None
Compound dynamo, 465, 467 magnets, 104 Condensation, 56 Cundenser, 56, 294, 808 capacity of, how measured, 413 dlschaixe of, 826, 515 in alternate circuit, 478, 474 liquid, 492 method of measuring a resist- ance, 411, 417 sUndard, 308 use of, 229, 802 Condensing electroscope, 79 ConducUnce, 402, 404 Conduction, 7, 80, 171, 402, 404, 476 by Uquids, 284, 404 of gases, 171, 822 Conductivity, 171, 822, 846, 848, 402, 404 Conductor cutting lines, 225, 889, 863,355 Conductors and Non-conductors, 8, 27, 30, 402 6< seq. Conductors electrified by rubbing, 18 opaque, 518 Consequent Poles, 117, 120, 882 Constant-current dynamos, 468 voltage dynamos, 467 Contact Electricity, 79, 168 Series of metals, 80 rings, 461 of surfaces, 12 Continuous-alternate transformers, 483 currents, 162 current dynamos, 468 current transformers, 482 electrophorus, 26, 49 Contraction due to magnetism, 124 Control of galvanometer, 209 Convective discharge, 312 Convexion of electricity, 49, 812, 897 currents, 397 induction machines (see In- fluence machines) streams at points, 38, 47, 274, 329 Cooking by electricity, 484 Cooling and heating of junction by current. 419 "Corkscrew Kule," 198 Cost of power derived from elec- tricity, 440 Coulomb, Torsion Balance, 18, 132 Law of Inverse Squares, 19, 129, 182, 261, 270 Cotdomb on. distribution of charge, 38,278 Coulomb, the, 162, 854 how many electrostatic units, 262 (^footnote) Couple, magnetic, 136 Coupling of alternators, 479 Creeping, stopped by par^n, 1^ magnetic. 868 CrookeSf William, on shadows in electric discharge, 821 on repulsion from negative electrode, 327 Crown of cups, 165 Cruickshank's Trough Battery, 180 Crystallization, 69 Crystals, electricity of, 74, 75 dielectric properties of, 297 magnetism of, 378 Camming, James, invents galvan- ometer, 200 thermo-electric inversion, 423 Cuneus"" discovery of Leyden jar, 60 Curbing telegraphic signals, 302 Current, effects due to, 167 Electricity, 162 strength of, 171, 190 unit of, 162, 207 Current, is the magnetic whirl, 202 balance, 396, and Appendix B sheets, 410 Currents, very lai^ge, measurement of, 412 Curvature affects sur&oe-density, 88,274 Curve-tracer, 368 Curves, magnetic (see Magnetic Figures) Curves of magnetization, 364 chai'acteristic of dynamos, 466 Cuthbertson, John, his electric machine, 41 Cycles of magnetization, 868 of alternate currents, 470 Cylinder Electrical machine, 42 Daily variations of compass, 156 Dal%bard*s lightning-roa, 829 romping galvanometers, 219 Darnell, John F., his cell, 181, 1S4 D'Arsonval. galvanometers, 216 Davy's (MarU) Battery, 198 Davy, Sir Humphry, magnetiza- tion by current 881 discovers electric light, 448 electrolyses caustic alkajies, 490(c) INDEX 613 The Numbers refer to the Numbered Paragraphs. -De Haldat, magnetic writing, 122 X>e la Rive's Floating Battery, 205 JDe la Rue, C'Moride of Silver Battery, 1S6, 818 on electrotyping, 496 on length of spark, 813 "Dead-beat galvanometers, 219 Declination, Magnetic, 151 variations of, 151,, 155 Decomposition of water, 235 of alkalies, 490 (o) T)e-electritication by flame, 814 Deflexions, method of, 131, 136 Deflexion of galvanometer, 210 Dellmann" 8 electrometer, 286 Demagnetize, how to, 368 Density (surface) of charge, 88, 278, magnetic, 134, 387 Depolarization, mechanical, ISO chemical, 180, 182, 188 electro-chemical, 180, 181 Deposition of metals, 494 Deviation of compass, 149 Dewar^ James, on currents gen- erated by light in the eye, 257 his capillary electrometer, 253 magnetic properties of iron at 200°, 111 oxygen, magnetic, 370 Dewar and Fleming, resistance at low temperature, 404 Diagram, thermo-electric, 424 Dial bridge, 415 Diamagnetic polarity, 369 Diamagnetism, 94, 369 of flames, 374 of gases, 370, 874 Diaphragm currents, 254 Dielectric capacity, 295 to 299 capacity, effect on intensity of field, 262, 298 coetticient, 283, 517 strength, 315 Dielectrics, 10, 25, 57, 295 Difference of potential, 265 magnetic potential, 337 Differential galvanometer, 217, 411 Dimensions of units, 356 Di-phase currents, 485 Dip, or Inclination, 152 variation of, 155 Diplex signalling, 503 Dipping Needle, 152 I "Direct" and "inverse" current, ' 228 Direction of Induced E.M.F., 226»46<> ' Discharge affected by magnet, 822 brush, 819, 824 by evaporation, 251 by flame, 8, 314 by points, 47, 319, 829 by water dropping, 884 conductive, 310 convective, 47, 312 disruptive, 311 effects of, 47, 815, 316, 317 glow, 319, 329 (footnote) limit of, 273 oscillatory, 515 sensitive state of, 322 striated, 820 through gas at low voltage, 322 velocitv of, 828 Discharger, Discharging-tongs, 59 Universal, 62 Disk armature, 468 Displacement, electric, 57 currents, 516 Disruption, electrification by, 68 Dissectible Levden jar, 68 Dissipation of Charge, 326 Dissociated gases conduct, 822 Distillation, electric, 251 Distributton of Electricity, 81 to 88, 273, 274 of Magnetism, 117, 184 Distribution by transformers, 480 Distribution of energy, 440 Distortion of dynamo-field, 468 Divided circuits, 409 Touch, 101 Dolbear, A. Dynamos, 461 08 motors, 448, 468 Dynamometer, 894 Dyne, the (unit offeree), 281 Earth, the, a magnet, 95 mn-ents, 8««i electrostatic capaci^ of, 808 intensity of magnetization, 865 magnetic force in absolute units, 861 used as return wire, 497 Earth's magnetism (see TerrestrkU Magnetism) Earth, potential, 269 Ehert, H., on oscillations, 522 K«l(l> -currents, 457, 477, 486 Edison, Thomas Alva, electric lamp, 452 carbon telephone, 511 meter for currents, 244, 442 quadruplex telegraphy, 508 EdlurCd on galvanic expansion, 2^ Eel, electric (Gymnotus), 76 Efficiency of transmission, 447 of dynamos, 464 of motors, 445 of transformers, 481 Electric Air-Thermometer, 817 l^age, 87 Candle, 451 Clocks, 609 Displacement, 57 Distillation, 251 Egg, the, 282, 820 Expansion, 800 Field, 18, 16, 20, 22, 24, 262, 279, 299, 524, 525 Force, 169 (footnote), 266 (Frictional) machines, 42 Fuze, 316, 429, 482 Images, 275 Kite, 829 Light, 448 Lines of Force, 18, 16, 20, 22, 24,299 MiU or Fly, 47 Oscillations, 516 Osmose, 250 Pistol, 316 Shadows, 321 Shock, 254 Stress, 18, 16, 20, 22, 24, 68, 279 Waves, 515 Wind, 47, 824 Electrics, 2 Electricity, theories of, 7, 827 word first used, 2 (footnote) Electro-capillary phenomena, 258 Electro-chemical Depoliuization, ISO equivalents, 240, 489 power of metals, 489 Electro-chemistry, 487 deposition, 494 Electrodes, 286 unpolarizable, 257 Electrodynamics, 3S9 Electrodynamometer, 394 Electrolysis, 237, 487 in discharge, 322 laws of, 240, 490 of copper sulphate, 288 of water, 236, 487 theory of, 491 Electrolytes, 236, 487 Electrolytic condenser, 492 convexion, 491 Electromagnet, alternate current, 477 Electromagnets, 107, 881 laws of, 880 calculations for, 875, 876 (and see p. 695) Electromagnetic engines (see Mo- tors) Electromagnetic systems, law oli 204, 379 system of units, 852 theory of Light, 617 waves, 515 Electromagnetics, 887 Electromagnetism, 387 Electrometallurgy, 494 Electrometer, absolute, 287 attracted-disk, 287 capillary, 263, 292 DeUmann*s, 286 PeUier's, 286, 83^ portable, 287 quadrant (Lord Kelvin* s), 288 repulsion, 286 torsion, 18 trap-door, 287 Electromotive-force, 169, 487 induced, 222 measurement of, 416 unit of, 354 Electromotive intensity, 266, 288 Electromotors, 443, 484 Electro-Optics, 524 Electrophorus, 26 continuous, 26, 49 Electroplating, 496 INDEX 616 The Numbers refer to the Numbered Paragraphs. Electroplatinjir. dynamos for, 402 Electroscopes, 14 Bennet'8 pold-leaf, 16, 28 Bohnenberger'8, 16, 291 J^echner'8, 291 Gilbert's straw-needle, 16 HankeVa, 291 Menley'8 quadrant, 17 Pith-ball, 8, 4 VoUa*8 condensing, 79 Electroscopic powders, 81, 47, 299, 824 Electrostatic Optical Stress, 025. voltmeter, 290 Electrostatics, 8, 259 Electrotypin?, 495 Element of Current, 844 Eltoell- Parker alternator, 478 End-on method, 188 Energy, 1, 64 of magnetic field, 202 of charge of Leyden jar, 806 of electric current, 486 paths, 518 points in circuit where it is lost or gained, 248, 486 supply and measurement of. Equator, Magnetic, 86 Equipotential surfaces, 267 magnetic, 887 (0 Equivalents, electro-chemical, 240 Erg, the (unit of work), 281 Ether, 1, 7, 64, 617 Evaporation produces electrification, 71,880 discharge by, 251 Everett, James i>., on atmospheric electricity, 884 on exact reading of galvan- ometer, 214 {footnote) on intensitv of magnetization of earth, '365 Etffingt James A., on limit of mag- netization, 868 curves of magnetization, 864 theory of magnetism, 127 Exchanges, telephone, 513 Excitation of Field-magnets, 465 Exciting power, 877 Expansion, electric, 800, 626 Extra-current, 459 Failitbe and exhaustion of bat- ' teries, 172 Fall of potential along a wire, 289, 412 Fnrnd. the (unit of capacity), 808, 854 Faraday, ARcIutelt molecular theory of electricity, 7 chemical theory of cell, 178 dark discharge, 819 diamagnetism, 869, 878, 374 discovered inductive capacity, 25, 296, 298 discovery of magneto-induc- tion, 222 Disk machine, 227 electromagnetic rotation, 898 experiment on dielectric po- larization, 299 gauze-bag experiment, 84 hollow-cube experiment, 84. ice-pail experiment, 87 laws of electrolysis, 240, 242 length of spark, 818 Magnetic lines-of-force, 119 magnetism in crystals, 878 on Arago's rotations, 457 on dissipation of charge, 814 on electrodynamics, 392 on identity of different kinds of electricity, 245, 246, 816 predicted retardation In ca- bles, 801 Ring, 228 rotation of plane of polarized light, 526 voltameter, 242 Faure^ Camille, his Secondary Bat- tery, 492 Favre*8 experiments on heat of currents, 428 Fechner's electroscope, 291 Feddersen, W., on electric oscilla- tions, 614 Feeders, 440 Ferromagnetic substances, 869 Field, electric, 13, 16, 20, 22, 24, 262, 2T9 299 525 magnetic, 115, 202, 887, 462, 526 Field-magnet, 462 Field-magnets, excitation of, 465 Field-plate, 5i) Figures, magnetic (see Magnetic Figures) electric, 81, 299, 824 Filament of incandescent lamps, 452 Filings for mapping fields, 121 Fire of St. Elmo, 329 {footnote) Flame, currents of, 314 diamagnetism of, 874 discharge by, 8, 814 produces erectriflcation, 70 618 ELECTRICITY AND MAGNETISM The Numbers refer to the Numbered Paragraphs. Hertz, Heinrich, kathode rays, 821 researches on electric waves, 520 HeydweUler, on length of spark, 818 Hutorf, on discharge, 822 Hiv'h frequency, 476, 615, 520 Holtz, W.i his electric machine, 58 on electric shadows, 821 un tnbes having unilateral resistance, 827 Hopkinaon, John, on dielectric ca- pacity of glass, 297 on residual charge and its return, 299 on magnetization, 864 his characteristic curves, 466 Horizontal component of magnetism, 186, 158, 861 Horse-power and watts, 485 Hot glass, a conductor, 81 Hughes J David Edward^ the Print- ing Telegraph, 497 the Microphone, 512 magnetic balance, 140 induction balance, 514 Humboldt, Alexander von, on elec- tric eels, 76 discovers galvanic smell, 264 produced electric contractions in fishes, 255 Hunter, Dr. John, on effect of cur- rent on sight, 254 Hydroelectric machine, 48 Hysteresis, 867, 868 IpiosTATio method of using volt- meter, 290 Images, electric, 276 Impedance, 472 (Impedance) coils, 474 Incandescent lamps, 452 Inclination (or Dip), 152 variation of, 155 Index Notation, 855 Inductance, 458 Induced charges of electricity, 22 currents, 222 Induction (electrostatic) of charges, (see Influence) {magnetic) lines of, 96 (magnetic) of magnetism, 96 {magneto^lectric) of cur- rents, 222 (voltaelectric) of currents by currents (see Self induc- tion, Mutual induction) Induction, the, meaning the Intern^ magnetization, 868 (foot-' note) Induction-coU or Inductorinm, 229 Indnction-convexion machines, 49 Inductive-capacity, specific, 26, 56, Inertia, electromagnetic, 468 Influence, 22 Influence-machine, 49-54 Insulators, 10, 80, 405 Intensity of current, 190 (footnote) of earth's magnetic force, 158, 858,861 of magnetic field, 888 of magnetization, 866 Internal resistance, 171, 406, 417 of armatures, 462 International ohm, 868 "Inverse" and "direct" currents, 228 Inverse Squares, Law of, 19, 129, 148, 261, 270 Inversion, Thermo-electric, 428 Ions, 289 Ironclad magnet, 888 Iron, properties of, 862 Iron rods red hot in water, 488 Isoclinic lines, 154 Isogonic lines, 154 Isolated, 271 Jablochkoff, Paul, his battery, 198 electric candle, 451 Jacobi, Moritz Hermann, on local action, 174 discovers galvanoplastic pro- cess, 495 his boat propelled by electri- city, 4^ on electromagnet, 880 theory of electromotors, 448 Jar, Leyden, 59 capacity of, 68, 294, 804 cascade arrangement of, 809 discharge of, 69, 810, 515 discovery of, 60 energy of charge of, seat of charge of, 68 spark of, 318, 828 theory of, 294 Unit, 285 INDEX 619 The Numbers refer to the Numbered Paragraphs. Jenkint Fleeming, on cable as con- denser. 801 on retardation in cables, 823 Joints in magnetic circuit, 878 Joule, James Prescott, on effects of magnetization, 124 evaluation of ohm, 858 Law of heat of current, 427, 489 limit of magnetization, 868 magnetic circuit, 875 Mechanical equivalent of heat, 489,488 on atmospheric electricity, 888 on lifting-power of electro- magnet, 884 Joule effect, 420 .loule, the, 854, 489 KAPPy OiSBBBT, on magnetic circuit, 877 Kathode, 170, 286 Kathodic " rays," 821 Ration, 239, 491 Keeper, 103 Kelvin, Lord (Sir William Thom- son) Attracted-disk Electrometer, 79, 287 Compass, 149 Current Balances, 896 Divided ring Electrometer, 79 Electric convexion of heat (Thomson eflfect), 424 Evaluation of ohm, 358 •• " **tr,"859 Modified Daniell's cell, 187 on atmospheric electricity, 888 on electric images, 275 on electrostatics, 287 {foot- note) on length of spark, 813 on nomenclature of magnetic poles, 89 {footnote) on sounds in condensers, 299 predicts electric oscillations, 515 proof of contact electricity, 79 Quadrant Electrometer, 288 Replenisher (or Mouse Mill), 49, 287, 288 Thermo-electric diagram, 424 Water-dropi»ing Collector, 334 Kerr, Dr. John, Electro-optic dis- coveries, 300, 525 Kerr, Dr. John, Magneto-optic dis- coveries, 125, 866, 527 Kerr's eflfect, 527 Kinnersley, Elijah, Electric Ther- mometer, 317 Kirchhoff, Gustav, Laws of Branched Circuits, 409 Kite, the electric, 329 KohlrautSch, Friederich, on resid- ual charge, 299 on electro-chemical equivalent, 240 on evaluation of ohm, 358 Kundtt August, his effect, 528 Lao and lead, 472 Lagging of magnetization, 868 Lamellar magnetization, 113 Laminated magnets, 104 Lamination of cores, 467, 468, 477, 480 Lamps, arc, 449 Lamps, incandescent, 452 Langley, S. P., his bolometer, 404 Law, cell, 180 Laws of electrolysis, 490 of inverse squares, 19, 129, 148, 261, 270 of electro-magnetic system, 204, 879 Lead, used in accumulators, 492 no Thomson-effect in, 424 Lead and lag, in phase, 472 Lead of brushes, 468 Leakage, magnetic, 377 photoelectric, 531 rate of electric, 326 Le Bailliff, diainagnetism, 869 LeclancM, Georges, his cell, 184 Lemonnier discovers atmospheric electricity, 333 Lenard, Philipp, aluminium " win- dow," 321 Length of spark, 818 Lenz's Law, 456 Lenz on electromagnet, 880 Ley den jar, 55 prevention of piercing spark, 62 oscillatory discharge of, 515 resonance between two, 517 seat of charge in, 63 Leydens (see Coiuiensers) Lichtenberg' s tifrures, 324 Life of Lamps, 452 Lifting-nower of magnets, 118, 114 of electromagnets, 384 620 ELECTRICITY AND MAGNETISM The Numbers refer to the Numbered ParagrapTis, Light affects reslHtance, &29 affects a magnet, 5:24 Electric, 4SJ5 Electromagnetic theory of, 1, 518 polarized, rotated by magnet, 125, »26, 527, 528 velocity of, 350, 518 Lightning, 11, 829, 881 Lightning conductors, 85, 882 duration of, 828, 881 best methods of protection fh)m, 832 Limit of heating of electromagnet, 8S6 magnetization, 868 Lines-of-force, electric, 18, 16, 20, 22, 24. 2ftS magnetic, 96, 119, 887 Line-Integral, 841 (footnote) Lippmann, O., Capillary Electro- meter, 258, 292 Liquids as conductors, 284, 490, 518 resistance of, 408, 404 Liquid condensers, 492 *' Local Action " in batteries, 178 Locomotion, electric, 446 Lodestone. S4 Lodge, Oliver, on resonance, 617 his oscillator, 521 his detector or coherer, 521 London, city of. Central Station, 478 " Long " and *' short " coils for mag- nets, 386 Long and short coil instruments, 40S Lorenz, L., on evaluation of ohm, 358 Loss of charge, 826, 681 Louis XV. Magnetism, permanent, 98 phenomenon of rotation, 526 residual, 112, 864 solenoidal, 118, 847 temporary, 98, 112 terrestrial, 95, 150 theories of, 99, 126, 526 unit of, 141, 852 Magnetite, 84 Magnetization, anomalous, 873 coefficient of (see Suscepti- bility) cycles of, 867, 863 Intensity of, 865 lamellar, 118 meclianical effects of, 124 methods of, 100-107 solenoidal, 118, 847 sound of, 124, 610 time needed for, 388 Magneto-electricity, 82, 222, 461 Magneto-electric machines, 461 Magnetographs, 160 Magnetometer, 137 self-registering, 160 Magnetomotive-force, 341, 375 Magneto-optic Rotations, 524 Magnets, see also electromagnet action of light on, 524 artificial, 85 compound, 104 forms of, 103 lamellar, 118 laminated, 104, 477 methods of making, 100-107 natural, 84, 108 power of, 114 unvarying, 110 Mance, Sir Henry, his method, 417 Manganese steel, 363 Manganin, 404 Maps, magnetic, 154 Mariner's Compass, 149 Marked pole, 88 Marum heating by discharge, 817 Mascart, E., on atmospheric elec- tricitv. 335 Matteucci, uarlo, on physiological ettects, 76, 256 on electromotive - force in muscle, 257 Maynooth Battery (see Callan*s Battery) Maxwell, James Clerk, Electro- magnetic theory of light, 897, 518 Law of alternate currents, 478 Maxwell, James Clerk, Law of electromagnetic system, 204, 849, 879 measurement of " v," 359 on Electric Images, 275 • on protection from lightning, 86,832 on residual charge of jar, 299 rule for action of current on magnet, 204, 849 Theorem of equivalent Mag- netic shell, 203, 361 Theory of Magnetism, 126 Measurement of capacity, 418 of currents, 221, 895, 412 of E.M.F., 416 of internal resistance, 417 of magnetic forces, 130 of mutual induction, 454 of permeability, 866 of power, 487 of resistance, 411, 412 of self-induction, 458 Mechanical depolarization, 180 effects of discharge, 47, 816 " of magnetization, 124 " in dielectric, 299, 525 Medical Applications of Electricity, Medium, action in, 6, 18, 279 elasticity and density of, 860 energy paths in, 519 velocity of waves, in, 869, 518 ^^ega-, 854 Megohm, 354 Meidinaer*s Battery, 187 Mellont, Macedonia, his thermo- l)ile, 425 Mendenhall, T. C, U. 8. Geodetic Survey, 155 Meridian, Magnetic, 151 Metallo-chromy, 490 Metals, electro-chemical power of, 489 electro-deposition of, 494 refining by electrici^, 494 specific resistance oi, 403 Meter Bridge, 415 Meters, 442 Metric system, the, 280 Mho, the, 402 Mica, dielectric capacity of, 296 Micro-, 354 Micro&rad, the, 283, 864 condenser, 808 Microphone, the, 612 Milli-, 854 622 ELECTRICITY AND MAGNETISM The Numbers refer to the Numbered Paragraphs. Mim-ami>ere, 8M Mimosa, tne electric behaviour of, 266 Minotto'8 ceU, 187 Mirror Galvanometer, 215 Molecular action of ma^etism, 126 actions of cmrent, 2^ theory of Electric action, 7 Moment of Couple, 136 Moment of circular coU, 846 of inertia, 861 maf?netic, 186, 861 Morse, Samuel F. B., his Telegraph instrument, 499 Morse Alphabets, the, 499a Mordey's alternator, 478 Motion, law of, in magnetic field, 204, 879 Motor-dynamos, 482 Motors, 448 alternate-current, 484 Mbulton, John Fletcher, on sensi- tive state, 322 Mouse-mill (see Replenisher) Miiller, Johannes, on strength of electromagnets, 380 Multicellular voltmeter, 290 Multiplier, Schtaeigger's, 200 Muscular contractions, 255, 267 Musschenbroek, Peter van, dis- covery of Leyden jar, 60 on Magnetic Figures, 121 Mutual induction, 464 potential, 851 Napoleon IIVs cell, 193 Navigation, electric, 443 Needle, magnetic, 87 telegraph, 498 Negative electrification, 5, 82T Network mains, 440 Neutralizing brush, 50 Newton, Sir Isaac, observations on action and reaction, 91 his lodestone, 114 suggests electric origin of lightning, 11, 829 suggests glass for electric machines, 41 Niagara Falls, transmission of power from, 447 Niaudet, Alfred, his celL 184 Nickel, 98, 364 Nohili, Leopoldo, on muscular con- tractions, 76 on currents of animal elec- tricity, 257 discovers NohilVs rings, 490 Non-conductors, 10, 405 Non-electrics, 3 North and south, 89, 150 magnetic pole, the, 89, 150 Null methods, 210, 289, 411 (c), 418, 416 (6), 417 (c), 418 {d) Oblique currents, laws of, -390 Oersted, Hans Christian, discovers magnetic action of current, 195, 196, 202 Ohm, Dr. Qeorg Simon, 190 *' Ohm's Law," 191, 899 Ohm, the, 854, and Appendix B evaluation of, 358 on, dielectric strength of, 815 One-fiuid theory of electricity, 7 Opposition method, 417 Optical strain, electrostatic, 526 rotation, electromagnetic, 526. 627 628 Oscillations, electric, 832, 615 method of (in galvanometry), 210 method of (for electrostatics), 188 (footnote) method of (for magnetic mea- surement), 188, 184, 861 Oscillator, 620, 622 Osmose, electric. 260 Other sources of electrification than friction, 12, 66 Output of dynamo, 464 Over-comnounding, 467 Overhead line for tramcars, 446 Ozone, 287, 816, 829 (footnote) PACmOTTPS armature, 463 Page, Charles O., discovers mag- netic sounds, 124 Parallel, capacities in, 807 ceUs in, 168, 406 circuits, laws of, 890 lamps in, 458 resistances in, 409 running of alternators, 479 Paramagnetic bodies, 869 " Passive " state of iron, 183 Pathological dose of current, 258 Peace, on length of spark, 818 Piclet, electrification by rubbing, 78 Peltier, Atharuise, his electrometer, 286,384 heating effect at Junctions, 420 theory of thunderstorms, 880 INDEX 623 The Numbers refer to the Numbered Paragraphs. Poltler effect, 420 Penetr«,tive power of discharge, 815 Periodic current, 470 Periodicity (see Frequency) of aurora and magnetic storms, 15S, 159, 886 Permeability, 96, 868, 518 measurement of, 866 Perry t John, his meter, 442 Persistence (see Time-constant) Phase, 470, 472 Phosphorescence caused by dis- charge, 320, 821 Photo-chemical excitation, 580 Photographic plate affected by dis- charge, 824 Photophone, 529 Photo-voltaic property of seleniom, 529 Physiological actions, 254, 825 Piercing glass, prevention of, 62 Plezo-electrlclty, 75 Plane, the proof-, 82 ". for magnetism, 282 Planti, Oaston, secondary cells, 492 globular lightning, 831 PUnts, electricitv of, 77, 256 Plate condenser, 56, 295, 304 electrical machine, 48 Platinoid, 404 PlUcker, Julius, on diamagnetism, etc., 870, 878 Poggendorff, J. C, his cell, 180 method of measuring E.M.F., 416 Points, density of charge on, 88, 274 discharge at, 42, 45, 46, 47, 274, 829 Poisson, magne-crystallic action, 878 Polarity, diamagnetic, 869 magnetic, 90, 116, 126 Polarization (electrolytic) in battery ceUs, 175, 487 of Voltameter, 487, 492 remedies for, 180 rotation of plane of, 526 et seq. Polarized mechanism, 887 relay, 501 Poles of magnets, 86, 134 of pyroelectric crystals, 74 of voltaic battery, 168 Polyphase currents, 485 Porous cell, 180 Porret's phenomenon, 250 Portable electrometer, 287 Portative force, 114 Post-Office Bridge, 415 relay, 501 Positive and negative electrification, 5, 327 Potential, electric, 40, 263 " zero, 40, 264 of conducting sphere, 269 galvanometers, 220 magnetic, 887, 847, 848 " due to current, 861 mutual, of two chxuits, 852, 857 Potential-divider nul method, 418 Potentiometer, 416 PouiUet, Claude S. Jf., sine galvan- ometer, 214 tangent galvanometer, 212 Powdered metals, conduction of, 400 sensitiveness to sparks, 521 Powders, electroscopic, 81, 47, 299, 324 Power, 485 transmission of, 447 Power-houses, 440 Poynting, John Henry, on energy- paths, 519 Practical units, 854 Preece, William Henry ^ telegraphy, 497 Pressure produces electrification, 75 efl'ect on electrolysis, 490 (voltage), 169 Priestley, Joseph, on electric ex- pansion, 800 on influence, 26 (Jbotnote) Prime conductor, 42 Printing telegraphs, 497 I'roof-plane, 82 magnetic,. 282 Protoplasm, electric property of, 256 Pyroelectricity, 74 Pyrometer, 404 Quadrant electrometer {Lord Kel- vin's), 288 electroscope (Henley's), 17 Qoadruplex telegraphy, 503 "Quantity" arrangement of cells, etc. 192 407 of electricity, unit of, 21, 262, 354 Quartz fibre, 299 Quartz, no residual charge from, 299 as insulator, 30, 299 Quetelet, E.^ on atmospheric elec- tricity, 888, 886 624 ELECTRICITY AND MAGNETISM The Numbers r^er to the Numbered Panagraphs. Quincke, Oeorg^ oo diaphragm currents, 252 on electric expansion, 800 on electro-optic phenomena, 525 Quinine, ase of» for mapping fields, 299 Radiajtt state of matter, 821 Kadio-micrometer, 425 Kate of change of cmrent, 454, 472 {footnote) Batio of electrostatic to electro- magnet units, 288, 859 Rav, electric (torpedo), 76 Rays, kathodic, 321 current balance, 896 Rayleigh, Lord^ determination of ohm, 858 Reactance, 478 Reciprocal accumulation, 4Q Recording instruments, 160, 884 Redistribution of charge, 89 Reduction of metals, 494 Reflecting galvanometer, 215 Reflexion of electric waves, 520 Refractive index, 518 Ref^stering magnetog^phs and elec- trometers, 160, 884 Reia^ Philipp, invention of tele- phone, 510 Relays, 501 Reluctance, 375 Reluctivity, 375 (footnote) Remanence, 367 Replenisher, 49, 287, 288 Repulsion and attraction of electri- fied bodies, 2, 4, 22, 24, 74, 262 and attraction, experiments on, 47 and attraction of currents, 388, 389, 894 and attraction of magnets, 84, 88 Repulsion electrometers, 286 Residual charge of Leyden jar, 61, 299 Residual charge of cable, 801 " of Voltameter, 492 magnetism, 112, 127, 867 Resinous electricity, 5 Resistance and heat, 426 Resistance, 30, 171, 400, 426 affected by temperature, 404 light, 529 " magnetism, 897 " sound, 512 Resistance, as a velocity, 857 bridge or balance, 418 coils, 414 Internal, of cell, 192, 407, 417 internal, of celL measurement of, 417 laws of, 400 xnagnetic, 875 measurement of, 4li et seq. of gases, 171, 822 of glow lamps, 452 of human body, 255 ofUquids,171, 408 of vacuum, 321 specific, 408 to alternate currents, 476 units of, 852 et sea. Resistivity, 402 Resonance, 517 Resonator, 520 Resultant magnetic force, 115 Retardation of currents through cables, 801, 823, 505 Retentivity (magnetic), 98, 867 Return shock or stroke, 29, 881 Reversal of influence machines, 53 Reversibility of processes in circuit, 248,436 Reversing-switch, 280, 498 Reymond, Du Bois, his galvan- ometer, 257 on animal electricity, 257 unpolarizable electrodes, 267 Rheostats, 400 Rheometer, 1 Rheoscope, [ 8ee footnote to 208 Rheotrope, J Rieas, Peter ^ on electric distribution, on length of spark, 818 electric thermometer, 817 Ritchie, magnetic circuit, 875 his motor, 443 Ritter, Johann Wilhelm, on action of current on sight, 254 his secondary pile, 492 on subjective galvanic sounds, 254 on the sensitive plant, 256 Rolling friction, 12, 73 Ronmgnosi, Dr., discovers magnetic action of current, 195 Romas, De, his electric kite, 829 Ronalds, Sir Francis^ invented a telegraph, 497 Rotation of plane of polarization, INDEX 625 The Nurrtbera refer to the Numbered Paragraphs. Botations, electromagnetic, 898 Arago's, 4ftT Rotatory magnetic field, '485 Koughness of surface as depolarizer, 180 Jtowland, Henry A., on magnetic eflPect of electric convexion, 897- on magnetic circuit, 875 Eiicker, Arthur William, on ration- alization of dimensions, 860 BUcker &nd Thorpe, magnetic sur- vey, 154 Ruhmkorjgf'8 electromagnet, 869 induction coil, 229 coil, mutual induction of, 454 St. Elmo's Firk, 829 (footnote) Safety-fUses, 429 Salts, electrolysis of, 288, 490 Sanderson^ J. Burdon, on electric sensitiveness of carnivorous plants, 256 Saturation, magnetic, 112, 868 et seq. Savei-y, 85 Sawdust battery, 187 Schallenhergers meter, 442 Schuckert, ammeter, 221 Schuster, Arthur, on electrolysis of gases, 322 Schweigger'8 multiplier, 200 Screening, magnetic, 96 inductive, 514 of eddy-currents, 457, 614 Secohm, 458 Secondary actions in electrolysis, 490 Secondary batteries, 492 Secular variations of magnetic ele- ments, 155 Seebeck, Thomas Johann, effect, 419 Selenium, photo-electric properties of, 529 resistance of, 403 (to&fo), 529 Self-exciting influence machine, 50 dynamo, 462 Self-induction, 458, 472 in electric discharge, 515 Self-recording instruments, 160, 884 Semaphore, Henley's, 17 Sensitive plant, behaviour of, 266 Series, arc lamps in, 450 capacities in, 808 cells in, 168, 406 dynamos, 465 resistances in, 406 28 Serrin, Victor, his lamp, 449 Shadows, electric, 47 in partial vacuum, 821 Sheet conductor, flow of electricity in, 410 SheU, magnetic, 118, 208, 860 potential due to, 848 Shieldmg, magnetic, 97 Shock, electric, 254, 825 Shunt, 215, 409 coil in arc lamps, 449 dynamo, 465 Shuttle armature, 461 Siemens, Alexander , on length of spark. 313 Siemens, Wemert on dynamos, 461 mercuiy unit, 858 electrodynamometer, 895 shuttle-wound armature, 461 heating in Leyden jar, 299 Sight affected by current, 254 Silurus, the, 76 Sine galvanometer, 214 Sine law, 476 Single-fluid colls, 180 Single-needle instrument, 498 Single touch, 100 Siphon recorder, 506 Skew-symmetry of crystals, 75 Skin effect, 476 Skin, E.M.F. in the, 257 Smee, Alfred, his Battery, 180 Smith, Frederick John, effect on photographic plate, 824 Smith, Willougnby, on selenium, 529 Soap-bubble, electrified, 4 Sodium by electrolysis, 490 Solenoid arc lamps, 449 Solenoid, 885 magnetizing force of, 841 Solid angles, 148 (Appendix A) Solidification, 69 Sound of magnetization, 124, 610 Sounder, the, 497 Sources of electricity, 12, 65 Spark, 11, 46, 47, 810 dui-ation of, 828 length of, 48, 818, 829 Sparking at commutator, 468 Specific resistance, 408 inductive capacity, 25, 66, 295, 299 Speed of motor, 444 of signalling, 801, 802, 828 ELECTRICITY AND MAGNETISM The Numbers refer to the Numbered Paragraphs. Sphere, distribation of charge over, 88, 278 «t seq. potential of, 269, 271 capacity of, 271 Bpiral shortens itself, 390 Spottiswoode, Wiuiam^ on strice, 822 Square rout of mean square, 471 Standard cells, 188 effect of temperature on, 194 Standards, 854 Steel hardening, 108 Steel, properties of, 8«2 racing, 495 Stewart, Balfour^ on atmospheric electricity, 885 on magnetic storms, 158 Storms, magnetic, 159 Straight conductor force near, 207, 848 Strain, dielectric, 64, 299, 625 Strength of current, 171, 190, 854 of current in magnetic mea- sure, 206, 207, 853 et seq. ofdielectric, 299, 811 of magnet pole, 112, 362 of magnetic shell, 848 Stress, electric, 18, 16, 20, 22, 24, 68, 279, 299, 811. 525 electric, optical effect of, 626 magnetic, 119, 840, 889 Striw in vacuum tubes, 820, 822 Sturgeon, WiUiam, his commuta- tor, 461 electro-magnets, 881 on magnetic circuit, 876 induction coil, 229 Submarine telegraphs, 504 Sucking-magnet. 885 Sulphur as depolarizer, 186 Sulphuretted hydrogen. Iron n^a- tive to copper in, 80. Sulzer'8 experiment, 264 Supply meters, 442 Surmce contact, 12 density of charge, 88, 278 limit of, 278 of magnetism, 184, 887 Surgical applications, 268 Susceptibility, 865 Suspended-coil galvanometers, 216 Swammerdam'' 8 frog experiment, 255 Swan's incandescent lamp, 452i Symmer, on two kinds of electrifica- tion, 5 Synchronizing, 479 Tait, Pbtbr Guthrie, electrifica- tion by evaporation of sul- phate of copper solution, 71 heating of iron electrode, 433 thermo-electric diagram, 424 Tangent galvanometer, 212 ofangleoflag, 478 Tapper, 498 Taste affected by current, 264 Telegraph, electric, 497 Bain's chemical, 246 Morse's instrument, 499 needle instrument, 498 Telegraphy, diplex, 608 duplex, 508 quadruplex, 508 submarine, 504 Telephone, Philipp Beis's, 510 currents of, 255 DoWear's, 299, 511 Edison's (carbon), 611 Graham Bell's (articulating), 510 Varley's (condenser), 299, 511 Exchanges, 518 Temperature affects resistance, 194, 404 affected by resistance, 426 effect on length of spu-k, 818, 814 of the arc, 448 Tempering of steel, 108 Tension, electric, 13, 16, 20, 22, 24, 68, 273 {footnote), 279, 299, 811, 525 Ter quern, A., parrot-cage experi- ment, 84 Terrestrial Magnetism, 96, 150, 861, 865 Test for weak currents (chemical), 246, 316 for weak currents (physiologi- cal), 255 Testing for feults, 502 Tetanization produced by inter- rupted currents, 256 Theories of Electricity, 7, 827, and Preface, Ix Theories of Magrnetism, 99, 126 " Ampere's, 898 " Evnng's, 127 " Maxwell's, 126 " Weber*8, 126, 127 Theory of Electrolysis, Grotthuss*s and Claus%us*s, 491 Theory of Earth's magnetism, 161 of Light, 518 INDEX 627 The Numbers refer to the Numbered Paragraphs. Thermo-electric currents, \ ^r. ..q Thermo-electricity, j **'» **^ Thermo-electric Diagram, 424 TheriAo-electromotive ISeries, 424 Thermopile, 425 Thompson, Silvanus Phillips, on magnetic figures due to cur- rents, 2(>2, 389 on positive and negative states, 827 on opacity of tourmaline, 518 Hiotnson, Joseph J., on Contact Electricity, 81 on conductivity of gases, 822 Tlwmson, Sir William (see Kelvin, Lord) effect, 424 Tliomson, Elihu^ his meter, 442 on alternate-current magnets, 477 on welding, 488 Thomson- Houston dynamos, 468, 478 Thorpe and JiUcker, magnetic sur- vey, 154 Three >vire system, 458 Thunder, 11, 881 Thunderstorms, 829 Theory of, 880 Time-constant, 460 Tinfoil Condensers, 65, 802 Tlvoli, transmission of power from, 447 Totpler, A., his Influence Machine, 51 Tongs, Discharging, 69 Torpedo (electric ftsh), 76, 246 Torpedoes, fuzes for firing, 816, 482 Torque, 186 Torque of motor, 444 Torsion affected by magnetization, 124 Torsion Balance, or ) Coulomb's, Torsion Electrometer, f 18, 182 Torsion method, 209, 210 Tourmaline, 74, 824, 518 Transformers, 228, 480 for vacuum tubes, 820 Transmission of jwwer, 447, 479 Tri-phase, 486 Trollev wheel for tramcars, 446 Th-oworidge, on magnetization at -100° C, 111 Tube of force, 887 (g) Tuning-fork method, 418 Two-fluid cells, 181 theory, 7 Two kinds of Electrification, 5, 6 Magnetic poles, 89 TyndaXl, John, dlamagnetic polarity, 872 magne-crystallic action, 878 ULTBA-GA8BOU8 MATTEB, 821 Ultra-violet waves, 818 discharge by, 531 effect on metal, 581 Unit, Board of Trade, 440, 488 Unit jar, 285 Units and standards. Board of Trade (see Appendix B) electromagnetic, 852 et seq, electrostatic, 283 et seq. fundamental and derived, 281, 282 ratio of electrostatic to electro- magnetic, 262 (footnote), 28J3, 359 Unipolar Machines, 469 Universal Discharger, 62 Unvarying magnets, 110 Upward, his ceU, 198 Ure, Dr., on animal electricity, 256 "v,'»869, 618 Vacuum, induction takes place through, 64, 96, 97 partial, spark in, 11, 820 spark will not pass through. 818, 821 tubes, 320, 821 •* Variation," the (see Declination) Variation of Declination and Dip — annual, 157 diurnal, 156 geographical, 151, 164 secular, 155 of electrification of the atmos- phere, 3;^5 Varley, Cromwell Fleetwood, his galvanometer, 316 on capacity of polarization, 492 telenaph, 497 Varley, Samtiel Alfi'ed, his tele- phone, 299, 610 early dynamo, 462 Vegetables, Electricity of, 77 carnivorous, sensittveness of. ELECTRICITY AND MAGNETISM The Numbers refer to the Numbered Paragraphs. Velocity of diiM)harge, S28 of B^ht, 859,618 of electric wares, 518 of rubbing, electrificfttioii de- pends on, 78 resistance as a, 857 Verdet'8 constant, 526 Vibration prodaoes Electrification, 67 Vibrator for measuring' capacity, 418 Villari, EmUio, eflTect of tension, 864 Violet waves (see UUra-violef) Virtual volts and amperes, 471 Vitreous electricity, 6 Volt, 169, 3M VoUa, Alessandro, his Electro- phorus, 26 Condensing Electroscope, 79 CJontact Series, 80 Crown of Cups, 165 on Atmospberic Electricity, 884 on Contact Electricity, 79, 168 on Electric Expansion, 800 on Electrification due to com- bustion, 70 Subjective Sounds due to Cur- rent, 254 VoUa's Law, 80, 168, 170 Voltaic Pile, 164 Voltaic Electricity (see Current Electricity) arc, 448 battery, 168, 178 ; pile, 164 cell, simple, 166 Voltameter, 242, 243, 244, 487 Voltmeter, 220 Cardew'8, 430 electrostatic, 290 Voss machine, 51 Walker, Charles F., used sulphur in cell, 185 Warburg, E., on hysteresis, 868 Water, Electrolysis of, 235, 487 Water-dropping, discharge by, 884 Watt, the, 854, 485 Wattmeter, 438 Watts, true and apparent, 475 Waves, electric, 515 Weber, the, 854 Wtber, ffUhelm, the Electro-dyna- mometer, 894 on diamagnetic polarity, 372 evaluation of ohm, 858 of"»,"359 theory of magnetism, 126, 127 Welding, 488 Weston, Edward, voltmeter, 220 standard cell, 188 temperature coefficient of alloys, 404 Wheatstone, Sir Charles, on the brush discharge, 819 Automatic Telegraph, 497 Dynamo - electric Machines, 462 on supposed velocity of elec- tricity, 323 Wheatstone's Bridge or Bal- ance, 413 Whirls, magnetic, 202, 889 Wiedemann, Gustav, on effect of magnetism on torsion, 124 diamagnetism, 870 {footnote) WUde, Henry, Magneto- electric Machine, 462 WUcke, A., electrophorus, 26 (foot- note) Wimshurst, James, Influence ma- chine, 52 Wind, electric, 47, 324 Winding of electromagnets, 876 et seq., 885, 886 (and see p. 596) Window, aluminum, 821 Wdhler's cell, 198 Wollaston's Battery, 180 Work bv conductor cutting lines, 339 Wroblewski, resistance of, at low temperatures, 404 ZambonTS Dry Pile, 16, 198, 291 ZaTiOtti, experiment on grass- hopper, 255 Zero potential, 40, 264 Zero of temperature, resistance near, 404 Zinc as fUel, 166 MACMILLAN & CO.'S PUBLICATIONS ON ELECTRICITY ^ MAGNETISM, BOTTONE. —A Guide to Electric Lighting. 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