gether, and freedom from poisoning. Disadvantages are rusting, and filling up of pipes. 7.- What are the advantages and disadvantages of tin- lined pipes ? A. — Advantage is in its freedom from poisoiJng water. Disadvantage in not being durable for hot-water pipes. 8. — What are the advantages and disadvantages of glass- lined pipe ? A. — Glass-lined pipe makes an excellent water pipe, but is liable to break in working and putting up. 9. — What are the advantages and disadvantages of gal- vanized iron pipe ? A. — Galvanized iron pipe is cheap and free from rust, but some water decomposes zinc, and its salts are poison- ous. 10.— What are the advantages and disadvantages of brass pipe? A. — When brass pipe is lined with tin, it is very light and strong; but, when the tin wears off, there is danger of poisoning the water. II. — What are the advantages and disadvantages of block-tin pipe ? 432 A. — They aiv not durable for hot water, and are very expensive. 12. — What are the advantages and disadvantages of tin- lined lead pipe ? A. — They are not durable. 13. — In usimg tin-lined lead pipe, vi^hat must be guarded against? A. — The lining must not be disturbed or the tin melted out. 14. — How should the supply pipe be connected with street mains? A. — By a brass tap and coupling. 15. — How should a lead pipe be joined to an iron piper A. — By a brass spud or soldering nipple. 16. — Should the supply pipe be so arranged that it can be emptied? and why? A. — Yes. To prevent freezing, and the waterjfrom stag- nating in the pipe. 17. — What precaution can be taken against freezing if ^he main is within three feet of surface? A. — By bending the pipe a few feet lower at the main, and continuing the pipe at the lower level. 18. — In crossing an area with a supply pipe, what precau- tion should be taken? A. — Cover the pipe with felt, or put it in a box filled with saw-dust, to prevent freezing? 19. — What is gained by putting a supply pipe from street main to house in a larger iron pipe? A. — The air in a larger iron pipe protects the supply, and steam can be injected to thaw pipe if it freezes. 20. — How can water supply be increased after service pipe enters house? A. — The flow of water can be greatly assisted by using a lar >er pipe after entering the house. 21. — Is there any way to arrange a pipe so that drawing water from a lower floor will not stop or retard the flow fro*:a upper floors ? A. — The best way would be to proportion branches on difterent floors according to pressure ; the smaller the press- ure the larger the outlet. 22. — Suppose a three-story house had a ^ tap from main to house, and connected from this tap to top of boiler with a iX iiich pipe; what size should the branch pipes to base- ment fixtures be ? A. — One-half to five-eighths should be large enough. 23. — The parlor floor contains a pantry sink, a wash- 433 basin and a water-closet ; how large should the supply pipe from basement to parlor floor be ? A. — About I inch in diameter. 24. — How large the branch pipes to fixtures ? A. /^ to ^ in diameter. 25. — The second floor contains a bath, two water-closets and five wash-basins ; how large should the pipe from par- lor to second floor be ? A. — About I inch in diameter. 26. — How large should the pipe from basement to tank be? A. — About 1% inch in diameter. 27. — In a building of six or more stories in height with cold water supply drawn from tank on upper floors, does any difficulty occur ? A. — Yes. On the lower floors the pressure is to great. 28. — How can it be remedied ? A. — By diminishing branch pipes to give a proportional supply. 29. — Can supply pipe be so arranged that water can be drawn from the main or from tank? A. — Yes. By using a special stop-cock for the pur- pose. 30. — What precautions should be takf^n to prevent pipes freezing ? A. — By placing as far from frost as possible, and by proper boxing and felting. 31. — Why are pipes liable to buist when they freeze ? A. — The expansion expands the pipes, and, consequently, they burst. 32. — What is the expanding pressure of freezing water ? A. — Thirty thousand pounds to the square inch. 33. — What means are taken to thaw out a service-pipe ? A. — The application of heat externally or steam and hot water internally is about the best means. 34.— Is the external application of heat objectionable with iron pipes ? A. — Yes ; as the sudden contraction is as dangerous as the expansion. 35. — In carrying supply pipes across a floor, what pre- caution can be taken to protect ceiling below from a leak ^ A. — By puttmg pi]:>es in a box lined with lead, and ha' ing a waste, or tell-tale, pipe at lowest ]:)oint. 36. — Does fresh mortar injure lead pipes ? A. — As the iime in fresh mortar is corrosive and forms a soluble compound, it is an Mijury to lead pipes. 434 PRESSURES ON TANKS. Q. — In a full cubical tank, what is the pressure on any giertical side ? A. — One-half the weight of the contents. Q.— In a full conical vessel standing on its base, what is the pressure on the base ? A. — Three times the weight of the contents. Q. — In a hollow sphere, lull of liquid, which is the press- ur.^ on the surface of the lower half? A. — Three tim^s the weight of contents. TINNING BY SIMPLE IMMERSION. Argentine is a name given to tin precipitated by gal- vanic action from its solution. This material is usually ob- tained by immersing plates of zinc in a solution of tin, con- taining 6 grammes (about 90 grains) of the metal to the litre (0.88). In this way tin scrap can be utilized. To apply the argentine according to M. P. Marino's process, a bath prepared from argentine and acid tartrate of potash, ren- dered soluble by boric acid. Pyrophosphate of soda, chlo- ride of ammonium, or caustic soda may be substituted for the acid tartrate. The bath being prepared, the objects to b( coated are plunged therein, first having been suitably pickled and scoured, and they may be subjected to the action of an electric current. But a simple immersion is enough. Th( bath for this must be brought to ebullition, and the object' of copper or brass, or coated therewith, may be immersed in it. HOW TO FIND THE AMOUNT OF STEAM-PIPE REQUIRED TO HEAT A BUILDING WITH STEAM. Rule for finding the superficial feet of steam-pipe requirec to heat any building with steam : One superficial foot o steam-pipe to six superficial feet of glass in the windows, oi one superficial foot of steam-pipe for every hundred squar( feet of wall, roof or ceiling, or one square foot of steam-pipt to eighty cubic feet of space. One cubic foot of boiler i; required for every fifteen hundred cubic feet of space to b( warmed. One horse-power boiler is sufficient for fort) thousand cubic feet of space Five cubic feet of steam, a seventy-five pounds pressure to the square inch, weighs one pound avoirdupois. 435 SEASONING TIMBER. Timber, when freshly cut, contains from thirty-seven to orty-eight per cent, of water, the kind, the age, and the eason of vegetation go t/cning the percentage. Older ^/ood generally heavier thai young wood, and the weight of ood cut m the active season is greater than that of wood ut m the dormant season. Water in wood is not chemically ombmed with the fiber, and, when exposed to the atmos- here, the moisture eva^ orates. The wood becomes lighter ntil a certain point is reached in the drying-out process. Iter which it gains or loses in the weight according to the ariations in the moisture and temperature of the atmos- phere. Following is a table showing the percentage in weight of water in round woods from young trees at different mgths of time after cutting: indofWood. 6mos. la mos. i8 mos. 24 mos. ^^S^ 30.44 23.46 1:8.60 19.95. l^^'l 32.71 26.74 z^.zs 20.28 [ornbeam 27.19 23.08 20.6v> 18.59 ^^^^ 39.72 29.-01 22.73 19.52 pPlar 40.45 26.22 17.77 17.92 }^ 33^7^ 16.87 15.21 18.00 "^^, 41.70 18.67 15.63 17.42 According to these figures, taken from actual trials, there nothing gained by keeping wood longer than eighteen onths, so far as drying or seasoning is concerned. In the oods mentioned, there appears to be an actual loss in ►me, and only a slow gain in others after that length of me. The pine, fir, and beech gained moisture, and the hers in the list lost only very slightly after the eighteen onths had passed. PROPOSED GREAT ENGINEERING FEAT. A gigantic scheme has been proposed, by which the can- is of the Rocky Mountains are to be dammed up from the madian boundary to Mexico, in order to form vast reser- >iis of water to be used in the irrigation of arid lands, and so e.ent floods in the lower Mississippi. Major Powell, direc- r of the national survey, estimates that at least 150,000 uare miles of land might thus be reclaimed — a territory ceeding in extent one-half of the land now cultivated in the mted States. The plan is to build dams across all the can- s in the mountains large enough and strong enough to hold ck tlie floods from heavy rains and melting snows, and then the water down as it may be needed upon the land to be :laimpc\ 43^ ON THE USE OF GLUE. In order to use glue successfully, says a writer of experi- ence, a great deal of experience is required, and it is useless for the amateur to try it; he will only spoil the work. So, unless the workman is well experienced in the treatment and the application of the glue, he had better leave it alone entirely. To render the operation successful, two consider- ations must t)e taken into account: First, to do good glu- ing requires that the timber be well seasoned and thoroughly dry, taking care that the joints to be glued are well fitted. Second, hi preparing the parts to be glued, each piece should he scratched with a sharp file or piece of a fine saw, to imake the glue hold better. The shop should be kept at a proper temperature, and the material heated so that the glue may flow quite freely. Having the glue properly pre- pared, spread it evenly upon the parts so as to fill up the pores and grain of the wood, then put the pieces together as rapidly as possible, using clamps and thumb-screws to draw the joints tightly together ; all superfluous glue should be washed off", taking great care not to use too much water^ or allowing any, to remain on the pieces put together. The greatest cause of bad gluing is in using inferior glue and in laying it on unevenly. Before using a new brand of glue it is safer to test it by gluing a piece of whitewood and ash together, clamping it with a thumb-screw, and, when dry, insert a chisel where it is put together, and, if the joint separates where it is glued, it is not fit to use, and should be rejected at once. The wood should split or give way rather than the substance promoting adhesion. This is a practi- cal and severe test, but it will pay to apply it, in the sta- bility of the work. GLUE PAINT FOR KITCHEN FLOOR. For a kitchen floor, especially one that is rough and uufiven, the following glue paint is recommended : To three pounds of spruce yellow add one pound, or two pounds if desired, of dry white lead, and mix well together. Dissolve two ounces of glue in one quart of water, stirring often until smooth and nearly boiling. Thicken the glue water after the manner of mush, nntil it will spread smoothly upon the floor. Use a common paint brush and apply hot. This will fill all crevices of a rough floor. It will dry soon, and when dry apply boiled linseed oil with a clean brush. In a few hours it will be found dry enough to use by laying papers or mats to Stsp fi"^./or a few days. When it needs cleaning, use hot suds. 437 EFFECT OF THE ATMOSPHERE ON BRICKS. Atmospheric influence upon bricks, tiles and other build- ing materials obtained by the burning of plastic clays, depends very much on the chemical composition of the clays and on the degree of burning. Thus, any distinct por- tions of limestone present in them would be converted into quicklime in the kiln, and, when the bricks were thor- oughly wetted, would expand in such a manner as to disin- tegrate the mass. If the clay used is too poor — that is to say, if it contains an excess of sand — the bricks will not become sufficiently fused, and, upon exposure to the weather, their constituent parts will separate. It is to be observed that in bricks, as in stones, decomposition does not take place with the greatest rapidity where constant moisture exists, but rather where, from the absence of capillarity, variable according to the moisture furnished by the atmos- phere, either directly or indirectly, a series of alternatiGS.a of dryness and humidity prevail. The foundation walls of buildings do not iii fact suffer so much in the parts immediately upon the ground as they do in those at a height of from one to three feet, according to the permeability of the materials employed. When bricks made of clay containing free silica are laid in mortar, and moisture can pass freely from either one or the other, it may be observed that the edges in contact become harder than the body of the bricks. No doubt this arises from the formation of a silicate of lime and alumina, the lime being furnished by the passage of the water through the bed of the mortar. THE GREAT EIFFEL TOWER. One of the principal features of interest at the Paris Expositions is the Eiffel tower. [It is constructed of iron, and rises to a height of 984 feet. As the greatest height yet reached in any structure is that of the Washington monument, 550 feet, some idea can be formed of the great distance upward that this tower rises. This tow^er weighs 7,000 tons, and cost 4,500,000 francs. One object of its construction is to light the Exposition grounds. The tower is supplied with elevators landing the passengers 971 feet from the earth. ' It is also supplied with electric lights of 19,000,000 candle power. Four such towers, with a capacity of 50,000,000 each, it is thought, would light the whole city of Paris. Perhaps this tower will decide the question whether or not it is possible to light an entire city from a few points, if not from one. ROT IN TIMBER. The principal cause of the lack of proper durability of timber in buildings is the porosity of the lumber used and the consequent liability to absorb moisture. Coarse-grained woods of quick growth are more liable to this defect than those of tough fiber and slow growth. When timber be- comes repeatedly wet and dry, it becomes brittle and weak- ened, or "its nature is gone," as the workmen say. Rot is of two kinds, wet and dry, and moisture is the essential element in both cases, the only difference being that in the first the moisture is quickly evaporated by exposure to the air, and in the latter, when there is no exposure, it produces 6. species of fungus and minute worms which eat in between the fibers, and gradually produce disintegration. Sap wood is more perishable than heart wood, for the former contains more of the saccharine principle, and renders the wood liable to a fermentive action. The prevalent practice of confining unseasoned timber by building it close into walls, thus preventing the ready evap- oration of whatever moisture happens to get to it, is a bad one. The ends of the wood, especially, should be sur- rounded by an open-air space, however small, as it is the ends where the dampness is most liable to penetrate into the structure of the wood. It is a well-known fact that a log of green timber, when kept immersed, w^ill become water-logged and sink, and, of course, become unfit for use afterward. The same process, only slower, applies when it is exposed to damp with no facilities for rapid evaporation. Quick- lime, when assisted by moisture, is a powerful aid in hasten- ing decomposition, in consequence of its affinity for carbon. Mild lime has not this effect, but mortar, as used in build- ings, requires a considerable length of time to become inert in its action as a corroding agent ; therefore bedding timber in damp mortar is very injurious, and often the cause of un- accountable decay. Wood, in a dry state, does not seem to be injured by contact with dry lime, it being rather a preser- vative. An example of this is shown in lathing covered with plaster, which often retains its original strength when sur- rounding timbers are completely rotted away. Anything that will hinder the absorbing process will ex- tend the life of a wood, such as a coating of tar, paint, or a charring of the surface. The latter method will prove the most effective, if sufficiently deep, as the charred coating is practically indestructible, closes the pores of the wood, and will prevent the bursting into flame in case of a fire. If all 439 joists, girders and inside beams of every kind were treated to a superficial charring process, it would tend, in conjunc- tion with fire-proof paint applied to outside finishing work, to make a building as nearly fire-proof as wood in any con- dition will allow. NUMBER OF BRICKS REQUIRED TO CONSTRUCT A BUILDING. Superficial Number of Bricks to Thickness c f feet of Wall. 4 Inch 8 Inch 12 Inch' 16 Inch 20 Inch 24 Inch I 7 15 22 29 37 45 2 15 30 45 60 75 90 3 23 45 68 90 113 135 4 30 60 90 I20 '§? 180 38 75 113 '¥" 188 225 5 45 90 135 180 225 270 7 53 105 158 210 263 360 8 60 120 180 240 300 9 6S 135 203 270 33^ 405 ID 75 150 225 300 375 450 20 150 300 450 600 750 900 30 225 450 675 900 1,125 1,350 40 300 600 900 1,200 1,500 1,800 50 375 750 1,125 1,500 1.875 2,250 60 450 900 1,350 1,800 2,250 2,700 70 525 1,050 1,575 2,100 2,625 3.150 3,600 80 600 1,200 1,800 2,400 3,000 90 67s 1.350 2,025 2,700 3,375 4,050 100 750 1,500 2,250 3,000 3.750 4,500 200 1,500 3,000 4,500 6,000 7,500 1 9,000 300 2,250 4,500 6,750 9,000 11,25c 1 T3'5oo 400 3,000 6,ooc 9,000 12,000 15,000 iS,ooo 1 n Sycamore is being introduced quite extensively for interior finish rsWhen properly selected it makes a very handsome finish Care should be taken in securing it, ns it is nearly as oad to warp as elm. It should be well backed with pir^. spruce or hemlock. 44^ FIRE-PROOFING WOODWORK. A door of the right construction to resist fire should be made of good pine, and should be of two or more thicknesses of matched boards nailed across each other, either at right angles or at forty-five degrees. If the doorway be more than seven feet by four feet, it v^^ould be better to use three thicknesses of same stuff; in other w^ords, the door should be of a thickness proportioned to its area. Such a door should always be made to shut into a rabbet, or flush with the wall when practicable ; or, if it is a slide door, then it should be made to shut into or behind a jamb, which would press it up against the wall. Both sides of the door and its (ambs, if of wood, should then be sheathed with tin, the Tplates being locked at joints, and securely nailed under the locking with nails at least one inch long. No air spaces f^'iiould be left in a door by paneling or otherwise, as the door vVill resist best that has the most solid material in it. In ?nost places it is much better to fit the door upon inclined metal sliders than upon hinges. This kind of door maybe fitted with automatic appliances, so that it will close of itself when subjected to the heat of a fire ; but these appliances do not interfere with the ordinary methods of opening and shutting the door. They only constitute a safegard against negligence. Under this heading may be classed all the doors of iron, whether sheet, plate, cast or rolled, single, double or hollow, plain or corrugated, none of which are capable of resisting fire for any length of time ; also wooden doors covered with tin on one side only, or covered with zinc, which melts at 700 degrees Fahrenheit, The wooden door covered with tin only serves its pur- pose when the wood is wholly encased in tin, put on in such a way that no air, or the minimum of air, can reach the wood when it is exposed to the heat of a fire. Under these conditions, the surface of the wood is converted into char- coal ; charcoal being a non-conductor of heat, itself tends to tetard the further combustion of the wood. But, if air penetrates the tin casing in any measure, the charcoal first made, and then the wood itself, are both consumed, and the door is destroyed. In like manner, if a door is tinned only only on one side, as soon as the heat suffices to convert the surface of the wood under the tin and next to the fire into charcoal, the oxygen reaches it from the outside, and the door is of little m )re value than a thin door of iron, or plain wooden door. 441 DIMENSIONS OF THE MO.^T IMPORTANT OF THE GREAT CATHEDRALS. Length, Breadth, Height, feet. feet. feet. St. Peter's , 613 450 438 St. Paul's 500 248 404 Duomo 555 240 375 Notre Dame 416 153 298 Cologne 444 283 Toledo 3q5 178 Rheims 480 163 I17 Rouen 469 146 465 Chartres 430 150 373 Antwerp . 384 171 402 Strasbourg 525 195 465 Milan 477 186 360 Canterbury 530 154 235 York 524 261 Winchester.. 554 208 Durham 411 170 214 Ely 617 178 Salisbury 473 229 279 SUGGESTIONS FOR COLORS. In forms, tints, and colors the ocean depths supply valu- able decorative suggestions. On silverware the iridescent hues of tropical shells are skillfully reproduced, and on ceramic ware their fascinating combinations of tints and the gradations of these shells have been too much hidden away in cabinets, instead of being studied by designers for their ele- gant curvatures and attractive colors. The delicate and varied hues of the sea anemone, and the curves, volutes and flowing lines of the univalves and bivalves are worthy of patient study with reference to graceful and fanciful orna- mentation. REMOVAL OF OLD VARNISH. A Mr. Myer has just patented, in Germany, a composi- tion for removing old varnish from objects. It is obtained by mixing five parts of 36 per cent, silicate of potash, one of 40 per cent, soda lye, and one of sal ammoniac (hydrochlor- ate of ammonia). 442 DECIMAL EQUIVALENTS OF INCHES, FEET AND YARDS. Frac. Dec. Dec. Ins. Feet. Yds. ^f an of an of a I = .0833 = 0277 Inch. Inch. Foot. 2 = 1666 = 0555 1-16 = .0625 = .00521 3 = 25 = . 0833 }i = .125 = .01041 4 = 3333 = nil 3-i6= .1875 = .01562 5 = 4166 = 1389 X = .25 = .02083 6 = 5 = 1666 5-16 = .3125 = .02604 7 = 5833 = 1944 Vs = -375 = .03125 8 = .666 = 2222 7-16 = .4375 = .03645 9 = 75 = 25 }4 = .5 = -04166 10 = 8333 = 2778 9-16= .5625 = 04688 II = 9166 = 3055 ^ = .625 == .05208 12 = I. = 3333 11-16 = .6875 = .05729 ^ = .75 =.06250 13-16 = .8125 = .06771 H = .875 = .07291 DECIMAL EQUIVALENTS OF OUNCES AND POUNDS. Oz. Lbs. Oz. Lbs. Oz. Lbs. X = -015625 4 = .25 8j4 = -5313 /z = .03125 4)4 = .2813 9 = -5625 X = .046875 5 = .3125 10 = .625 I = .0625 5)4 = .3438 II =.6875 1)4 = .09375 6 = -375 12 = .75 2 =.125 6)4 = .4063 13 = .8125 2X = -15625 7 = .4375 14 = .875 3 =-1875 7/2 =^ .4688 . 15 = -9375 3'A = -21875 8 =.5 16 = I. NOTES ON THE LAW AFFECTING ARCHI- TECTS. A person followmg the occupation of forming plans, draw- ings and specifications for building purposes, representing himself as an architect, is presumed in law not only as being such, but to be learned in the profession. If there is any obscurity in the drawings and specifications, the contractor should apply to the architect for directions, or be liable for the consequences. There is no fixed rule as to compensation of architects in the United States law. / The architect's contract does not survive to his represent- ative. So, if there is a contract to complete certain work 443 for acertain sum, the representative of a deceased architect cannot recover for the part performance. In competitions it should always be made clearly under- stood that the drawings, etc., are subject to approval, for otherwise the party receiving them will be liable tor ttieir value, whether used or not. An architect has not the right to substitute another per. son in his stead. . . -, r ^ • If the architect fraudulentlv or capriciously refuses to give proper certificates when required, the builder may maintain an action for specific performance or against the architect for damages. PRESERVATION OF WOOD BY LIME. I have for many years been in the habit of preparing home-grown timber of the inferior sort of fir — Scotch spruce and silver — by steeping: it in a tank (that is, a hole dug m clay or peat, which was fairly water-tight/ mi a saturated solu- tion of lime. Its effect on the sap-wood is to so harden it and fill it with pores that it perfectly resists the attacks of the little wood-boring beetle, and makes it, in fact, equally as dura- ble as the made wood. I had a mill which was lofted with Scotch fir prepared in this way in 1850, and it is in perfect preservation. The timber is packed as closely as it will he in the tank, water is let in, and unslacked lime is thrown on the top and well stirred about. There is no danger that the solution will not find its way to everything in the tank I leave the wood in the solution for two or three months, by the end ot which tim_e an inch board will be fully permeated by it. J oists and beams would, of course, take a longer time for saturation ; but, in practice, we find that the protection afforded by two or three months' steeping is sufficient, if the scantlings are cut to the sizes at which they are to be used. A VERY DURABLE WOOD. The interesting fact is stated that so indestructible by wear or decay is the African teak wood that vessels built of it have lasted one hundred years, to be then only broken up b-ecause of their poor sailing qualities from faulty models. The wood, in fact, is one of the most remarkab e known, on account of its very great weight, hardness and durability its weight varying from forty-two to fifty-two pounds per cubic foot It works easily, but, on account of the large quantity of silex contained in it, the tools employed are quickly worn away It also contains oil, which prevents spikes and other iron work, with which it comes in contact, from riistmg. 444 HOW TO BUILD AN ICE HOUSE. I. The ice house floor should be above the level of the ground, or, at least, should be above some neighboring area to give ail outfall for a drain, put in such a way as to keep the floor clear of standing water. 2. The walls should be hollow. A four inch lining-wall, tied to the outer wall with hoop iron, and with a three-inch air space, would answer ; but it w^ould be better, if the air space is thoroughly drained, to fill it with mineral wool, or some similar substance, to prevent the movement of the air entangled in the fibers, and thus check the transference by convection of heat from the outside of the lining wall. 3. A roof of thick plank will keep out heat far better than one of thin boards with an air space under it. 4. Shingles will be much better for roofing than slate. 5. It is best to ventilate the upper portion of the build- ing. If no ventilation is provided, the confined air under the roof becomes intensely heated in summer ; and outlets should be provided, at the highest part, with inlets at con- venient points, to keep the temperature of the air over the ice at least down to that of the exterior atmosphere. TESTING EXTERIOR STAINS. Since the use of stains for exterior w^ork became so gen- eral, several stains, some good and some bad, have appearrd on the market, so that a few points on estimating their com- parative values may not be amiss. The nose, and, to a less degree, the eye, are admirable allies for this work, but, unassisted, are not infallible. The following is about the simplest method of testing : 1. S:^arch for kerosene by warming, and then noting the smell. AlsD, note the thinness and lack of covering power which, kerosene causes. Kerosene is simply a cheapener. 2. See how fine it brushes out on a smooth shingle. There should not be the slightest grit or any perceptible grains of pigment, the presence of w4iich will prove that the coloring was mixed dry with the vehicle, and Avas never ground fine. 3. Pour out some of the stain in a tumbler. If it begins to settle at once, except in the case of a chrome yellow or gi'een, it is made as above stated, by mixing a dry paint with the vehicle, and therefore should be avoided. A well-ground oil stain tested in this way held up a whole day, and a creosote stain a day and a half. Of course, when debating between two -tains, it is best 445 to try them side by side. In such case the comparative color- strength may be determined by diluting equal quantities of both stains at about the same shade, with equal quantities of turpentine, and then applying the diluted colors to wood, and noting the depth of the color. One part of stain to ten parts of turpentine is a good strength. HOW TO PREPARE CALCIMINE. Soak one pound of white glue over night; then dissolve it in boiling water, and add twenty pounds of Paris white, diluting with water until the mixture is of the consistency of rich milk. To this any tint can be given that is de- sired. Lilac — Add to the calcimine two parts of Prussian blue and one of vermilion, stirring thoroughly, and takmg care to avoid too high a color. Gray — Raw umber, with a trifling amount of lamjv black. Rose — Three parts of vermilion and one of red lead, added in very small quantities until a delicate shade is pro* duced. Lavendej" — Mix a light blue, and tint it slightly with vermilion. Stra^v — Chrome yellow, with a touch of Spanish brown. Buff^'liyNO parts spruce, or Indian yellow, and one part burnt sienna. HOW BASSWOOD MOLDINGS ARE MADE. Basswood may be enormously compressed, after which it may be steamed and expanded to its original volume. Advan- tage has been taken of this principle in the manufacture of certain kinds of moldings. The portions of the wood to be left in relief are first compressed or pushed down by suitable dies below the general level of the board, then the board is planed dov/n to a level surface, and afterward steamed. The compressed portions of the board are expanded by the steam^ :o that they stand out in relief. BUILDING BLOCKS MADE OF CORNCOBS. Buikling blocks made of corncobs form the object of a new Italian patent. The cobs are pressed by machinery into forms similar to bricks, and held together by wire. They are mad ^ Avater-tight by soaking with tar. These molds are very hard ctnd strong. Their weight is less than one-third of that c^f hollow brick, and they can never get damp. 446 REDWOOD FINISH. The following formula and directions have been highly recommended. Take one quart spirits turpentme. Add one pound corn starch. Add % " burnt sienna. Add one tablespoonful raw linseed oil. Add ** '' brown Japan. Mix thoroughly, apply with a brush, let it stand say fif- teen minutes; rub off all you can with fine shavings or a soft rag, then let it stand at least twenty-four hours ^ that it may sink into and harden the fibers of the wood; afterward apply two coats of white shellac, rub down well with fine flint paper, then put on from two to five coats best polishing var- nish; after it is well dried, rub with water and pumice-stone gi-ound very fine, stand a day to dry; after being washed clean with chamois, rub with water and rotten-stone; dry, wash as before clean, and rub with olive oil unti] dry. Some use cork for sand-papering and polishing, but a smooth block of hard wood, like maple, is better. When treated in this way, redwood will be found the peer of any wood for real beauty and life as a house trim or finish. A NEW WALL PLASTER. A new material for use instead of common plaster is ow prepared, which offers many advantages, as it can be app..ed more quickly, and dries in less than twenty-four hours. It is impervious to dampness, and there is no possibility of the window and door casings contracting or swelling and causing cracks, as very little water is required in the mixing. It is known as "Adamant " wall-plaster, and deserves its name, as, when once dry, it is very hard to break. From a sanitary point of view, it is also valuable, as it is non-absorbent. A RELIABLE CEMENT. A reliable cement, one that will resist the action o! water and acids, especially acetic acid, is : Finely powdered litharge, fine, dry white sand and plaster of Paris — each three quarts by measure — finely pulverized resin one part. Mix and make into a paste with boiled linseed oil, to which a little dryer has been added, and let it stand for four or five hours before using. After fifteen hours' standing, it loses Strength. The cement is said to have been successfully used in Zoological Gardens, London. 44/ PAVEMENTS. Bricks, impregnated at a warm temperature with as- phaltum, have been successfully used in Berlin, for street pavement. After driving out the water with heat, bricks will take up from fifteen to thirty per centum of bitumei}, and the porous, brittle material becomes durable and elastic under pressure, the bricks are then put endwise on tC betoit bed, and set with hot tar. It is said that the rough usage which the pavement made of these bricks will stand is aston- ishing. A few years ago, in California^ a pavement was laid of bricks, those that were soft-burned being selected, which were saturated with boiling coal tar. They were placed end- wise on a bed of concrete, and the interstices filled with the hot tar, sand being scattered to the depth of about one-half (J4)inch upon the pavement, and afterward swept off. And now we learn from an exchange that bricks impregnated with creosote or bitumen have been adopted for paving pur- poses in Nashville, Tenn. , and with very satisfactory results. I'he wear is very uniform, as the softer and more porous bricks absorb more bitumen, v/hichhas the effect of harden- ing them, at the same time making them absolutely imper- vious, and thus protecting them from the disintegrating effect of frost. It is stated that pavement of this type, exposed for three and a half (3 j^) years to the wear of fairly heavy traffic, was, at the end of that period, found to be in excel- lent condition. The process of bitumenizing, however, rather more than doubles the cost of the brick. A POLISH FOR WOOD. The Vvooden parts of tools, such as the stocks of planes and handles of chisels, are often made to have a nice appeal - ance l)y French polishing ; but this adds nothing to their durability. A much better plan is to let ihem soak in lin- seed oil for a week, and rub with a new cloth for a few min- utes every day for a week or two. This produces a beauti- ful surface, and has a solidifying effect on the wood. TO CALCULATE THE NUMBER OF SHINGLES FOR A ROOF. To calculate number of shingles for a roof, ascertain num- ber of square feet, and multiply by four, if two inches to weather, 8 for 4^^ inches; and 7 1-5 if 5 inches are exposed. The length of a rafter of one- third pitch is e(iual to three- fifths of width of building, adding projection. 448 VALUABLE FIGURES. The following figures are wort A remembering, as they will save a good deal of calculation and give approximately accurate results with a minimum of labor : A cord of stone, three bushels of lime and a cubic yard of sand, will lay one hundred cubic feet of wall. Five courses of brick will lay a foot in height on a chimney. Nine bricks in a course will make a flue eight inches wide and tw^enty inches long, and eight bricks in a course will make a flue eight inches wide and sixteen inches long. Eight bushels of good lime, sixteen bushels of sand and one bushel of hair, will make enough mortar to plaster one hundred square yards. One-fifth more s:ding and flooring is needed than the number of square feet of surface to be covered, because of the lap in the siding and matching of the floor. One thousand laths will cover seventy yards of surface, and eleven pounds of lath nails will nail them on. One thousand shingles laid four inches to the weather, will cover one hundred square feet of surface, and five pound*. of shingle nails will fasten them on. FROSTED GLASS. Verre Givre, or hoar frost glass, is an article now made in Paris, so called from the pattern upon it, which resembles the feathery forms traced by frost on the inside of the win- dows in cold weather. The process of making the glass is simple. The surface is first ground, either by the sand blast or the ordinary method, and is then covered with a sort of varnish. On being dried, either in the sun or by artificial heat, the varnish contracts strongly, taking with it the parti- cles of glass to which it adheres ; and, as the contraction takes place along definite lines, the pattern produced by the removal of the particles of glass resembles very closely the branching crystals of frostwork. A single coat gives a small, delicate ettect, while a thick film, formed by putting on two, three or more coats, con- tracts so strongly as to produce a large and bold design. Hy using colored glass, a pattern in half-tint may be made on the colored ground, and, after decorating white glass, the hpak may be silvered or gilded. 449 PERFECT MITERING. BY OWEN B. MAGINNIS. The many awkward ways in which so many woodworking mechanics endeavor to mark and cut in soft and hard wood moldings, and the botching results of their efforts, has in- duced the writer to give the following simple and successfal methods which are perfect in their accuracy. The different conditions which exist through the careless- ness of those who precede him, when an operator commences to set in his molding, often cause him much trouble and losy j>f patience, as for instance, a molding being run standing on the little rebated lip or a raised molding being out of square, or an obtuse angle, instead of a little tender^ or an acute angle. This will of course necessitate, either the re-rebating of the molding by hand, or taking the arris of the corner of the panel sinkage as shown at A. Fig. i. Then the moldinp Fig. I, is often stuck too thin for sinkage, as will be clearly seen on .he left hand side of the panel at B^ and again the surface of the door, on account of the inequalities of the thickness of the pieces, especially on the back side, often varies as much as /^ of an inch. This difficulty is easily overcome by the following sure process. Take a small strip, and, placing the end of it down in the icrner, mark the arrises with a sharp pocket knife. Measure these depths; in the case shown here they will be, for exam- ple, respectively, ^-inch, j^-inch, -j\;-inch, full, ^-inch full, smd ^-inch, scant. Havingdone this, make4Strips, or saddles> 45<^ ecjuai fu width to the different depths of the sinkage, as )^-incla wide, i^—^^g^ wide, and so on, each being about ^-inch thick and Icng isnough to go into the miter box between the saw cuts. Fig. 2. Plac3 it in the box as represented at Fig. 2, with the lip of the molding resting on the saddle as it will rest on the door frame, at the miter and saw the left-hand end (say on the ji scant saddle): To get the neat and exact length without gauging on the door. From the point where the saw crosses the saddle at Fig. 3, square across the bottom of the box with the Den -knife. These lines are the neat and exact lengths for either end, so if the thin edge — B, Figs, i and 3, of the molding, be marked at the opposite arris, holding the already mitered end close into its corners — -and then this mark be placed at the asterisk or intersection, and the molding sawn on the saddle necessary for the opposite cor- ner (say yi full saddle), and so on all around the panel, it will, if cut out of one piece, perfectly utersect in its profile, <:he lip will come to a close joint on the frame, and the thin sdge close to the panel. The dotted line in Fig. 3 shows now the molding should be neld down in the box. The best way is to try a pair of pattern pieces as shown at Fig. i (on the necessary saddle), trying the patterns in each corner. . C==^ ?f z 3. /771»u/c?V< A^ X 2: Fig. 3. By this means it will be easy to find the exact saddle which will bring a good miter. Be sure they will come right before commencing to cut the molding all round. If it be too thick for the sinkage, of course it must be planed down on the back until it is a shaving thin, so that it will not strike the fillet, but press closely on the panel. Great care should be exercised in cutting ^he miter box, as 43 i perfect mitering is almost reliant on a good box, cut exactly on the angle of forty-five degrees. To set the level, lay ont a square on a drawing-board about four inches wide. Join the opposite angles like at Fig. 4 (be certain it is exact to a hair, or the bevel will not reverse itself). Place the bevel on- to the lines joining the angles as it lies on the board and mark the miter box by it. This is the only perfect way to miter and. cut in raised moldings, and will always, without error, assure accuracy and good mitering. Fig. 4. X ,1 ) Mitering flush molding or molding which does not rise above the surface of the frame is comparatively simple, and is usually done with a jack, except in the case of large mold- ing. All that is necessary is to first miter the left-hand end and mark the right hand. The handiest way is to commence at the right-hand corner next to you, and work to the farthest corner, and soon all round, returning to the one started from. Should the lengths, when placed in the panel before drawing down, be too long, take a rebate plane, shaving off until they be a snug, tight fit. THE VENTILATION OF BUILDINGS. Perhaps no single feature of modern architectural construe- ion is likely to secure such immediate regard in the near future, and'is already so conspicuously engaging the attention of the foremost men in the profession, as that of proper ven- tilation. Nor can it be denied that no feature is mor^ im- portant for health considerations in private homes, .ffice 452 buildings and public institiitions, than ttie securing of a steady supply of pure air and tlie coincident and correspond- ing removal of tlie vitiatec? air, so that the atmosphere m the rooms is, at all times, fresh and pure. The two points cov- ered in the last sentence constitute what is known as, and is technically termed, "ventilation." The expedients for obtaining a supply of fresh air to the room, so that there is a constant dilution and consequent bettering of the atmosphere, are comparativoTy simple. They merely imply that the air warmed by the hot-air fur- nace or steam coils in the cellar be taken from a place where it is pure (not, for instance, above a cesspool), that the ducts in cellar, through which the air trav^els, be air-tight (prefer- ably so constructed of No. 22 or No. 24 galvanized iron, rather than of wood), and that some automatic means be adopted to regulate the tem:-)erature of the air supplied to the rooms, without shutting off such air supply. Or, when steam radiators are in rooms, that they be placed helow win- dows, and air pass by means of proper orifices from outside through the radiators. Furthermore, in large structures, a fan driven by electric or steam power is often instituted for forcing in a larger amount of fresh air than could be secured by the natural suction of the warmed air. C But the mere supply of warmed fresh air to the rooms is not enough. For note, if the air in the room has no escape, it does not take long, whatever the fresh air supply, before the vitiated air contaminates and makes foul the air as it enters the apartment. To open the windows is the remedy which the uninitiated at once suggest, and, in fact, in most houses this is the only palliative at hand. It is, however, one of the first principles of ventilation, that the windows must not enter as an expedient. In a properly ventilated building the windows should never be open when people are in the rooms, at least in the winter months. For. opening the windows secures the admission of cold air in bulk, but does not remove the foul air, and more especially causes pneumonia-giving draughts, and chills the room, and in this way more damage is done than .by even the presence itself of vitiated air in the rooms. A warm or hot room does not necessarily signify an im- pure atmosphere; while we may have a room cold and the atmosphere still terribly impure. The unthinking never take this into account, and are apt to confuse the term warm with impure, and the term cold with pure atmosphere, as far as the rooms they are in are concerned. ^ The proper way to remove the vitiated air is by means of '•ent-ducts, or vertical flues leading from the rooms to the roof of tne building. These flues should have an aggregate cross-sectional area at least equal to, and preferably about ten per cent, greater than, the cross-sectional area of the fresh air inlets; and should be situated on the opposite (preferably diagonally opposite) side of the room. These vent-ducts should have openings controlled by registers, near the floor and near the ceilings of the rooms, •"ut the two registers should not be opened at the same time. The cross-sectional area of the registers should be twenty-five per cent, more than that of the vent-ducts. The bottom register is the one ordinarily to be used; for the heavy, vitiated air sinks to the floor, while the fresher, un- polluted air rises. When the people in the room are smoking profusely, it is better to close the bottom and open the top registers of the vent-ducts, for the smoke rises to the top, and is then more speedily removed. These vent-ducts cause a gentle draught in the same way that a chimney of a steam boiler or hot-air furnace does. The temperature in the room being higher than that of the external air, the temperature in the vent-ducts is also higher, and consequently a draught or removal of the vitiated air is secured, the amount depending on the area and height of the duct, and the difference of temperature between the ex- ternal air and the air in the room. ^ This system is known as that of natural ventilation. To make this removal of vitiated air still more rapid than IS secured by the natural draught just mentioned and ex- plained, one of several expedients may be adopted. An exhaust-fan, driven by steam or electric power, may be placed near the top of vent -duct, and the air exhausted from duct by means of this fan, thus increasing the fresh air supply through fresh air inlet. This is frequently adopted in public build- ings, where the rooms are, at times, full of people. Or the temperature of the air in the vent-ducts, and consequently the drabght and the removal of vitiated air, may be in- creased by any of the following means: 1. Gas jets may be burnad in the venc-fiues near thebot- fom. 2. Steam risers, through which steam of high or low pressure circulates, may run through the vent -ducts. 3. Such steam risers may have a large coil near top or right above vent-flues proper. For private homes and dwellings; natural ventilation sufiices. For public buildings and large halls, either the fan 454 or tlic 5tt?am system should be preferably adopted. The ga^ jets give ouc a comparatively little additional heat^ but are inexpensive in first cost, and in running expense. In a paper " On the Relative Economy of Ventilation by Heated Chimneys and Ventilation by Fans," read by Prof. Wm. P. Trowbridge, of the School of Mines, Columbia Col- lege, before the American Society of Mechanical Engineers, Prof. Trov^^bridge decides that in all cases of moderate ven- tilation of rooms or buildings, where, as a condition of health or comfort, the air must be heated before it enters the rooms, and spontaneous ventilation is produced by the passage of this heated air upward through vertical flues, such ventila- tion, if sufficient, is faultless as far as cost is concerned. He consideres this a condition of things which may be realized in most dwelling houses, and in many halls, school-rooms and public buildings, inlet and outlet flues of ample cross-section being provided, and the heated air being properly distrib- uted. If, however, starting from this condition of things, a more active ventilation is demanded, the question of relative econ- omy of fan and heated chimney is not so simple a problem. Prof. Trowbridge points out that ventilation by chimneys is disadvantageous under one point of view in any case, viz : the difficulty of accelerating the ventilation at will when larger quantities of air are needed in emergencies; while the fan or blower possesses the advantage in this respect, that by in- creasing the number of revolutions of the fan the head or pressure is increased. This latter fact makes the fan prefer- able for the ventilation of hospitals or public buildings of considerable magnitude, whenever, as is customary, the activ- ity of the ventilation must be varied occasionally. Where the power required is only a small fraction of a horse-power, as in ventilating single large rooms or small buildings, Prof. Trowbridge concludes it to be evident that as regards cost of fuel and the care and attention required, ven- tilation by heated chimneys is preferable, except, of course, for cases where a fan is driven by machinery employed for other purposes than ventilation, the cost of attendance charge- able to ventilation being then trifling and the fan evidently being more appropriate. The construction of the building, of course, enters as an important factor, and often precludes the adoption of the ex- haust-fan system. In large structures it is always important to take into account, and decide upon, the system of ventila- tion before the plans of the building proper are finished or finally adopted. 455 BURYING A SCREW HEAD OUT uF SIGHT. To get the heads of nails and screws out of sight, where ghie can be used without any objection, just raise up a chip with a thin paring chisel, as shown in the drawing, and then set the nail in solid. This " leaf" can be covered with a coat- ing of glue and laid back again in place, where it must ht on all sides to perfection. A dead weight v/ill hold everything in place till the glue dries, and a few moments with the scraper makes the job complete. It will add to the nicety of the work to draw lengthwise with the grain two deep cuts with a thin case-knife just the width of the chisel, and this keeps the sides of the chips from splitting. The chisel should be set at a steep angle at first till the proper depth is reached, and then made to turn out a cut of even thickness until there is room to drive a nail. If too sharp a curve is given, the leaf is likely to break apart in being straightened out again. In blind nailing a narrow chip is taken with a tool made especially for this purpose, that lifts the cut just high enough to let in the nail on the slant, a set slightly concaved, being used to keep it from ever slipping off the head, and the upraised cut driven down again with the hammer. HIP AND VALLEY ROOF FRAMING. A simple way of laying out a hip or valley roof and finding the length of jack rafters, cuts and bevels, is shown in the accompanying sketch. The method followed is com- paratively simple and easily understood. Lay down the plan of the building A, B, C, 7J, fmd the center line of the ridge ^ F, and show the plan of hips A F and B F, also the jacks G If and IK. To find the length of the common or straight side rafters, lay off on the ridge line F F the height of the pitch E M. From the point A^, which is the outside edge of the wall plate, join N M. This will give N M as the extreme length, on the upper edge, of the common rafter which is to stand over the seat F N. In order to find the length of the hip rafi^iS vvhichi will stand over the seats C E or B I\ draw the line O E square with the line E C, and make O E=AI E the height ot the pitch. Joiri the point C with the point O, thus 45^ obtained, which will give the length to the hip rafter on its upper edge. The length of the jack rafters U generally obtained by direct measurement, but the following method will be found correct. Produce the line JV £^, and make tV /^ equal to the length of the common rafter, so that ^V /'=/!/ A', join P C, which will equal C O; produce the seat of the jack rafters k i and g h, until they intersect P C m I and m^ and then i I and g in will be the correct lengths for the jack rafters. In raising a roof of this description, it is usual to cut the ridge E F and the common rafters which abut against it at each end ac ? t R F, In placing them in position they are fastened plumb over their seats by braces, and the side rafters are placed each against its mate, as i against /, 2 against 2, j against j, and so on. When all the side rafters are in position, the hips are inserted, and their accompanying jacks. PAINTING AND VARNISHING FLOORS. A French writer observes that painting floors with any color containing white lead is injurious, as it renders the wood soft and less capable of wear. Other paints without white lead, such as cchre, raw umber or sienna, are not in- jurious and can be used with advantage. Varnish made of drying lead salts is also said to be destructive, and it is reccommended that the borate of manganese should be used io dispose the varnish to dry. A recipe for a good floor var* ^5/ ' nish is given as follows: Take two pounds of pure white borate of manganese, finely powdered, and add it little by little to a saucepan containing ten pounds of linseed oil, which is to be well stirred and raised to a temperature of 360"^ Fahr. Heat 100 pounds of linseed oil in a boiler till ebullition takes place; then add to it the first liquid, increase the heat and allow it to boil for twenty minutes. Then remove from the fire and filter the solution through cotton cloth. The var- nish is then ready for use, two coats of which may be used.^ with a final coat of shellac, if a brilliant polish is required. A COLOSSAL STICK OF TIMBER. A colosal stick of lumber from Puget Sound has been con* iributed to the Mechanics Exhibition at San Francisco. Its length is 151 feet, and it is twenty by twenty inches through. It is believed to be the longest i^iece of timber ever turned out of any saw mill. A i^\^ years ago mechanics cared 'very little about winter work of any kind. They rather looked forward with pleas- ure to the prospects of a long rest. Things have been chang- ing recently, and the tendency now is to secure all the winter work possible: One reason is, there are more building and loan associations, more insurance societies, more lodges and more organizations of one kind and another, all of which must be kept up. Besides, there is an increasing amount of work that has heretofore been done in summer. The cost of labor in a good many vocations is less in winter than it is in summer, owing to the small amount to be done and the greater number seeking it. PLASTER FOR MOLDINGS. Where walls and ceilings are to be molded whilst yet in a plastic state, some decorators are using a fibrous plaster, with the object of securing greater firmness and tenacity. The idea itself is not new, animal hair having formerly been inter- mixed with lime, but this is a new application. In England and France a fine wire netting is at times inserted between two courses of plaster, to afford greater firmness in holding picture frames. The tenacity of some of the old moldings in old New York houses, whilom aristocratic, is very remarkable, retaining as they do their original sharpness oi outline. 458 THE SWEATING OF CHIMNEYS. Tlie sweating of chimneys is now believed to be due to condensation of the moisture in the air that is conflned in a poorly ventilated chimney fiue. The trouble, as our corre- spondent indicates, is chiefly to be found occurring in small chimneys, and in such chimneys whose flues start from the second or third story of a building. The sweating is the most copious when a fire is started in a place that has been for some time in disuse, or, in other words, when the flue is cold. The humidity of the air is a large factor in the phenomena of sweating. If the air be charged with moisture, the flue cold, and a fire newly kindled, the conditions are favorable for sweating. It is only under these favorable conditions that a well-ventilated chimney will begin to sweat, but the sweating will not continue. If sweating should continue in a chimney after a fire is fairly under way, it can be safely concluded that the chimney needs an opening near the ground to provide a better circulation of air within the flue. It may be, as our correspondent suggests, that rain may beat in and cause the same effect as sweating, especially where the rain has continued for several days together, and in that case a cowl, such as has been lately described in Building, in House and Stable Fittings," would cure the disease by excluding the rain; but such occurrences are exceedingly rare, and we have seen chimneys guilty of sweat- ing that were provided wi^^h the most approved form of cowl, and the remedy applied has been to insert an air-brick at the r>ase of the chimney to secure better ventilation, so as to lessen condensation, and the device has proved successful. Cowls prove useful only so far as they promote ventilation by increasing the circulation within the chimney flue. A cowl may be so improperly applied to a flue as to promote. Instead of abolishing, sweating. The main point is to pro- vide an ingress of air sufficient to tax the extractive capacity of the cowl that is used. STRENGTH OF HORSES. It is stated that, if one horse can draw a certain load over a level road on iron rails, it will take one and two-thirds horses to draw the same load on asphalt, three and one-third horses to draw it on the best Belgian block, five on the ordinary Belgian pavement, seven on good cobblestones, thirteen od bad cobblestones, twenty on an ordinary earth road, and toty on a sandy road. 459 SMOKY CHIMNEYS AND HOW TO CURE THEM. A smoky chimney is a complaint we are often called upon to deal with, and the best way of building chimneys which should not smoke into the rooms, and of remedying existing chimneys which are liable to do so, is a matter of great im- portance to estate clerks of works. There are many small matters in building new chimneys which, together, may be a means of preventing them from smoking at the wrong end ; but my intention at present is to deal crJy with the shaft or stack, or portion outside the roof, and my object is not to give ornamental elevations of chimney heads, which are un- necessary for the purpose of this article, but to explain a way of forming them which 1 have many timesfound to give relief to inveterate smokers. A common shaft, such a one as would be adapted for existing old cottages, is 2^ bricks or I fto ioj4 in. in width, and in my opinion none should be less than this, with a 9-inch earthenware flue-pipe built in solid; this I usually commence on the damp course, which should be just above the flashings of roof. As the area of the round pipe is smaller than the 14-inch by o-inch brick flue on which it is placed, a quicker current of air or draught is thereby generated, and in windy weather a check is given to sudden down-draughts. Another advantage in a flue-lined stack is that there is no danger of the brickwork cracking when the soot in the flue is on fire, and which, owing to the scarcity of chimney-sweeps, is often the case in country places. Stoneware drain pipes, however, are quite unfit, as they are liable to split with the heat ; but the tubes made of fire-clay or terra-cotta, only should be used. Another help is to keep the stack dry ; a damp flue is generally a smoky one, and if a fire is lighted in the fire-place, say, of a disused bed-room, it is a common occurrence to see the smoke puff down violently and the chimney is said to have a down-draught, and by many people is assumed to be badly constructed, whereas, perhaps, it may be built in the best possible manner except that it will not keep out rain and damp. The rain may come through the sides of the stack, or it may come downward through the head ; at any rate the chimney for some distance from the top is, in wet weather, cold and soppy. I roof the chimney top with plain tiles, with the object of protecting the head and permitting the rain to drop off at the eaves instead of running down the stack and making the flue cold^ and the stack outwardly black and soot stained I bed the tiles in cement, using copper nails driven into the laUer through the pin holes— or a plain, cemented weather- 460 iiig looks fairly well. But by forming the covering with tiles a good drip is obtained, which is not so readily dene with cement. Another point is not to make the slope or pitch of a suitable angle, and this, in my opinion, should be about 45 degrees, as I find that inclination most effectual; when the wind strikes the slope it takes an upward direction, and, as a matter of course, carries the smoke with it. Some time since a gentleman living by the seaside was much troubled with smoky chimneys, and asked me what was the best thing to do ; I told him near about what I have just now written, and a short time afterward I received a letter (which I must confess somewhat scared me) saying he had decided to pull down his chimneys and rebuild them on my principle, and desired me to order for him two truck loads of George Jennings' flue pipes at once. This I did, and waited anxiously for the result; at last I was gratified by hearing " Chimneys are a great success," but it was summer time,'and I was not so sure how they would act in cold, boisterous weather by the seaside, where every patented smoke-curer had apparently been tried by some one or other ; but eventu- ally I was glad to learn that they continued to draw well. I have proved this system of chimney stack building to be good in a large number of cases ; for instance, my ofiice chimney is directly under the branches of a large tree, and the fire is on the hearth, yet I am never troubled v/ith smoke. For economizing heat in single houses or detached cot- tages, we all know it is the best plan to get the chimney on the inside, and not forming a portion of the outer walls, as in the latter case they are much more likely to smoke, and we also know that register grates, or grates with doors a few- inches above the fire, generally make the fire draw ; they not only draw the smoke, but a greater portion of the heat as well, and necessitate getting very close to the fire to obtain a portion of the heat going up the chimney. To my mind, there is nothing to equal a fire on the hearth, and wood, if Vou.can get it, in preference to coals. There is much might be said about set-offs in flues, and I know they are objected to as a rule, but I believe a chimney "with . one or two set-offs is all the better for it. I also believe chimney heads built in cement mortar true economy; the latter makes good Avork and looks well, long after chim- ney heads buiit with lime mortar, which soon show startling mortar joints and crumbly bricks. How often do we find old chimney heads want repointing, for the weathe** loosens the mortar and the birds carry it away. 461 The summary of my experience is briefly this: 1. Put a dam^) course to new chimneys, or insert one in old chimneys. 2. Line the chimneys with fine pipes above the damp course. 3. Roof the chimney tops'carefuUy. 4. Don't forget a good projecting eaves-drip to the chim- ney-head. ■i. Build the heads with cement mortar. FACTS ABOUT FUENACES. In February, 1881, the committee of hygiene of the Medi- cal Society of Kings County rendered a report, which is published in full in the proceedings of that society, upon catarrh, and whether .that disease was aggravated by resi- dence in cities. The opinions of a large number of phy- sicians of long experience were obtained, and their testimony showed "that, though climatic and city influences have much to do with the creation of catarrh, yet defective heating, lighting, airing, sunning and drainage of houses, with im- proper views as to air, clothing, bathing and exercise, are the main causes," Individual physicians laid special stress upon individual influences, as "dry and irritating air from villainous furnaces, increased furnace heat and artificial methods of living." Furnace air jper se is not so unwholesome, but it is the absence of ventilation which makes it so. If a furnace is of sufficient size to warm a building without opening every draft and heating the fire-pot red-hot, and if the fresh air supply is taken from a proper source and not from a damp area or uncleajU cellar; and, furthermore, if there are sufft cient openings at the top of the house to allow the impure air which rises to that point to escape and thus cause a con- stant circulation of sufficiently warmed but not overheated air through the house, under these conditions a furnace is not objectionable. Furnaces are often badly located. It is easier to force warm air through a furnace flue fifty feet away from the prevalent wind than ten feet in the opposite direction. Hence the furnace should be placed nearest the northern side of the building, or two should be provided. Hot-air flues should not be carried for any distance through cold cel- lars, halls or basements, as they will become chilled, and will not draw without being cased with some non-conducting material, as mineral wool. 4^2 Don't set a furnace in a pit, especially in a wet soil where water will collect after every rain storm, but stand it on brick arches, so as to raise it above the ground ; also cement the pit. It is unfortunately very common to find such depressions filled with water ; this causes rusting of the fur- nace itself and damp in the cellar. In very many houses occupied by persons of means, the furnaces are no longer used, but have been replaced by open fires. This is costly comfort, but it is a commendable plan, as it furnishes ample ventilation to the living rooms. It is desirable that one room should at least be thus supplied with a careful and sanitary fire. Where fresh-air inlets are carried from the house drain to the front of a house at the yard level, they should not be located near to the cold-air supply, as there is a chance that during heavy states of the atmosphere a down-draft may be created, and the foul air sucked into the air box and thence upward into the house. Registers should never be placed at ihe floor level, as they will collect dust and sweepings, which are Hable to take fire. Farnaces with heavy castings heat slowly and are less easily cracked or warped, and they cool more slowly, so that the heat evolved is more uniform. It is well to retain the air close to the fire -pot, and thus keep it longer in contact with the fire-heating surface. Water pans are often badly arranged so that they admit dust, and as they are seldom cleaned that may become offen- sive. They should always be supplied by a ball-cock so as to be autom.atic, rather than by a stop-cock which has to be opened by a servant, who may be neglectful. Attempts have been made to filter the air before entering the furnace, but they usually lail. A screen of galvanized iron wire of 1-16 mesh will exclude most floating material from the air. The air supply is sometimes taken from the attic, but it is apt to be dusty and impure. Others take it from vestibules of halls or piazzas, which are not bad places. STEAM vs. HOT-WATER HEATING. Hot water as a heating agent is one of the oldest in use, nnd has a number of advantages in its favor. For mild climates it answers very well. For northern latitudes, how- ever, and in countries such as Canada and most of our north- ern States, having long, severe winters, hot-water heating ii not in general use on account of the following objections: 4t>3 High First Cost — Hot water, as generally used, only gives off two-thirds the amount of hc^at per square foot of radiating surface which steam will give under similar cir- cumstances. To get the same results as from steam it therefore requires about fifty per cent, more of radiators, and a corresponding increase of piping. Added to the expense of this extra material is that of labor, which increases in the same proportion, thus making the entire first cost of hot water about one- third higher than steam. Leakage — As all the pipes are continually full of water, any leakage will rapidly flood the house, causing trouble and damage. With steam , the flow-pipes contain no water whatever, and the return drip-pipes but very little, so that in event of a leakage the wate would be discovered and stopped long before it could do any damage. No Way to Shut Off—V^e have never yet seen, a hot water radiator which can be turned off and yet allow the water within it to flow back to the boiler; the construc- tion of the radiator being such that all the water must circulate up and down between divisions connected alternately at the toj) and bottom. When the radiator is turned off, these divisions still re- main full of water which has no chance to run off. It is therefore necessary to keep all the radiators in the house running all the time, or else take the chances of their freezing and giving trouble if they are shut ofl. Now there are certain rooms in almost every house, such as guest-rooms, which are only occupied occasionally, and it would be a useless expense and inconvenience to keep them constantly warmed. The advantage of steam over hot water in this respect is evident. With steam you can shut off any radiator you please, and keep every room in your house at the exact temperature disired, without in- convenience or waste of heat. k Freezing and Bursting — It is a curious fact that hot water will cool down and freeze much quicker than ordin- ary water under the same circumstances. The first effect in boiling water is to drive off all its air, hence, becoming more solid and condensed, it is very susceptible to cold and will freeze very easily. If the fire in the boiler from any reason goes out, the water of course soon stops circu- lating, and in cold weather the pipes will rapidly freeze and burst ^ 464 Difficulty of Eegulation-^-ln zero weather it is difficult lo keep warm by hot water, unless thfehi'S is a great amount of heating surface, and t>ien in mild weather you ar^ liable at any time to have too much heat. This is especially notice- able in any sudden change of temperature. Hot water, being slow in acquiring heat and slow in part- ing with it, is consequently difficult to regulate with any degree of satisfaction. This feature is seen in greenhouse heating particularly. When the sun is shining, on account of the great amount of natural heating glass surface, the temperature soon runs up above the normal, causing a necessity for opening the ven- tilators and so wasting the heat. And should the tempera- ture once get down, it takes a long time to get it up again. The advantage of steam in this case is apparent, as it is capable of being handled and regulated rapidly, and there- fore is superior to any other method wherever an even and uniform temperature is desired either for a greenhouse or a dwelling. Comparative Economy.— Ca,Yefu\ experiments have recently been made by parties owning many greenhouses— some of which are warmed by steam and others by the most approved of hot- water heaters— for the purpose of accurately deter- mining the relative cost of fuel in each case. They had nothing to gain by such experiments except the truth, as, with all florists, coal is a very heavy item and one of the principal expenses attending the running of a greenhouse. Without entering into details, it has been demonstrated that greenhouses may be heated by steam on two-thirds the quantity of coal required, for a hot-water apparatus. This fact has become so well ^established, that to-day steam is very rapidly taking the place of every other method for warming greenhouses. The objections to hot water for this class of buildings is, moreover, much less than for residences, on nearly all the preceding five points. For instance, a leakage of a pipe can do no harm, as in a house, and there is, of course, no occa- sion to shut off any portion of the system, as is sometimes desired in a house. Although the expense of a change from hot water to steam is heavy, yet the advantages secured are so great and ai)- parent that it will not be long before hot water as a heating agent will be practically abandoned in every kind of building. 405 INTERESTING FACTS ABOUT ISINGLASS. Isinglass consists of the dried swimming bladder of fishes. The bladders vary in shape, according to their origin, and tiicy are prepared for the market in various ways. Some are simply dried while slightly distended, forming pipe isinglass. When there are natural openings in these tubes they are called pi^i-sers. When the swimming bladders are slit open, flattened, and dried, they are known as leaf isin- glass. Other things being equal, the value of a sample is determined by the amount of impurities present. These im- purities are ordinary airt, mucus naturally present inside thff bladder technically called grease, and blood stains. If tiie bladders^ were hung up to dry with the orifice downward, the mucus could be drained off; but usually the fishermen fear the reduction in weight, and take care to retain all they can. It is necessary to insist on having the bladders slit up and rinsed, clean as soon as they are removed from the fish. This would so much increase the value of the product that the extra labor would be very profitable. Blood stains cannot be removed without injuring the quality. If any process could be devised effectual for this purpose, a valuable dis- covery would be made. The uses of isinglass are not very varied. The largest", quantity is used by brewers and wine merchants for clarifying. This property is extraordinary, for gelatin, which seems chem- ically the same thing as isinglass, does not possess it. For clarifying purposes the isinglass is " cut " or dissolved in acid, sulphurous acid being used by brewers, as it tends to preserve the beer. When reduced to the right consistence, a little is placed in each cask before sending it out for consump- tion. There seems to be only six isinglass cutters in England, all. being in London. The sorted isinglass is very hard and diflicult to manipulate. It is soaked till it becomes a little E liable, and is then trimmed. Sometimes it is just pressed l)y and on a board with a rounded surface ; at others it is run once between strong rollers to flatten it a little. The next process is that of rolling. Very hard steel rollers, powerful and accurately adjusted, are used. They are capable of exerting a pressure of lootons. Twoareemployed, the first to bring tlie ismglass to a uniform thickness, and the smaller ones, kept cool *?ya current of water running through them to reduce it to 460 little more than the thickness of writing paper. From the finer rollers it comes in a beautifully transparent ribbon, many yards to the pound, " shot " like watered silk in parallel lines about an inch broad. It is now hung up to dry in a separate room, the drying being an operation of considerable nicety. When sufficiently dried, it is stored till wanted for cutting, or it is sold as ribbon isinglass to all who prefer this form. MODERN USES OF TIN. The uses of tin have greatly increased during the last few centuries of our era. Salmon, in his splendid work on casting tin (1788), describes the methods of work, and mentions the objeccs manufactured from this metal. We see from the plates of his atlas that table services (spoons and forks) pitchers, jugs, candelabra, lamps, surgical instruments, chem- ical apparatus, boilers for dyeing scarlet, etc., were being put upon the market in the most varied forms of that epoch. Griffith, between i840and 1850, perfected the manufacture of tin utensils in a single piece. This industry became espe- cially developed in France from 1850 to i860. In i860 America began manufacturing impermeable boxes, without soldering, from single pieces of metal. To-day tin is being used in the manufacture of bronzes for guns, money and medals, and in the alloys used for making measures of capacity for liquids. Its unalterability in the air, and the harmlessness of its salts when they exist in small quantity, cause it to be employed in our day in the manufac- ture of culinary vessels and utensils. Advantage is taken of its malleability to form from it those thin sheets that are used as wrappers for chocolate, tea, etc. In the various bronzes that it forms with copper, we have evidence of the influence that relative proportions of the two metals have upon the properties of the ailoy. Thus gun bronze, which contains ten parts of tin to ninety of copper, is remark- able for tenacity. The bronze of tom-toms and bells, which differs from the last named only in its larger proportion of tin (twenty to eighty of copper) is, on the contrary, very brit- tle, although it fortunately possesses greater sonorousness than gun metal does. On still further increasing the propor- tion of tin to thirty-three parts per sixty-seven of copper, we obtain a white alloy capable of taking a polish that causes it to be used for the manufacture of telescope mirrors. Upon uniting with tin, copper loses its ductility. The alloys of these two metals increase in density through being hardenedf as they do also by being hammered. 407 A mixture of twenty parts of tin with eighty of copper g^ives an alloy which is brittle at a bright red heat and when cold, but wnich is malleable at a dark red heat. When alloyed with lead, the tin forms plumbers' solder. Associated with mercury, it gives the silvering of looking- glasses. Besides this, it enters into a host of fusible alloys or compositions, known under the general name of white metal. One of these alloys, composed of tin, antimony and copper, is very much used as a bushing for engine bearings. For thie purpose the following are very good proportions : Tin, 1005 antimony, 10 ; copper, 10. It is also alloyed with antimony alone, or with bismuth. It serves for tinning copper and iroiv kitchen utensils. To this effect the wrought -iron utensils are cleaned with sand and then wiped, and afterward im- mersed in a bath of molten tin, and finally rubbed with tow saturated with sal-ammoniac. Food cooked in tin vessels has a slight fishy taste, because it dissolves a little of the tin, just as food prepared in iron contracts a slight taste of ink: Tin is used in enormous quantities also in the manufacture of tinplate, In order to prepare this, the sheet iron designed for the manufacture of it is cleansed by plunging into diluted sulphuric acid, which dissolves the pellicles of oxide. Then it is rubbed with sand and immersed in melted tallow, and afterward in a bath of tin covered with tallow. When taken out it is tinned, there having formed upon the surface of the theet iron a true alloy of iron and tin covered with pure tin. Tin plate is as unalterable as tin itself, because the iron does not come into contact with the air at any point; but if, upon cutting it, we expose the iron, oxidation proceeds more rapidly than it would if the iron had not been tinned. Upon washing the surface of the tinplate with a mixture of hydrochloric and nitric acids, we remove the superficial layer, and render visible the crystallized surface of the tin and iron alloy. We thus obtain what is called moire metallic or crystallized tinplate. It now remains for us to say a few words about the new and important use of tin for the preparation of phosphor bronze. In the melting of bronze the absorption of oxygen is very detrimental, the formation of an oxide of tin rendering the metal brittle. In former times an endeavor was made to prevent this oxidation by stir/ing the mass with wood, or by adding a little zinc to it ; but for the last fifteen years greater success has been obtained by the addition of a little phosphorus This substance extraordinarily increases the compactness, toughness and elasticity of the product, and 468 gives it, in addition, a beautiful golden color. GuiiS, statues, ornaments and bearings are now cast from phosphor bronze with the greatest success. Kunzel, of Dresden, has taken out a patent for an alloy composed one-half to three parts, by weight, of phosphorus, from four to fifteen of lead, from four to fifteen of tin, and for the rest, copper up to lOO. Schiller & Sewald, of Graupen, prepare two kinds of phosphor broaze ; one with 2^ and the other 5 per cent, of phospnorus. The demand for this article is daily becoming more extensive. The most ihiportant uses of tin are, in Asia, for tinning copper, and in Europe and America, for the manufacture of objects from tinplate. The manufacture of bronze and white metal likewise consumes a large quantity. USES OF MICA. The peculiar physical characteristics of mica, its resistance to heat, transparency, capacity of flexure and high electric resistance, adapt it to applications for which there does not appear te be any perfect substitute. Its use in windows, in the peep-holes on the furnaces used in metallurgical pro- cesses, as well as the ordinary use in stoves for domestic pur- poses, are examples of its adaptability to specific purposes which it does not seem to share with any other material. Its fitness for use in physical apparatus is represented by its application for the vanes on the Coulomb meter, recently in- vented by Prof. George Forbes, F. R. S. For electrical purposes mica has proved useful, acting as an insulator be- tween the segments of commutators of dynamos and safety fuses in lighting circuits, also as the base part of switches handling heavy currents, to obviate the dangers of ignition by the arc formed when the switch is changed. For this latter jmrpose it shares the field with sheets of slate. Both of these uses were first suggested a number of years ago by an insurance expert in America in the course of regulations gov- erning the safe installation of electricdight plants. As a lubricator, mica answers a veiy peculiar purpose for classes of heavy bearing, where the powdered mica serves a useful office in keeping the surface separate, thereby permitting the free ingress of oil. "^It is used in roof-covering mixtures in a powdered condition in combination with coal tar, ground steatite and other materials, its foliated structure tending to bond the material together. Not affected by ordinary chem- icals which are corrosive to many other substances, it has J69 been applied in the valves to sensitive automaiic sprinklers, where a sheet of mica placed over a leather disk has proved to be non-corrosive, and without possibility of adhering to the seat, while the leather packing rendered the whole suffi- ciently elastic to provide a tight joint. IMPROVED PROCESS OF TINNING. An improved process of coating metals with tin, by Borthel and Holler, of Hamburg, is said (by a metropolitan contem- porary) to possess the advantage of preventing, or at least delaying, oxidation. The process can be employed with special advantage for tinning cast-iron cooking utensils, household and other implements of cast iron, as the employ- ment of poisonous enamel is avoided and a much higher degree of polish attained. The process can also be employed for protecting architectural or other iron decorations from rusting by the coating of tin or other metal, without detri- ment to the sharpness of the form, as is the case with the customary oil or bronze paints. In order to produce a per- fectly even coating of tin on cast iron, the same is first provided with a thin coating of chemically pure iron, regardless of the form of casting. This coating is produced in galvanic man- ner in a bath composed as follows : Six hundred grammes of sulphate of iron, FeS04, are dissolved in five liters of water, to which add a solution of about 2,400 grammes of carbonate of soda, Na2C03, in five liters of water. The precipitate of ferro-carbonate (FeCo3) resulting is dissolved in small quan- tities in so much concentrated sulphuric acid until the fluid has a green color. The bath is then rendered aqueous by adding about twenty liters of water. Blue litmus paper dipped in the bath must assume a deep claret color, and red litmus paper remains unchanged. The objects to be provided with a coating ot chemically pure iron are placed in the bath opposite to the abode of cast or wrought iron or iron ore, and both parts connected to the corresponding poles of a dynamo machine, electric battery, or other appropriate source of electricity. In a very short time the,obiects placed in the bath are covererl with a coating of iron, the thickness of which depended on the duration of the action of the bath or the strength of electric e T-rods for iron boxes were covered with a bronze-like surface, and at the end of ten months, although exposed during th-e whole time to the action of the acid fumes of a ' b^ratory, they had undergone no trace of any change. MAIS JFACTURE OF RUSSIAN SHEET IRON. There appears to be much misunderstanding in reference to the manufacture of sheet iron in Russia, and questions are frequently asked the writer : " What are the secrets con- nected with it ? " " How is it made ? " " Could admission be obtained to the iron works in the Urals, \a here the iron is made ? " It is difficult to understand why such questions should be asked by persons versed in the literature of iron and steel, for Dr. Percy wrote a very excellent and accurate monograph on the subject a number of years ago. Not having had the opportunity of personally visiting the Russian iron works in the Urals, Dr. Percy's paper was com- piled from data furnished him by a number of persons who had actually visited these sheet iron works. Since it has been my good fortune to have the opportunity of seeing some of these works in the Urals, but a short time ago, I will, at the risk of tellmg an old story, briefly describe the process of manufacture as I saw it. The ores used for the manufacture of this iron are mostly from the celebrated mines of Maloblagodatj, and average about the following chemical composition: Metallic iron, 60 per cent.; silica, 5 per cent. ; phosphorus from o. 15 to 0.06 per cent. The ore is generally smelted into charcoal pig iron, and then converted into malleable iron by puddling or by a Franche-Comte hearth. Frequently, however, the malleable iron is made directly from the ore to various kinds of bloomaries. The blooms or billets thus obtamed are rolled into bars 6 inches wide, ^ inch thick and 30 inches in length. These bars are assorted, the inferior ones " piled " and re-rolled, while the others are carefully heated to redness and cross- rolled into sheets about thirty inches square, requiring from eight to ten passes through the rolls. These sheets are twice again heated to redness, and rolled in sets of three each, care being taken that every sheet before being pas?ed through tb^ 475 rolls is brushed off with a wet broom made of fir, and at the same time that powdered charcoal is dextrously sprinkled between the sheets. Ten passes are thus made, and the resulting sheets trimmed to a standard size of twenty-five to fifty-six inches. After being sorted and the defective ones thrown out, each sheet is wetted with water, dusted with charcoal powder and dried. They are then made into pack- ets containing from sixty to one hundred, and bound up with waste sheets. The packets are placed one at a time, with a log of wood at each of the four sides, in a nearly air-tight chamber, and carefully annealed for five or six hours. When this has been completed the packet is removed and hammered with a trip- hammer weighing about a ton, the area of its striking surface being about six to fourteen inches. The face of the hammer is made of this somewhat unusual shape in order to secure a wavy appearance on the surface of the packet. After the packet has received ninety blows, equally distributed over its surface, it is reheated and the hammering repeated, in the same manner. Sometime after the first hammering the packet is broken and the sheets wetted with a mop, to harden the surface. After the second hammering the packet is broken, the sheets examined, to ascertain if any are welded together, and completely finished cold sheets are placed alternately between those of the packet, thus making a- large packet of from 140 to 200 sheets. It is supposed that the interposition of these cold sheets produces the peculiar greenis>> color that the finished sheets possess on cooling. This large packet is then given what is known as the finishing or polishing hammering. For *^^his purpose the trip- hammer used has a larger face than vne others, having an area of about 17 to 21 inches. When the hammering has been properly done the packet has received 60 blows, equally distributed, and the sheets should have a perfectly smooth, mirror-like surface. The packet is now broken before cool- ing, each sheet cleaned with a wet fir broom to remove the remaining charcoal powder, carefully inspected, and the good sheets stood on their edges in vertical racks, to cool. These sheets are trimmed to regulation size (28 by 56 inches) and assorted into Nos. i, 2 and 3, according to their appearance, and again assorted according to weight, which varies from 10 to 12 lbs. per sheet. The quality varies according to color and freedom from flaws or spots. A first-class sheet must be without the slightest flaw, and have a peculiar metallic gray color, and on bending a number of times with the fingers, very little or no scale is separated, as in the case >» 476 ordinarv sfieet iron. The peculiar property of Russian sheet iron is the beautiful polished coating of oxides (* glanz") which it possesses. If there is any secret in the process, it probably lies in the " trick " of giving this polish. As far as I was able to judge, from personal observation and conversa- tion with the Russian iron masters, the excellence of this sheet iron appeared to be due to no secret, but to a variety of conditions peculiar to and nearly always present in the Russian iron works of the Urals. Besides the few partic- ulars already noted in the above description of this process, it should be borne in mind that the iron ores of the Urals are particularly pure, and that the fuel used is exclusively char- coal and wood. Another and equally important considera- tion lies in the fact that this same process of manufacturing sheet iron has been carried on in the Urals for the last hun- dred years. As a consequence, the workmen have acquired a peculiar skill, the want of which has made attempts to manu- facture equally as good iron outside of Russia generally unsuccessful. It is difficult to understand what effect the use of charcoal powder between the sheets, as they are rolled and hammered, has upon the quality. It is equally as difficult to understand the effect of the interposition of the cold-finished sheets upon the production of the polished coating of oxide. The Russian iron-masters seem to attribute the excellence of their product more to this peculiar treatment than to any other cause. One thing is ^quite certain, there is no secret about the process, and if the Russian sheet iron is so much superior to any other, it is due to the combination of causes a-lready indicated. THE LARGEST ELECTRIC LIGHT IN THE WORLD. The largest electric light in the world is on wSt. Catharine's Point lighthouse, Isle of Wight. Some idea of the power of this light will be conveyed when it is known that the carbon? employed in electric arc lamps commonly used fpr street lighting are about J^ inch in thickness, while these^have a diameter of nearly 2)^ inches. . .There are two dynamos,, and if both worked in coiijunc' tion it- is computed that the concentrated light; from the lantern w^^ld equal six milli<^iis of candles. The indviction arrangernent of .each machine consists of sixty permanent, ma^ets, and.'each magnet is made up of eight steel plates. The armature, 2ft (6/in» in diameter, is composed of five rings with twenty-four bobbins , in each., arranged in groups: of four in tension and six in quantitar* 477 LUMBER MEASUREMENT TABLF. LENGTH LENGTH LENGTH LENGTH LENGTH LENGTH 2x4 2x6 2x8 2x10 12 20 3x6 3x8 12 8 12 12 12 16 12 18 12 24 14 9 16 II 14 14 16 16 14 19 16 21 14 23 16 27 14 21 16 24 14 28 16 32 18 12 18 18 18 24 18 30 18 27 18 36 20 13 20 20 20 27 20 33 20 30 20 40 22 15 22 22 22 29 22 37 22 33 22 44 24 10 26 17 24 24 26 26 24 32 26 35 24 40 26 43 24 36 26 39 24 48 26 52 3x10 3x12 4x4 4x6 4x8 .6x6 12 30 12 36 12 16 12 24 12 32 12 36 H 35 16 40 18 45 14 42 16 48 18 54 14 19 16 21 18 .24 14 28 16 32 18 36 14 37 16 43 18 48 14 42 16 48 18 54 20 50 20 60 20 27 20 40 20 53 20 60 22 55 22 66 22 29 22 44 22 59 22 66 24 60 26 65 24 72 26 78 24 32 26 35 24 48 26 52 24 64 26 69 24 72 26 78 6xS 8x8 8x10 10x10 10x12 12x12 12 48 12 64 12 80 12 lOO 12 120 12 144 14 56 16 64 18 72 14 75 16 85 18 96 14 93 16 107 18 120 14 117 16 133 18 150 14 140 16 160 18 180 14 168 16 192 18 216 20 80 . 20,107 20 133 20 167 20 200 20 240 22 88 22 a.17 22 147 22 183 22 220 22 264 ; 24 96 26 104 24 128 26 139 24 160 26 173 24 200 26 217 24 240 26 260 24 288 ■ 26 312 A blast at 800 degrees temperature will ignite charcoal ;. 900 degrees will ignite coke, and 1,300 degrees wiU ignite anthracite. 478 THE DYNAMO. HOW MADE AND HOW USED. The interest awakened in machines for the generation of current electricity, consequent upon the demand for electric lighting and transmission of power, has induced many amateurs to turn their energies to the construction of small dynamos, such as might replace a battery of eight or ten cells, without the disagreeable features of changing acids, cleaning plates, etc. Such efforts have not generally met with success, owing to the fact that no work of a practical nat- ure has yet appeared in which the construction of the dynamo is fully explained. When the principles which con- trol the manufacture of such machines is understood, dynamos can be constructed with as much ease and cer- tainty as induction coils. § I. What a Dynamo is. — As understood at present, the dynamo-electric machine may be defined as a machine whereby energy (motion) is converted into electricty by the aid of the permanent magnetism present in certain iron por- tions: which electricity is caused to reaet on the iron and so heighten its magnetism; and this increased magnetism in its turn gives rise to more powerful electrical effects, and so on, until a limit is reached, depending partly on the velocity of the motion, partly upon the relative apportionments of the size and quality of the wire and iron employed in its con- struction, and partly on the resistance throughout the cir- cuit. Mthough this principle was fully understood, and de- scribed by Soren Hjorth, of Copenhagen, in his patents, dated October, 1854, and April, 1855, yetthename "dynamo" (from dynamis, Qx,^ force) does not appear to have been used in this connection until Dr. Werner Siemens employed it in a communication to the Berlin Academy, January 17, 1867. % 2. Faraday'' s Discovery. — The closeness of the relation- ship between the phenomena which we call electricity and magnetism had struck many philosophers of the eighteenth century. Oersted, of Copenhagen, in 1819, was the first to prove, by a series of masterly experiments, the magnetic properties of current electricity; Ampere and Arago, in France, and Sir Humphry Davy in England, then distin- guished themselves by their zeal and activity in this research; but the keystone of the arch was laid when Faraday, in November, 1831, showed that it was possible to call forth electric currents by means of a magnet. In order that the 479 reader should have an intelligent knowledge of the principles which underlie the construction of the dynamo, it would be well for him to repeat some of the experiments about to be described, more especially as they are easy of performance and trifling in cost. The first thing required will be a galvanometer^ an instrument for indicating the presence of current electricity (and in some cases to measure its quantity). To make this, a piece of spring steel, 2 inches long and ^ of an inch in width, is "softened" by heating the middle portion ov^»- a gas jet or other flame, until red hot, then allow to cool gradually. By laying this across a knife blade the exact center is found and marked. By means of a screw-arill a hole about -^.^ of an inch diameter clear through the center of this steel "needle," as it is called, is bored. By filing from the center toward the side the needle is brought to the shape of a lozenge, as seen at Fig. i, A. Holding this needle by means of a piece of copper wire passed through the hole, it is heated to dull redness over a flame and plunged into cold water to restore its temper. A piece of brass rod, y^ of an inch in diameter, and about Yz of an inch long, is now soldered centrally, just over the hole. This is easily done by cleaning the needle with a bit of sandpaper, specially round the hole, cleaning also the little piece of brass rod, on its end, then putting a little piqce (as big as a grain of mustard-seed) of plumbers' solder just over the hole bored in the needle. Holding the needle with a pair of forceps (a little rosin powder having been previously applied round about the hole) over the flame of a spirit-lamp or gas-burner, wiV cause the solder to melt and adhere to the steel. The piece of brass is now taken up with another pair of forceps, and laid (flat side downward) as centrally as possible over the hole. Keeping the needle still over the flame, the solder will also flow round the brass and adhere to it, making a firm junction, when it may be removed from the flame, and placed at once on a cold metal or stone surface. It should now 4^o present the appearance shown at Fig. i, B. Any solder which may have exuded from between the brass and steel should be filed away. Usmg the same bit in the screw-drill that was employed originally to bore the hole through the steel, a conical hole, reaching nearly but not quite to the opposite surface of the brass piece, is drilled from the hole in the steel. This serves as a pivot on which to poise the needle. A trial may now be made to find whether the needle is fairly centered; but no attempt need be made yet to balance it if not true. Having cut off the head of a fine-pointed pin, drive it, blunt end downward, into the center of a little slab of well-seasoned pine 3 inches by 3 inches l)y ^ an inch, leaving not less than |^ of an inch protruding. On the point ■poise the needle, and mark with a pencil the end which hangs (if either does). Fig. i, C, will show what is meant. The needle must now be magnetized by being allowed to remain for some tim.e (twenty minutes or half an hour) across, and in contact with the poles of a horse-shoe magnet, care being taken that having once placed the needle in one position it should not be reversed, as its polarity would be reversed ffthis were done; and since in our latitude the 7toj't/i-seekmg f He of a freely suspended needle hangs doivnward^ if the needle, when tried previous to magnetizing, had one end heavier than the other, thatoxi^ must be placed against the north pole of the horse-shoe roMgnet, by which means it will acquire south-seek- ing polarity, and consequently neutralize to a certain extent the inclination of the poised needle. After magnetization it should be again poised, any deviation from the horizontal line noted am corrected by cautiously filing the needle on one of ics fiat sides, at its heavier extremity, with a fine file, until perfect equilibrium is obtained. Fig. i, D, illustrates the positioa in which the needle should be placed with rela- tion Xn the magnet during magnetization. When the needle has be^tn) -well balanced it ought to turn very freely on its pivot, making several free swings, but finally taking up a poDi'don pointing north and south. It should also show de- cided polarity when tested with a magnet; that is to say, one extremity should be strongly attracted^ and the other just as stro7t iy repelled on the approach of the north pole of a hors(>shoe or bar magnet. When all these conditions have been satisfied, it will be well to mark with a pencil the letter N on the extremity of the needle, which is repelled by the north seeking (or marked) end of the magnet. This extrem- 4»i ity will be the north-seeking end of the needle, and is gener- ^ally (though inaccurately) called its north pole. {S3. We have now succeeded in making and poising a magnetic needle. In so doing we have learned two impor- tant facts : {a) that steel becomes permanently magnetic when placed in proximity to a magnet; [b] that each pole of the new magnet thus formed evinces a polarity of opposite kind to that possessed by the pole of the original magnet which induced its magnetic condition; in other words, the no7'th pole of the orighial magnet induces south polarity in that portion of the steel nearest to it, while the south pole induces north polarity. Our next step is to surround the needle with a coil of in- sulated copper wire. To this end a piece of wood 2^ inches wide by ij^ inches thick, and of convenient length to hold in the hand, is prepared as a form, the edges being slightly rounded to admit of the wire being slipped off; this is then wound with about ten feet of No. 30 silk- covered copper wire, as shown at Fig. 2, A, leaving about three inches of wire projecting at each extremity The four corners of the rectangle thus formed should be bound with silk, so as to prevent uncoiling when the rectangle is drawn off the wooden form. The coil, on removal from the form, should present the appearance sho\vn at B, in which the ends of the silk used to tie the corners are purposely exaggerated in length, the better to show their position. The center of the coil being found, the wires forming one of the flat sides are slightly parted by means of a blunt pin (care being taken not to abrade the silken covering), and the coil passed over the pin-point fastened in the center of the little baseboard above described (§ 2), and attached thereto with a little dab of hot sealing-wax, or, better still, with good elastic cement. The needle is then replaced, and tried, to see whether it oscillates freely without catching at any point in the coil. The two free ends of the wire are now to be de- nuded of their silk covering, cleaned with a bit of sand or glass paper, and attached to two small binding screws (those known as telephone binding-screws, and sold at most elec- 482 tricians' av 50 '^ents per dozen, will do admirably), inserted one at each corner of the base- board. The galvanometer or multiplier is now complete, and should appear as figured at ^'> >• c. C. When all is in position, note from which binding-screw starts the wire which goes over the needle. Mark this binding-screw by writing *' over " near it. The galvanometer is used to detect the presence of current electricity by causing any such current to pass through the coils of the instrument. For this purpose the two opposite extremities of any circuit, through which it is supposed a current is flowing, are each connected to one of the binding-screws. If a current passes, the needle (which previously must be made to lie parallel with the coil, by turning the baseboard round until the coil points north and south, like the needle) will immediately start out from its position of parallelism with the coil, and take up a position which will approach nearer to right angles with the coil, in proportion as the current is stronger. To test whether the galvanometer just made be fairly delicate, attach a piece of copper wire about 3^3 ^^ ^"^ \xvq)[v thick and six inches long to one of the binding-screws; to the other attach a similar piece of iron wire. Now bring the free ends of the wire (by bending) within y^ of an inch of each other. Turn the baseboard round until the north end of the needle points between the two binding-screws, perfectly parallel to the coil. Put a single drop of vinegar on a little piece of glass, and bring it under the two ends of the wires, which must be lowered until they are both m the drop of vinegar, but do not touch each other. By the action of the vinegar on the two metals, an electrical disturbance is set up, which produces a so-called" current " which starts from the iron; passes through the vinegar, along the copper mre, through the coils of the galvanometer, and back again into the iron, this action being continuous as long as the vinegar acts on the iron. Simulta- neously with this, the needle is seen to deflect from the line of the coil, and if our galvanometer i5 a success, it should stand out at least 20° from the central line of the coil. Far- aday's great discovery, on which all Jynamos are based, con- sisted in proving that a magnet could be caused to excite a current, similar to that produced by the action of acids on 4^3 metals. We can now repeat his experiment with the aid of our galvanometer. Let A, Fig. 3, be a rod of ^ inch soft iron, about 6 inches long, bent to the shape of the letter U, and wound round its central portion with about 100 feet of No. 24 cotton-covered copper wire, the two ends of which (about a yard each end) having been stripped of their covering, must be attached to the binding- screws of the galvanometer. If a good horse- shoe magnet, B, be placed in contact with the two legs of the coiled U, this latter being kept motionless, while the magnet is alter- nately approached to and separated from it, it will be found that the needle of the galvanometer is powerfully affected, first in one sense and then in the other, according to whether we make, or bjrak contact with the U, or annaticre, as it is called. . We shall also find that, although the most powerful effectij are noticed when actual contact and actual separation take place, yet currents are also produced on approaching or removing the magnet to or from a distance. In other words, motion in the field of a magnet gives rise to electricity. If we study the effects thus obtained, we shall find that they differ in some points very markedly from those obtained by the action of acids on metals (voltaic electricity — galvanism), inasmuch as first, the action is not continuous ; secondly, it is contrary in direction when contact is made to what it is when it is broken. % 4. The student will do well to compare the effects pro- duced on the galvanometer by the battery current, and by the current obtained from the magnet. Any single cell will do for this purpose ; and in order to have an intelligent per- ception of what takes place, the student must bear in mind, that in the battery itself, the electricity (undulatory move- ment of the molecules) passes from the zinc to the negative plate (be it copper, silver, platmum, or graphite), while out- side the battery, the electricity passes from this latter round through the wires, galvonometer, or other circuit open to its passage, back again to the zinc plate. (See Fig. 4, where the direction of the undulation, or "current," is shown by the e04 arrows ; the plate marked Z being zinc, the one marked C being carbon, copper, or other conductor ; W W being the wires forming the poles or electrodes. ) If the positive pole (the one from which the " current " is flowing, the wire attached the C plate) of such a battery be connected to the galva- ometer by means of the binding-screw marked " over," the ther pole being attached to the other binding-screw, the north x)le of the needle having previously been adjusted so as to lie jet ween the two binding-screws, it will be found that the north pole of the needle will deflect to the left of the line of the coil ; the operator being sup- posed to be standing at the binding-screw end of the galvanometer. Since the wire of our coil returns beloiv the needle, it is evident that a positive current (an out- flow of undulation) passing over the north pole of a horizontally suspended needle, of a negative current (an influx of undula- tion) passing tinder such a north pole, causes it to deflect to the left. If we disconnect the battery and reverse the connections — that is, join the negative pole (the wire coming from the zinc) to the binding-screw marked " over, " the other pole being connected to the other screw — the opposite effect results, viz., the north pole now deflects to the right of the coil. This will be understood by reference to Fig. 5, in which a represents the effect of the positive current flowing/r^;;/ the operator over the needle, the north pole in both illusirations being nearest to him; in b the positive current is supposed to be flowing from the operator, below the needle, in either case returning to the battery the oppos- ite way. §5. The effect will enable us at once to recognize, by means of our galvanometer, the direction in which a current is traveling; for, on connecting the two terminals o^ any source of electricity to the binding-screws of the galvanom- eter, .^while the north pole is in a line with the coik, be- tween the two binding-sCrews, the operator facing tie' north pole of the needle, it is evident that if the north pole oif" the needle is deflected to the left^ the terminal at- 48s tached to the binding-screw marked " over " is positive; but that if the north pole deflects to the right, then the 'said terminal is negative. It must be borne in mind that by the term positive in this connection is meant the point from which electricity is flowing, negative being the point toward which it is flowing, or at which it enters. This power of FIG, C. recognizing the direction of a current will be found of greal service to us in the construction of the dynamo. § 6. Returning now to our experiments with the magnet (see latter portion of § 3), and using in preference a straight soft iron rod, about 6 inches in length and yi inch in diameter. 4^6 coiled with about loo feet of No. 24 covered wire as our armature, and a good bar magnet to produce the electrical effects, we shall find, on coupling up the armature wires to the galvanometer, and approaching one end of the armature to or receding it from the north pole of the magnet, that the electrical flow set up is always in one direction in approach- ing or making contact, and in the opposite direction on re- ceding or breaking contact. Fig. 6 will make this clear. The arrow at a shows the direction of the current produced on approaching or making contact with the north pole of a magnet; b illustrates the direction of current produced on receding from or breaking contact with the north pole of a magnet. If now we reverse the experiment by presenting the south pole of the magnet to the coiled armature, we shall find that the direction of flow is also reversed; that is to say, the withdrawal of a south pole produces the same effect as the approach of a north pole, and vice versa, the approach of a south pole is equivalent in its effects to the recession of a north pole. It must be noted that the direction in which the wire is coiled round the soft iron rod (or arma- ture), while it has no influence on the direction of the elec- trical c^carent set up round the iron rod (which is always the reverse to the hands of a clock in the face approaching the north pole) determines the extremity of the said wire at which the current leaves or enters the coil. In the figure we have supposed the wire to be wound from left over toward right ; had we wound our rod from left under toward right, the opposite ends of the wire would have been respectively + and — . This must be borne in mind when we proceed to actual work. § 7. Currents can produce Magnetism, — If we take the coiled soft iron U, of which we made use § 3, and apply it to pieces of soft iron, nails, filings, etc., we shall find that it possesses little or no magnetic power of attraction; bu.t if we couple the projecting ends of the coiled wires one to each terminal of a single-cell battery, we shall find that the U will become powerfully magnetic, retaining its magnetism as long as electricity flows around the coils, but losing nearly all the instant that the flow is caused to cease, either by breaking connection with the battery or by any other interruption. The rapidity and completeness with which the iron loses its magnetism depends almost entirely on its softness and ptwity. Anything which tends to put a strain on the molecules of the ^3- 48? iron, such as hammering, filing, twisting, sudden cooling, vibration, etc., render it liable to retain magnetism, or increase its coercitive force ; whereas raising to a high tem- perature and very gradual cooling, which allows the mole- cules to range themselves with little or no strain, furnishes a soft iron, eminently incapable of retaining magnetism, or possessing little coeiritive force. % 8. The direction in which the flow of electricity takes place around the iron bar decides which end of the bar acquires nortk-seekijig, and which south-seeking po- larity. Let us suppose as in Fig. 7, A, that one ex- tremity of the bar be made to face us, and that the current be caused to flow in the direction of the motion of the hands of the clock; in this case, the farther ex- tremity of the bar becomes a north-seeking pole, while the nearer extremity becomes south-seek- ing. The direction of the current, and consequently the polarity of the bar, may be reversed by joining up the ^//^j"//^ electrodes of the battery (or other source of electricity) to the ends of the wire coiled round the bar, as shown at B; where, as the wire is joined to the electrodes in a manner just the reverse to that shown at A, so also the current enters at the op- posite end of the wire, and produces \^ contrary magnetic effects. The same result may also be attained by coiling the wire around the bar in the con- trary direction, while leaving the connection with the electrodes un- changed, as represented at C (Fig. 7«). Perhaps the simplest means of remembering the relation which exists between the direction of rto t* the current and the position of the magnetic poles produced, is oneknown as " Ampere's Rule," in which the ex- perimenter considers himself to be swimming head foremost, ivith the current, along the wire, always facing the iron core; then the NORTH-seek- ING roLE will always be at his left hand. (See Fig. 8). 488 § 9. It must be borne in mind, as p • being of the greatest importance in ^* ^ the construction of successful dyna- mos, that although steel, or hard iron, when subjected to this induc- ing action of the current, becomes magnetic, yet it does not acquire nearly such powerful magnetism as soft iron; and, in fact, the softness of the iron, and its capacity for be- coming powerfully magnetic, run side by side. On the other hand, it must not be forgotten, as we learned at § 7, that the softer the iron the sooner it loses the magnetism imparted to it; while the harder brands of iron (and more especially steel) retain nearly all the magnetism which it is possible to confer upon them. § 10. The student who has carefully and intelligently performed the experiments described in the previous sec- tions, will now find himself in a position to understand the principles which underlie the ponstruction of the dynamo, even though he may have little \^x no previous knowledge of electricity. The first machine constructed after Faraday's discovery was that of H. Pixii, in 1832. In this machine a powerful horse-shoe magnet was caused to rotate rapidly before a soft iron U-piece, wound with insulated cop- per wire, the two extremities of which were prolonged by two brass springs pressing against a rotating split collar of brass, whose office was to rectify the direction of the currents pro- duced by rotation of the magnet, before the iron core; cur- rents which, as we have set. (^ 4), are in different directions, according to whether a given pole of a magnet is appi^oaching to or receding from the core. This arrangement for causing alternating currents to flow in one direction, is known as the commutator, and it, or some modification of it, is most extensively used in all dynamos in which it is of importance that the current should flow in one direction only. The chief disadvantage in this machine was that of having to rotate a heavy magnet (built up of a number of thin steel plates), since the mere rotation tended to destroy, or at all events, to weaken its magnetism. In 1833 Mr. Sexton had the happy idea of fixing the heavier and causing the lighter portions of the apparatus to rotate: in other words, the magnet (or magnets) was now made a fixture, while the U- 4^9 shaped soft iron armature, with its surrounding coils of wire, was caused to rotate rapidly before it, on axis or spindle, either by gear-wheels or wheel and band. Mr. E. M. Clarke, :n 1834, noticed that the thickitess of the wire coiled round the armature had a considerable mfluence on the nature of the current produced by these machines. If the wire em- ployed be very thin, say about the yf,(. of an inch in diameter, and a large number of convolutions be coiled around the legs of the armature, the electricity produced is of high tension, capable of overcoming considerable resistances, and of giving severe shocks. If, on the contrary, a smaller quantity of a much thicker wire, say from the ^r to the ^^ of an inch be made use of, the current produced is that .cnown as a quantity cttrrent, o>* a " large " current, possess- ing but little power of overcoming resistances, not capable of giving shocks, but giving fine large sparks- and able to de- compose water, and other chemical bodies. Jlarke usually furnished two armatures with his machines, one wound with about 1,500 yards of covered wire ^-^ of an inch in diameter, which he designated the " intensity " armature; the other, wound with about 40 yards of wire --^^ of an inch thick, to which he gave the name of the " quantity " armature. One pecu- liarity of the machines turned out by Clarke was the fact ot the rotating U-shaped armature being made to rotate near the flat sides of the magnet instead of in front of the poles. This, though it facilitates somewhat the mechanical arrange- ments, is open to some objections on the score of lesser efficiency, since the most active portion of the mag- net is certainly in front of the poles. As Clarke's machine embodies near- ly all the principles found in later dynam.os, we shall give an illustra- tion, together with detailed explana- tion of the commutator, etc., in our next paragraph. § II. In Clarke's machine the horseshi^v? magnet. A, Fig. 9, is clamped to a rigid backboard, which is mortised to the baseboard. In front of this magnet, and in close proximity to its poles, is the armature B B', which can be made to rotate on its axis at -<*, which passes right through the backboard, behind which /3C it is supported on bearings. The distant end of the axis ; fitted with a pulley, around which plays a band or gut coming; from the fly-wheel f. On turning the handle of f^ the small pulley enters into rotation, carrying with it \\\t armature. This armature (which represents the U-piece described at "J 3, Fig. 3) is really constructed of three pieces of very soft iron, two short circular bars and a cross-piece, held /^ ^q together by screws, as shown at <^. Around the two bars is carefully coiled the insulated* copper wire, m such a manner that, if the bars were straightened out, the winding would be always in one continuous di- rection,either from left over to rights or vice ve7'sd^ and the two extreme ^^ „ ends of the wire are brought out ^^^ and joined metallically with the two metal half-cylinders which form the commutator c. This commutator is illustrated more fully -at Fig. 10 r. Against the commutator press the two brass springs ^and d\ to which are connected the wires e and e\ which form the real electrodes or poles of the m? chine. Fig. 10 shows how the wire is wound round the two soft iron cores B and B', which are screwed to the soft iron cross-piece at A and \', thus con- stituting virtually a coiled U-piece. The two ends of the wire which forms these bobbins come out at opposite sides ot the bobbins, and are soldered or screwed to the half-cylinders (of brass) c and <:', as shown at b and b' . In order that the two cheeks of the commutator, c and c' (which are shown sep- arately to the right-hand of Fig. 10), should not allow the electricity to escape from one to the other, the spindle which carries the bobbins B B' and the cross-piece A A', is encased in a thick ring of ivory, baked boxwood or other insulator, which in the illustration is shaded darkly. Function of the Commutator. — % 12. If we follow one of the bobbins of the armature durmg its revolution be- fore the poles of the magnet, we shall find that it change? its magnetic condition, and consequently its electrical state, iwice viurmg each revolution. Let us take, for instance, che bob- * A body is said to be insulated when surrounded by substances which prevent the passage of electricity. bin B' in either figure in its rotation from the north pole of the magnet toward the south pole, as we learnt at ^ 6, /eav- ing a north pole or approachijig a soutli pole produces the same effect; and this effect will be that a current will flow round the bobbin from the right over toward the left. Hence, if the wire (which is coiled round the bobbin in the same di- rection) have its corresponding extremity joined to any cir- cuit, this extremity will be found to be negative. In practice this extremity is actually connected with the cheek c' of the commutator. This cheek c' during the whole of the semi- revolution of the bobbin B' from north to south, is being pressed against by the spring d' ^ which, with its wire e\ is consequently kept continuously in a negative state until the bobbin B'' has arrived quite opposite the south pole of the magnet. At this instant the spring d' touches neither of the brass half-cylinders, but presses against the ivory, boxwood, or other insulator, which separates the two half-cylinders of the commutator c and c' , Hence, no current flows; but di- rectly B' leaves the middle of the south pole and begins to complete the under half of the revolution, its cheek comes into contact with the spring on the opposite side, inversely as the square of the distance. For instance, we find that a magnet which exerts a " pull " of i lb. on a given piece of iron at 6 inches, if placed at 3 inches, or twice the nearness, pulls with a force of 2 X 2 == 41b.; and if placed four times as near, namely i^ inches, pulls with a force of 4 X 4 = 16 lb. p ,^, It would appear that in the case of electro magnets the ratio between the distance and the effect increases even more rapidly, being, according to the best authorities, equal to in- versely the cube of th^ distance nearly. Hence it struck Dr. Werner Siemens, of Berlin, that if the armature could be constructed of such a form as to allow of its remaining always very close to the poles of the magnet during its rotation, greatly exalted electrical effects would 494 -L^sult; and in 1856 he patented in this country the special ?rm of armature represented at Fig. il a, so well known as .lie "Siemens" or "H -girder" arrnature. On reference tO the armatures depicted at Figs. 9 and 10, it will be seen that during a considerable portion of their rotation they are at some distance from the legs of the magnets, and even when near them are not at the points of greatest action. On the contrary, the Siemens armature is placed as nearly as possible at the most active portion of the magnet's poles — viz., their extremities, and at every por- tion of its rotation some portion of the armature is ex- posed to the action of the said poles. The Siemens arma- ture, as shown at Fig. 11 a, consists of a cylinder of soft iron between three and four times as long as its diameter, around the sides and ends of which is cut a deep groove or channel, rather more than one-third the diameter of the cylinder. This is shown in section at d. The soft iron cylinder c, has brass heads and axes fitted to it as shown 9 1 f and g — the latter carrying a pulley or rigger^ by which the armature can be rotated; while the former is encircled by the commutator e e^ to which are attached the two ends of the insulated wire, which is wound in the channel. When in action this arma- ture is placed between the poles of a compound horse-shoe magnet, and supported on trunnions or bearings at both ends; two springs pressing against the commutator carry off the electric- ity generated by the rotation of the armature, the motion being imparted by means of a band passing over the pulley at the farther end of the armature. A general idea oS this arrangement may be gathered by inspecting Fig. 1 1 il. Currents given by these Machines not continuous. ^ \^, Since the direction of the current changes at every semi-revolution of the armature in such machines as those of Clarke, Pixii, and Siemens, and at every passage of the com- pound armature before the poles of the inducing magnets in Soren Hjorth's machine, we are constrained to use a com- mutator whenever we desire to produce a current in one di- rection only. But the commutator, by the very fact of its ^eing necessarily constructed of two or more portions of ^ aietallic cylinder, separated by intervals of insulating m^ 495 terial, interrupts the passage of the electricity every time that the springs press against the insulating spaces. Hence the electricity furnished by these machines partakes more of the nature of rapidly succeeding waves, than of a steady continu- ous current, like that furnished by the battery. Still, when the armature is rotated at a high speed (and the Siemens re- quires to be driven at about 3,000 revolutions per minute, to give the best effects), these waves succeed each other with such rapidity as to simulate a steady current, no break in continuity being perceptible to ordinary tests. Rapid Magnetization and Demagnetization produces Heat. ^ 16. It is found that the sudden change from north magnet- ism to south magnetism, which takes place in each half of the above described armatures, as they pass over from before a south pole to before a north pole of the inducing magnets, is accompanied by a very considerable rise in temperature; and that this rise increases with the rapidity of change of magnetism, which in its turn depends on the rapidity of rotation. So marked is this rise of temperature, that a dynamo fitted with a Siemens armature of the pattern figured at § 14, and started at an initial temperature of 10^ C, rises in about twenty min . utes to nearly 50^ C, when driven at 3,000 revolutions pei minute. This rise in temperature is detrimental to the effi. ciency of the machine: — ist. Because the wires of the arma- ture, becoming heated, conduct less freely; hen^e "^oss of current. 2d. Because the armature itself is not capable of such intense magnetisation when hot as when cold (a red-hot mass of iron is hardly affected by the magnet); hence another loss of current. 3d. Because the insulating covering of the wire is impaired, if not actually ruined, if the temperature exceeds a very moderate limit. For these reasons it is important to keep the temperature of the armature as low as possible. The first successful step in this direction was taken by Dr. Pacmotti, of Florence, in i860, who constructed an armature of soft iron, in the shape of a ring around which were coiled, in successive sections, helices of insulated copper wire, the ends of which were joined up to a divided ring commutator The ring armature of soft iron, with its covering of wire, was supported on a central axle, and rotated before the poles of a magnet, either permanent or electro. At no part of the revolution is ^ich 49b a ring taken as a whole farther from, or nearer to, the poles of the magnet; and although its magnetism is constantly changing, yet the change is not abrupt, but gradual and con- tinuous; as will h^. explained in the following paragraph. Pacinotti's Ring Armature. § 17. The descilption and illustration of this machine is to be found in the Niiovo Cimento for the year 1864, under the heading of " Una Descrizione d'una Piccola Macchina Elettro- Magnetica." The machine itself, as described, can be used either as a motor, or as a generator of electricity; and its adaptability to either purpose was specially dwelt upon by Dr. A. Pacinotti, in his communication; but it is only under the aspect of a generator that we shall stop to consider it here. Two electro-magnets, S, N, Fig. 12 (which may, or may not, be united together below), are fastened to a baseboard, and so arranged that the upper ex- tremity of one is a north pole, while the other is a south pole. These poles are furnished with semi-circular prolongations B B, B' B', between which is poised, on the axis C D, a soft iron ring A A. This ring is attached to the axis by means of radial arms. Coils of insulated wire are wrapped round the ring at short intervals about its periphery, the end of each coil being brought down the axis at D and at- tached to one of the small copper strips at E (of which there are as many as there are coils around the ring), the wire beginning the next coil being also metallically connected to this same strip. The wire terminating the next coil is fastened to the next strip, from whence starts a fresh coil, and so on, until all the strips, which form the compound commutator E are connected to the coils in. such a manner thai the end of one coil, by its attachment to its strip, forms the commencement of the next. Consequently, the wire forming the coils, although capable of communicating electri- cally with the springs F F at opposite points of the diameter of the coromutator, is really continuous. The ring A A ij. ^iq 12, 497 caused to rotate by means or the rigger G and the driving belt H. It will be evident on reflection that the half of ring oppo- site the pole marked N will acquire by induction south magnetis7n^ while the half facing the pole S will for a similar reason become north. Hence the ring, w^hether in motion or at rest, will, provided the electro-magnets be active, become a circular magnet, with the south pole facing the north pole or the electro-magnet, and its north pole facing the south pole of the electro. When the ring is rotated, though if viewed as a whole, this magnetic condition remains unaltered, yet, of course, any given portion of the ring will gradually change as it passes over from one " horn " or prolongation of the magnets to the other). Still, the change which takes place is not abrupt, but gradual, and partakes more of the nature of a wave than oi shock. So also, since the springs of the commutator press on several strips at the same time, at no time is contact ever entirely broken between the commutator and the springs; therefore the current which is produced as a contmuous wave, ahvaysin one direction^ is collected in a sim- ilar continuous manner by the springs F F, and may be em- ployed where required by coupling up the wires I I. This machine, discovered more than twenty years ago, em- bodies all the essential characteristics of the best modern machines, and the much vaunted machines of Gramme, Brush, Siemens- Alteneck, Maxim, Edison, etc., are, at best, but trifling modifications of the Pacinotti ring machine — modifica- tions which have not always been improvements. Having now brought our brief sketch of the essentials of a dynamo to a close, we shall proceed in our next section to construct- ive details. The Patterns. § i8. In the dynamo we are about to construct, three sepa- rate pieces for patterns are absolutely necessary — viz., one for the armature, one for the legs of the field magnets, and one for the standard which supports the fly-wheel. There is no necessity for the amateur to put himself to the trouble of cut- ting out a pattern for the flywheel, since such wheels with handles already fixed can be had for a dollar or so. In con- structing the wooden patterns, from which the iron castings are afterward to be procured, the amateur ^. juld remember to cnoose^ry, well seasoned wood, free from knots. Red pine, for such small work as is required, will b^ found Z3 498 good as ^ny. Any joints that are absolutely necessary (and joints skould be avoided as much as possible) should be at- tached together with dowels and glue. It must be borne in mind tha the molder places the patterns in green (moist) sand, and that ihismoisture causes ordinary glued joints to come un- done or e3\ >and. Any roughnesses left on the pattern also swell up, catch t^^^ sand, and thus destroy the sharpness and beauty of the m<)\ \ and therefore of the resulting casting. It is therefore advisable, after having got the wooden pattern to the hignest possible degree of smoothness and true- ne^s by means of emery-paper, etc., to give it a coating of melted paraffine wax, and polish the surfaces carefully with a roll of flannel. This renders the surfaces not only extremely smooth but impervious to moisture, so that the pat- tern does not warp or swell when placed in the sand. In order that the pattern should come clean out of the sand and not break away any portion of the mold, care must be taken that the edges be slightly rounded, so as to give whg,t is technically called clearance. The possessor of a lathe can turn up many portions of the fittings with much greater accur- acy and rapidity than one provided with only ordinary tools ; but in the ensuing directions the amateur is supposed to pos- sess tools of the simplest kind only. § 19. The pattern for the aj-matiirc first demands our at- tention. When completed, it presents the appearance shown at Fig. 13, a being the elevation and b the section, on a scale of about half the real size, and consists of a wooden cylinder i^ inches in diameter by 3;^ inches in length, with a deep channel round the ends and sides. To construct this pattern, procure a piece of pine 8 inches long by i^ inches wide and % of an inch thick. Lay this on a table on its widest side, and draw a line along its whole length, that shall divide it into two halves of ^^ of an inch each. Now, draw a line on each side of this central line, rather better than y% of an inch from it. Holding a metal rule against one of these sidelines, with a sharp penknife, cut into the wood along the line to a depth of about y% of an inch — rather less than more. Now, perform the same operation on the other side line to the same depth. With a sharp ^ inch chisel, shave away the wood on the outside of the cut lines to the depth of y% of an inch on the outsides, but rising up very slightly toward the center, as shown at Fig. 13, c. This precaution will ensure the pattern lifting out clear from the mold. 500 Now, take a piece of stout cardboard, and with a pair of compasses strike out a circle i^ inches in diameter. Cut the circle out of the cardboard so as to leave a clean circular aperture of the diameter specified. This is to serve as the teviplct, or gauge, of the size and general truth of our arma- ture. Strike out, also, in a similar manner a circle in a piece of stoutish zinc, or tinned iron, also ij^ inches in diameter, and cut this into halves (one of which is shown ■at dy These will serve to shave away the last irreg- ularities from the wood, when it has been roughly trimmed up to the shape shown at e^ by means of a small plane, or penknife. The piece may now be cut into two halves across its length, doweled and fastened together with glue, and cut down to the exact length required — namely, 3^ inches. All roughnesses should now be carefully sand-papered, and care should be taken that the finished pattern should pass exactly through the cardboard pattern, being apprecial}ly 50X neither thicker nor thinner at any part. When this has been effectea satisfactorily, a small quantity of paraffine wax (a piece of paraffine candle will do) should be melted in an iron spoon, and well rubbed into the pattern at all points with a roll of flannel until it is thoroughly impregnated with the wax; rubbing the pattern until it acquires a polish com- pletes the operation, and renders it ready for the founder. The thin central portion, which joins the semi-circular por- tions, should be about 2^ inches in length, having radier more than ^ an inch cut away at each end, so that the chan- nel is continuous round the armature, being ^ of an inch wide and about ^ an inch deep all round. § 20. The pattern for the legs of the electro-magnet (field mag7tets, exciting viagnets) wiD next require our care. Since the two legs are exact counter- parts, the one of the other, so we need only make one pattern, from which, however, two cast- ings must be obtained. Fig. 14 illustrates the form and dimen- sions of this pattern on a scale of about one-quarter the real size. The dimensions are marked in inches. A represents the outside view, i.e.^ as seen from the side which is farthest frcm the armature; B gives the view from the inside (close to which the armature rotates). To make this pattern, procure a piece of pine 6 inches in length, 4 inches in width, and ^ an inch thick, planed smooth, and free from knots and roughness. Glue the dowel along the bottom edge a strip 1]/^ inch wide, 4 inches long, and ^ of an inch thick, as shown at Fig. 15, a. Now, with a sharp plane, remove half the inner edge, as shown at Fig. 15, <^, so that it makes an angle with the edge of the 6-inch piece. With a fine saw cut a recess on each side of the jointed piece V/i inclies long by 4 inches deeOj 502 as shown at <:, and glue and dowel in each recess the two flanges, made of ^-inch stuff, of the shape and dimen- sions given at d. To insure the slot e being exactly at the same point in each flange, the two flanges, after being roughly- shaped with a fretsaw, or other wise, should be clamped together, and the finishing touches given with a rat-tail file, for the slot ^, and with sandpaper along the rounded edges. Care must be taken that these flanges should be a trifle thin- ner near the edge marked \% than on the opposite edge, to insure the pattern coming out clean from the mold. For this reason the slot e must not be narrower at the outside than at the inside, but rather the contrary. The slot e must be % of an inch wide, and must reach in depth to the 6-inch piece, to which the flanges are attached. At this point our pattern will present somewhat the appearance shown at/. A piece of wood 4 inches long hy Ij4 inches wide, and X ^^ an inch thick, perfectly smooth, square, and free from knots, must now be chosen, and the two sides planed away, on the upper side to such an extent as to make an angle of 60° with the base. (See Fig. 17, a.) With some good, thin, hot glue this piece is to be glued along the bottom edge of the 6-inch piece, on the side opposite the flanges, and in such a manner that the slope of the base is continued by the slope of the piece, as shown at Fig. 17, d. When the glue is quite dry, by means of an inch gouge, cautiously hollow out along the entire length of this piece, in a simicircular form, nearly to 5-'3 the depth of the original 6-inch piece, so as to fit accurately the pattern of the armature which has already been made. {^ 19.) When this is as trup and smooth as it can be made with the gouge, fold a piece of fine glasspaper over the pat- tern of the armature, rough side outward, lay the armature in the channel, and work it backward and forward until per- fect smoothness and a perfect fit are insured. The pattern should now present the appearance given at Fig. 17, c. When this end has been attained, four small dowels should be inserted into the thicker portions of this semicircular piece, to hold it firmly down to the 6-inch piece. We now need only make the top flange, by which the bracket or stand- ard that bears the wheel is clamped to the legs of the dyna- mo. This is made most easily in two pieces, one being squared up to 4 inches long, ^ of an inch thick by ^ of an inch wide. The other piece is to be Ys of an inch thick, and must be cut into a perfect semicircle, with a radius of 1)4 inches. By means of glue and a couple of dowels, this is neatly attached to one side of the other square piece, as 504 illustrated at Fig. l*] d, and then the whole is carefully and squarely glued and doweled, in like manner, to the top of the 6-inch piece, so that it now presents the appearance shown at A and B, Fig. 14. The holes shown in the bottom and top flanges may be bored, and core prints inserted, if the founder will take the trouble to put them in his mold; but, as a rule, founders do not care to cast small castings with holes in them, as they seldom come true, so that it will be, perhaps, as well to have them bored afterward, which can be done at a small cost. This pattern must now be carefully smoothed, Fig it *v.. the sharp edges rounded, to insure parting from the mold and iinally parafined arid polished, as recommended for the armature (§ 19), when it will be ready for the molder. §21. The next pattern to be made is that of the standard^ which supports the driving-wheel. This should be made out of 34^ -inch stuff, a piece of which 5X inches long by 2% inches wide must be cut to the shape shown at A, Fig. 16* (one-quarter the real size). In order not to split the top while boring the hole, it is as well to bore the hole (which should be y^ an inch in diameter) before shaping the piece. For the same reason, the piece marked C, which should be ^ an inch thick and i inch in diameter when fin- ished, should be glued to the center of the top end of the piece A, and the whole bored (by means of a brace and sharp ^-inch 505 center-bit) oefore trimming up to shape. From the sarxie 54^ -inch stuff, another piece, figured at B, is cut out, being )^ an inch wide at the top, sloping gradually, and becoming wider to about half its length {c/) when it should sharply curve to a width of 4 inches. The length of this piece should be 5 inches, and it is to be glued and doweled to the center of the piece A, close against the boss C, as shown at B. A small piece e must now be glued and doweled to the edge of the curved flange, so as to make it flush with the front A. When this has been smoothed and polished with parafline, the patterns are ready for the foundry. The three holes shown at cf may be bored in the castings. The Castings. § 22. The patterns may now be sent to the foundry, with the following instructions: First, the armature should be carefully annealed, so as to constitute a 7nalleable ii^on casting; second, two legs should be cast from the pattern shown at Fig. 14, and these also must be carefully annealed,. and be made as soft as possible; third, the standard (Fig. 17, B) will be better if left pretty hard, as in this way it will retain sufficient magnetism to start the machine without adventiticjs aid. Particular stress must be laid on the importance of the iron in the armature and legs bemg very soft, since much of the efficiency of the dynamo will depend on this point. ^See § 9. ) When the castings return from the foundry, their degree of hardness may be tested by trying with a rather coarse file. If the file bites easily, the iron is fairly soft; if it slips over without filing, it is altogether too hard. (This does not apply to the standard, which may be left quite hard without any detriment to the machine). The armature must now be cleaned and trued up. If the student be the happy possessor of a lathe, this will not prove a difficult job; if other- wise, he may, by careful fihng, remove any irregularities, and square up the ends. These must be made quite true; other- wise it will be impossible to center the armature so as to rotate it between the poles of the magnet. The thin central portion shown at a. Fig. 13, and there marked 2^, must have its edges rounded, so as not to cut the wire, which will have to be wound round it. No trouble should be spared to get the armature as truly cylindrical as possible; as care ex- pended at thisportionof the process will render the remainder of the work very much easier, and more satisfactory. The 500 armature having been thus rendered true, the legs will demand our attention. Having gone over the surface with a bastard file to remove any irregularities, the curved channels, shown at A and B, Fig. 14, must be carefully cleaned out. Perhaps the quickest way to do this, and to clean the armature at the same time, is to lay the two pieces, channels uppermost, on a table, putting a little fine sand and water in the channels, and then to work the armature up and down the channels, first in one and then in the other, alternating also the sides of the armature, until the channels, as well as the external surfaces of the armature, are rendered quite smooth and bright. The sharp corners of the legs of the magnets around which the wire has to be coiled must also be rounded, and the top semi- circular flanges, between which the standard has to be clamped, must be filed quite flat on their inner surfaces, and made per- fectly parallel with the portions marked 3% B, Fig. 14. The standard must also be cleaned in like manner, particular care being taken that the two sides of the piece marked B, Fig. 16, be perfectly parallel. The edges of the front piece e must be made perfectly square and true, so as to fit exactly on to the top of the two legs of the magnets, Fig. 14. § 23. Before winding the armature and field-magnets with the wire in which the electricity is at once generated and con- ducted, it is necessary to fit together accurately the different portions, and mark theni, so as to be able to put them together again in precisely the same position after winding; since no filing or fitting can be attempted on the castings after the wire has been wourid without almost certain destruction of the insulation, and certain ruin to the neat appearance of the evenly-laid wire. The part that calls for the greatest care and attention is the armature, which, as it must rotate in very close proximity to the poles of the field-magnets at a rate varying from 1,000 to 3,000 revolutions per minute, requires to be centered most accurately on its bearings or trunnions. This to the possessor of a lathe presents but little difficulty; for the benefit of those who de- pend Oft. ordinary tools only, the following method, by which the armature can be mounted on its bearings in a fairly accu- rate manner, is described. With a pair of calipers, the diam- eters of the two opposite extremities of the armature are taken. (If the armature casting were finished up quite exactly, these two measurements would be exactly alike, viz., a trifle under 1 1^ inches each. But unless turned on the lathe, it is FvgAB: 5^/ very rare to get such precision. ) Two circles, of exactly the same diameters as the two extremities of the armature, are BOW to be struck out of a piece of hard sheet brass, ^ of an inch thick, care being taken to mark the center and the cir- (^umference in an exact and bold manner with the compasses. These circles will have to be cut out of the brass with a saw or file, so as to get two discs, fiting each one to its respective armature extremity; but before cutting out the circles thus marked, three holes should be drilled in each, viz., one in the exact center -\- of an inch in diameter, which is to take the driving shaft or trunnion, and one on each side of this center, ^ of an inch in diameter, to admit the screws which serve to attach these heads or discs to the iron portion of the armature. Besides these three holes, which are common to both "heads," another pair^ also ^ of an inch in diameter, must be drilled in one of the heads, to allow the ends of the wire which is to be coiled around the armature to emerge from them, and pass through to the commutator All these holes are shown///// szze, and in their correct position at Fig. i8, where a is the central aperture, to take the shaft; d b the two holes to admit the screws, whereby the heads are attached to the arma- ture ; and c c holes drilled in one head only, to admit of the passage of wires to the commutator. These holes being bored, and the discs accurately cut out, two pieces of hard-drawn iron wire (not galvanized) ^ of an inch diameter and 2 inches long, are carefully straightened, and by means of a screw-plate, a thread is put on one end of each. With the corresponding tap, a female screw is cut in the central hole of each brass disc. The two iron rods are then screwed in, particular care being taken that they enter perpendicularly and centrally. They must be screwed in until they just pro- trude through to the other side; then the long end being allowed to slip between the jaws of a vise, while the disc rests flat upon the surface of the jaws, a few steady blows with a flat-pened hammer will spread the head of the screw end of the iron rod, so as to rivet it firmly to the disc, and thus prevent it working out. To render assurance doubly sure, a drop or two of soft solder may be run round the flat 5o8 side of the end of the rod and disc. Now we come to a part of the work that very few amateurs can do at home — viz., drilUn-g the holes in the faces of the armature. Any black- smith will, however, do this for a few cents. Four holes are required, two at each end of the armature (one end is showa real size at d d), and these holes must be tapped with a female screw, so as to take the screws which serve to uni^e the whole together. It will be well to let the blacksmith drill and tap these holes to any sized screw that he has near- est approaching /^ of an inch in diameter. Now will be also the time to get the blacksmith to drill the three holes, right through the top end of the legs and standard, which serve to allow these portions to be clamped together by means of bolts and nuts. These holes should be about }^ of an inch in diameter. Further de- tails as to position and size will be given a little farther on. If our work has been properly per- formed, the heads may now be screwed down to the armature with flat-headed screws, which should project about --^ of an inch above the level of the disc. Fig. 19 gives a representation of the finished armature about half the real size. § 24. Our next proceeding is to clamp together the stand- ard, or bracket, which serves to support the wheel to the two legs of the field-magnets. At the concluding portion of ^ 23, we adverted to the advisibility of getting the holes bored right through the top end of the legs and standard, at the same time that the holes were being drilled in the armature. The position of these holes is indicated at Fig. 20; they should be about X of an inch in diameter, and the two lower ones should be at least ^ of an inch from the bend of the flange, so as to allow the nuts to be easily turned and tightened up. These two bcttorxi holes should be about two inches apart, while the upper one should st^^nd equi- distant from the others, but at about y^ 5^9 an inch from the top of the flange. The amateur %vill find at ^ any hardware store, very neat skate-screws with nuts to fit, of the form illustrated at Fig. 21. These screws have usually rounded heads, without the slot for the screw-driver to enter; but these can be easily cut with a metal saw. Oi course, i any small bolts and nuts hav- [oj Tc\ ing a section of about X of an \ I I I inch will do, but the ones men- I I ■ ' I I I tioned are very neat in appear- j ^1 (^ I ance. The holes being drilled and the bolts and nuts chosen, the bracket and limbs of the field-magnet may be tempo- rarily clamped together, in order to see what opening is left between the legs for the armature to turn in, at a, Fig. 22. In all probability some filing of the faces of the flanges and of the bracket will be nec- essary to insure a proper fit. A well-fitted armature, if placed in the center of the channels at a, should leave a space of a trifle more than 2^ df an inch to turn in; that is to say, there should be ratner more than ^o of an inch clear space all round between the armature and the field-magnets. Perhaps the quickest way to insure this distance being obtained is to roll tightly a single fold of stout brown paper round the armature and seal down the edge to prevent it slipping; then having inserted the armature in the channels, to file away at the inner faces of the flanges, either toward the lower por- tions at d b, if the channels are too wide apart, or at the upper extremities at c c, if too close, until the whole fits accurately together.. It is needless to remark that when the armature thus wrapped in paper is placed between the field- magnets, to obtain a correct fit, the solid portions of the armature should lie against the legs, and Tjot the portion of the armature which is hollowed but for the reception of the wire. (See Fig. 22.') '" tj) 25. The magnets and brackets being thus properly clamped together, the hole in the top of the bracket (which ought to have been left in the casting, but it not maybe 510 bored now) should be cleaned out to % an inch in diameter. When this is done, two pieces of hard rolled brass sheet Y^ of an inch thick, 6 inches long by I inch wide, must be cut out and squared up. One of these, which we shall for the future call the " back bearing," and which must be made to lit that end of the dynamo at which the driving wheel is to be placed, and which we shall henceforward call the " back *• of the dynamo, is to be bent four times at right angles, as shown at Fig. 23, a^ where the dimensions are given. In <- — jyz inches •••••.••• > iSE •^••"•••— •»—"-— •"••••■ tf/Jfi •*«**«a«»a»s««*a«.wia (^ ; order not lo crack the brass while bending to shape, it will be well, after having given the general form by bending gently and gradually over the jaws of a vice, to heat the bends over the flame of a spirit-lamp until nearly red hot, and then to hammer up more exactly to shape, repeating the heating after each hammering until the desired sharpness of outline ha^ been obtained. When this object has been attained, another almost similar bearing is formed out of the remaining piece of sheet brass, the principal difference being that, as this is to be the front bearing, between which the commutator will have to turn, a much greater depth must be given to the central bent portion, as may be seen at Fig. 23, b, the dimensions being given in inches as before. When the brass has been bent to these forms, the bearings thus produced should be laid each against its own respective end of the dynamo, in such a position that the center of the bend comes in the center of the channel, the two flat extensions lying close to, and flat agamst, the slotted lugs shown at Fig. 22, d d. The bearings should now be cut m a sloping fashion to follow the outline of the lugs, as shown at Fig. 23, c ; but the outline of the slotted portion should not be followed, as a ^-i^^h hole must be drilled in the brass at this point to take a 5-inch bolt and nut. Tlie exact position of these holes may be obtained by holding each bearing in succession against its own proper extremity, and scratching with a steel point on to the brass the position in which the slots in the lugs fall ; '.hen, with a Morse twist drill, a ^-inch hole can be drilled at each extremity nearest to the center of the bearing, as shown at Fig. 23, d. Having got so far, let us clamp the back bearing in its place by means of two bolts about 5 inches long, passing through the holes in the bearings and through the slots in the lugs, held in their places by two nuts screwed down on to the front lugs of the dynamo. Taking the armature in one hand, we roll, as before, one fold of paper round it, and put a dot of Brunswick black on the extremity of the trun- nion rod at the back end of the armature (the end where the holes are bored for the wire to come out is the front, the other is the back), and then insert it into the channel between the legs of the field-magnets, until the trunnion rod on shaft touches the brass forming the back bearing. In so doing it will leave a mark of Brunswick black, which will be the point at which a %-\x\Q:\i hole must be bored. This must be done most carefully, so as to preserve centricity ; and when done must be rimed out and bushed with a piece of brass tubing of about -^(r external diameter, the internal diameter of which must exactly correspond with the external diameter of the driving-shaft or trunnion of the armature ; in fact, this latter must fit exactly into the tube, without anv 5T2 shake. This piece of tubing should be about iX inches in length, and should be soldered into the central hole in the back bearing, and should extend inward to such a degree that when the back bearing is clamped in its place, with the armature in its position, with the back trunnion in the tube, and the back head flush with the back of the magnets, it should just rest against the back head of the armature. In a precisely similar manner the center of the front bearing is found ; that is to say, the back bearing being removed, the front bearing is clamped to the front of the dynamo, the armature, rolled in one fold of paper, is inserted from the back end of the dynamo, front end forward, and care taken to moisten the front end of the driving-shaft with Brunswick black or other color, so as to get a mark where it touches. The hole being drilled and rimed out, as in the previous case, is to be likewise bushed vdth the same kind of 513 brass tubing ; but in the front bearing, the tube should be only flush with the inside of the bearing, and skottld not extend in toward the armature, % 26, The Com77iutator w^yX claims our care. This essen- tial piece of apparatus serves, as the student may remember (§ 12), to rectify, or send in one direction, the vibrations or currents which are produced in opposite directions, as each pole of the armature passes alternately before the north and south pole of the field-magnets. In screwing the brass heads down to the armature, the student was advised (§ 23, Fig. 19) to employ flat-headed screws, projecting about | of an inch above the level of the discs. The use of the projecting heads is to prevent the commutator slipping round the axis or trunnion of the armature when the latter revolves. The body of the commutator may be turned up out of a piece of sound boxwood, which previous to turning up should have been allowed to soak for a couple of hours in melted paraffine. It should, when finished, present the appearance shown at Fig. 24, a. While on the lathe, a hole, perfectly central, should be drifted right through it, into which the front shaft or trunnion of the armature fits tightly. The length of this should be §2 of an inch, so that it just clears the front bearing when in its place. The diameter should be about \ of an inch, so that the two flat-headed screws of the front arma- ture head should be covered by the cyHnder on opposite sides of its circumference to the extent of about ^ of an inch. Tvvo semicircular nicks must be cut out of the bottom of the cylinder to allow these screw heads to enter, so that the cylinder when driven home rests quite against the disc or head. The front of this cylinder (the part farthest from the disc) must be rounded slightly, so as not to present too great a surface for friction against the front bearing. A piece 01 brass tube, y% of an inch shorter than the cylinder, and of such internal diameter as to fit tightly on it, is now cleaned up and cut into two exactly equal halves longitudinally. The cuts must not be quite parallel to the axis of the cylinder, but must make a small angle with it, in order that the " brush " or spring which takes the current off the commutator should at no time abruptly leave one half tube before it rests on the other; otherwise the commutator sparks badly while at work, and the sparks injure both commutator and brushes, besides entailing loss of current. The amount of angular deviation from the line of axis should not, in this machine, exceed two 5H or three degrees of arc, and care must be taken they are equi -distant, and both inclmed in the same direction. To insure this, stand the tube (already cut to length and cleaned) on one end. Take the exact diameter with a pair of com- passes, and strike out on a piece of card a circle of exactly similar diameter. Rule two fine lines across this circle, both cutting the center, but exactly ^ of an inch apart at the cir- cumference, like a letter X. Lay this card on the top of a tube, and with a steel point or file make a mark on the rim of the tube at each of the points where the lines touch the circumference of the circle. Now lay the tube on its side, and draw four lines straight along the length of the tube, starting from the points just marked. Fach opposite pair ol lines will be exactly ^ of an inch apart, and quite parallel. Having done this, bring one pair of lines uppermost, and draw a diagonal line from the top of the right hand to the bottom of the left-hand line. Now turn the tube half a rev- olution, so as to bring the lower pair of lines uppermost, and draw a similar diagonal line, in the same direction — viz., from the top of the right hand line to the bottom of the left- hand line. Now, with a fine fretsaw cut the tube into two halves in the direction of the two diagonal lines just de- scribed. The tube, with the diagonal lines marked ready for cutting, is shown, as if transparent, at Fig. 24, b. It will be noticed that though, when seen through, these lines cross each other, yet when either portion of the marked tube is uppermost the line of division is from right downward to left. The split tube is now to be fastened to the boxwood cylinder in such a position that the middles of the lines JFi/Cf • -J J" Z/^*^^ °^ division shall be exactly •^ * / / J^ in a line with the middle of the channel of the armature. (See Fig. 25.) These two half-tubes may be attached to the boxwood cylinder or core by means of two short flat -headed screws, care be- ing taken that these screws do not reach to make con- tact with the trunnion or touch the "head" of the armature. The split ring. 5^5 when fastened in its place, should reach to within about }i of an inch of each end of the boxwood core; and if screws are used to fasten it down these should be placed at the end nearer the armature. But another \ery neat and effective way of attaching the split tube or ring to the core is by means of two narrow ivory or bone rings, forced over the split tube, one at each end. Care must be taken, in either case, that the divisions in the split tube are maintained; for, of course, if the two halves of the tube were allowed to touch at any point the current would flow round at that point or " short circuit," and no current would be perceptible on the outside. To insure the distance being maintained, it is well to place a shaving of paraffined wood of the same thickness as the saw- cuts between the two halves of the split tube on both sides. ^ 27. Those who have not a lathe can make a very fair substitute for the boxwood cylinder by rolling and gluing a stout piece of brown paper, just as if making a rocket-case, around a piece of the same iron rod that served for the trun- nions of the armature, until a cylinder J4 of an inch thick and U of an inch long has been produced. This should be rolled very hard while on the iron rod, so as to insure its being truly cylindrical; the rod on which it was rolled should then be pulled out, and the tube allowed to dry thor- oughly. When dry it should be soaked for half an hour in melted paraffine. then reared on end to drain and cool. It will be found to work extremely well. Of course the split ring can be attached to this, either by screws or by two rings, as in the former case. § 28. Tw^o rectangular pieces of boxwood (previously boiled in paraflfine) must now be cut, planed and drilled. These are the " brush blocks," which serve to support the metallic^springs or " brushes " which press against the com- mutator. Some operators prefer to mount their blocks on the stand, separate from the dynamo castings; nere che plan followed is to cause the bolts which clamp the bearings to the field-magnets to carry the brush blocks. To this end the two pieces of boxwood should be cut so as to fit exactly the space left between the shoulders of the front bearings o/i the outside^ and bored so as to allow the bolts to come right through to take the nuts; that is to say, the blocks will be almost cubicalin shape, being i inch long, |^ of an inch wide, by % of an inch thick. Fig. 26 shows one of these blocks in its place, clamped to the bearing by the nut and bolt- 5^0 § 29. In order to communicate the motion from the fly, Wrheel to the armature, a small pulley-wheel, either of iron or brass, is fitted to the back trunnion, just outside the bearing. Such a pulley- wheel may be bought at any hard- jFCj^ . it) ■f-^ ^ /V^27^ ware store, and should be about i^ inches in diameter, and rather over ]^ of an inch thick, with the central hole some* what smaller than the diameter of the rod which serves foi the armature trunnion. This may be attached to the trunnioii in either of the two following ways: ist. By " keying, "which consists in filing the trunnion along its length in one direction only, so as to produce a flattened side ; then, having with a rat- tail file cleaned out the central hole of the pulley to such an ex- tent that the said trunnion will only just enter, to deepen one side (corresponding to the flattened side of the trunnion) so as to admit of a small steel wedge or " key " being inserted. (See Fig. 27, a.) 2nd. By filing the trunnion-rod to a slightly conical shape, and producing a similar " coning '' in the interior of the pulley hole, which may then be driven on. (See Fig. 27, ^, where the " coning "of the trunnion is exaggerated, to render this mode of attachment more plainly visible.) Which- ^ — Sfi -- SJ7 ever mode of attachment is adopted, one precaution must b^ taken — viz., that the distance between the back of the field-magnets and the pulley should not be less than i^ inches; otherwise, when the limbs of magnets are wound wit'j wire, the fly-wheel will run too close to them to be altogethei safe. § 30. The fly-wheel which gives motion to the armature should be a pretty heavy wheel, about 13 inches in diameter, with a groove in the rim to take the band which drives the pulley, furnished with a wooden handle for convenience of rotating. Such wheels may be obtamed ready made in cast- iron, from most hardware or agricultural implement dealers, as they are sent out with "rotary blowers," "portable forges," etc. Fig. 28 a gives an idea of the kind of wheel necessary, on a scale of ij^ inches to the foot. The central hole is turned, and only requires fittting with an iron pin, on which it turns. Since the aperture in these wheels is about 3^ of an inch in diam- eter, the pin must be filed down to ^ an inch diameter, where it h^s to fit the hole in the flange at the top of the dynamo. The farthest end should have a rounded head, to prevent the wheel from working off, wnile the portion which passes into the eye at the top of the flange must have a thread put on it, so as to take a nut. (See Fig. 28, b.) § 31. All the portions of the dynamo being now fitted, they should be marked so as to insure putting together again in right order after winding. When this has been done; the limbs of the field-magnets, at all parts except the channel for the arma- ture, and the inner face of the semicircular top which rests against the wheel bracket, should receive a coat of good Brunswick-black, allowing them to dry between each applica- tion, in a warm oven. The bracket should likewise receive a coat or two of the same varnish, exce]:)t where semicircular tops clinch it. This portion viust be left metallic, so as to insure magnetic contact; otherwise much magnetic power is lost. Two strips of silk (color immaterial) 10 inches long by 3^ inches wide, should now be quickly brushed over with Brunswick-black, and wrapped, while still sticky, one round the one limb, and the other round the other limb of the field- magnets, in the space between the armature channel and the bend at the top. (See Fig. 14, where the portions indicated are marked respectively 4" and 3X"-) '^^^^ object of this silk 5i8 wrapping is to insulate the wire thoroughly from the iron, and to prevent any accidental abrasion of the covering wire, which may take place during careless winding from short en-- cuiting to the iron below. When the silk has been laid smoothly and tightly on, the limbs may be returned to the oven, and allowed to dry at a gentle heat. In precisely the same manner the interior faces and their central portion of the armature (technically known as the " web ") must be var- nished with Brunswick-black, and wrapped with one layer of similarly prepared silk. Three pieces will be required to do this effectually — viz., two pieces 3^ inches long by 1% inches wide, shaped as in Fig. 29, to fit against the inner faces, and one piece 6 inches long, by %. of an inch wide, to wrap round the web. Particular care must be taken that every portion of the inside of the armature's channel be entirely covered in silk. When this has been satisfactorily performed, another coat of Brunswick-black may be given (avoiding to soil the outside), and the armature allowed to dry thoroughly in a warm oven. § 32. Our dynamo is now ready fcr wiring. For this pur- pose we shall require about 7 lb. of No. 16 single cotton- covered copper wire for the iield-magnets, and about ^ lb. No. 20 double silk-covered for the armature. The amateur should be careful to get 7iew wire, of the highest conductivity, and very soft; the employment of old, kinky, and hard wire is fatal to success. § 33. The quantity of wire above mentioned having been duly selected, it should be tested for continuity. The No. 16 will give evidence to the sight alone, whether there be any break in it or not. Should there be such, the covering from the two broken ends should be uncovered for about an inch on each end, the two extremities filed down to a fine flat wedge, so as to fit one another, when each one separately should be warmed for a second over the flame of a spirit- lamp, dipped into powdered resin, and rubbed, while being held in the flame of the lamp, with a rod of solder, until each has taken a good coating of solder. The two ends may then be applied with their flattened portions together over the flame of the spirit-lamp until the solder coating melts. Keeping the ends pressed together, the wire is to be removed from the flame. The solder coon hardens, and the wires will be found firmly united. It is now only neces^sary to file away any roughness, and rewind the cotton covermg over the 519 bared portion, adding a little darning-cotton if the covering be deficient. The finer wire, which is generally bought on reels, had better be tested with the galvanometer (Firf. 2). To this end, find the two extremities of the wire, attach one to one binding-screw of the galvanometer, the other extrem- ity being in good metallic contact with the pole of any single- cell battery. Connect the other pole of the battery with the other binding-screw of the galvanometer. An immediate and large deflection of the needle will show that the wire is continuous. If not, the wire must be unwound from the reel, and carefully wound on to another until the point at which the break occurs has been discovered. The two broken ends maybe joined as described above, great care being taken after joining to recover the point of junction thoroughly, so as to preclude all danger of leakage, more silk being used to this end if necessary. It having been ascertained that the wire is perfect and in good condition, the next step is to soak it in melted paraffine wax, The good effect of this is twofold*. (a) The ii:sulation is thereby rendered very much better; {d) a damp atmosphere has then little or no effect on the in- sulation, since the paraffined cotton and silk covering is no longer hygroscopic, and may actually be pumped upon with- out becoming wetted or spoiling the insulation. To parafifine nicely the wire should be laid in a shallow dish large enough to contain it easily — a circular tin baking dish will do admir- ably. It should then be placed in a warm oven, not too hot, until it is about the heat of the hand — say, 90^ Fahr. About }4 lb. of good parafiine wax should now be placed in the tin, and the oven closed until the paraffine is all melted. The wire may then be turned over two or three times until it is seen to be thoroughly soaked with the paraffine. Two or three metal rods should now be placed across the top of the dish, on which the wire may be placed to drain for a few seconds while still in the oven. When it ceases to drip it tnay be removed from the oven and allowed to cool. The superfluous paraffine, while still hot, may be poured into a cup (whica has been just previously breathed into) to set, when it may be used for other insulations. 2 34.. ^vinding tiie armature next clains our attention. Having marked t 1 t h"ads,soasto know which belongs to a given extremityc )[ the armature, we unscrew and remove them; about 6 iiiciit^sof the extremity of the No. 20 wire should be coiled tightly round the end of a pencil, so as to S20 form a tight helix from which the pencil must then be slipped out. This helix will form one of the spare ends of the wire which, will be attached to the commutator, and should be, for the time being, tied with a bit of silk to the outside of the armature, so as to be out of the way while winding. Hold- ing the armature in the left hand, with the end which corre- sponds to the commutator facing us, and beginning at the left- hand cheek, we wind the wire in the channel, continuing to wind until we reach the right-hand cheek, taking care to lay the wire on as closely as possible, never allowing it to ride over its neighbor, nor yet to leave gaps between. When one layer has thus been carefully wound on, as shown at Fig. 30, it should be tested for insulation, since the amateur is very apt to wind care- lessly and cut the insulating covering, either by catching in the sharp corners of the channel or otherwise. To test for insulation, tie the end of the wire (without detaching it from the reel or hank) against one cheek of the arma- ture, to prevent its unwinding during the trial; then connect one pole of a battery to one binding-screw of a gal- vanometer, and the helix end of the wound wire to the other binding-screw. On touching the iron of the armature at any point with the other pole of the bat- tery, no deflection of ^he needle should take place. Should a deflection show itself, evincing a metallic contact and want of insulation at some point, the wire must be unwound, the flaw localized and remedied by a fresh covering of silk, basted with 23araffine, and again vvcimd on and tested until the insulation is satisfactory. A layer of thin paraffined paper should now be laid over the first layer of wire; and the winding proceeded with in exactly similar manner, until the second layer has been laid on, remembering that the essentials of success are to wind the wire as closely as possible in each laver without overlapping; to avoid grazing the covering of the wire, so as to maintain insulation, and to wind always in one direction — viz., from tis, over to tinder. There is no necessity (when using silk- covered wire) to place a stratum of paraffined paper between each layer of wire, as this, by incfeasing the distance between 521 tne layers, soraewhat decreases the efficiency of the machine; this is only advisable when the insulation of the wire has been found to be imperfect. The winding should be proceeded with, layer after layer, evenly, tightly and smoothly, until the wire just fills the channel. Care must be taken that it does not exceed this, for if it comes higher than the cheeks it will surely catch in the limbs of the field-magnets during rotation. From eight to nine layers of wire may be laid on, according to the tightness with which it is pulled during winding. When the due proportion of wire has been laid on, it should be fastened down by tying, so as not to unwind, with its free end at the same extremity (the commutator end) as we started from. The helix may now be straightened out, and its condition observed, to insure that it is well insulated. The end at which we finished winding should also be straightened out and examined for good covering "T^hen a stick of elastic glue should be heated and ribbed over the covered ends right up to the armature, so as to thicken them to such an extent that they will only just pass through the holes bored in the head to which the commutator is attached. (See Fig. i8, r, c.l The wire ends should be passed one through each of these Iioles (care being taken that the head be put on as it was previous to removal), pulled pretty tightly, but not so roughly as to graze or injure the covering, and having been cut so as to just reach the heads of the screws, which fasten the two halves of the split tube of the commutator to its cylinder (see Fig. 25), should have their extreme ends unwound and cleaned, and then be soldered down, one to each half of the split tube, care being taken that neither the solder nor the wire passes beyond the line of the screws; so as to leave plenty of room for the brushes to press against the commutator. The heads may now be screw^ed up in their place, and a coat of good sealing- v^ax varnish (best made by dissolv- ing good scarlet sealing-wax in methylai ed spirit) painted over the layers of wire, both for the sake of appearance and to keep the wires from moving out of place during rotation, though if the wires are tightly wound this would be hardly needful. This coat of varnish must be allowed to dry off in a warm atmosphere (not in the oven), and the armature will be complete. i 35 Our labors are now drawing to a close. To wind the Seld-magnets it will be as well to rig up a little piece of apparatus, since, although they may be wound without, it is very difficult to lay the wire as closely, as tightly, and as neatly as can be done by its aid; and since the effi- ciency of the machine is greatly exalted by the greater proxim- ity of the wire to the core, it is a matter of considerable importance that this should be attended to. The apparatus necessary consists of a handle fastened to an axle passing through a standard supported on a base; the axle having a prolongation to which each limb of the field-magnets can be screwed down in its turn. On turning the handle, it is evi- dent that the iron mass of the field-magnet will rotate on its axis, and i^^are be taken that the center of the mass coincides with the center of motion, the motion imparted to the iron will be smooth and even, and the wire may be laid on with great exactitude and closeness. This apparatus is illustrated at Fig. 31, a, with one of the limbs of the field-magnets screwed in its place, ready for winding. It should be made out of ^-inch stuff, the base being about 5 inches wide by 6 inches long. The upright through which the axle passes should also be about the same size, and screwed to the edge of the baseboard, so as to stand at right an- gles to it. A short piece of broomstick, about % of an inch in diameter, may be used as the axle, and a hole must be bored in the upright, at about 4 inches from this base, to admit this axle. To the external portion of the axle is fastened a handle; while to the internal portion, which should protude about i^ inches, is screwed a piece of ^^-inch stuff about ij^ inches square, half the axle being cut away to admit of its lying fiat. Previous to screwing down, the handle, as well as this latter square piece, should be rubbed over with a little good hot glue at the places where they touch the axle, to insure a good sound joint. This " winder " being completed, it may be clamped to a bench or table by means of a sewing-machine or fretsaw clamp, the leg of the field-magnet having been previously screwed to it by means of the three holes in the flange, in the position shown in the figure. Though shown in ^^ '>23 the cut to the left^ the handle of the winder should be to the right of the operator, unless he be left-handed. In commenc- ing to wind the wire, the operator should stand over his work, a sheet of paper having been placed on the floor, and the coil of paraffined wire at his feet, with a two-gallon stone bottle filled with water, to keep the bottle from upsetting, in the center of the coil to prevent its tangling or kinking. The surface of this jar being glazed, the wire slips from it without injuring the covering. The winding should be commenced at the extremity farthest from the handle — that is, nearest to the channel in the field-magnets in which the armature ro- tates. Six or eight inches of the wire should be coiled round a pencil, and so as to form a tight helix, which, with a piece of strong twine, should be tied to the leg of the magnet, as shown in Fig. 31, b. Holding the loose end of the wire in the left hand, keeping it pretty tightly pulled, and straightening it out from its coiled shape as it passes through the fingers, it is easy in this manner to wind the wire per- fectly flat and smooth by turning the handle of the winder in the direction of the motion of the hands of a watch. (In or- der to prevent any accidental contact though abrasion against the corners, etc, it is advisable previously to cover the legs of the field-magnets, at all events as far as the wire is to ex- tend — viz., from do d'vcv the present figure — with a band of silk dipped in melted paraffine, and applied hot to the iron, when it will immediately adhere. This band must be care- fully smoothed down, so as not to cause unevenness in the winding of the wire.) If the wire be nicely laid on, it will be found possible to wind forty rows between c and d. Be- fore arriving at d it will be necessary to place two pieces of tape about ^ an inch wide and 3 inches long, as shown at ^ ^ in the figure, the free ends of which must be turned back smoothly and tightly over the layer just put on when d is reached. Continuing the rotation of the handle in the same direction, another layer of wire is now laid over the first; by holding the ends of the tape fast while beginning to wind this second layer, all tendency of sinking into the layer beneath, which may be displayed by the second layer, is overcome. Without this precaution it is almost impossible to prevent the outer layers of wire sinking into the interspaces of the layers below. Continuing in this manner, layer after layer should be laid on until seven layers have been wound, remembering to use tapes toward the end 524 of each layer, and that each layer will diminish by two^rows. When the seven layers have been laid on, the wu-e must be tied down to the magnet to prevent uncoiling, and cut c 7 from the hank of w^ire, leaving about 6 inches free for attach- ment. In exactly a similar manner as regards attachment, direc- tion of winding, etc. , must the second limb be wound. The only difference that need be made is that, for convenience of having both ends of wire at the same end of the dynamo, it will be w^ell to fasten the beginning of the wire (the helix) to the inside of the leg instead of to the outside. Fig. 31, f, will make this clear. % 36. Both for the sake of appearance and to further pro- tect the insulation from damp air, etc. , it is advisable to give the wires on the limbs of the field-magnets a coat of good varnish. The best for this purpose is made by mix- ing about 2 ounces of the best red lead with ^ an ounce of good white hard varnish. The two should be v/ell incor- porated together by working with the brush intended to be used for laying on the varnish. The varnish should be applied in a thin layer with a soft brush, so as to disturb the paraffine coating as little as possible, since if the paraffine mixes with the varnish, this latter never dries, but remains a sticky mess. For this reason the coating of varnish should be allowed to dry without the application of heat, which, if the " white hard " be good, it will do in about eight to twelve hours. A second coat may be given if desired; but as this generally fills up the interstices between the layers of wire, it detracts somewhat from the neatness of the appearance. § 37. The varnish being quite dry^ the dynamo may again be put together, care being taken that the parts are ad- justed in the position which they occupied after fitting. If this has been properly done, the armature ought to turn freely in its bearings quite close to the limbs of the field-mag-^ nets, but without catching anywhere. Supposing this to be all right (and it must be so, or the dynamo cannot work properly), the dynamo must be screwed down to a baseboard, v/hich should consist of a slab of oak, walnut, or m.ahogany, 10 inches long by 8 inches wide, and at least i inch thick. The two lioles in the lower flange in the limb of the field- magnets, near the channel in which the armature revolves, are expressly for the Durpose of clamiping 525 the dynamo to its baseboard. The baseboard should be chosen of a well-seasoned nature— polished, for appearance sake; and the dynamo should be screwed to it centrally, with the narrowest portion of the dynamo parallel with the narrow- est portion of the baseboard. Attachment of the Wires. § 38. The dynamo having been wound as described (and care must be taken to have fulfilled the instructions exactly, or else the resulting magnet will have two /^^r//^ poles, or t wo j-^//^^ poles, instead of one north and one south), we can proceed to couple up the various parts. To this end we begin by joinmg the wires at the two extremities at which we left off winding. This may be effected by removing a portion of the covering of the wires (by scraping with a sharp knife) for about an inch along the places where the two wires cross each other if made to touch. (See Fig. 32^.) The wire must be made quite bright and clean by rubbing with a bit of sandpaper at this point, and then the wires are twisted tightly together by the aid of a pair of pincers. A drop of solder, taken up on a hot soldering-iron and run along the twisted portion will insure the contact remaining good. The excess of wire should now be cut off from the twisted end with a pair of cutting pliers; the bared twist bound round with a layer of darning-cotton^ varnished with the red varnish (§ 36), and turned in out of the way between the limbs of the magnet. (P'ig. 32, b.) We may nowproceed to magnetize the field-magnets. For this purpose we need only attach the poles of a single-cell bichro- mate battery, exposing from 8 to 10 square inches of negative surface, to the wires of the dynamo for a few seconds; but in or- der to obtain results which may be deducible from reason, and which can be corrected if mistakes are made, it is desirable to determine beforehand which shall be the north pole of our future magnet. It will be remembered {% 8) that we have it in our power to prcduce a north pole, to onr Icft^ in t. mass 526 of iron, by passing a current of electricity away from us, over it; and if we wish to produce 2 north pole to the right^ the current must come toward us, over the mass. Let us decide to make a north pole of the limb on which we began to wind the wire on the outside. (See Fig. 31, r.) To do this the current ought evidently to flow from the limb of the magnet to the observer; in other words, this wire must be attached to the negative pole of the cell. (The negative pole of the bichromate cell is the wire proceeding from the zinc, the one attached to the graphite being posi- tive.) The positive pole of the ce^l must be coupled to the other wire, that is, the one which was started from the iitside in winding. (See Fig. 31, /!) While the battery is thus coupled up to the dynamo, we can test if we have produced the effect desired by bring- ing a suspended magnetized needle near the supposed north pole of the dynamo. If all has been properly performed, it will be found to attract the south pole of the poised needle, and repel its north pole, A few seconds' connection with the battery will impart as much magnetism to the field-magnet as it will retain; but that httle will be suffici'^^nt for our purpose. Our next step IS to discover in which direction the current flows in our armature, when we rotate the fly-wheel in the usual way with the right hand (in the direction of the motion of the hands of a clock). Before we can do this we must fasten two " brushes" or collectors on the brush-blocks, in order to collect the electricity generated by the rf^volution of the armature. The Brushes. §.39. These consist of two pieces of springy sheet brass, y2 of an inch thick, 3^4 inches long, and about }i of an inch wide. They must be bent twice at right angles, so as to fit tightly on to the brush-blocks ($ 28, Fig. 26), and shghtly curved inward at the longer portions so as to press with some force against the commutator. (See Fig. 32, c.) To fasten these on to the blocks, a lateral slot is cut about half-way into each brush, at about Y^ of an inch from the longest portion, of such a width as to admit the shank of a small screw passing into it. The por tion of the brush which rests against the armature should be slit into two or three divisions, and curved slightly upward to avoid scratching the armature. 5^7 These^wo brushes, though alike in shape, must be put in opposite positions on the dynamo ; that is to say, the one which goes on the block to the right of the observer has the longer portion above the block, while the one which goes on the left-hand block has the longer portion below the block. Thus the commutator is rubbed by these two brushes at diametrically opposite points. Care must be taken that the two screws which serve to fasten the brushes to the blocks do not touch the metal of the bolts which clamp the bear- ings to the dynamo, for if they did the current would short- circuit, and the machine would not work. It will also be nec- essary to observe that sufficient curvature be given to the longer portion of the brushes to clear the bearings alto- gether, otherwise, of course, the current would pass into the bear- ings and be short-circuited. Fig. 33 shows the brushes in. their proper position ; a^ a being the commutator (exaggerated in size omewhat to show its position). 3, b the brush-blocks, r, c the brushes, and d, d the screws which, by being tightened or loosened, can increase or decrease the pressure of the springs on the commutator, and to which the two wires which form the electrodes of the commutator are to be attached. These two wires, which in our machine may be about 3 inches long, with a loop at each end, as shown at Fig. 34 ^, should be of No. 16 cotton-covered copper wire, the covering beir.g removed from the two loops, which must be made quite bright. Before putting in the screws ^ <'/, d^ Fig. 33, each one should be passed o 1 iv/» into one eye of one of the said wires, then '^ screwed partly into the brush-block, when the brush itself may be pushed into its place over the block, and under the screw, the slot in the side admitting of this; lastly, the screw is tightened up until the desired pressure on the commutator is obtained. Fig. 34 shows the position of the wire, screw, and left-hand brush on the left-hand block. The two free ends of the wires just described project straight forward to the front of the machine; they may be screwed down on the baseboard, at the distance of about 3 inches apart, by means 5^8 of a small pair of binding-screws ; the loi, ^/ / field-magnet, arjd the negative brush of the commutators respectively; and since the magnetism of the field-magnet depends entirely on the amount of current flowing around it, and this again influences the cur- rent set up in the armature, it is evident that every variation in the resistance or the interpolar or out- side circuit will produce a corres- ponding variation in the current, if the dynamo be connected up as above described; and that a very much larger current will traverse the circuit when the resistance is small than when the resistance is great. When the machine is doing its best work — that is to say, when the resistance of the interpolar is equal to the internal resistance of the machine — the current is equal to that of eight or ten Bunsen's cells against an equal resist- ance. Sometimes it is necessary to send the current through a greater resistance; in this case, in order not to weaken too greatly the magnetism of the field-magnet by diminishing so ^ & 530 greatly the current, it is necessary to shunt off a portion of the current, and send it round the limbs of the field-magnet by another circuit, which diminishes the total resistance. To render this clearer, let us suppose that we wish to light up four five-candle lamps, having each an approximate resist- ance of eight ohms, and requiring a current of about one ampere each to cause them to give out their proper light. If we arrange them m series, as in Fig. 36, a, when the total re- sistance IS the sum of their separate resistances = thirty-two ohms, then, as the electromotive force of our machine when at best IS about ten \olts, so i| represents the gurrent flow- ing through the lamps, supposing even that the dynamo lost no power by the diminution of current (which it does to a very great e\cent), and this current is not sufficient to light the lamps. But if we arrange the lamps in parallel arc, as at Fig. 36, /^ then the total resistance falls to a quarter of one single lamp— that is to say; it is equal to two ohms only; hence the currrent now flowing becomes ^§ = 5 amperes, and this divided among the four lamps gives \}{ amperes each, which is ample. Again, we find that coupling up one single lamp to the dynamo presents too great a resistance, so that no Ught is given off, since not sufficient current can pass round the field-magnets to give an elec- tromotive force of ten volts. But if we insert a " shunt," consisting of about a dozen inches of No. 30 iron wire between the two binding- screws aforesaid, as shown at Fig. 37, and then connect the lamp also to the said screws or terminals, more current circulates round the field-magnets, since two roads are now open to the current, the field- magnet becomes more powerfully magnetic, and in its turn induces a much more powerful current in the armature, and so on until current enough is produced to 531 light up the lamp. The resistance of the "shunt" to be inserted between the terminals, to produce the best result, will depend on the resistance of the interpolar. If this latter be low, no " shunt " (or one of very great resistance) will be required; but if the resistance of the interpolar be very high, the resistance of the " shunt " must be corre- spondingly low, or else not enough current will pass to magnetize the field-magnet, and the dynamo w^ll give no current. Fig. 38 represents the dynamo complete. The machinist, mechanic, engineer, artisan, student or schoolboy who has not only carefully read the preceding pages on the dynamo, but has made.^ or attempted to make, a machine by closely following the ins.'ructions, will have ac- quired a knowledge of the rudiments of electrical science which will enable him to explore still further into this fasci- nating branch of the mechanical arts. This book is merely designed to start the explorer on his interesting journey; new discoveries, new inventions, and new surprises are daily events in the electrical world; but, the fundar^ental prin- ciples, the foundation laws, never change, and, wHh a fair understanding of the underlying structure, the growling fabric can be watched with satisfactory understanding. The wide-awake mechanic will endeavor to keep abreast with the times. He will be quick to note any novel dis- covery, any important innovation, and in no branch of his art are the possibilities of world-thrillinp sensations greater than in the electrical field. Suppose, then, that you have made a dynamo, such as described in this article ; suppose that you have it in active operation, and it is giving you a current equal to eight or ten Bunsen's cells; you have an instrument which wall be of the highest value to you in your future researches; instead of finding the study a laborious grind, a dry, musty. Drain killer, you will find yourself fascinated Vv^ith the opening pages of the mysterious book when it is read by the light of the electrical current generated by the dynamo made by the skill of your own hands. Too much value cannot be given a knowledge of the science of electricity and its application to the mechanical arts, in- creasing every day, will bring it in contact with every mechanic and arusan in the country. Make a dynamo as described, study as you make, and you will be aCle to keep abreast of the times. 532 MANAGEMENT OF DYNAMOS. The use of dynamos is becoming so general for electric lighting and power that the following hints on the manage- ment and care of dynamos may be of use to engineers, es- pecially as the care of the dynamo is usually placed in the hands of the engineer, and the machine placed in the engine- room. Before the dynamo is started for its day's run all the lubri- cators should be filled up. For this purpose none but cop- per oil-cans should be used. Next in order, the brushes should receive attention, and should be carefully examined to see that they are properly trimmed and thoroughly well screwed up to their holders. If the brushes touch at a bevel angle, they should be oc- casionally trimmed with a file, so that they will preserve an even bearing upon the commutator To do this properly the brushes should be removed from the machine. Never leave files or iron tools near the dynamo. If the machine is in a shop where iron fihngs are flying about it should be examined frequently to see if any filings have been attracted, and if any are found they should be removed. It is always best, if the dynamo is of necessity placed in such a position, that it should be boxed in as completely as possible. After the machine has been started the brushes should be put down; when the run is over the brushes should be raised before the engine is stopped. The commutator must be kept clean and bright and free from metallic dust of any kind. It should be occasionally wiped with a clean rag (never use waste), very slightly smeared with oil or vaseline; should the brushes press too heavily it will be worn into ruts, should they not press firmly enough its segments will v/ear unequally along their edges. As soon as the dynamo is started the brushes should be carefully so rocked that they touch at the neutral points; if this position is not carefully observed the sparking may rapidly ruin the commutator. 533 ELECTRICITY SIMPLIFIED. No one knows what electricity really is. It seems, how* ever, to be present everywhere. In the air, in the earth, in the water, in trees, animals, man, fishes, metals, everywhere, but no one can tell what it is. We know what steam is, for we can divide it into its various parts. We know what a gas is, for we can smell it, or taste it, or weigh it. We know what the air is; but we cannot see electricity, it has no taste, it has no weight, no substance, but it is called a forcci which is made known to us by the peculiar fact that it willat- tract or repel. For instance, if you take a piece of glass — a small glass rod or tube, and a piece of sealing-wax, and bring them near some small scraps of paper, or shreds of cotton, a feather, or gold leaf, or bran, you will not notice anything particular. There will be no movement of any kind. But, suppose you rub the glass and the sealing-wax briskly with a piece of dry woolen cloth, then bring them near the light substances men- tioned, you will find that the paper, or cotton, or gold leaf, or bran, or feathers, will spring or jump toward the glass rod or sealing-wax, even if quite a little distance is between them, and will cling to the glass and wax. You will further notice, that, after a time, the paper, etc., will jump away (not simply/^//) from the glass, or waj^ as if they had been snapped off. ?'hus, there was so7?tething happened when the glass or \vdx was ruboed by the woolen cloth, something which gave the glass or wax the property of attracting the paper, etc. and afterward of repelling or casting off the same paper, etc. This something was the electricity excited by the friction between the glass or wax and the woolen cloth. The writer of this article is smoking an ordinary pipe, which has an amber mouth piece. He first wiped the moist- ure from the amber, and then rubbed it for a few seconds upon the green cloth of his desk, and, bringing it near some little bits of paper, he found that the paper sprang and remained upon the amber, ai?d, not only that, but the bit of paper next to the amber attracted another bit of paper, and that second piece another, until three little bits of paper, like a chain, were hanging from the amber. First, the amber was electrified, then each bit of paper, as 534 it came in contact with the electrified amber, became electri fied, and attractec another bit to itself. Now, there are two kinds of electricity, positive and negative. The positive at- tracts and the negative repels. This last statement can be easily proved. Make two little balls from the pith of the elder bush, or any other plant that has a dry, light pith. When quite dry, fasten a fine silk thread to each pith ball, and. suspend them from some convenient point so they will swing freely. Electrify the sealing-wax with the woolen cloth, but, elec- trify the glass rod witli a piece of soft silk. Touch one pith ball with the wax, and it will follow it for a moment and then shoot away, just as the paper did. At the same time touch the other pith ball with the glass and it will do the same thing. If you bring the wax and glass nearer the pith balls after they have been repelled, you will notice that they will keep away from them. Now quickly change the wax and glass, so that they will touch the pith ball that was first at- tracted and then repelled by the glass, and you will see that the wax will attract it, and, if you touch the other pith ball witk the glass, it will be attracted also. If you have taken the trouble to. try this simple experi- ment, you have learned that there is 2i positive electricity, or the electricity that attracts, and a negative electricity, or the electricity that repels. You have also learned that the ball which was repelled by the glass was attracted by the sealing-wax, and the ball that was repelled by the sealing-wax, was attracted by the glass. This proves that the electricity developed on glass is differ- ent in kind frovi that developed on sealing-wax, and by re- peating the experiment with other substances, it will be found that all electrified bodies act like either the glass or the sealing- wax. There is another thing, two bodies charged with (or hav- ing) positive electricity will repel each other, and the same thing will happen if the two bodies are chargeo. with negative electricity, but, if one is charged vix'Cci posaize^ and the other with 7iegative electricity, they will be attracted to each other. The electricity which is excited by rubbing two substances together is cdiW^dfrictional electricity. It has been shown by the above experiments that an elec- frified substance can impart electricity to another. This is called conduction. It is not necessary that the bodies should 535 c*ouch. They may be connectec* by a copper wire or a flax thread. But, if connected by a silk thread, or a piece of rub- ber, the electrified body will not electrify the other. Some substances transmit electricity readily and others do not. Those that offer little resistance to the passage of electricity are called conductors; those that offer great resistance are called non-conductors or insulators. Conductors which are held up, or wrapped in non-conductors are said to be insu^ lated. Silver, copper and iron are conductors. Rubber, gutta-percha, glass, porcelain and silk are non-conductors or insulators. A copper wire, if wrapped in silk or rubber, would be insulated. For practical work, conductors are made of wire, either copper or iron, usually having a covering made of woven silk or cotton. Frictional electricity is generated, for purposes where a large quantity is needed, by electric machines, which con- sists of a circular glass plate from one to four feet ni diaiia- eter, that is turned by a crank. Against the sides of this, plate are cushions made of silk or leather, coated with mercury. On turning the crank, the glass plate revolves between the silk cushions and is electrified. The electricity is gathered or caught by metal points called combs, and is carried off by conductors. Electricity is also developed by chemical action. AU chem- ical changes produce electric action. This is true whether the substance is a solid, liquid or gas, but the chemical action between liquids and metals gives the most satisfactory result. Electricity thus developed is called the Voltaic or Galvanic electricity. As was said before, we do not know just what electricity is, but we do know that by combining certain liquids and metals, or by making certain chemical combina- tions, we can make all the electricity we want. If we take a strip of copper and one of zinc, and place them in a glass jar which contains some dilute sulphuric acid (that is, water which has had sulphuric acid put in it), keep- ing the zinc and copper separated, but connecting them above the glass jar by a wire, conductor, we will have a current of electricity produced. In fact, two curreitts, opposite in kind and direction, are produced — but, remember that, whenever the direction of the electric current is referred to, it means the direction of i\iQ positive current. It is necessary, for the production of an electric curr^-<- '•? 536 this way, that the liquid should have a greater action upon one metal than upon the other. The metal which is most vigorously acted upon by the acid is called the positive plate {itgenerates^on^ might say,the electricity), the other is the negative plate (it collects the electricity). So the cur- rent starts from the positive plate, through the liquid to the negative plate, then out of the glass jar through the wire joined to the negative plate, and back through the other wire to the positive plate. In the apparatus de- scribed above(called a galvanic or voltaic element or cell) the zinc is the positive plate, copper the negative plate. The wires attached to the copper and zinc are called electrodes or poles. The electrode attached to the copper plate (which is the negative) is called the positive elec- trode. The one attached to the zinc plate (which is the positive plate), is called the negative elect'^ode. When two or more voltaic or galvanic elements(or cells) are connected together,the apparatus is called agalbanic or voltaic battery. In a battery the positive plate of one cell is connected to the negative plate of the next cell, and so on. When this is done, they are said to be coupled in series. Sometimes all of the positive plates are connected by wire, and all of the negative plates by another wire. The cells are then said to be joined in '' multiple arc." Batteries for producing electricity are divided into two classes, called "open circuit" batteries, and "closed cir- cuit' ' batteries. The open circuit batteries are used when the electricity is not required constantly, but is used for a short time at different periods. Such batteries are used with telephones, electric bells, hotel annunciators, etc. Closed batteries are used where the work is continu- ous, as for electric lights, motors, etc. (As galvanic cells can be readily purchased, and are not expensive, it is recommended that a cell for open circuit and one for closed circuit be purchased. For open circuit buy one of the following makes: Leclanche cell, or the Law; for closed circuit, the Grenet. These cells can now be bought of any electric supply store). Batteries as described, generating or producing elec tricity by the action and combination of ckemicals liquids and metals, are called ''Primary Batteries.'' There is another style of batteries, called Secondary or Storage batteries. A secondary battery docs not of itself 537 make an electric current, but is used to store up and hold the energy of an electric current, which is led to It from a primary battery or a dynamo. The electrica' energy can then be kept until it is wanted for use. A secondary or storage battery usually consists of a glass jar, holding plates, made of lead, and some water, which is made slightly acid. There are always two lead plates in a secondary battery, but there may be any number above that, and these plates are called electrodes. Upon the positive electrode is spread a paste made of red lead. Upon the neg- ative electrode is spread a paste made of litharge. When the plates are thus prepared, they are put into the acidulated water (which is held by the glass jar), and a wire from each plate is connected with conductors from a dynamo or a primary battery. When all is ready for charging, the current is turned on, and enters by one plate, coming out by the other. ' The electric current, of course, meets with some resistance from the plate and the paste, and this resistance causes it to work upon the paste in such a manner that a chemical change is made, that is, the paste on the positive electrode has been changed to peroxide of lead, and that in the negative electrode into spongy lead. When the current has passed from one plate to another in this way for a time, the wires are disconnected from the dynamo or primary battery. As the acidulated water is still left in the glass jar, the paste upon the plates begins to work to get back to its orig- inal shape, and it is this working that causes a current of electricity, which will light lamps, run a motor or do anything the current from the dynamo or primary battery would do. After the paste has resumed its original form, the battery is said to be discharged, and can then be again charged. It is customary, in practical use of secondary or storage batteries, to charge them from a dynamo. These batteries are largely used for street car purposes. A motor is attached to the axle of the car, and is energized by the storage bat- teries placed beneath the seats, the batteries having been charged from a dynamo located at the terminus of the road. In the article on "How to Build a Dynamo," commencing on page 478, the magnetizing effects of an electric current are explicitly explained. 55^ Electricity, although it has no weight or tangible form, is measured as accurately as is sterdn, or air, or coal. The three measurements most commonly used are ; The Volt;^ The Ampere; The Ohm. The Volt is the practical unit of measurement of press- jtre. That is, " volP^ bears the same relation to electricity as " pounds " does to steam. When we speak of steam in a boiler or in the cylinder of a steam engine, we say: " There is a pressure of ten or fifty or a hundred pounds to the square inch," and steam pressure is calculated and measured in pounds; thus, a " pound " is the unit of pressure or intensity. Now, electricity moves with a certain force and pressure; this force is called the electro-motive force (represented by the letters E. M. F.), and the unit of pressure or inte^isity of this force, is called a volt. Thus we say that a dynamo has an electro-motive force of 117 volts, or that the intensity of a galvanic cell is l^ volts, etc. Suppose, instead of steam, we had used the water which comes into the house from the water-works, as an illustra- tion. That water comes in through pij^es and is forced through these pipes by pumps. Now, the water comes with a pressure of so many pounds to the inch, and " pound" is the unit by which this pressure is measured. The water would not flow through the pipes unless it was pushed or forced through, neither would elec- tricity flow through the wires without there was pressure back of it, and this pressure is measured in volts. The Ampere is the practical unit of the rate of flow of electricity. Electricity flows through the wire at a certain pressure, just as water flows through pipes at a certain pressure. Now, if we wanted to speak of the water coming through the pipes, we would say that the water was flowing at the rate offiYQ gallons per minute, and if the pressure on the water was ten pounds, we would say that the water was flowing at the rate of five gallons per minute, at a pressure of ten pounds to the inch. In speaking of the electric current, we say, " that a certain current of electricity is flowing at the rate of one ai?ipere. acted upon by an electro-motive force of 90 volts^ or a lamp requires a current of two amperes ^ at a pressure of lOO Zfolts to light it. 539 Thus, the volts of pressure forces the current to flow througli the wires at a certam rate per second, and this rate is called the a77ipere. The Ohm (pronounced like " ome " in home) is the practi- cal unit of measurement of resistance. Electricity is conducted or carried from one place to another, for the purpose of telegraphing, telephoning, light, power, etc., by means of wires, made of copper or iron. These wires do not permit the current to flow through them without hindrance. There is always a certain amount of resistance to the current, and the smaller the wire, the more resistance there is. Sometimes the current is too strong for the wire, and it becomes hot, gets red, and burns up. That is, the wire is too small for the volts pressure, and amperes of current of electricity, and the current, trying to get through, and fighting to overcome this resistance, becomes red hot and then may melt. This resistance is measured by the ohm; thus, a copper wire of such a size has a resistance of so many ohms. RULES AND REGULATIONS. FOR Properly Wiring and Installing Electric Light Plants. The following rules and regulations for the prevention of fire risks arising from electric lighting, were issued by the Society of Telegraph Engineers and Electricians of England, and every person, connected with an establishment using electric lights, whether owners or employes, should care- fully read them, and be governed thereby % The chief difficulties which beset the electrical engineer are internal and invisible, and can only be effectually guarded against by testing with special apparatus, and electric cur- rents. They arise from leakage and bad connections and joints, which lead to waste of energy and the production of heat to a dangerous extent. Moisture Danger. — The necessity for guarding against the presence of moisture, which leads to loss of current and to the destruction of the conductors and apparatus, by cor- rosion and otherwise, cannot be too strongly urged. y/LO Earth Danger. — Injudicious connections of any part of tfte circuit with the "earth" tend to magnify every other source of difficulty and danger. Ignorance and Injudicious Economy. — Many of the dangers in the appUcation of electricity arise from ignorance and inexperience on the part of those who supply and fit up inadequate plants, and frequently from injudicious economy on the part of the user. Safety in Consulting Experienced Engineers.— The greatest element of safety is, therefore, the employment of skilled and experienced electrical engineers to specify the method in which the work is to be done, and ihe quality of the materials to be employed, and to supervise the execution of the work. CONDUCTORS. 1. Sectional Area. — Conductors (wires) must have a sectional area and conductivity so porportioned to the work they have to do, that, if double the current proposed is sent through them, the temperature of such conductors shall nof exceed 150° Fahr. 2. Accessibility. — The conductors, or their coverings, should be placed in sight, if possible, and they should always be as accessible as circumstances will permit. 3. Insulating. — Within buildings they should be insu- lated; and this rule applies equally to all conductors and parts of fittings which may have to be handled. 4. Maximum Temperature.— Whatever insulating mate- rial is employed it should not soften until a temperature of 170° Fahr., has been reached, and, in all cases, the material must be damp-proof. 5. Casings. — When wires pass through roofs, floors, walls or partitions, and where they cross, or are liable to touch metallic substances, such as bell wires, iron girders, or pipes they should be thoroughly protected by suitable addi^iiona' covering; and, where they are liable to abrasion from an 541 cause, or the depredations of rats or mice, they should be encased in some suitable hard material. 6. Distance Apart. — Conductors should be kept as far apart as circumstances will permit, the spacing between them being governed by their potential difference. 7. Inflammable Structures. — When conductors are carried in very inflammable structures, precaution should be taken to isolate them therefrom. 8. Metallic Armor. — Conductors which are protected on the outside by lead, or metallic armor of any kind, require the greatest care in fixing, on account of the large conducting surface which would become connected to the core in the event of metallic contact be^^ween them. 9. Joints. — All joints must be mechanically and electrically perfect, to prevent heat being generated at these points. When soldering fluids are used in ma,king joints, the latter should be carefully washed and dried before insulation is applied. 10. Gas and Water Pipes. — Under all circumstances complete metal circuits must be employed. Gas and water pipes must never form part of a circuit, as their joints are rarely electrically good, and therefore become a source of danger. 11. Overhead Conductors. — Overhead conductors, whether passing over or attached to buildings, must be insu- lated at their points of support. Precaution must be taken to obviate all risks of short-cir- cuiting, where they are likely to touch a building, or other overhead conductors and wires, either by their own fall or by being fallen upon by other conductors. 12. Lightning Protector. — In the case of overhead wires, every main should have a lightning protector at each point, where it enters or branches into a building. 542 13- Insulation Resistance. — The insulation of i syr^iem of distribution should be such, that the greatest leakage from any conductor to earth (and, in case of parallel w orkmg, from one conductor to the other, when all branches are switched on, but the lamps, motors, etc., removed), does not exceed one Jive thousandth part {-^^^^ of the total current intended for the supply of the said lamps, motors, etc., the test being made at the usual working electro-motive force. SWITCHES. 14. Construction and Action. — Every switch or com- mutator should be of such construction as to comply with the following condition, namely: That when the handle is moved or turned to or from the positions of " on " and " off," it is impossible for it to remain in any intermediate position, or to permit of a permanent arc, or heating. 15. Insulated Handles.— The handles of every switch must be completely insulated from the circuit. 16. Main Switches, Pqsition of. — The main switches of a building should be placed as near as possible to the point of entrance of the conductors, or to the generators of the cur- rent if they are within the building itself. Sv/itches should be provided on both leads. 17. Switch Boards. — Switch boards should bear clear instructions for their use by the inexperienced. ELECTRICAL FITTINGS GENERALLY. 18. Bases. — Switches, commutators, resistances, bare connections, lamps, etc., mast be mounted on incombustible bases; cut-outs, mounted on bases of wood, rendered unin- flammable, are admissible; vulcanite bases are undesirable in damp situations. The cracking of porcelain and earthen- ware fittings is a source of danger which can be avoided by precautions in fixing. 543 CUT-OUTS. 19. Imperative Use of. — All circuits should be protected by cut-outs ; and all leads from the mains, or small conductors from larger ones, must be fitted with cut-outs at their branch- ing pomts 20. Situation. — Where fusible cut-outs are used, the section should be so situated within ijts frame that the fused metal cannot fall where it may cause a " short circuit " or an ignition. 21. For ( + ) AND ( — ) Mains. — For all main conductors a cut-out should be provided for both the " flow " and "return;" and the two fusible sections must not be in the same compartment. 22. For Portable Fittings. — The flexible wires of por- table fittings must in all cases be protected by cut-outs at their fixed points of connection. ARC LAMPS. 23. Globes, etc. — Arc lamps must always be guarded by globes, netted or otherwise, so to prevent danger from ascending sparks, or from falling glass and incandescent pieces of carbon. 24. Insulation of Parts. — All parts of the lanips and lanterns which are liable to be handled (except by the persons employed to trim them), should be insulated. THE DYNAMO. 25. Insulation, Situation, etc. — The armatures and field magnet coils should be thoroughly insulated. Dynamos should always be fixed in dry places, and they must not be exposed to dust flyings or other industrial waste products carried in suspension in the a.r. They should not be per- 544 mitted in the working rooms of mills, where the liability to such dangers exists, or, where any inflammable manufactures are carried on, or inflammable materials are stored. 26. Motors. — Motors should be subject to the same con- ditions; but when it is necessary to use them in positions such as those above referred to, they must be securely cased in, such cases having a n on -combustible lining. BATTERIES. 27. Insulation. — Both primary and secondary batteries should be placed and used under the same precautions as pre- scribed for dynamos; and the room in which they are placed should be well ventilated. The batteries themselves must be well insulated. MAINTENANCE. 28. Testing. — The value of frequently testing and inspect- ing the apparatus and circuits cannot be too strongly urged as a precaution against fire. Records should be kept of all tests, so that any gradual deterioration of the system may be detected. 29. Cleanliness. — Cleanliness of all^parts of the appara- tus and fittings is essential to good maintenance. 30. Repairs. — No repairs or alterations must be made when the current is " on." GENERAL. All the above rules for the reduction to a minimum of the risks from fire, are also applicable in principle to installations of electricity for other uses than that of lighting : they also include precautions necessary to avoid risks of injury to per- sons, whether the conductors and apparatus are situated inside or outside a building. 545 DEFINITIONS OF ELECTRICAL AND MECHANICAL TERMS. ABSOLUTE TEMPERATURE.— Temperature as reck- oned from the absolute zero, which is 461.2 degrees below the Fahrenheit zero. ACCELERATION.— Rate of change of velocity. ACCUMULATOR. — i. Any apparatus which increases the current strength, as a dynamo electric machine. 2. A secondary storage battery. 3. A condenser. ACCUMULATOR, CHARGING.— Sending an electric current into a storage battery for the purpose of render- ing it an electric source. ACTION, LINES OF INDUCTIVE.— i. Lines of elec- trostatic force. 2. Lines within the space, separating a charge and neighboring body, along which electrostatic induction takes place. ^> ACTION, LOCAL, OF VOLTAIC CELL.— A waste of energy. Consumption of the zinc, or positive element of a voltai ccell, when the circuit is open or closed, or in regularly. ACTIVITY, UNIT OF.— Rate of doing work. One unit of work performed in one unit of time equals one unit of activity. In C. G. S. system, unit of activity equals one erg per second. Practical unit in same system is the watt, equal to one joule per second. In British system, unit of activity is the horse power, equal to 550 foot- pounds per second or 33,000 foot-pounds per minute. The ratio between the two systems is i H. P. = 746 watts (about). ADDENDUM. — That part of the tooth of a gear wheel which extends outward from and beyond the pitch line. ADHERENCE, MAGNETIC. —Adhesion between sur- faces due to magnetic attraction. ADIABATIC EXPANSION OF A GAS.— The expansion when no heat is given to or taken away while so doing. ADJUSTABLE REAMER.— A reamer the teeth of which 1 may be adjusted to the necessary diameter. ADMISSION. — Point of stroke at which steam is admitted to a steam cylinder. S4^ /iDMISSION LINE.— The line traced on an indicatov card from beginning of stroke to point of cut-off. AIR BLAST FOR COMMUTATOR.— A device to pre- vent th'e injurious action of destructive flashes at the commutator of a dynamo electric machine. AIR PUMP. — The pump used to remove air and water from a condenser. AIR THERMOMETER. — One generally made of glass tubing in which the expansion and contraction of a cer- tain volume of air raises and lowers a column of water, and this, by a suitable scale, indicates the temperature. ALLEN VALVE. — An ordinary D valve with an interior passage allowing steam to be admitted at two places. ALLOYS. — A few of the more important combinations are : Solder, plumber's; tin 66 parts, lead 34 parts. Pewter, hard; tin 92 parts, lead 8 parts. Britania Metal; tin 87 parts, antimony 8 parts, copper 4 parts, bismuth I part. Type Metal; lead 80, antimony 20 parts. Brass, white; copper 65, zinc 35. Brass, red; copper 90, zinc, 10 parts. Speculum Metal; copper 67, tin 33 parts. Bell Metal; copper 78, tin 22 parts. Aluminum Bronze; copper 90, aluminum 10 parts. German silver; copper 50, zinc 25, nickel 25 parts. Pailard Palladium; copper 15, palladium 60,. iron I part. Platinum Silver; platinum I, silver 2 parts. ALTERNATION.— A to-and-fro motion. Changes in the direction of a current. ALTERNATIONS, COMPLETE.— A complete to-and-fro change. ALTERNATIONS, FREQUENCY OF.— The number of alternations in unit time or per second. ALTERNATOR. — An alternating current dynamo. A re- versing commutator. ALTERNATOR, COMPENSATED EXCITATION OF. — An excitation of an alternating current machine, in which the field is but partially excited by separate excite- ment, the remainder of its exciting current being derived from the commuted currents of the machine itself. AMALGAM. — A mixture of metal with mercury applied to rubbers of frictional electrical machines. 547 ■^.MMETER. — A form of galvanometer for measuring the current strength of amperes. AMMETER, GRAVITY. — One in which a magnetic needle moves against the force of gravity. AMMETER, MAGNETIC-VANE.— A fixed and a mova- ble vane in the field, which repel each other and so measure the current. AMMETER, PERMANENT MAGNET. — A magnetic needle moved against the field of a permanent magnet. AMPERE. — The unit of electric current. That current which can be driven by the pressure of one volt, the unit of electromotive force, throup-h one ohm, the unit of electrical f"esistance. Such a rate of flow of electricity as transmits one coulomb per second. A current of such strength as would deposit .ro5o84 grains of copper per second. The unit rate of flow per second. AMPERE FEET. — The product of the current in amperes by the distance in feet. AMPERE HOUR. — Equal to one ampere flowing for one hour, or 3600 coulombs. AMPERE-VOLT.— A watt or 746 of i H. P. The follow^ ing expression signifies that C, the current in amperes, is equal to E, the electro-motive force in volts, divided by E R, the resistance in, ohms: C= — . This is Ohm's law. R AMPERE'S RULE FOR CURRENT EFFECTS ON NEEDLE. A magnetic needle if placed near a current of electricity flowing from the observer, who is facing the needle, is deflected to his left. ANEMOMETER. — An apparatus to electrically record the direction of the wind. ANGLE OF LAP. — Angle through which eccentric must be turned to admit steam at beginning of stroke when the lap is added to a valve. ANGLE OF LEAD. — Angle through which an the eccentric is turned to give lead to a valve. ANGLE -TOOTH. — A gear wheel tooth which runs across the face of a wheel in a line that develops part of the circumference of the wheel. ANNEALING. — The heating of metals, glass, etc., to a high degree and cooling slowly. To temper or soften. ANNUNCIATOR.— A device for indicating the place a;* which electric circuits have. been closed. 548 ANODE. — ^The positive terminal of an electric source, in opposition to Kathode, the negative terminal. APRON. — I. In an iron planer, the piece that carries the tool post or clamp. 2. Applied to parts which act as a shield. ARBOR. — A mandrel. A shaft or spindle. ARC. — I. The source of light of the electric arc lamp. The bow of light which appears betvreen two electrodes. An arc formed between two electrodes. 2. A section or part of, a circle. ARC OF APPROACH.— The arch (measured on the pitch circles) covered from the time any one pair of teeth of two gear wheels come ii. to contact until the point of con- tact is on the line of centers. ARC, COMPOUND.— An arc formed between more than two electrodes. ARC OF PITCH.— The pitch of gear wheel teeth from measurement around the pitch circle. ARC OF RECESS.— The arc (measured on the pitch cir- cles) covered from the time the point of contact of any one pair of teeth of two gear wheels is on the center line, until they leave contact. ARC, WATT. — ^The energy required to maintain a given arc or candle power. ARM. — I. One of the paths of an electric balance. 2. A support for insulators carrying electric coils. 3. A mov- able sign employed as a signal on railroads. ^RM, ROCKER. — An arm on which the brushes of a dynamo or motor are mounted for the purpose of shifting their position on the commutot'or. ARMATURE. — The coils of insulated wire together with the iron armature core, on which the coils are wound. A mass of iron or other magnetizable material placed on or near the pole of a mbgnet. The iron sheathing of a cable. I ARMATURE, BI-POLAR.— An armature of a dynamo electric machine, the polarity of which is reversed twice in every revolution. ARMATURE, DRUM.— One in which the armature core is solid, or nearly so, the wires being wound longitudi- nally along the core and across the ends. ARMATURE, NON-POLARIZED.— An armature of soft iron which is attracted, whatever the direction of the current. 549 ARMATURE, POLARIZED.— Having a polarity inde- pendent of that imparted by the magnetic pole. ARMATURE, RING.— An armature, the coils of which are wound on a ring-shaped core. ARMATURE, UNIPOLAR.— An armature, the polarity of which is not reversed during its rotation. ASTATIC. — Standing, or possessing no direct power. Not opposed to the earth's magnetism, B B. — A symbol for internal magnetization. BACK-GEAR. — The gears on the back of the head-stock of a lathe which can be thrown in or out to change the speed. BACK-KNIFE GAUGE LATHE.— A lathe in which the work is finished and cut to desired shape by a knife at its back. BACK PRESSURE.— Pressured caused on the back side of the piston by the exhaust steam. BALL AND SOCKET JOINT.— A joint consisting of a ball in a socket which encases it, but permits it to be moved in the casing; a universal joint. BALL-PENE. — The spherical pene of a hammer. BAND-SAW. — An endless steel band having saw-teeth on one edge and run on pulleys like a belt. BARS, OMNIBUS OR BUS.— The bars carrying the cur- rent from an electric generating plant. BASTARD FILE.— A file, the teeth of which are coarser than those of a second-cut file and finer than those of a coarse-cut file, the difference usually being one grade or degree. BATTERY. — The combination of a number of separate electric sources, as two or more voltaic cells or series of cells coupled together. BATTERY, DYNAMO.— The coupling together of sev- eral dynamo-electric machines. BATTERY, MAGNETIC— The combination as a single magnet or a number of separate magnets. BATTERY, OPEN CIRCUIT.— A battery through which the circuit is closed only when transmitting signals. BATTERY, PLUNGE.— A number of separate cells con- nected so as to form a single source and be simultane- ously placed or plunged in the exciting liquid. 550 BEARING,— A rest for a shaft or rod which holds it in position. BELT-SHIPPER.— A shipper used to move a belt from one pulley to another, BELT-TIGHTENER.— A pulley employed for tightening a belt on another pulley, and used to cause the belt to transmit power periodically instead of continuously. BEVEL-GEAR. — A gear wheel whose teeth are at an angle to its shaft. BLAST-PIPE.— A pipe conveyieg the air-blast to a cupola or other furnace. BLOW OFF.— The opening generally at the lowest point in a boiler where the boiler is to be emptied. BOARD, HANGER, — A su^Dporting and connecting plate for arc lamps. BOARD, SWITCH. —A board provided with switches which open, close or interchange circuits. BOBBIN.— An insulated coil of wire for an electro-magnet, BOILER STAYS.— Rods or bars or plates put in in such a way as to guy or stay flat surfaces to other parts. BOILER, TUBULAR, — One containing a large number of small tubes through which gases from the fire pass, BOILER, WATER TUBE. — One made up of a large number of small tubes in which water circulates. BOLT.— Metal rod having a head on one end and a threaded stem to receive a nut at the other; used for holding. BORE. — The inside of a cylinder. BORING-BAR. — A bar that drives boring or cuttine; tools BORING-MACHINE.— A machine for boring holes in metal or other material, BOSS.— A raised portion about a hole through which a bolt, screw, pin or shaft passes. BOTTOMING-TAP.— A tap with a thread up to its extreme end so that it will cut a thread to the bottom of a hole. BOURDON PRESSURE GAUGE.— The ordinary steam gauge m which the pointer is moved by the pressure act- mg inside a curved tube of elliptical cross section which it tends to straighten. BOX-CHUCK.— A two-jawed chuck used in finishing brass. BOX, DISTRIBUTION OR JUNCTION.— A manhole in an electric conduit at the junction of lead or other win^s. BOX-TOOL. — A tool for use in screw machines and turret >^ heads which guides the work. It often carries more than one cutting tool. 55i BOX -WRENCH. — A wrench which fits endwise over the head o-f a bolt. BRAKE, ELECTRO-MAGNETIC— An electro-magnetic brake for car wheels. BRAKE, PRONY OR FRICTION.— A mechanical device for measuring the power of a driving shaft. BREAK OR GAP LATHE.— A lathe whose bed beneath plate is cut out out so as to permit work of large dia- meter to be swung. BRIDGE. — An apparatus for balancing or measuring ele- trical resistance. BRIDGE WALL.— The wall just back of the grate of a boiler furnace reaching up close to boiler and causing flame to hug the boiler. BRIDGE OF VALVE SEAT.— The thickness of metal between the exhaust and steam ports of a steam engine. BRUSH. — Strips of metal, bundles of wire, plates of car- bon, etc., that bear on the commutator cylinder of a dynamo-electric machine, and carry the current from and to it. BRUSH LEAD. — The moving forward of the brushes in the direction of rotation to get the best output and reduce sparking. BUCKLING. — Irregularities or bending of the plates of storage cells, sometimes due to a too rapid discharge. BUNTER-DOG. — A work-gripping tool for a planing machine, consisting of a piece having a hook end to engage in the T-slot of the table and a set-screw to bind the work. BUTT-JOINT. — A riveted joint in which the ends of the plate or material abut directly; distinguished from a lap or other form of joint. BUTTON, CARBON.— A carbon resistance in the shape of a button. BUTT-STRAP.— A band, usually of iron, for holding to- gether the pieces in a butt-joint. BUTT-WELD. — A weld in which the two pieces abut when put together to weld, as distinguished from a lap or other form of weld. C CABLE, CAPACITY OF.— The quantity of electricity required to raise a given length of cable to a given poten- tial, or given difference of potential. 552 CALIBRATE. — ^To determine the relative value of the scale divisions or of the indications of a measuring device, as a galvanometer, voltmeter or ammeter. CALORIC.~A heat unit. CALORIMETER.— An instrument by which the amount of moisture in steam is determined. CAM. — A disk whose surface is not a true circle, which ac- tuates other parts by revolving. CANDLE POWER.— The unit of photometric intensity. A light equal to that produced by a standard candle. CAPACITY. — Such a capacity of a condenser or conductor that an electromotive force of one volt will charge it with a quantity of electricity equal to one coulomb. CAP-SCREW. — A square-headed screw with a collar. CARBONS, ARTIFICIAL.— Carbon obtained by the car- bonization of a mixture of pulverized carbon with differ- ent carbonizable liquids. CARBON, GORED.— A cylindrical carbon electrode for an arc lamp that is molded around a central core of charcoal, or soft carbon. CASE-HARDENING.— A process for hardening the sur- face of wrought iron, the hardened surface being about 1-32" deep. CAT-HEAD. — A sleeve running in a bearing and screwed to light lathe work to steady it. CAULKING. — ^The upsetting of the edges of the plates near riveted joints, thus making the joints tight. CELL, BICHROMATE.— A zinc-carbon couple, in a solu- tion of bichromate of potash and sulphuric acid in water. CELL, BUNSEN'S. — A zinc-carbon couple, immersed re- spectively, the zinc in dilute sulphuric acid and the car- bon in nitric acid. CELL, DANIELL'S. — A zinc-copper couple immersed, the zinc in dilute sulphuric rcid and the copper in a sul- phate of copper solution. CELL, GRAVITY. — A zinc-copper couple in solution of zinc sulphate and saturated solution of sulphate of copper. CELL, GROVE. — A zinc-platinum couple in sulphuric and nitric acid respectively. CELL, LECLANCHE. — A zinc-carbon couple in sal- ammoniac. CELL, POROUS. — A jar of unglazed earthenware, em- ployed in double fluid voltaic cells, to keep the two liquids separate. 553 CELL, SELENIUM. — A cell consisting of a mass of sele- nium fused in between two conducting wires or electrodes. CELL, SMEE — Zinc-silver couple in dilute sulphuric acid. CELL,, STORAGE. — A cell made of two relatively inert metal plates, immersed in an electrolyte, that stores elec- tric energy when passed into it, and reproduces same when connected externally. CELL, VOLTAIC. — The combination of two metals which when dipped into an electrolyte and connected outside the liquid by a conductor will produce a current of electricity. CENTRIFUGAL FORCE.— Force canised by a body tend- ing to fly off at a tangent when revolving in a circle. CHANGE-GEARS. — The gear wheels which are used tc change the revolutions of a feed or lead screw. CHASER, — A tool for cutting threads in a lathe by hand. CHECK-NUT. — An additional nut screwed against the first to check the tendency to worl^ back. CHISEL-TOOTH SAW.— A saw ^ ith inserted teeth hav- ing a heavy front rake. CHUCK. — A tool to hold work in a lathe or device to hold another tool, as a drill-chuck. CHUCK-PLATE.— A face plate constructed so that work can be chucked on it. CIRCUIT, CONSTANT POTENTIAL.— A circuit the potential of which remains constant. CIRCUIT, EARTH.— A circuit in which the ground forms the return path. CIRCUIT, METALLIC— A circuit in which metallic con- ductors are alone employed, and ground is not used for return. CIRCUIT, MULTIPLE, Multiple-arc-parallel or Quantity. — ^Two or more generators or receptive devices having their positive poles connected to one conductor and all their negative poles connected to a second conductor. CIRCUIT, MULTIPLE-SERIES.— Two or more groups of electrical apparatus connected in multiple, the sepa- rate parts of each group being connected in series. CIRCUIT SERIES. — A compound circuit, as a chain, in which the sources, or receptive devices form links and are so arranged that the current must pass successively through from the first to the last. CIRCUIT, SHUNT. — A branch, by-path or second cir- cuit of comparatively high resistance through which a portion of the circuit flows. 554 CIRCULATING PUMP.— The pump employed to drive the cooling water through a condenser. CLEARANCE. — The volume included between the piston and the valve seat when the piston is at the end of its stroke. CLEMENTS-DRIVER.— A device for driving workk in a lathe, which equalizes the strain on the two ends of the carrier or dog. CLUTCH. — An engaging and disengaging device which enables motion to be communicated from one part to an- other, or the same to be stopped. COG. — A wooden tooth for a gear wheel. COIL, CHOKING OR IMPEDENCE.— A coil of iron so wound on a core of iron as to possess high self-induction. COIL, INDUCTION, RHUMKORFF. — Two parallel coils of insulated wire employed for the production of currents by mutual induction. COIL, PRIMARY. — The coil or conductor of an induction coil or transformer through which the rapidly interrupted ar alternating primary or inducing current is sent. COIL, SECONDARY.— That coil of an induction coil or transformer in which currents are induced by alternations or interruptions of the current passed through the primary coil. COILS. ARMATURE. OF DYNAMO-ELECTRIC MA- CHINE. — The conductor wound or placed on the arma- ture. COLD, PRODUCTION OF, BY ELECTRICITY.— When an electric current passes across a thermo-electric junc- tion, the junction is either heated or cooled, according to the direction of the current. COLLAPSING-TAP.— A tap so formed that its teeth close inwards when the thread is cut. permitting the tap to be withdrawn without winding it backward. COMBINATION-CHUCK.— A chuck so constructed that the jaws may be moved either simultaneously or indivi- dually. COMMUTATOR, DYNAMO-ELECTRIC MACHINE.— That part of a dynamo-electric machine which is designed to cause the alternating currents produced in the armature to flow in one and the same direction in the external circuit. COMPOUND-GEARS.— A train of gear wheels in which ) two wheels of different diameters are fixed on one shaft so that the vek^city may be varied. ^ 555 COMPOUND SLIDE-REST.— A slide-rest with two slides, one above the other. COMPRESSION. —The pressure caused at the end of stroke by closing the exhaust port. COMPRESSION LINE.— The line traced on an indicator card from the time the exhaust port is closed to the begin- ning of the stroke. CONDENSATION, INITIAL.— The condensation which takes place when steam enters the cylinder at the begin- ning of each stroke. CONDENSEP.. — I. Cooling apparatus for condensing ex- haust steam. 2. (Leyden jar). Device for increasing the capacity of an insulated conductor; and induction device. CONDENSER, CAPACITY OF,— The quantity of elec- tricity in coulombs a condenser is capable of holding before its potential in volts is raised to a given amount. CONDENSER, SURFACE. — One in which the steam comes in contact with surfaces cooled by air or water. CONE-BEARING. — A journal bearing which has a second sleeve that may be moved endvv^ise to take up wear. CONE-MANDREL. — A mandrel which employs two cones to hold hollow work. CONE-PLATE. — A device with a coned mouth which sup- ports one end of work in a lathe, thereby steadying it. CONTACT-BREAKER, AUTOMATIC— A device for causing an electric current to rapidly make and break its own circuit. CONTROLLER. — An automatic magnetic regulator for a dynamotelectric machine. CONVERSION, EFFICIENCY OF, OF DYNAMO.— The total electricity energy develop by a dynamo, divided by the total mechanical energy required to drive the dynamo. CONVERTER. — The inverted transformer or induction coil used on alternating current systems. CORE, ARMATURE OF DYNAMO-ELECTRIC MA- CHINE. — Iron core on or around which the armature coils of a dynamo-electric machine are wound or placed. CORE, ARMATURE, LAMINATION OF. — A subdi- vided core in separate insulated plates or strips for the purpose of avoiding eddy currents. CORE, ARMATURE, VENTILATION OF.— Means for passing air through the armature core of a dynamo-elec- tric machine in order to reduce the heating. 5ii6 CORE. LAMINATIONS OF.— Structural subdivisions of the cores of magnets. CORE, SOLENOID. — A core so arranged as to be drawn into a solenoid on the passage of the current through the coils. COULOMB. — The unit of electrical quantity. That quan- tity of electricity which would pass in one second through a resistance of one ohm with a pressure of one volt. COUNTER-SHAFT.— A small shaft with pulleys upon it, one usually being an idler, to permit a machine to be started and stopped without stopping the main shaft or driving belt, and also to vary the speed of the machine. COUNTERSINK. — A tool for cutting an enlargement, cone-shaped or perpendicular, at the mouth of a hole. COUPLE, ASTATIC— Two magnets of equal strength suspended one over the other in the same vertical plane so as to completely neutralize each other. COUPLE, THERMO-ELECTRIC,— Two dissimilar met- als which, when connected at their ends only so as to form a complete circuit and one of the ends is heated, will produce an electric current. COUPLE, VOLTAIC, GALVANIC,— Two dissimilar met- als in an electrolyte and capable of producing an electric current. C. P. — Contraction for candle power. CRANK. — Arm which turns the engine shaft of an engine. CRANK-PIN.— The pin in end of the crank to which the connecting rod is attached. CROSSING, LIVE TROLLEY.— A device whereby a trol- ley moving over a line that crosses a second line at an angle is enabled to maintain its electrical connection with the line while crossing. CROWK-WHEEL. — A gear wheel whose teeth are on its side face. CURRENT DENSITY.— The current which passes in any part of a circuit as compared with the area of cross-sec- tion of that part of the circuit. CURRENT, ELECTRIC— The quantity of electricity which passes per second through any conductor or circuit. CURRENT, GENERATION OF BY DYNAMO-ELEC- TRIC MACHINE.— The difference of potential devel- oped in the armature coil by the cutting of the lines of magnetic force of the field by the coils during the rota- tion of the armature. 557 CURRENT, INDUCED.— The current produced in a con- ductor by cutting lines of force. CURRENT, ROTATING.— Term applied to a current which results by combining a number of alternating currents whose places are displaced with respect to one another. CURRENT STRENGTH.— The product obtained by di- viding the electro-motive force by the resistance. Accord- ing to ohm's law. the strength for a constant current is: E (electromotive force) C (current) == R (resistance) CURRENT, TRANSFORMING A.— Changing the elec- tromotive force of a current by its passage through a con- verter or transformer. CURRENT UNIT, STRENGTH OF.— Such a strength of current that when passed through a circuit one centi- meter in length, arranged in an arc one centimeter in radius, will exert a force, of one dyne on a unit magnet pole placed at the center, equal to ten amperes. CURRENTS, EDDY.— Useless currents produced in the pole pieces, armatures and field-magnet cores of dynamo electric machines or motors. CURRENTS, SIMPLE PERIODIC. — Alternating cur rents. A current of such a nature that the continuous variation of the flow past any cross section of the con- ductor, or the variation in the electro-motive force of which can be expressed by a simple, periodic curve. CURRENTS, UNDULATORY.— Currents, the strength and direction of whose flow gradually changes. CURVE, CHARACTERISTIC — A diagram in which a curve is employed to represent the ratio of certain vary- ing values. CUSHIONING. — The closing of the exhaust port before the end of the stroke to allow the steam thus enclosed to take up the shock of reciprocating parts. CUT-OFF. — The point of stroke at which the steam port is closed. CUT-OUT. — A device that will remove an electro-receptive device from the circuit. CUT-OUT, T0.< — ^To remove an electro-receptive device rrom the circuit of an electric source by disconnecting oi diverting the circuit from it. CYCLOID. — A curve generated by a pencil fixed in the perimeter of a circle when rolled upon another circle. 55» CYCLE, MAGNETIC— Single round of magnetic charges to which a magnetizable substance is subjected when it is magnetized from zero to a certain maximum and then decreased to zero and so on. D DAMPER. — A retarding device: A metallic device sur- rounding the core of an induction coil for the purpose of varying the intensity of the induced currents. DAMPER, ARC-LAMP.— The dash-pot or other device offering resistance to quick motion. DEAD-BEAT. — A swinging magnetic needle which is quickly brought to rest. Such a motion of a galvano. meter needle in which the needle moves sharply over the scale from point to point and comes quickly to rest. DEAD-POINT ) Position of crank-pin when piston rod, or >• connecting rod, and crank are in a DEAD-CENTER. ) straight line. DECLINATION, ANGLE OF.— The angle which meas- ures the deviation of the magnetic needle from the true geographical north. DEKA (AS A PREFIX). —Ten times, as deka-ampere. DEMAGNETIZATION.— A process by which a magnet is deprived of its magnetism. DENSITY. ELECTRIC— The quantity of free electricity an any unit of area or furface. DEPOLARIZATION.— Depriving a voltaic cell of its polarization. DEPOSIT, ELECTRO-METALLURGICAL.— The de- posit of metal by the process of electro-metallurgy. DETECTOR, GROUND.— A device in an incandescent lamp-system for showing the location of a ground. DEVICE, ELECTRO-RECEPTIVE.— Any device placed in an electric circuit and energized by the current, such as motors, telegraphs and telephones, lamps, transform- ers, etc. DIAMAGNETIC. — The reverse to magnetic attraction; metals, etc., which are repelled by the poles of magnets are called diamagnetic. DIAPHRAGM. — A plate or sheet securely fixed at its edges, as a drum head, and capable of being set in vibra- ti<-^n, as a telephone diaphragm. -^ 559 DIELECTRIC, — A substance which permits induction to take place through its mass. DIMMER. — A choking coil employed on transformer cir- cuits to regulate the potential. DIP, MAGNETIC. — Deviation of a magnetic needle from a true horizontal position. Its inclination towards the earth. DISC, ARAGO'S. — A non-magnetic metal disc, as of cop- per, which, when rapidly rotated under a freely supported magnetic needle, will cause the needle to be deflected or to rotate. DISC, FARADAY'S. — Anon-magnetic metal disc fixed on an axis parallel to the direction of the magnetic field in which it is to move. DISCHARGE. — To equalize the potential. The equaliza- tion of the difference of potential by metalically con- necting the terminals. DISCHARGE, BRUSH.— A faintly luminous discharge that occurs from a pointed positive conductor. DISCHARGE, OSCILLATING. — Successive discharges and recharges which occur on the disruptive discharge of a condenser. DISCHARGE, VELOCITY OF.— The time required for the passage of a discharge through a given length of conductor. DISTRIBUTION, CENTER OF.— In electrical engineer- ing, any place in a system of multiple-distiibution where branch cut-outs and switches are located. DOG. — A device for holding or steadying w^ork. DOG-HEAD. — A hammer for straightening saw or other plates. DOME. — The upright cylindrical drum attached directly to a boiler; used as a steam-chamber. DOUBLE-DECK BOILER.— One composed of two cylin- drical shells placed vertically above each other. DRIFT-PIN. — The punch-like tool driven into rivet holes when the holes of two plates do not coincide. DROP-HAMMER. — A hammer for forgin^g, stamping or other work, which is raised by power and falls by gravity. DRUM. — A cylindrical chamber connected in some way to the main boiler. DOUBLE SLIDE-REST.— A feed motion in which there ^are two slide-rests on one slide-way. DUTY. — The amount of work done by an engine as com- pared with the work or fuel consumed. DYNAMO, INDUCTOR. — A dynamo machine for alter- nating currents in which the difference of potential caus- ing the currents is obtained by magnetic changes in the cores of the armature and field coils by the movement past them of laminated masses of iron inductors. DYNAMO, POLYPHASE.— A dynamo from which two or more alternating currents are taken. DYNAMO, ROTARY-PHASE.— Rotating current dynamo. DYNAMO, SEPARATELY-EXGITED.— Dynamo whose fields are separately excited. DYNAMOMETER.— Instrument for measuring power. DYNAMOMETER, ELECTRO.— A form of galvanometer for the measuring of electric currents. DYNE.— The unit of force. The force which, in one sec- ond, can impart a velocity of one centimetre per second to a mass of one gramme. EARTH OR GROUND.— A plate buried in the ground to make connection between line and earth where the earth is used as the return circuit. A fault in a line caused by its contact with the earth. That part of the earth which forms part of an electric circuit. ECCENTRIC— A disk placed off the center on a shaft. ECCENTRIC, THROW OFF.— Amount of offset given an eccentric. EFFECT, FERRANTI. — A difference of potential of mains towards their ends furthest from the terminals con- nected with a source of constant potential. EFFECT, HALL.— The Hall effect is produced by plac- ing a thin, metallic strip, conveying an electric current, in a strong, magnetic field. A transverse electromotive force, produced by a magnetic field in substances under- going electric displacement. EFFECT, JOULE.— The beating effect produced by the passage of an electric current through a conductor. EFFECT, THERMO-ELECTRIC— The production of an electromotive force at a thermo-electric junction by a difference of temperature. EFFECT, THOMSON.— The production of an electro- motive force in unequally heated homogeneous conduct- ing substances. 56i EFFECT, VOLTAIC— A difference of potential at the point of contact of the two dissimilar metals. EFFICIENCY, BOILER.— Ratio of total amount of heat in the steam given out by a boiler to the total heat given out by the fuel. EFFICIENCY, COMMERCIAL OF DYNAMO. —The available electrical energy in the external circuit, divided by the total mechanical energy required to drive the dynamo that produced it. EFFICIENCY, ELECTRIC— The useful electrical energy of anv source, divided by the total electrical energy. EFFICIENCY, ENGINE. — Ratio of amount of energy given out by an engine in the form of work to total amount of energy given to the engine in the form of heat in the steam. EFFICIENCY, QUANTITY, OF STORAGE BATTERY. The ratio of the number of ampere-hours taken out of a secondary battery, to the number of ampere hours put in the battery in charging it. EFFICIENCY, REAL, OF STORAGE BATTERY.— The ratio of the number of watt-hours taken out of a storage battery, to the number of watt-hours put into the battery in charging it. ELECTRICITY, DISTRIBUTION OF, BY ALTER- NATING CURRENTS.— A system of electric distribu- tion by the use of alternating currents, transformed before passing through lamps, motors, etc. ELECTRICITY, DISTRIBUTION OF, BY CONSTANT CURRENTS. — A system for the distribution of electri- city by means of direct i. e. continuous, steady or non- alternating currents. ELECTRICITY, DISTRIBUTION OF, BY CONTINU- OUS CURRENTS, BY MEANS OF TRANSFORM- ERS. — A system for the transmission of electric energy by means of direct currents that are sent over the line to stations where motor-dynamos are used for trans- formers. ELECTRICITY, MAGNETO. —Electricity produced by the motion of magnets past conductors, or of conductors past magnets. ELECTRICITY, NEGATIVE. — The kind of electric charge produced on rosin when rubbed with cotton. The opposite to positive electricity. 5^2 ELECTRICITY, POSITIVE.— The kind of electric charge produced on cotton when rubbed against rosin. ELECTRICITY, STATIC— A term applied to electricity produced by friction. ELECTRICITY, THERMO. — Electricity produced by difference of temperature of dissimilar metals. ELECTRICITY, UNIT OF QUANTITY. —The current of electricity conveyed by unit current per second. The coulomb which is the quantity conveyed by a current of one ampere in one second. ELECTRODE. — The terminals of an electric source. ELECTRODES, CARBON, FOR ARC LAMPS.— Rods of artificial carbon employed in arc lamps. ELECTROLYSIS. — Chemical decomposition effected by means of an electric current. ELECTROLYTE, POLARIZATION OF. —When the poles of all the molecules of any chain are turned in the same direction, viz: with their positive poles facing the negative Dlate, and the negative poles facing the positive plate. ELECTROMETER, QUADRANT.— An electrometer in which an electrostatic charge is measured by the attract- ive and repulsive force of four plates or quadrants, on a light needle suspended within them. ELECTROSCOPE. — An apparatus for indicating the pres- ence of an electric charge and determining whether the charge is positive or negative. ELECTROSCOPE, GOLD-LEAF.— An electroscope em- ploying two leaves of gold to detect the presence and polarity of a charge, ELECTROSTATICS.— That which treats of the phenom- ena and measurement of electric charges. ELECTROTYPE. — An impression consisting of a thin shell, or coating of metal, usually copper, deposited on a plate by means of electro metallurgy, being afterwards backed by soft metal. ELEMENT. — Matter that is composed of but one kind of atoms and cannot be decomposed into simpler matter. ENERGIZING, ELECTRICALLY.— An effect caused by electricity in an electro-receptive device, as energizing an electro-magnet by passing current through the coils. ENERGY, ELECTRIC— The power which electricity posseses of doing work. The current in amperes, multi- plied by the differential of potential in volts, divided by 563 74^, equals the rate of doing work in horse-power. 746 volt amperes, or watts, equals one horse-power. ENERGY, ELECTRIC, TRANSMISSION OF.— The transmission of mechanical energy between two distant points connected by an electric conductor, by converting the mechanical energy into electrical energy at one point, sending the current so produced through the conductor, and reconverting the electrical into mechanical energy at the other point. ENERGY, POTENTIAL OR STATIC— Energy possess- ing the power of doing work, but not actually perform- ing such work. Stored energy, or the power of doing work by a body at rest. ENGINE, BLAST.— One used to force a blast of air, as for a blast furnace. ENGINE, COMPOUND.— One in which the same steam is used in two or more cylinders. ENGINE, CONDENSING.— One in which the exhaust steam, is condensed back into water. ENGINE, DOUBLE, TRIPLE, QUADRUPLE, EX- PANSION. One in which the same steam is used in 2, 3 and 4 cylinders respectively. EQUATOR, MAGNETIC. — An irregular line passing through the earth approximately midway between the earth's magnetic poles. EQUIVALENCE, CHEMICAL. —The quotient obtained by dividing the atomic weight of any elementary sub- stance by its atomicity. That quantity of an elementary substance that is capable of combining with or replacing one atom of hydrogen. EQUIVALENCE, ELECTRO-CHEMICAL.-'^The chemi- cal equivalent of a substance multiplied by the electro- chemical equivalent of hydrogen. EQUIVALENCE, ELECTRO-CHEMICAL, LOSS OF. — ^The amount of chemical action produced by an elec- tric current, passed through various chemical substances, is proportional to the chemical equivalent of each sub- stance. ERG. — ^The work done when a body is moved through a distance of one centimeter with the force of one dyn^. A dyne centimetero EVAPORATION, ELECTRIC— The formation of vapors at the surface of substances by the iofluence of negative electrification. 5^4 EXPANDING CHUCK.^ -A chuck that usually holds work from its bore and is capable of expanding to adjust itself to a difference in diameter of a piece of work. EXPANDING-MANDREL.— Mandrel whose diameter may be varied, generally constructed with adjustable jaws. EXPANSION-JOINT.— A joint placed in a pipe to allow the same to expand and contract under changes in temperature. EXPLODER, ELECTRIC MINE OR ELECTRO-MAG- NETIC. — A magneto-electric machine used to produce the currents of high electro-motive force employed in the direct firing of blasts. EXTENSION LATHE.— A lathe with a bed in two longi- ttidinal parts so that the upper one supporting the carriage may be moved from the face-plate, leaving a gap and permitting work of larger diameter to be chucked. FACE-CAM. — A cam whose actuating surface is on its side or sides. FARAD. — The practical unit of electric capacity. FEATHERING PADDLE WHEEL.— One in which the floats are raised out of the water edgewise. FEED, CHECK-VALVE.— The valve placed in the feed pipe of a boiler to prevent water from leaking back through the pump or injector. FEED, CLOCKWORK FOR ARC LAMPS.— An auto- matically started arrangement of clockwork for obtaining a uniform feed motion of one or both electrodes of an arc lamp. FEED-MOTOR.— The part of a machine which feeds either the tool or the work, so that a cut may be made. FEED-WATER HEATER.— A sort of boiler generally heated by exhaust steam through, which feed water for a boiler is passed for the purpose of heating it. FENCE. — A plate in a machine to hold work in position. FIDDLE-DRILL.— A drill that is revolved back and forth by means of a bow with a string to it. FIELD, AIR. — That portion of a magnetic field in which the lines of force pass through air only. FIELD, ALTERNATING, MAGNETIC— A magnetic field the direction of whose lines of force is alternately reversed. 565 FIELD, ELECTRO-MAGNETIC.^The space traversed by the magnetic force produced by an electro-magnet. FIELD, ELECTROSTATIC— The region of electrostatic influence surrounding a charged body. FIELD, MAGNETIC— The region of magnetic influence surrounding the poles of a magnet. FIELD, MAGNETIC, ALTERNATING.— The magnetic field produced by an alternating current. FIELD, MAGNETIC, REVERSING. — That portion of the field of a dynamo-electric machine, produced by the field-magnet coils, in which the currents flowing in the armature coils are stopped or reversed after the coil has passed its theoretical position of neutrality. FIFTH-WHEEL.— The circular slideway which permits the front axle of a vehicle to be turned horizontally. FILLISTER-HEAD.— A cylindrical serew-head that con- tains a screw-slot. FINDER-WIRE, — Galvanometer used to locate the corre- ponding ends of different wires in a bunched cable, FIRE-BOX. — ^The chamber or box containing the fire in all boilers in which the same is surrounded by water. FIT-STRIP. — A projection about an inrh in width for the purpose of being fitted to bed a piece properly, to obvi- ate bedding the entire surface of the piece. FLAT-CHISEL. — A machinist's chisel, wedge-shaped. FLAT-DRILL. — A drill of rectangular cross-section. FLATTER. — A swage for plane or flat surfaces. FLEXIBLE-SHAFT.— A wire shaft constructed similar to wire rope, for transmitting rotary motion. It may be bent and still perform its oflice. FLUX or FLOW, MAGNETIC— The total number of magnetic force in any magnetic field. FLY-WHEEL. — ^The wheel with a heavy rim placed on an engine shaft to give a steady motion to the engine. FOLLOW-BOARD.— A piece constructed to fit a pattern, to prevent the latter from warping. FOLLOW-REST.— A rest which steadies work on a lathe and travels with the carriage. FOOT-BLOCK. — A work-holding device with a dead cen- ter, for use on a milling machine. FOOT-POUND.— The unit of work. The amount of work required to raise a pound vertically through a distance of one foot. St)0 FORCE, CENTRIFUGAL.— Force that is supposed to urge li. rotating body directly away from the center of rotation. FORCE, CONTACT.— A difference of electrostatic poten- tial produced by the contact of dissimilar metals. FORCE, ELECTROMOTIVE. ABSOLUTE UNIT OF. — A unit of electromotive force, expressed in absolute or C. G. S. units. The one-hundred millionth part of a volt. FORCE, ELECTROMOTIVE, COUNTER OR BACK. — A reverse electromotive force, which tends to cause a current in the opposite direction to that actually produced by the source. FORCE ELECTROMOTIVE, COUNTER OF MUTU- AL INDUCTION. — The counter electromotive force produced in the primary circuit of an induction coil by the action thereon of a simple-periodic e. m. f. FORCE, EI ECTROMOTIVE, DIRECT.— An e. m. f . act- ing ni the Same direction as another e. m. f . already existing. FORCE, ELECTROMOTIVE, IMPRESSED.— The e. m. f. acting on any circuit to produce a current therein. FORCE, ELECTROMOTIVE, SIMPLE PERIODIC.-^ An e. m. f . which varies in such manner as to produce a simple-periodic current, or an e. m. f., the variations of which are correctly represented by a simple-periodic curve. FORCE, ELECTROSTATIC, LINES OF.— Lines ex- tending in the direction in which the force of electro' static attraction or repulsion acts. FORCE, MAGNETO-MOTIVE.— That difference of mag- netic potential or magnetic pressure existing in a magnetic circuit which creates the magnetic lines of force. FORCE, MAGNETO-MOTIVE. PRACTICAL UNIT OF. — A value of the magneto-motive force equal to All =1.25564 times the amperes of one turn. (The 10 Greek letter pi is used in engineering as the symbol for ratio of circumference to diameter, i. e., 3.1416; the diameter multiplied by // equals circumference. FORCED-DRAUGHT.— Forcing of air through a furnace by means other than the natural draught of a chimney. FORK, TROLLEY. — The mechanism connecting the trol- ley-wheel mechanism to the trolley pole. FORMER. — A piece that guides or controls the movement of a cutting tool; also a template to which pieces are shaped. 5^7 FRICTION-GEARING. —Wheels which transmit motion by frictional contact on their circumference. FROG, TROLLEY. — A device employed in fastening together trolley wires where they branch off, and as a guide to the trolley wheel. FURNACE, ELECTRIC— An electrically heated furnace, employed for the purpose of effecting difficult fusion. FUSIBLE-PLUG,— Plugs of metal placed in holes in the parts of a boiler exposed to the highest heat whicli would melt before the plates could be injured by heat. GALVANIC ACTION or ) Corroding of plates and stays VOLTAIC ACTION. f supposed to be caused by elec- tric currents being generated by the impurities in water acting on the plates, especially where copper is used. GALVANOMETER. — An apparatus for measurmg the strength of an electric current. GALVANOMETER, ASTATIC— One having two needles so arranged that the earth's magnetism has little or no effect on them. GALVANOMETER, BALLISTIC— A galvanometer de- signed to measure the strength of a current that lasts but for a moment, such, for example, as the current caused by the discharge of a condenser. GALVANOMETER, DIFFERENTIAL.— A galvanometer containing two coils so wound as to tend to deflect t':e needle in opposite directions. GALVANOMETER, MARINE.— A galvanometer for use on steam ships where the motion of magnetized masses of iron would seriously disturb the needles of ordinary instruments. GALVANOMETER, MIRROR OR REFLECTING.— A galvanometer in which instead of reading the deflections of the needle directly by its movement, over a graduated scale, thep are read by the movement of a spot of light reflected from a mirror attached to the needle. GALVANOMETER, VOLTMETER.— An instrument for the measuring of differences of electrical potential. GANG-MILLS. — Milling machine cutters placed side by side on the gangs. GAP, AIR. — An opening or gap in a magnetic circuit coi> taining air ohly. 568 GAP-LATHE. — A lathe having a gap in its bed to permit work to be chucked which would not otherwise clear the guides. GAUGE-COCK. — A stop cock placed at different levels on a boiler; the level of the water being determined by the issuing of steam or water from it. GAUGE, WIRE, MICROMETER.— A micrometer gauge employed for measuring the diameter of a wire in thou sandths of an inch. GAUGES, WIRE, VARIETIES OF.— The principal wire gauges in use are given in the following table: There are three standards as follows: Brown & Sharp, or Ameri- can; Birmingham or Stub's; English Legal Standard. An idea of the gauges compared, can be had from the following (the diameter of the wire is given in mills) : No. o No. lo No. 30 Gauges. Wire. Wire. Wire. B. & S 324.86 101.89 10.925 Birmingham. . .^ 340. 134. 12. English Standard 324. 128. 12. 4 GEAR-WHEELo — A wheel provided with teeth for engag- ing with those of a similar wheel. GENERATOR, DYNAMO-ELECTRIC— A machine in which electricity is produced by the movement of con- ductors through a magnetic field in such a manner as to cut the lines of force. A Dynamo-electric machine. GOOSE-NECK. — A frame constituting a fulcrum for a rachet brace. GOVERNOR. — A device for maintaining constant the speed of a steam engine or other prime mover, despite sudden changes in load. GOVERNOR, CENTRIFUGAL.— One which depends for its action upon the change in the centrifugal force ex- erted upon certain of its parts due to change of speed. GOVERNOR, FLY-WHEEL OR SHAFT.— One used on automatic engine? and contained in the fly or belt wheel and connected to the eccentric. GRAMME. — A unit of weight in the metric system, equal to 15,43235 grains. Also written Gram. GRAVIS. — A hand tool of rectangular cross section having cutting edges at its end, which are formed by grinding ^the end face at an acute angle to the body of the tool. 569 GRID. — A lead plate, provided with perforations employed in storage cells for the support of the active material. GROUND. — Contact of an electric conductor with the earth. GROUND RETURN.— A term applied when the earth is used as part of an electric circuit. GUIDE-BAR. — A bar on which slides a moving or recipro- cating part, as an engine's cross-head. GUM. — The bottom section between saw teeth. GUSSET-STAYS. — Triangular shaped stays made of boiler plate used for such places as staying the eijd of a boiler to the side. H HALF-CHECK JOINT.— A joint in which a piece is let into another so that the surface comes level. HAMMER-TEST. — Test of a boiler made by hammering the plates, defects being located by the sound. HAND-HOLE. — The holes placed in the sides of a boiler large enough to admit the hand for cleaning, etc. HEAD-END. — End of the cylinder away from the crank. HEAT OF EVAPORATION.— Amount of heat necessary at a given pressure to turn a unit of water into dry steam. HEAT, MECHANICAL EQUIVALENT OF. — The ; amount of mechanical energy converted into heat. The mchanical equivalent of one unit of heat is equal to 772 foot pounds of work. HEAT, SPECIFIC— The capacity of a body for heat compared with that of an equal quantity of some other substance, usually water. HEAT UNIT (BRITISH).— The quantity of heat required to raised the temperature of a pound of water from 32 to 33 degrees Fahrenheit. HEATING-SURFACE.— The surface plates of a steam boiler which receive the flame or heat on one side and which have water on the reverse side. HINDLEY'S SCREW.— Short length of screw, sometime: called an endless screw, used to drive a worm wheel. HORSE POWER (H. P.).— A commercial unit for power or rate of doing work. A rate of doing work equal to raising 550 pounds one foot in one second, or 33,000 pounds one foot in one minute, and always involveing the three factors, force, distance and time. HOUR LAMP. — A service of electric current which will maintain one electric lamp yne hour. 570 HOUR, WATT. — An expenditure of one watt for one hour. A unit of electrical work. HUNTING-TOOTH.— An extra tooth placed in a pair of gear wheels to vary the number of teeth, so that the same teeth will not always engage together. HYPOCYCLOID.— A cycloidal curve in which the rolling circle is rolled within the buse (or fixed) circle. I IMPEDANCE. — The sum of all resistance, ohmic and spurious, in a circuit, expressed in ohms. INCLINATION, ANGLE OF.— The angle of magnetic dip. The angle which a magnetic needle, free to move in a vertical and horizontal plane, makes with a horizon- tal line passing through its point of support. INDEX-PLATE. —A circular disk divided (generally by holes bored in its face) so that a complete circumference or 360"^ may by equally divided into any number of parts, within the limits of the plate. INDICATOR — An instrument for recording the pressure in a cylinder at each point of the stroke. INDICATOR, SPEED.— A device for indicating the revo- lutions per minute of a shaft or machinery. A tachometer. INDUCTION. — The influence which a charged body or ■ magnetic field exerts on bodies near but not in contact with it. INDUCTION, ELECTROSTATIC— The charge produced when a conductor enters an electrostatic field. INDUCTION, MAGNETIC. —The magnetization in a magnetic field of any magnetizable substance. INDUCTION, SELF, CO-EFFICIENT OF.— The quan- tity of induction passing through a circuit per unit cur- rent in the circuit. INSULATION OR INSULATOR.— A non-conductor of electric current, used to prevent leakage of current. INTENSITY, PHOTOMETRIC, UNIT OF.— The light produced by the consumption in a wax candle of two grains of spermaceti wax per minute. INVOLUTE. — Curve formed by the path of a given point in a straight line when the line is rolled upon a circle. IONS. — The products of decomposition in any given elec- trolysis ; those adhering to the positive are Kathion and to the negative Anion. 571 IRON-WORK FAULT OF DYNAMO. —The short-cir- cuiting of a dynamo by improper contact between its coils and any iron. ISOCHRONISM.— Equality of the periods of vibration. ISOTHERMAL EXPANSION. — Expansion of a gas where its temperature is kept constant by supplying heat externally. JACKET. — An annular space around a cylinder. JAR, LEYDEN. — A static condenser in the form of a jar. The coatings of metal are placed on the lower exterior and interior walls, about two-thirds the depth of the jar, the rest being varnished or shellacked. It has a cork cover through which a brass rod extends making contact with its interior. The rod has a ball on top. JOINTS OF BELTS, BUTT AND LAP.— The butt joint in a belt is one in which the two ends are cut square, brought together so that they abutt directly and laced. In the lap joint the ends are overlapped and laced or riveted through. JOULE. — The practical C. G. S. unit of electrical energy or work. One joule = 10,000,000 ergs. One joule per second = i watt. JOURNAL. — The part of a shaft that runs in a bearing or journal box. K KATHODE OR CATHODE.— The terminal connected to the negative or carbon plate of an electrolytic cell. KEY, DISCHARGE AND CHARGE.— A key by the use of which the discharge from a condenser is passed through a galvanometer for measurement. KILODYNE.— One thousand dynes. KILOGRAMME. — One thousand grammes. About 21-5 pounds avoirdupois. KINETICS, ELECTRO.— Electric currrents, or electricity in motion, in contradistinction with electrostatics, or elec- tricity at rest. KNURLING OR MILLING TOOL.— A tool to form in- ^ dentations or corrugations upon the surfaces of metal pa-rts so that the hand may grip the part more securely. tl^ LAG, ANGLE OF.— The angle describing the shifting of the magnetic axis of the armature core of a dynamo, caused by the resistance of the core to the sudden revers- als of magnetism. LAG, MAGNETIC— The viscosity of iron or steel, which renders it slow to take up and part with magnetism. This sluggishness is one of the causes necessitating **lead" of the brushes. LAMP, INCANDESCENT, STRAIGHT-FILAMENT.— Lamp with a straight filament, rendered luminous by high frequency electrostatic waves. It is the invention of Tesla. LAMP, INCANDESCENT, THREE-FILAMENT.— An incandescent lamp provided withe three filaments and three leacling-ii? wires connected thereto. It is used on three-phase circuits. LANTERN. — A form of gear of early practice in which rungs are employed in place of teeth. LAP. — Projection of the valve beyond the ports when in mid-position. LATENT HEAT. — Heat which is used up in changing the molecular condition of a body without changing its tem- perature, as in changing ice at 32 degrees to water at 32 degrees, and water at 212 degrees to steam at 212 degrees Fahrenheit. LAW OF JACOBL— The work of an electric motor is at its maximum when the counter e. m. f. is equal to half the e. m. f . expended on the motor, or the impressed e. m. f. LAW OF JOULE. — A current heating power is propor- tional to the product of the square of the current strength and the resistance. LAW OF OHM.— The funda^nental law of the relations between current, e. m. f . and resistance in an electric cir- cuit, or the law of current strength. The strength of a continuous current is directly proportional to the e. m. f. in the circuit, and inversely proportion to the resistance in it, or the e. m. f . divided by the resistance, The alge- braic expression for Ohm's law is C (current) _ E (electromotive force)^ ^^ ^^^ ^^ .^ ^^^ R (resistance) of the other two factors, we have: E = C R, or C X R; and for a similar expression for R, we have, R=« — -. 573 LAW OF VOLTA.— A law for the e. m. f. between dissi- milar metals in an electro chemical series. It is: **The difference of potential between any two metals is equal to the sum of the differences of potential between the intervening substances in the contact series." LAWS OF COULOMB, OF ELECTROSTATIC AT- TRACTION AND REPULSION.— I. The attractions and repulsions between two bodies electrified are in in- verse ratio of the square of their distance. 2. The force of attraction or repulsion between two electrified bodies is directly as the product of the quantities of electricity they are charged with, the distance remaining the same. LAWS OF FARADAY.— Laws expressing the effects of electrolysis. LAWS OF JOULE.— Laws for the development of heat in electric circuits. LAWS, LENZ'S. — The rules for determining the directions of currents produced by electro-dynamic induction for- mulated by Lenz. LEG. — A wire used on a telephone switchboard for placing one subscriber in circuit with two or more telephones. LIGHTING, ELECTRIC, BY HIGH FREQUENCY.— A system invented by Tesla, in which rods of carbon or other refractory substances are placed in an electrostatic field rapidly alternating, and raised to incandescence. LINE-SHAFT. — Shaft that receives motion directly from an engine or other motor, and transmits it to various points. LINES, KAPP. — Proposed as a unit for lines of magnetic force, I Kapp line to equal 6,000 C. G. S. units. LINES, VORTEX-STREAM.— Lines whick extend in the direction of the motion of the particles of a fluid. LINK. — The curved slotted piece to which the two eccen- tric rods are attached on a reversing engine. LIQUID, ELECTROPOION. — A liquid for a battery, composed as follows: 2^ pounds of sulphuric acid are placed in 10 pounds of water, in which I pound of bicro- mate of potash is dissolved. LOAD, LIQUID. — Resistance, or load, made by placing the terminals of a dynamo in water, which completes the circuit. LOG, ELECTRIC. — An electric indicator for measuring the speed of a ship. LOOP, DRIP. — A pendant or downward loop formed in electric wires immediately before entering a building to prev^it the passage of water on the wire into the building. 5/4 LUBRICATOR. — A cup arranged to feed oil to rubbing surfaces and into the steam which is being supplied to an engine. M MACHINE, DYNAMO-ELECTRIC— Device or machine by means of which mechanical power is transformed into electric by magneto electric induction, or by which electric is converted into mechanical power, the latter being called a motor. Such a machine consists, first, of a circuit of iron, made up of frame, pole pieces and an armature core which rotates between the pole pieces as close to their faces as practicable; second, coils of copper wire around the iron poles, which, when energized by an electric cur- rent, make electromagnets or fields of the poles and cause a magnetic circuit to flow through the poles and armature core; third, coils of copper wdre wound around the armature core, which, on being rotated, cut the mag- netic lines of force and develop electromotive force; fourth, a collecting device connected with the armature, called a commutator in direct current machines; fifth, brushes of copper or carbon resting on this collecting cylinder which carry off the current generated. MACHINE, DYNAMO, ALTERNATING CURRENT. — A dynamo which produces alternating currents for work. It is an ordinary dynamo the currents from which are not commuted or made to flow in one direction by means of a commutator. The field are usually separately excited, as a direct current is required for their excitation. MACHINE, DYNAMO, OUTPUT OF. —The current generated in and put out by a dynamo, measured in watts, or kilowatts. MACHINE, DYNAMO, SEPARATELY-EXCITED.— A dynamo w^hose field coils receive current for their excita- tion from some source other than its own armature. They are usually alternating current dynamos. MACHINE, DYNAMO, SHUNT.— A dynamo in which part of the current goes through the fields to excite them. There are two leads from the brushes, one to the fields and one to the outside circuit. The fields are wound in shunt with the outside circuit. A shunt and separately- excited dynam.o is compound-wound, one field coil receiv- ing curreet from the armature, the other from a separate source. 575 MAGHINE, ELECTROSTATIC INDUCTION. A ma- chine having a rapidly rotating disc of electric substance. A small charge is greatly increased by its inductive ac- tion on the disc. MACHINE, MAGNETO-ELECTRIC— A machine simi- lar to a dynamo, except that the fields are permanent magnets instead of electro-magnets. MACHINE, TOEPPLER, HOLTZ.— A changed form of the electrostatic induction machine devised by Holtz. MAGNET, COMPENSATING.— A magnet placed above a magnetic needle, usually of a galvanometer, so as to counteract the action on said needle of the metal in that vicinity. MAGNET, CONTROLLING.— A magnet which has con- trol over a certain action : as one attached to a galvano- meter to regulate the directive tendency of the magnetic needle. MAGNET, ELECTRO.— Magnetizable material, usually soft iron, magnetized by surrounding with a coil or. insu- lated wire through which a current of electricity is passed. The wire is called the helix and the iron the core. The electro-magnet loses its magnetism upon the cessation of the magnetizing current. MAGNET, FIELD. — A magnet employed to produce the field in dynamo-electric machines. MAGNET, RELAY.— A magnet used in telegraphy to cause a local battery to act at the receiving station. Its coils are connected to the main line. MAGNET, TABULAR. —Iron-clad horseshoe magnet in which a tube is employed, to increase its liftingpower. MAGNETISM, AMPERE'S THEORY OF. —A theory advanced by Ampere accounting for the phenomena of magnetism. It assumes the presence of currents in the atoms of matter. MAGNETISM, ANIMAL. — Sometimes applied to mes- merism, hypnotism and similar manifestations of occult power. MAGNETISM, EWING'S THEORY OF.— A hypothesis to account for magnetism, advanced by Prof. Ewing. MAGNETISM, RESIDUAL. — Magnetism remaining in magnetizable material after it is removed from a magnet- izing field is residual magnetism, but the term is restricted to that which remains in soft iron cores of electromagnets after the circuit is broken. 57& MAGNETISM, TERRESTRIAL.— Magnetism of the earth. MAGNETITE. — That which, when magnetized, forms lodestone. Magnetic oxide of iron. MAGNETIZATION.— Causing material to partake of mag- netic properties. MAGNETIZATION, CO-EFFICIENT OF. — A number that represents the strength or intensity of magnetization divided by the magnetizing force H. MAGNETIZATION, INTENSITY OF.— The amount of magnetism present in a magnetizable substance, expressed in magnetic lines of force. MAGNETOMETER.— A form of reflecting galvanometer, used particularly for measuring the intensity of the earth's field. MAIN, ELECTRIC. — The most important conductor in any electric distributive system, either of lighting or power. MANDREL. — A bar, or arbor, usually round, which is driven into work, or on which work is driven, for revolv- ing it in a lathe. MANGLE-WHEEL.— A gear wheel, the teeth of which are arranged so that the wheel moves back and forth without making a complete revolution. MANOMETER. — An apparatus used in ascertaining the tension of gases, either in atmospheres or inches of mer- cury. There are two kinds: mercurial and metallic. MASS, UNIT OF. — One cubic centimeter of water at 39 degrees F. is the C. G. S. unit of mass. MATCHER OR MATCHING-MACHINE, — A machine which cuts a groove on one edge of a board and a tongue on the other edge. MATERIALS, INSULATING. — Substances, usually sol- ids, such as rubber, fiber, mica, etc., which, on account of their high non-conducting properties ase used to insu- late electric conductors to prevent leakage. MECHANICAL, EQUIVALENT OF HEAT.— Number of units of work which, by means of friction or other- wise, will produce one unit of heat. 772 foot-pounds of work are equivalent to one unit of heat. MEDIUM, ELECTRO-MAGNETIC— The universal or luminiferous ether through which electro-magnetic waves are propagated. MEG OR MEGA. — Used as a prefix to mean i,ooo.cxXJ times; as, megadyne, 1,000,000 dynes. 577 MERCURY-GAUGE. — A gauge for measuring pressure of gases by balancing this pressure by a column of mercury in a tube. MERIDIAN, MAGNETIC.— The magnetic meridian may be regarded as the vertical plane in which a freely sus- pended magnetic needle comes to rest in the earth's mag- netic field. METALLURGY, ELECTRO.— The science of electrical reduction or treatment of metals. METER, ELECTRIC. — An instrument for measuring the quantity (or amperes), or the pressure (or voltage) of an electric current. METRE-MILLIMETRE.— A unit of length for resistances, having a cross-section of one square millimetre and a length of one metre. It may be of any material. MICRO. — One millionth part, as microvolt, one millionth part of a volt. MICROMETER.— A small tool, finely graduated, for meas- uring with accuracy small distances, usually in thou- sandths or ten-thousandths of an inch. MICROPHONE. — A device for multiplying the vibrations of sound waves, so as to render a faint or distant sound audible. Used in telephony as transmitters. MICROTASIMETER.— A device for indicating minute at- mospheric changes of temperature and moisture. MIL. — A unit of length used in measuring the diameter of wires. It is one-thousandth (.001) part of a lineal inch. MILE, STANDARD. — A standard of resistance employed by Matthiessen. It is I mile of copper wire 1-16 inch in diameter at 15.5 degrees C. MILLI-CALORIE.— The small calorie. Amoimt of heat necessary to raise one gramme of water from zero to I degree C. MILLING-MACHINE. — A machine in which revolving cutters are used to cut, shape and dress metal. MITER-JOINT.— A joint whose angle to the plane of the piece it joins is 45 degrees. MOTOR, ELECTRIC. — A machine for converting electri- cal into mechanical energy, by passing an electric current through it. The discovery that the armature of a dyna- mo will rotate when a current is passed through it, was one of the most important in electrical science. MOTOR, ELECTRIC, ALTERNATING-CURRENT.— An electric motor operated by an alternating current o^ 578 electricity. There are two kinds: one being an ordinary alternating current dynamo reversed, the other Tesla's or Thomson's. MOTOR, PYROMAGNETIC. — A motor operated by py- romagnetism, or the heating of metals, which, when sub- jected to heat, lose while heated their property of being magnetizable. MOTOR, SERIES. — A motor wound like a series dynamo, with fields and armature connected in series with the external circuit. MUD-DRUM.— A drum placed at the lowest part, gener- ally of water tube boilers, to catch sediment, etc. MULTIPLE-DRILLING MACHINE.— A drilling machine which may carry more than one drilling tool, so that holes of various sizes may be drilled in one piece, with- out changing drills. N NEEDLE, MAGNETIC— A bar magnet in the form of a needle freely poised so as to permit its magnetic axis to be placed in the magnetic meridian. It is usually poised in the center, on a jewel pivot. Those which move in a horizontal plane are called mariner's, while those which move in a vertical plane are called dip needles. NEEDLE, MAGNETIC, DECLINATION OF. —The declination or movement of the magnetic needle from the North pole. Its movement is either east or west. NEEDLE, MAGNETIC, DIPPING OF. —A magnetic needle which moves only in a vertical plane. It is used to ascertain the magnetic inclination, or angle of dip. NON-CONDUCTORS.— Materials which offer such high resistance to the passage of electricity that it will take some other path of less resistance. They are used as insulators of electric conductors. Rubber, gutta-percha, mica and fibre possess high non-conductive properties. NUMBER, DIACRITICAL.— The number of ampere turns required to give an iron core half its magnetic saturation. O ODONTOGRAPH.— A device used in designing the teetb of gear wheels. OHM. — ^The practical unit of electrical resistance. A re- sistance through which an electric current of one ampere, 579 or of one coulomb per second, will flow, under a pressure of one volt. OHM, BOARD OF TRADE (ENGLISH).— The resistance of a column of mercury, 106.3 centimetres in length, having an area of cross-section of one square millimetre at o degrees C. OHM, BRITISH ASSOCIATION. — The resistance of a cplumn of mercury, 104.9 centimetres in length, having an area of cross-section of one square millimetre, a o degrees C. OHM, LEGAL. — The resistance of a column of mercury 106 centimetres in length, having a area of cross sec- tion of one square milimetre, at o degrees O or 32 degrees F. Thie is now the international value of the ohm. OLIVER. — A blacksmith's foot-power hammer, used for forging bolts and nuts. OSMOSE, ELECTRIC— A difference in the level of liquids, caused by osmotic action. It takes place when two liquids are separated by a porous diaphragm, and a strong current is caused to flow through the liquid on one side of the diaphragm, into the liquid on the other, the latter rising in level. PANTELEGRAPHY.-— A system of fac-simile telegraphy for transmitting diagrams, charts, etc. PARAMAGNETIC. — Possessing magnetic properties, hav- ing high permeability for lines of force: opposed to dia- magnetic. Iron is most paramagnetic; nickel, cobalt, manganese and platinum also have these properties. If a bar of paramagnetic substance is suspended near its center and placed in a magnetic field, the longer axis will place itself parallel with the magnetic field, as a piece of wood so suspended in a rapid stream of water would place its longer end parallel to the direction of the current. PEN, ELECTRIC. — A stylus with a needle oscillated very rapidly within, by means of an electric current, with which a paper is perforated is such a manner as to be used as a stencil for printing a number of copies. PERMANENCY, ELECTRIC. —The power of electric conductors to retain their conductive properties imchanged regardless of the passing of time. 5«o PERMEABILITY, MAGNETIC.-The degree to which any substance is permeable to lines of magnetic force; its contuctibility of such lines; its property of being the agent of magnetic induction. The permeability of a material, such as a soft iron core, decrease with the rise of the magnetizing force, or, as the saturation increases. PHONAUTOGRAPH.— An apparatus, working automatic- ally, for the reproduction and registration in visible mark- ings of the vibrations of sound waves. PHONOZENOGRAPH. — An apparatus for indicating whence a distant sound issues. A microphone, telephone and Wheatstone bridge, connected together, are necessary to operate it. PHOTOMETER.— Apparatus for the measurement of light given out by any illuminating power or luminous body in standard candle power. PHOTOPHORE, TROUVE'S.— An instrument containing a small incandescent light. Used by physicians in medi- cal examinations in cavities of the body. PHOTO-TELEGRAPHY.— The reproduction, at a dis- tance, of writing, drawings, pictures, etc., by means of electricity. The most successful is that of Amstutz. PILLOW-BLOCK (sometimes called Pillar of Plumber's- block)— A pillow or bed that forms the bearing for a shaft, and is made fast to a frame or bed, as the pillow- block of an engine. PINION. — The smaller of a pair of wheels or train of gears. PISTON.— A piece, disc-shaped, that closely fits a cylinder bore, as an engine piston, which receives the thrust or pressure of the steam, and is caused to reciprocate. PITCH-CIRCLES. — The circle in a gear wheel considered its diameter for measurements of speed, etc.; it passes through the point in the tooth where the face meets the flank. PLANE, PROOF.— A small conductor for the purpose of collecting electricity from bodies charged electrostatically, and of which the measurement is then taken. PLATE, NEGATIVE. OF ELECTRIC CELL.— The negative element or kathode of a battery. In a storage battery, the plate connected with the negative terminal of the source of charge. In a voltaic cell, the carbon element, which is not attacked by the electrolyte. PLATE, POSITIVE, OF ELECTRIC CELL.—The posi- tive element or anode of a battery. In a storage battery SSI the plate connected with the positive terminal of the source of charge. In a voltaic cell, the zinc element, which is attacked by the electrolyte. PLOW. — ^The connection from the motor to the current conductor, in underground system of distribution for an electric railway. It corresponds to the trolley. PLUG, SAFETY.— A bar, wire or plate of fusible metal, which allows a normal passage of electricity, but which fuses, thus breaking the circuit, when an abnormal amount tries to pass. PLUM-LEVEL. — A tool for determining whether a surface or line is horizontal, consisting principally of a plumb- bob and straight edge. PLUNGER. — A large cylindrical piston-rod used to cause a displacement in a cylinder by it size alone. POLARITY, MAGNETIC— When iron or other magnet- izable substance enters a magnetic field it acquires polar- ity, the South pole being the end at which the magnetic lines enter and from which they flow, and the North pole being the end from which they immerge and toward which they flow. POLE, NEGATIVE.— The pole or terminal of a battery or dynamo by which the current returns to the generator after flowing through the external circuit. Careful dis- tinction must be made between the positive and negative poles and the positive and negative plates of a voltaic cell. A terminal connected with a positive plate of an electric source (anode) is negative, and the one connected with the negative plate (kathode), is positive. The term **poles" as properly applied to an electric circuit signifies the free ends of a break in such a circuit. When applied to the binding posts of a voltaic cell, the fact should be fixed in the mind that the end which extends down into the electrolyte is the opposite. The negative pole is con- nected to the positive plate, and the positive pole to the negative plate. In storage batteries this is reversed. POTENTIAL, UNIT OF ELECTRIC— The erg. The difference of potential existing between two points which renders necessary the expenditure of one erg of work to force one unit of electricity over the distance between those points, is the the unit difference of potential. POTEN ITOME TER. — A device somewhat on the principle of a Wheatstone bridge for measuring the electromotive torce of a battery. A known resistance is placed in opposi- 582 tion to the difference of potential to be determined, the equality or inequality being shown by the deflection ot galvanometer needles. POWER, CANDLE.— One candle power is the light given out by one standard candle, which is the burning of two grains of sperm candle per minute. POWER, HORSE, ELECTRIC. — A rate of doing work equivalent to 746 watts per second. PYROMETER. — A device for measuring temperatures above the range of the ordinary thermometer, ordinarily operated by the expansion of a metal. In Siemens', a platinum wire is exposed to the heat tc be measured, its resistance determining the temperature. R RAILROAD, ELECTRIC, DEPENDENT SYSTEM. — The current is conductd from the generating station along bare wires above or below the cars and taken off and carried to the motors by means of rolling or sliding contacts. There are three kinds: the overhead, the un- derground and the surface. In the overhead system the wires are strung directly above the track; in the under- ground system they are placed in a conduit with an open slot between the rails in which slides the arm which car- ries off the current; in the surface system, the wire is con- ducted along the surface of the roadbed and the current taken off by a properly arranged contact. RAILROAD, ELECTRIC, INDEPENDENT. —A rail- road in which the motive power is supplied by primary or storage batteries placed in each car, so that each is inde- pendent of the others or of any source of energy other than its own. RE-EVAPORATION. — The evaporation of any water there may be in a cylinder after the steam is cut off by the heat in the side of the cylinder and piston as the pressure falls. REFINING OF METALS, ELECTRIC. —The electro- lytic refining of metals. RELAY. — An instrument at the receiving end of a tele- graph line, by means of which a local circuit is opened and closed. The impulse which operates the relay may be too weak to operate the receiver, but the local circr' may be of any strength. §83 KELUCTANCE, MAGNETIC— A term synonymous with magnetic resistance. The total number of lines or mag- ,. n Magnetomotive Force netic flux = — 5 ■ . Magnetic Reluctance RESISTANCE.— The quality of a conductor of electricity in virtue of which it resists the passage through it of an electric current. To overcome this opposition requires electromotive force. The e. m. f. is converted into heat energy. Resistances are placed in circuits to cut down the e. m. f . or the current. RESISTANCE UNIT.— Conductor or part thereof through which unit current is obtained by unit e. m. f . Jacobi's is the resistance of 25 ft. of copper wire weighing 345 grains. REVERSIBILITY OF DYNAMO OR MOTOR.— The ability of a dynamo to run as a 'motor when supplied with current, or of a motor to run as a dynamo when driven by mechanical power. R.HEOSTAT. — An adjustable resistance; applied usually to a resistance easily varied without opening the circuit, the varying values being known. ROUTING-MACHINE.— A machine in which a revolving cutter cuts away parts of a surface and leaves other parts in relief; used by engravers particularly. SATURATION, MAGNETIC. —Magnetic substance the intensity of magnetization of which has reached its max- imum. The development of the largest possible number of lines of force in the core of an electromagnet. SCREEN, MAGNETIC— An iron box or circuit of wire placed over or around a magnet, or other device, to pre- vent magnetic induction from taking place, or to screen it from external magnetism. SCRIBING-BLOCK.— A tool, often called a surface gauge, for marking on work the size it is to be when finished. SECOHM. — A ternTji sometime used instead of henry, the practical unit of self-induction. SERIES, THERMO-ELECTRIC— A series of metals ar- ranged with reference to their thermo-electric properties, so that each is electro-positive to any other following it. SHELL. — The external casing, especially of a steam boiler. SHELLAC (often spelled Shellack). — A solution applied with a brush, for an insulation and a dialectric; com- posed largely of resin. SHELL-REAMER.— A reamer that fits a mandrel; usually coned. SHUNT. — A connection in parallel with a portion of an electric circuit. An additional path for current. Used also as a verb. SIDE-CHISEL. — A chisel shaped properly for cutting the walls or sides of keyway slots. SIDE-TOOL. — A tool for cutting the ends of pieces while being held between the centers of a lathe. SOLENOID. — An electro-magnetic helix, or cylindrical coil of wire, with a soft iron core. Such an electro- magnet differs from the ordinary, the core being movable, its movements being dependent on the intensity of mag- netization. SOUNDER. — An instrument, used in telegraphy, consist- ing of an electro-magnet acting on a movable lever. It is operated by a relay. SPECIFIC HEAT OF A SUBSTANCE. — The ratio of the amount of heat necessary to raise a given weight of a substance one degree in temperature, compared to the amount of heat required to raise the same weight of water one degree. SPIRAL CUTTER. — A milling cutter whose teeth are cut spirally instead of parallel to the axis of the bore. SPIRIT LEVEL. — Tool for leveling which employs a bubble in alcohol, held in a slightly curved glass tube, secured iu a frame, to indicate a perfectly horizontal position. SPUR WHEEL. — A gear wheel whose pitch surface is a cylinder. STATICS, ELECTRO. — ^The science of electric charges. STEAM-CHEST. — The chest or box into which steam is admitted before entering the cylinder. STEAM-GAUGE. — Instrument showing the steam pressure. STEAM, SATURED.— Steam which is made in contact, or is in contact, with water so that there is no heat in it except the heat of evaporation. STEAM, SUPERHEATED.— Steam heated away from the presence of water, thus containing more heat than that of evaporation. STEAM, WET. — Steam containing free particles of water. 585 SUPER-HEATER. ^A sort of secondary boiler, generally placed between the main boiler and chimney through which the steam passes being thus superheated. SUPPLY, UNIT OF ELECTRIC— A unit adopted by the English Board of Trade, equal to looo amperes for one hour, under pressure of one volt, looo watt-hours, or 1.34 horse power for one hour. SWITCH. — An apparatus by which circuits are opened and closed. SYNCHRONISM.— The rhythmatic or silmultaneous oc- currence of vibrations, pulsations, etc. It is the principle on which the action of certain electrical devices depends. SYSTEM, THREE-WIRE.— A system invented by Edison, for the distribution of electric current for constant poten- tial service, in which three wires are used instead of two, one being a neutral wire. Two dynamos are employed. TAILINGS. — Errors in the record in automatic telegraphy, due to retardation, or to current flowing after the circuit is broken. TAPE, INSULATING.— A ribbon in the preparation of which some insulating material is used. It is for winding joints and other exposed places. Rubber tape is used largely. TREE OR T. — Pipe fitting with two branches at right angles. TELEGRAPHY, AUTOMATIC— A system by which a perforated sheet, representing dots and dashes, is caused to automatically transmit the characters represented. TELEGRAPHY, DUPLEX.— The simultaneous transmis- mission of two messages over one wire in the same direc- tion. Gray's harmonic multiple system is for sending musical notes of various pitch over one wire. For each tone a separate message is transmitted. TELEPHONE. — A device or combination of devices, for the electric transmission of sounds, especially articulate speech. TEMPER.— The degree of hardness of steel. It is first heated, then plunged into a cooling bath. Each variety of steel and work requires a different temper. THERAPEUTICS, ELECTRO, or ELECTRO-THER- APY. — The use of electricity in the curing of diseases. 586 THERMOSTAT. — An instrument operated by the expan- sion of a body by heat, which opens or closes a circuit, thus automatically maintaining a certain temperature. THERMAL-UNIT. — Amount of heat necessary to raise a pound of water from 39.1 to 40. I degrees F. THROW-LINE. — The line described by a part actuated by an eccentric. TORQUE. — Turning movement of the force exerted on a dynamo armature to rotate it. Torsion around an axis. TRACTION, MAGNETIC— The force which tends to keep a magnet in contact with its armature. Must not be confused with magnetic attraction. TRANSFORMER.— An induction coil used in systems of lighting by alternating current to transform or convert high initial electromotive force to low initial electromotive force such as can be conveniently and safely used for commercial work, or the reverse. The transformer is employed because high voltage currents are transmitted more economically than those of low voltage. TRANSMITTER, CARBON.— The carbon button trans- mitter in a telephone. TRIP-HAMMER. — Hammer w^hose helve btam is tripped by a cam. It is used mostly in forging. TROLLEY. — A grooved wheel moving on the overhead conductor of electric railway lines, and receiving from it the current to operate the motor and move the car. TRUNDLE. — A gear-wheel whose engaging surfaces are rungs instead of teeth, as in a lantern. TUBES, GEISSLER, GLASS VACUUM. —Tubes of a great variety of forms used to illustrate the luminous effects of electric discharges through gases. TURN, AMPERE. — The passage of one ampere around a circle, once. A single turn of wire in a coil through which but one ampere passes, sometimes called ampere- winding. The ampere- turns in a coil determine the magneto-motive force of the magnet. TUYERE. — Nozzle through which air is forced into a cupo- la, or an ordinary blacksmith's fire, operated with bellows. TWIN-MILLS. — Milling cutters with teeth on their side faces and circumferences. They are operated in pairs. I 587 u UNIT, ABSOLUTE. —A unit based upon the centimetre, gramme and second. UNITS, PRACTICAL.— The volt, ohm, ampere, coulomb, watt and other units. These are multiples of C. G. S. units absolute, which are too small for convenient use. U. S. STANDARD.— A V-shaped thread with a flat sur- face at the top and bottom. V VACUUM, ABSOLUTE.— A space containing no material substance. The existence of such a space is doubtful. VALVE-STEM. — The rod connecting the valve with me- chanism outside the steam chest. VIBRATION, PERIOD OF.— The time required for an oscillating body to make a vibration. VIBRATION, SYMPATHETIC. — Vibration caused in a body by the placing of a vibrating body in its immediate vicinity: as a tuning fork made to sound by placing a vibrating fork near it. VOLT. — The practical unit of electrical pressure, or elec- tromotive force. The pressure required to move one ampere against a resistance of one ohm. The electro- motive force induced in a conductor, usually an armature coil, which is cutting one hundred million magnetic lines (of force) per second. VOLTMETER. — An instrument for direct reading on a scale the volts or electromotive force in a circuit, or the difference of potential between any two points thereof. They are connected on a shunt to the circle, or in parallel. W WALKING-BEAM. — The oscillating beam in the engine of that name to which are attached the connecting rod to the piston on one end, and the connecting rod to the crank on the other. WATT. — The unit of electric activity or power equal to one joule per second or 10,000,000 ergs per second. WELDING, ELECTRIC— Welding metals by the appli- cation of electricity. This is done by passing a heavy current through the point of junction at a low e. m. f., or by forming a voltaic arc between the parts to be welded. 5«« WINDING SERIES.— A dynamo or motor field ha\dng but one coil which is connected in series with the arma- ture and the outside circuit. WORK, ELECTRIC— The joule. One volt-coulomb or one watt for one second. WORK, UNIT OF.— A unit force acting through a unit distance gives one uni«t of work. In the C. G. S. system the unit of work is the erg equal to a force of one dyne acting through a distance of one centimetre. The prac- tical unit is the joule = 10,000,000 ergs. The British unit is the foot-pound and is equal to a force of one foot. The ratio between the two systems is: I foot-pound «= 13,563,000 ergs (about) = 1.3563 joules (about). Y-Z YOKE. — A piece that carries or secures two or more other pieces, and adjusts their distance apart. That part of a dynamo frame which connects the limbs of the field magnets. ZINC, AMALGAMATION OF.— The coating of amal- gamation of zinc plates. The amalgam is a combina- tion or alloy. The most important constituent is mercury. INDIA-RUBBER, TESTS FOR. India-rubber should not give any sign of superficial cracks on being bent to an angle of 180® after five hours' exposure in a closed air bath to a temperature of 125 ^ Cent. Rubber containing not more than 50 per cent, by weight of metallic oxides should strech to five times its length without breaking. Pure caoutchouc free from all foreign matter, except the sulphur necessary for its vulcanization, should stretch seven times its length without breaking. The extension measured immediately after rupture should not exceed over 12 per cent, of the original length of the test-piece. The test-pieces should be from 3 to 12 milli- metres wide, and not more than 6 millimetres thick and 3 centimetres long. The percentage of ash gives a certam indication of the degree of softness, and may form a basis for the choice between different qualities for certain pur- poses. Any excess of sulphur over that required for vul- canisation should be removed at the works, and should not appear on the surface of any object.