An aid to the miner, quarryman and sculptor. An actuator for pumps. Engraves glass and cleans castings. Dust and dirt removed by air exhaustion. Westinghouse air-brakes and signals 417

XXIX. CONCRETE AND ITS REINFORCEMENT

Pouring and ramming are easier and cheaper than cutting and carving. Concrete for dwellings ensures comfort and safety from fire. Strengthened with steel it builds warehouses, factories and bridges of new excellence 429

XXX. MOTIVE POWERS PRODUCED WITH NEW ECONOMY

Improvements in steam practice. Mechanical draft. Automatic stokers. Better boilers. Superheaters. Economical condensers. Steam turbines on land and sea 446

XXXI. MOTIVE POWERS, CONTINUED. HEATING SERVICES

Producer gas. Mond gas. Gas engines. Steam and gas engines compared. Diesel engine best heat motor of all. Gasoline motors. Alcohol engines. Steam and gas motors united. Heat and power production together. District steam heating. Isolated plants. Electric traction. Gas for a service of heat, light and power 457

XXXII. A FEW SOCIAL ASPECTS OF INVENTION

Why cities gain at the expense of the country. The factory system. Small shops multiplied. Subdivided labor has passed due bounds and is being modified. Tendencies against centralization and monopoly. Dwellings united for new services. Self-contained houses warmed from a center. The literature of invention and discovery as purveyed in public libraries 478

INDEX 489

LIST OF ILLUSTRATIONS

PROFESSOR ALEXANDER GRAHAM BELL Frontispiece BELL HOMESTEAD, BRANTFORD, ONTARIO facing 2 Lens of ice focussing a sunbeam 5 Rubber strip suspended plank-wise and joist-wise 7 Board doubled breadthwise and edgewise 7 Telegraph poles under compression. Wires under tension 8 Rubber cylinder, flattened by compression, lengthened by tension 9 Rubber joist compressed along top, extended along bottom 10 Girder cut from joist 10 Rubber I-beam suspended flatwise and edgewise 10 Girder contours simple, built up, in locomotive draw-bars 11 Steel ore car 12 Bulb angle column, New York Subway 12 Strap rail and stringer, Mohawk & Hudson R. R., 1830 13 PLIMMON H. DUDLEY facing 14 Dudley rails 16 Steel cross-ties and rails 17 King-post truss 18 Frames of four sides 19 Cross-section Arctic ship “Roosevelt” 20 Pair of compasses stretch a rubber strip 20 Queen-post truss 21 Upper part of roof truss, Interborough Power House, New York 21 Two queen-post trusses from a bridge 22 Palladio trusses 22 Burr Bridge, Waterford, N. Y. 23 Howe and Pratt trusses 24 Baltimore truss 25 Whipple Bridge 25 Simple cantilevers 26 Victoria Bridge, Montreal, original form 27 Victoria Bridge, Montreal, present form 28 Cantilever Bridge, near Quebec 29 Kentucky River Cantilever Bridge 30 Arch Bridge, Niagara Falls 31 Bowstring Bridge, Philadelphia 32 Williamsburg Bridge, New York City 33 Continuous Girder Bridge, Lachine, near Montreal 34 Rubber strip supported at 4 points, and at 2 points 34 Plate girder bridge 35 Lattice girder bridge, showing rivets 36 Bookshelf laden and unladen, showing camber 36 Pin connecting parts of bridge 37 Bridge rollers in section and in plan 38 Girder sections in various forms 39 Rubber cylinders solid and hollow compared in sag 40 Handle bar of bicycle in steel tubing 40 A sulky in steel tubing 41 Pneumatic hammer in steel tubing 41 Fishing rod in steel tubing 41 Bridge of steel pipe 41 Arch bridge of steel pipe 42 Spiral fire-lighter 42 Spiral weld steel tube 42 Largest stone arch in the world, Plauen, Germany 43 Church of St. Remy, Rheims, France 43 Curve of suspended chain 44 Dam across Bear Valley, California 44 Ferguson locking-bar 45 Hand-hole plates, Erie City water-tube boiler 46 Bullock cart with solid wheels 47 Ball thrust collar bearings 48 Rigid bearings for axles of automobiles 48 Hyatt helical roller bearing. Ditto supporting an axle 49 Treads and risers of stairs joined by curves 49 Corner Madison Square Garden, New York 50 Two pipes with funnel-shaped junction 50 MODEL BASIN, U. S. NAVY, WASHINGTON, D. C. facing 54 Viking Ship 56 Clipper ship “Young America” 58 Steamship Kaiser Wilhelm II 60 Cargo steamer 61 U. S. Torpedo-boat destroyer 62 Cross-sections of ships 63 Racing automobile. Wedge front and spokeless wheels 66 Bilgram skew gearing 67 Grain elevator 68 Robins conveying belt 68 Ewart detachable link belting 69 Curves of turbines 70 Steel vanes of windmill 70 Pelton water wheel and jet 71 Luxfer prism 74 Fresnel lens 74 Lamp and reflector a unit 75 Inverted arc-light 75 Sacramento perch totally reflected in aquarium 77 Diagram illustrating total reflection 78 Holophane globe, sections 79 Holophane globe, diffusing curves 80 Holophane globe, three varieties 80 Holophane globe, and Welsbach mantle 81 Wire shortened while original direction is resumed 81 Four mirrors reflect a ray in a line parallel to first path 82 Prisms for Zeiss binocular glasses 82 Sections for Zeiss binocular glasses 83 Tools for producing optical surfaces 84 Bi-focal lens for spectacles 85 Canadian box-stove 86 Canadian dumb-stove 86 Tubing for radiator 87 Gold’s electric heater 87 Stolp wired tube for automobiles 87 Corrugated boiler 88 Pipe allowing contraction or expansion 88 Carving chisels and gouges 90 Lathe cutters 90 Ratchet bit brace 90 Eskimo skin scraper 91 Double tool drill cutting boiler plate 91 Common drill compared with ring drill 92 Twist drill 93 How a tool cuts metal 94 Dacotah fire-drill 94 Lathe, with parts in detail 95 Compound slide rest 96 Blanchard lathe 96 Turret lathe, with side and top views 97 Ericsson’s Monitor 98 Iron planer 99 Iron shaper 99 Milling machine 100 Milling cutters with inserted teeth 100 Milling cutters executing curves 101 Emery wheels 102 Carborundum wheel edges 102 Rolls to reduce steel in thickness 104 Gourd-shaded vessel, Arkansas 108 Gourd and derived pottery forms 109 Pomo basket 109 Bilhoola basket 110 Bilhoola basket, a square inch of 111 A free-hand scroll: same as woven 111 Yokut basket bowl 112 Sampler on cardboard 115 Bark vessel and derived form in clay 115 Vase from tumulus, St. George, Utah 116 Wooden tray. Clay derivative 116 Shell vessel. Earthen derivative 116 Electric lamps in candle shapes 117 Notre Dame de Bonsecours, Montreal 118 NEW AMSTERDAM THEATER, NEW YORK facing 118 Cinders large and small on hearth 120 Cube subdivided into 8 cubes 121 Cube built of 27 cubes 122 Two rubber strips, varying as one and three in dimensions, compared in sag 127 Air bubbles rising in oil 128 Dvorak sound-mill 132 Beam of light deflects dust 133 DR. CARL FREIHERR AUER VON WELSBACH facing 156 Boivin burner for alcohol 157 Alcohol lamp with ventilating hood 158 Welsbach mantle 159 Tantalum lamp 160 Tungsten lamp of Dr Kuzel 160 Hewitt mercury-vapor lamp 161 SECTIONS PEARLITE AND STEEL facing 164 CLEANING CARS BY THE “VACUUM” METHOD facing 164 Open hearth furnace 165 PROFESSOR ERNST ABBE facing 182 Bliss forming die 184 Bliss process of shell making 184 Mandolin pressed in aluminium 185 Pressed seamless pitcher 185 Barrel of pressed steel 185 Range front of pressed steel 186 Pressed paint tube and cover 186 Norwegian cooker 189 Aladdin oven 190 Mayer’s floating magnets 193 Alum crystal, broken and restored 194 Marble before and after deformation by pressure 195 PROFESSOR ERNEST RUTHERFORD facing 202 PROFESSOR A. A. MICHELSON facing 214 Michelson interferometer 215 Light-wave distorted by heated air 216 Ancient Egyptian balance 219 Rueprecht balance 220 Earnshaw compensated balance wheel 223 Riefler clock 224 Photometer 227 Compass needle deflected by electric wire 230 Compass needle deflected by electric coil 231 Maxwell galvanometer 231 Weston voltmeter 232 Micrometer caliper measuring 1/1000 inch 236 Plug and ring for standard measurements 237 Two lenses as pressed together by Newton 237 Newton’s rings 238 Flat jig or guide 239 Deciduous cypress 247 Deciduous cypress, hypothetical diagram 248 Section of pipe or moor grass; of bulrush 251 Human hip joint 252 Valves of veins 252 Built-up gun 253 Achromatic prisms and lens 255 Three levers 256 Arm holding ball 256 Beaver teeth 258 Narwhal with twisted tusk 259 Lower part of warrior ants’ nest, showing dome 260 Wasp using pebble as hammer 260 Cuban firefly 263 DR. R. S. WOODWARD facing 276 Perforated sails for ships 292 Edison phonograph 312 TELEGRAPHONE 314 and facing 314 GRAY TELAUTOGRAPH 315 and facing 318 Hussey’s mower or reaper 321 Mergenthaler linotype, justifying wedges 323 Schuckers’ double-wedge justifier 324 Two wedges partly in contact, and fully in contact 325 Polarized light shows strains in glass 327 Stop-motion 330 Dexter feeding mechanism 331 Schumann’s “Traumerei” in musical score and on Pianola roll 334 Mechanism of Pianola 335 AUTOMATIC TELEPHONE 336 and facing 336 Blenkinsop’s locomotive, 1811 345 Notes on loose cards in alphabetical order 350 Sectional bookcase, desk and drawers 351 Burke telegraphic code 353 Burke simplified telegraphic signals 354 Pupin long-distance telephony 367 Water-gauge direct and reversed 370 THOMAS ALVA EDISON facing 374 Cube-root extractor 376 Square-root extractor 377 Sturtevant ventilating and heating apparatus 380 Bicycle suspended from axle 382 Telephones receiving sound through a beam of light 395 Selenium cylinder with reflector 398 Perforated disc yielding sound from light 399 SIR HENRY BESSEMER facing 402 First Bessemer converter and ladle 406 New Ingersoll coal cutter 418 Drill steels 418 SCULPTOR AT WORK WITH PNEUMATIC CHISEL facing 418 Haeseler air-hammer 419 Rock drill used as hammer 420 Little Giant wood-boring machine 420 Water lifted by compressed air 421 Harris system of pumping by compressed air 422 Hardie nozzle for painting by compressed air 423 Vacuum renovators for carpets and upholstery 424 Injector sand-blast, Drucklieb’s 425 Vertical receiver, inter- and outer-cooler 426 Concrete silo foundation 431 Concrete silo 432 MANSION IN CONCRETE, FORT THOMAS, KENTUCKY facing 432 Wall of two-piece concrete blocks 434 Ransome bar for concrete 436 Corrugated steel bar 436 Thacher bar 436 Kahn bar 437 Hennebique armored concrete girder 437 Monier netting 437 Expanded metal diamond lath 438 Tree box in expanded steel 438 ROYAL BANK OF CANADA, HAVANA facing 438 Lock-woven wire fabric 439 Column forms for concrete, Ingalls Building, Cincinnati 440 Section of chimney, Los Angeles, Cal. 441 Coignet netting and hook 442 Section of conduit, Newark, N. J. 442 Water culvert 443 River des Pêres Bridge, Forest Park, St. Louis 444 Memorial Bridge, Washington, D. C. 444 Francis vertical turbine wheel 446 5000 HORSE-POWER ALLIS-CHALMERS STEAM ENGINE facing 448 Smoke-jack 449 POWER HOUSE, INTERBOROUGH CO., NEW YORK, exterior facing 450 Schmidt superheater 451 POWER HOUSE, INTERBOROUGH CO., NEW YORK, interior facing 452 De Laval steam turbine, sections 453 WESTINGHOUSE-PARSONS STEAM TURBINE facing 454 Combustible gas from a candle 458 Taylor gas-producer 460 Four-cycle gas engine 463 Fire syringe 467 Sturtevant fan wheel, without casing 472 Sturtevant Monogram exhauster and solid base heater 473 NEW YORK CENTRAL R. R. ELECTRIC LOCOMOTIVE WITH FIVE-CAR TRAIN facing 476