None
counterfeit presentment of the features of so remark- able a man, of one so worthy to be remembered among distinguished electricians and great inventors. Your disappointment cannot be greater than mine when I tell you that all my efforts to procure a portrait of the deceased inventor have been unavailing. Only this I have been able to learn as the result of numerous in- quiries; that an oil-painting of him existed a few years ago in the possession of his only daughter, then resident in Manchester, whose address is now, unfortunately, unknown. But if his face must remain unknown to us, we shall none the less proudly concur in honoring the memory of one whose presence once honored this hall wherein we are met, and whose work has won for him an imperishable name. UsTDEX. AIR-GAP, effect of, in magnetic circuit, 221 effect of, on magnetic reluctance, 117, 119, 144 Andre, equalizing the pull of a mag- net, 258 Ampere, researches of, 1C Ampere turns, calculation of, 166 Arago, researches of, 16 Arc lamp mechanism, 54 Brockie-Pell, 250 Brush, 253 De Puydt, 260 Duboscq, 263 Gaiffe, 248 Giilcher, 273 Paterson and Cooper, 250, 260 Pilsen, 247 Serrin, 263 Thomson-Houston, 264 West on, 253 Armature, effect of, on permanent magnets, 200 effect of shape, 80 length and cross-section of, 196 position and form of, 197 pulled obliquely, 259 round vs. flat, 197 Aron, sheath for magnet coils, 278 Ayrton, distribution of free magnet- ism, 109 magnetic shunts, 13 Ayrton and Perry's coiled ribbon voltmeters, 255 tubular electromagnet, 254 T3 AR electromagnet, 49 J—' Barlow, magnetism of long bars, 151 Barlow's wheel, 16 Battery grouping for quickest action, 215 resistance for best effect, 78, 185 used by Sturgeon, 18 Bell (A. G.), iron-clad electromagnet, 135 Bernoulli's rule for traction, 98 Bidwell, electromagnetic pop-gun, 206 measurement of permeability, 68 Bosanquet, investigations of, 90 magneto-motive force, 12 measurement of permeability, 59,63 Brett, polarized magnets, 266 Brisson, method of winding, 184 Brockie-Pell, differential coil-and- plunger, 250 Brown and Williams, repulsion mech- anism, 273 Bruger, coils and plungers, 244 Burnett, equalizing the pull of a magnet, 2L9 /~"1 AMACHCTS electromagnet, 202 ^-^ Cancels electromagnet, 202 Cast iron, magnetization of, 56 Clark, electromagnetic tools, 277 Coil-and-plunger coil, 251 diagram of force and work of, 235 differential, 250 282 INDEX. Coil-and-plunger electromagnet, 50, 222, 228, 242, 244 modifications of, 250 Coil moved in permanent magnetic field, 270 Coils, effect of position. 192 effect of size, 191 how connected for quickest ac- tion, 213 Coned plungers, effect of, 246 Cook's experiments, 38 Cores, effect of shape, 80 determination of length, 154 effect of shape of section, 193 hollow versus solid, 78 lamination of, 207, 213 of different thicknesses, 243 of irregular shapes, 248 proper length of, 94, 118 square versus round, 78 tubular, 158 Coulomb, law of inverse squares, 111 two magnet ic fluids, 9 Cowper, lamination of cores, 207 range of action, 225 Gumming, magnetic conductivity, 10 galvanometer, 16 Curves of hysteresis, 75 of magnetization and permeabil- ity, 71 T~\ 'ARSON VAL, galvanometer, 270 •*— ' Davy, mode of controlling armature, 261 Davy, researches of, 16 De La Rive, floating battery and coil, 16 magnetic circuit, 10 Deprez, electric hammer, 256 Diacritical point of magnetization, 74 Diamagnetic action, 255 Dove, magnetic circuit, 10 Dub, best position of coils, 192 cores of different thicknesses, 243 distance between poles, 194 Dub, flat vs. pointed poles, 125, 127 magnetic circuit, 10 magnetism of long bars, 152 polar extensions of core, 126 thickness of armatures, 158 Du Moncel, best position of coils, 192 club-footed electromagnet, 189 distance between poles, 194 effect of polar projections, 198 effect of position of armature, 151 electric motor, 256 electromagnetic pop-gun, 205 experiments with pole-pieces, 132 length of armatures, 158 on armatures, 197 tubular cores, 159 THLECTRIC bells, 275 •Jr^ invented by Mirand, 274 Electric indicators, 275 motors, not practicable, 225 Electromagnet, Ayrton and Perry's, 254 bar, 49, 188 Camacho's, 202 Cancels, 202 club-footed, 189 coil-and-plunger, 50, 222 coils, resistance of, 78 design of, for various uses, 9 Du Moncel's, 189 Fabre's, 135 Faulkner's, 135 first publicly described, 7, 17 for rapid working, 195 Gaiser's, 253 Guillemin's, 135 Henry's, 27 Hjorth's, 224 horseshoe, 49, 188 Hughes', 195, 267 in Bell's telephone, 135 invented in 1825, 16 iron-clad, 50, 78, 133, 135, 188 Jensen's, 191 INDEX. Electromagnet, Joule's, 39, 46 law of, 8 long vs. short limbs, 154 of Brush arc lamp, 207 Radford's, 46 Roberts', 46 RolofTs, 254 Romershausen's, 135 RuhmkorfTs, 204 Smith's, 253 Stevens and Hard}', 252 Sturgeon's, 18 Varley's, 188, 202 Wagoner's, 204 without iron, 251 Electromagnetic clutch, 273 engines, 223 inertia, 187, 208 mechanism, 222, 270 pop-gun, 205 repulsion, 208 tools, 277 vibrators, 274 Electromagnets, diminutive, 100 fallacies and facts about, 77 for alternating currents, 206 for arc lamp (see arc lamp mechanism) for lifting, 52 for maximum range of attrac- tion, 203 for maximum traction, £03 for minimum weight, 203 formulae for, 74 for quickest action, 209 for traction, 41, 52 heating of, 76 in telegraph apparatus, 207, 221 saturation of, 44 specifications of, 185 to produce rapid vibrations, 53 with iron between the windings, 208 with long versus short limbs, 79, 171, 220 Elphinstone, Lord, application of magnetic circuit in dynamo design, 12 Equalizing the pull of a magnet, 258 Ewing, curves of magnetization, 57 hysteresis, 75 maximum magnetization, 72 measurement of permeability, 59, 63 on effect of joints, 155 FABRE, iron-clad electromagnet, 135 Faraday, lines of force, 11 rotation of permanent magnet, 16 Faulkner, iron-clad electromagnet, 135 Forbes, electromagnetic brake, 272 formulae for estimation of leak- age, 144 magnetic leakage, 13 polarized apparatus, 269 Frolich, law of the electromagnet, 73 Froment s equalizer, 260 vibrating mechanism, 274 AISER'S electromagnet, 253 Galvanometer coils, 270 VJT Gauss, magnetic measurements, 113 Gloesner, polarized magnets, 266 Grove, range of action, 225 Guillemin, iron-clad electromagnet, 135 TT ACKER'S rule for traction, 98 •*"*• Hankel, magnetism of long bars, 152 Hankel, working of coil-and-plunger, 242 Heating of magnet coils, 96, 98, 173, 174, 175, 176, 183, 204, 207, 208, 257 Heaviside, magnetic reluctance, 82 Helmholtz, law regarding inter- rupted currents, 8 "284 INDEX. Henry's first experiments, 27 Hjorth's electromagnet, 224 polarized magnets, 266 Hopkinson, curves of magnetization, 65 design of dynamos, 13 maximum magnetization, 72 measurement of permeability, 59, 63 Horseshoe electromagnet, 49 Houdin's equalizer, 262 Hughes, distance between poles, 194 magnetic balance, 59 polarized magnet, 267 printing telegraph magnets, 194, 196 Hunt, range of action of electromag- nets, 224 Hysteresis, 75 viscous, 77 IRON-CLAD electromagnet, 50, 78, 133, 135 range of action, 249 Iron, magnetic qualities affected by hammering, rolling, etc., 77 maximum magnetization of, 92 permeability of. 92 permeability of, compared with air, 85, 118 the magnetic properties of , 54, 56 TENSEN'S electromagnet, 191 «J indicator, 275 Joints, effect of, on magnetic reluc- tance, 155 Joule, experiment with Sturgeon's magnet, 20 lamination of cores, 207 law of mutual attraction, 40 law of traction, 100 length of electromagnet, 94 magnetic saturation, 56 maximum magnetization, 72 Joule, maximum power of an elec- tromagnet, 11 range of action, 225 researches, 39, 81 results of traction experiments, 91 tubular cores, 158 TT^APP, design of dynamos, 13 -*•*. maximum magnetization, 72 Keeper, effect of position on tractive power, 78 effect of removing suddenly, 78, 202 Kirchhoff, measurement of permea- bility, 59 Krizik, coned and cylindrical plung- ers, 247 T- ANGDON-DAVIES' rate gover- •M nor, 275 suppression of sparking. 279 Laplace, two magnetic fluids, 9 Law of inverse squares, 13, 78, 110, 112, 226, 251 a point law, 111 apparatus to illustrate, 113, 115 defined, 111 Law of the electromagnet, 73 Law of the magnetic circuit, applied to traction, 87 as stated by Maxwell, 88 explanation of symbols, 82 Law of Helmholtz, 209 Law of traction, 71, 100, 101, 102 verified, 90 Leakage of magnetic lines, 85, 1 8, 110, 112, 129 Leakage reluctances, 148 Lemont, law of the electromagnet, 73 Lenz, magnetism of long bars, 151 Leupold, winding for range of ac- tion, 248 Lines of force, 11, 55 Lyttle's patent for winding, 184 INDEX. 285 MAGNETIC adherence, 271 balance of Prof. Hughes, 59 brake, 272 centre of gravity, 112, 113 circuit, 10,11, 12, 13,47 application of, in dynamo de- sign, 12, 13 for greatest traction, 97 formulae for, 86, 87, 101, 102 tendency to become more compact, 123, 204 various parts of, 49 conductivity, 10, 11, 83 field, action of, on small iron sphere, 255 flux, calculation of, 83, 164 gear, 271 insulation, 84 leakage, 13 calculation of, 122, 161 calculation of coefficient, 168 coefficient of, "v,11 145 due to air-gaps, 120, 144 estimation of, 144, 150, 169 measurement of, 137 [193 proportional to the surface, relation of, to pull, 139 memory, 172, 221 moments, 13, 87, 158 output of electromagnets, 185 permeability, 11, 54, 83 polarity, rule for determining, 51 pole of the earth, 113 reluctance, calculation of, £3, 95, 165 of divided iron ring, 117 of iron ring, 117 of waste and stray field, for- mulae for, 146, 150 resistance, 12, 82 saturation, 47, 56, 58 shunts, 13 Magnetism, free, 9 of long iron bars, 151 Magnetization and magnetic traction, tabular data, 89 Magnetization, calculation of, 161, 164 defined, 87 internal, 9, 54 internal distribution of, 63, 78, 138 of different materials, 57 surface, 9, 13, 48 Magnetometer, 114 Magneto-motive force, 11, 12, 81 calculation of, 82, 83 Maikoff and De Kabath, repulsion mechanism, 274 Marsh, first vibrating mechanism, 274 vibrating pendulum, 16 Maxwell, galvanometer, 270 law of the magnetic circuit stated, 88 law regarding circulation of al- ternating currents, 8 magnetic conductivity, 11 Mirand, inventor of the electric bell, 274 Mitis metal, magnetization of, 72 Moll's experiments, 22, 34 Moseley's indicator, 275 Mttller, law of the electromagnet, 73 magnetism of long bars, 152 measurement of permeability, 58 NEEF, vibrating mechanism, 274 Newton's signet ring load- stone, 100 Nickles, classification of magnets, 188 distance between limbs of horse- shoe magnet s, 158 distance between poles, 194 length of armatures, 158 magnetic brake, 272 magnetic gear, 271 traction affected by extent of polar surface, 104 tubular cores, 158 approach, 258, 263 Oersted's discovery, 16 Ohm's law, 8, 12, 26, 81, 209 286 INDEX. PAGE, electric motor, 256 sectioned coils, 256 electromagnetic engine, 223 Paine, sheath for magnets, 278 Permanent magnets contrasted with electromagnets, 199 uses of, 264 Permeability, calculation of, 163 methods of measuring, 58 Permeameter, 70 Permeance, of telegraph instrument magnets, 150 Perry, magnetic shunts, 13 Pfaff , tubular cores, 158 Plungers, coned vs. cylindrical, 247 of iron and steel, 244 Point poles, 114, 115 action of single coil on, 230 Poisson, two magnetic fluids, 9 Polar distribution of magnetic lines, 137 region, defined, 112, 113 Polarized apparatus for indicators, 276 mechanism, 264 Pole-pieces, convex versus flat, 79, 104 Dub's experiments with, 126 Du Moncel's experiments with, 132 effect of position on tractive power, 79 effect on lifting power, 78 on horseshoe magnets, 198 Poles, effect of distance between, 194 flat vs. pointed, 125, 127 Preece, self-induction in relays, 218 winding of coils, 184 IT) adford's electromagnet, 46 -*- ^ Range of action of electromag- nets, 224, 225, 248 Rate governor, 275 Reluctance, 12, 82 Repulsion mechanism, 273 Residual magnetism, 67 Resistance of electromagnet and battery, 185 of insulated wire, rule for, 176 Ritchie, magnetic circuit, 10 steel magnets, 172 Roberts1 electromagnet, 46 Robertson, galvanometer, 270 Roloff s electromagnet, 254 Romershausen, iron-clad electro : n ag- net, 135 Rowan, electromagnetic tools, 277 Rowland, analogy of magnetic and electric circuits, 12 first statement of the law of the magnetic circuit, 81 magnetic permeability, 11 maximum magnetization, 72 measurement of permeability, 59, 63 Ruhmkorff 's electromagnet, 204 O ATURATION, curve of, 153 distribution of, 138 effect of, on permeability, 118 Schweigger's multiplier, 16, 28 Sectioned coils with plunger, 256 Self-induction, effect of, 217 in telegraph magnets, 214, 218 Siemens, differential coil-and-plung- er, 250 relay, 270 Siphon recorder, 270 Smith, plunger electromagnet, 253 Sparking, suppression of, 277 Steel, magnetization of, 58 permeability of, 61 Stephenson, electric motors not practicable, 225 Stevens and Hardy, plunger electro- magnet, 252 Stowletow, measurement of permea- bility, 59 Sturgeon, biographical sketch, 17 experiments on bar magnets, 125 experiments on leakage, 122 INDEX. 287 Sturgeon, first description of electro- magnet, 7, 17 magnetic circuit, 10 polar extensions j 132 polarized apparatus, 266 portrait wanted, 27 9 tubular cores, 158 Sturgeon's apparatus lost, 20 first electromagnet, 18 first experiments, 20 Surface magnetism, 108, 109 r MIME-CONST ANT of electric cir- - cuit, 211, 213, 216, 218 Thomas, wire gauge table, 178 Thomson (Elihu), electromagnetic phenomena, 208 (J J.), on effect of joints, 155 (Sir Wm.), current meters, 255 polarized magnets, 266 range of action, 225 rule for winding electromagnets, 188 siphon recorder, 270 winding galvanometer coils, 257 Thorpe's semaphore indicator, 275 Traction, formula for, 98 in terms of weight of magnet, 98 Tractive power of magnets affected by surface contact, 135, 151 integral formula for, 89 Treve, iron wire coil, 248 Tubular coils, action of, on a unit pole, 232 attraction between, 243 winding of, 256 Two magnetic fluids, doctrine of, 9 Tyndall, range of action, 225 V ARLEY, copper sheath for mag- net coils, 27H electromagnet, 202 iron-clad electromagnet, 188 Varley, polarized magnets, 266 Vaschy, coefficients of self-induc- tion, 218 Vibrators, 274 Vincent, application of magnetic cir- cuit in dynamo design, 12 Viscous hysteresis, 77 Von Feilitzsch, plungers of iron and steel, 244 magnetism of long bars, 152 measurement of permeability, 59 tubular cores, 158 Von Koike, distribution or magnetic lines, 137 Von Waltenhofen, attraction of two tubular coils, 243 WAGENER'S electromagnet, 204 Wagner, vibrating mechan- ism, 274 Walmsley, magnetic reluctance of air, 148 Wheatstone, Henry's visit to, 38 equalizer for telegraph instru- ment, 264 oblique approach, 259 polarized apparatus, 266 Winding a magnet in sections, 256 calculation of, 95, 173, 183, 190 coils in multiple arc, 258 differential, 278 effect of, on range of action, 248 for constant pressure and for constant current, 182 iron vs. copper wire, 202 of tubular coils, 256 position of coils, 193 size of coils, 191 thick versus thin wire, 78 wire of graduated thickness, 257 Wire gauge and ampereage table, 178 Wrought iron, magnetization of, 56, . 64,65 557f>94 UNIVERSITY OF CALIFORNIA LIBRARY. 