None
BeccariUt Father d on atmospheric electricity, 306 BecquereL Antoine Cesar^ on atmo- spheric electricity, 307 oi^diamagnetism, 339 Becquerelf Edtnotid^ on photo- voltaic currents, 389 Becq tiered Henri, on magneto-optic rotation, 387 Bellf Alexander Graham^ his Tele- phone. 435 ^ The ' Phptophone, 38^ Bells, electric, 432 Bennefs Doubler, 23 Electroscope, 13, 25 Bertsch's Electric Machine, 45 Best grouping of cells, 351 Bichromate Battery,, 165 Bifilar Suspension, 118, 262, 336 Biotf Jean Baptiste^ Exporiment with he^ii spheres, jo Law of magnetic distribution, ^1^8 en atmospheric electricity, 307 Bismuth, diamagnetic properties of, 87, 313 339 _ Blasting by electricity, 280, 370 Blood, diamagnetism of, 339 .Boracite, 67 *' Bound" electricity, 24^^ 149 {foot- note) Boltzmann, on Dielectric capacity, 270, 271, 390 BoyUy Hpn» Robert , on electrical attraction, 2 Branched circuif, 353 Breaking a magnet, 106 Breath-figures, 297 Bridge, Wheatstone*^^ 358 British Association Unit, 323, 364, Brugtnans discovers magnetic repul- sion, of bisniufh, 339 Brush discharge, 290 Brush* s dynamo-electric machine, 41 1 Bunsen*s Battery, 172 Cable, Atlantic, 274 (Jbotnote), 275, 296, 429 submarine, 429 „ as condenser, 274, 296, 430 Cabot, iiebasimn^ on magnetic de- 'clination, 136 Cailletet on resistance of air, 291 Calibration of Galvanometer. xo8 Callan*s Battery, 172 Callauds Battery, 176' CajttoHi John^ discovers £IectrosGi]tic Induction, 18 ^ on Electric Amalgam, 4* Candle, electric, 373 Capacity, definition of, 246 measurement of, 362 of accumulator or condenser, 50, 267, 277 of conductor, 37, 47, 247, 277 of Leyden Jar, 50, 267 specific inductive, 21, 49, 268 272 unit of (electrostatic), 247 unit of (practical), 276 Capillary Electrometer, 225, 265 Carnivorous Plants, sensitive tcTelec- tricity, 230 Carrit F., Dielectric machine, 45 on magnets of cast mctaJ, 97 Cascade arrangement of Jars, 279 Cautery by electricity, 369 Cavallo Tiberius, his attempt to telegraph. 487 Coercive force, 89 Colour of spark, 28J Columbus^ C risto/erOi on magnetic variation, 136 Combustion a source of electrification, 02 Commutator, 375, 399, 407 ^ Compass (magnetic). Mariner's, 79, 134 ' .. Compound curcuit, 181 Condensation 48 Condensers, 48, 267 standard, 276 use of, 275 Condensing electrorcope, 71, 149 Conduction, 27, 158 by liquids, 205 of gases, 158 Conductivity, 158, 346, 348 Conductors and Non-conductors, 8, 27 Consequent Poles, 104, 109 Contact Electricity, 71, 149 Series of metals, 72 Continuous electrophorus, 23, 45 Convection of Electricity, 45, 337 Convection-currents, properties of, 337 Convection-induction machines, 45 Convection-streams at points, 35 (a), 43» 249 ,. Cooling and heating of junction by current, 380 Cost of power denved from electricity, 378 Coidomh^ Torsion Balance, 15, 119 Law of Inverse Squares, 16, 117, 119, 235, 245 on distribution of charge, 35, 248 Coulomb, the, 32 s Couple, magnetic, 123 Cfookea^ ll^illiam, on shadows in electric discharge, 293 on repuhion from negative electr'".ie, 300 Crown of cups, 151 Cruickahank' i Trough Batter>^ 160 Crystals, electricity of, 66 dielectric properties of, 270 magnetism of, 343 Cryotcilli nation, 61 CumtniHg s phenomenon, 382 Cuneui,' discovery of Ley den Jar, 52 Current, effect? «lue 10, 153 Current Electricity. 147 strength of, 158, 1^9 ,, unit 01, 196 Current-rev er»er (see Commutator) Current sneets, 340 Curvature aifects surface-density, 35, 249 Curves, magnetic (see Magnetic Figures) CuthbertsorCs Electric machine, 38, 289 Cylinder Electrical machine, 39 Daily variations of magnet, 14? /?a//3«n/'5 lightning-rod. 302 DanleWs Battery, 170 Davy 5 (Marie) Battery, 175 Davy, Sir Humphrey, magnetisation biy current, 326 discovers electric light, 371 electrolyses caustit alkalies, 417 w De Haldat. magnetic writing, iii De la Rive s Floating Battery, 194 DelaRue, Chloride of Silver Battery, 174, 291 on electrotyping, 420 on length of spark, 291 Declination, Magnetic, 136 variations of, 136, 141 Decomposition of water, 206, 413 of alkalies, 417 Deflections, method of, 118, 123, 325a Dellmann^s electrometer, 260 Density (surface) of charge, 35, 248 magnetic, 127, 311 Dewar, James, on currents generated by light Li the eye, 231* his capillary electrometer, 225 Diagram, thermo-electric, 383 Diamagnetic polarity, 342 Diamagnetism, 87, 339 of flames, 544 of gases, 340 Diaphragm currents, 224 Dielectric capacity (see Specific In ductive Capacity) strain, 56, 272 strength, 284 Dielectrics, 8, 49, 270 Diff"erential Galvanometer, 203 Dimensions of Units (see Units) Dip, or Inclination, 137 variation of, 141 Diplex signalling, 428 Dipping Needle, 137 Discharge atfected by magnet,^94 brush, 43 by evaporation, 223 by flame, 7, 291 conductive, 282 convective, 43, 283 disruptive, 381 INDEX. Discharge affected by points, 43, 390, 302 effects of» 43, 384, 386 electrical, 7, sSo glow, 2po, 302 ijbotnote) umit of; 248 iensitive state of, 294 velocity of, 296 31scliarger, Discharging-tongs, 51 Universal, 54 Disruption produces electrification, 60 Dissectable Leyden Jar, 55 Dissipation of Charge, 299 Distillation, electric, 225 ^ Distribution of Electricity, 28, 35, 248, 249 of Current, 240 of Magnetbm, 104, 122 Divided Circuit, 353 Touch, 93 Dolbeaf^s Telephone, 436 Doubler, 23, 45 Double Touch, 94 I>ry-Pile, 182, 264 Duboscq^s Lamp, 372 Vu Fa/s experiments, 4, 27 Duplex Telegraphy, 275, 428 I^uration of Spark, 296 ID^uier on Electric Expansion, 273 Dynamic Electricity (see Current Electricity) Dynamo-electric machine's, 408 Dyne, the (unit of force), 255 Earth, the, a magnet, 88 currents, 2^5, 403 ^ electrostatic capacity of, 325b intensity of magnetisation, 313 magnetic moment of,* 325b used as return wire, 423 Earth's magnetism {s^^'^Terresirial Magnetism) Edison, Thomas A Iva^ ^QCtriclaxti'Pf 374 ; steam-dynamo, 411 (5'" carbon telephone, 436 meter for currents, 216 quadruplex telegraphy, 428 Edlund on galvanic expansion, 221 Eel, electric (Gymnotus), 68 Electrics; z Electric Air-Thermometer, 288 Cage, 34 Candle, 373 Clocks, ^33 Distillation, 333 (Frictional) machines, 39 Electric Egg, the, 29a Expansion, 273 Force, 155 {/ootnoie\ 841 Fuze, 286, 370 Images, 2^0 Kite, 302 Lamps, 372 Light, 371 Mill or Fly, 43 Oscillations, 295 Osmose, 222 Pistol, 386 Shadows, 293 Shock, 226 Wind, 43 Electricity, theories of, 6, 300 Electro-capillary phenomena, 225 Electro-chemic^ equivalents, 211, 21 s Electro-chemistry, 412 Electrodes, 207 unpolarisable, 231 Eiectrodjmamics, 331 Elcctrody^amometer, 336,378 {his,) Electrolysis, 208 laws of, 211, 414, 417 of copper sulphate, 209 of water, 207, 413 theory of, 414 Electrolytes, 207, 417 Electrolytic convection, 4s 3 Electromagnets, 98, 326 laws of, ^30 Electromagnetic engines (motors), 375 Electromagnetics, 3x0 Electromagnetic theory of Light, 390 Electromagnetism, 326 Electrometallurgy, 419 Electrometer, absolute, 261 attracted-disc, 261 capillary, 225, 265 Dell9Hann*5f 260 divided-ring, 71 Peltier's, 260, 307 portable, 261 quadrant {Sir W, Thonisofii^x 262 repulsion, 260 torsion, 15 trap-door, 261 Electromotive-force, 155 measurement of, 360 unit of, 322, 323 Electromotors, 375 Electro-Optics, 385 Electrophorus, 22 continuous, 23, 45 Electroplating, 421 Electroscopes, 11 Bohnenbergef' s, 13* a64 INDEX. 4^9 Electroscopes, Bennefs gold-leaf, 13, 25 Fechner^s, 264 Gangain*s discharging, 259 Gilberts straw-needle, 12 HankeVsy 264 Henley s quadrant, 14 Pith-ball, 2, 3 VoltcCs condensing, 71, 149 Electrostatics, 7, 233 Electrotyping, 420 Energy of charge of Leyden Jar, 270 of electric current, 378 Equator,^ Magnetic, 78 Equipotential surfaces, 242, 310 (f) magnetic, 310 Equivalents, electro -chemical, 212 Erg, the (unit of work), 255 Evaporation produces electrification, 63* 303- discharge by, 223 Everett, James D,, on atmdipheric electricity, 307 on exact reading of galvan- ometer, 202 (footnote) on intensity of magnetisation of earth, 313 Expansion, electric, 273, 386 Extra-ctirrent (self-induced), 404 P Failure and exhaustion of batteries, 160 Fall of Potential along a wire, 263, 357 Farad, the (unit of capacity), 276, 323 Faraday^ Michael, molecular theory of electricity, 6 chemical theory of cell, 166 dark discharge, 290 Diamagnetism, 33^, 340, 344 , discovered inductive capacity, 21, 269, 271 Discovery of magneto •induc- . tion, 391 Electro-magnetic rotation, 375 experiment on dielectric polar- isation, 272 gauze-bag experiment, 31 hollow-cube experiment, 31 ice-pail experimeni, 34 laws of electrolysis, 211, 214 Magnetic lines-Qf-foifce, io8, 402 on Aragds rotations, 401 on dissi{)ation of charge, 291 on identity of different kinds of electricity, 217, 218, 286 Yolrameter, 214 Faraday, Michael, Magneto -optic discovery, 387 predicted retaraation in cables, 274 /?Vr«r^j Secondary Battery, 415 Favr^s experiments on Heat of Cur- rents, 368 Fechner^s electroscope, 264 Feddersen, IV., on electric oscilla- tions, 296 Ferromagnetic substances, 339 Field, magnetic, 105, 191, 312 Figures, magnetic (see Magnetic figures) electric, 297 Fire of St. Elmo, 302 (footnote) Flame, currents of, 291 diamagnetism of, 344 discharge by, 7, 291 produces electrification, 62 Fleming's Battery, 182 Fontana on electric expansion, 273 Force, electric, 155 (footnote), 241, 251, 252 magnetic, 83, 155 (footnote)^ 328 electromotive, 155 Foucaulfs Regulator Lamp, 372 Interruptor, 398 Franklin, Benja7nin, discovered action of points, mentioned in, 35(c), 43, 302 cascade arrangement of Leyden Jars, 279^ Electric Chimes, 43 Electric Kite, 502 Electric portraits, 288 his charged pane of glass, 47 invents Lightning Conductors, .305 kills turkey by electric shock, 2f6 One-fluid theory of Electricity, • ^ on seat of charge, 55 theory of the Aurora, 309 " Free " electricity, 24, 149 (footnote) Friction produces electrification, i, ro Frog's legs, contractions of, 148, / Fromenfs Electromotor, 375 Fuze, electric, 286, 370 Gaivani, Aloysius\ observed mOVO* ments of frog's leg, 148 49o; INDEX. Galvaniy AloystuSy on preparation of frog's limbs, 22p on Animal Electncitj", 231 Galvanic Batteries (see Voltaic Batteries) Electricity (see Current E he- ir icity) Taste, 227 Galvanism (see Current Electricity) Galvanometer, iq/ absolute, 200 astatic, 19S, 23s ballistic, 204 constant of, 200 differential, 203 r>ii B )i<' Reytnofid^Sf 231 Heljuholtzs, 190 reflecting {Sir Jr. Thomso7^s\ or mirror, 202 sine, 201 tangent, 199 Galvanoplastic (see Electrotyping) Galvanoscope, 188 Gas Battery, 416 Gases, resi.uance of, 158 Gassiot^ J, P , nn strics, 294, 300 Gaugain^ Jean Mothie^ discharging electroscope, 259 on Pyroelectricity, 66 Tangent Galvanometer, 199 GausSy E.f invented absolute measure- ment, 325a magnetic moment of earth, 325b magnetic observations, 313 Cay^ Lussac, on atmospheric elec- tricity, 307 Geiss/er*s tubes, 291 Genrez on electric distillation, 223 Gibson and Barclay on dielectric capacity of paraftin, 270 Gilbe7t, Dr, Williain^ discovers electrics, i, discovered magnetic reaction, discovers that the earth is a magnet, 88, 135 heat destroys magnetism, 09 his balanced - needle electro- scope, 12 observation of moisture, 9 observations on magnets, 78 on de - electrifying power of flame, 291 on magnetic figures, 108 on magnetic substances, 85 on magnetic permeability, 84 on methods of magnetisation, 96. 97 Gilding by Electricity, 431 Globular lightning, 304 Glow Discharge, 290, 302 (^footnote) Glowing of wires, 369 Gold-leaf Electroscope (see Electro- scope) Gordon y /. E, //., on magneto-optic rotatory power, 587 on dielectric capacity. 270, 271 on length of spark, 291 Gramme's dynamo-electric machine, 410 Gravitation Battery, 176 Gray^ Stephen^ discovers conduction, 27 on lightning, 302 Grotthuss* theory, 160, 418 Grove ^ Sir William ^,, his ,Gas Battery, 416 Groves Battery, 171 magnetic experiment, 113 en electric property of Flame, 291 Guard-ring, Guard-plate, 248, 261 Guerickey Otto von^ discovered elee trie repulsion, 3 invents electric machine, 38 observes electric sparks, 9 Gunpowder fired by electricity, 286, 288, 370 Gymnotus (electric eel), 68, 2x8 Halts phenomenon, 337 Hanker s electroscope, 264 Harris^ Sir W, Sftovit his unit Leydenjar, 259 attracted • disc electrometer, 261 on length of spark, 291 Heat, eflfect of, on magnets, 99, 100 „ batteries, 183 „ conductivity, 349 Heating eflfects of currents, 171, 366, 380 due to magnetisation, 1x3, 401 eHect of sparks, 288 ,, dielectric stress, 272 local, at electrodes, 41' Helmkoltz, Hermann L, on eflfect of current on s% , 22R Electrolytic convection, 418 Equations of Self-induction, 405 Galvanometer, 199 Hcnry^ Joseph^ invented thu ** sounder," 423 INDEX. 401 Henry ^ Joseph^ on induced currents of higher orders, 406 Hoitz^ W,, his electric machine. 46 on electric shadows, 293 {^foot- note) on tubes having unilateral re- sistance, 300 HopktnsoKy John^ on dielectric cap- acity of glass> 270 on residual charge and its return, 53, 272 Horizontal component of magnetism, Hughes t David Edward^ the Print-, ing Telegraph, 423 the Microphone, 437 Humboldt i Alexander von, on elefc- tric eels, 68 discovers galvanic smell, 228 produced electric contractions in fishes, 229 Hunter, Dr,^ John, on effect of current on sight, 228 Hydroelectric machine, 44 Images, electric, 250 Incandescent electric lights, 374 Inclination (or Dip), 137 variation of, 141 Index Notation, 325b Induced charges of electricity, x8 currents, 391 Induction {electrostatic) of charges, x8 {mag>utic\ lines of, 89 {magnetic) of magnetism, 89, „ coemcient of, 342 (magneto-electric) of currents. Induction-coil or Inductorium, 398 Induciion-convsction machines, 45 Ind ictjve-capacity, specific, 21, 49, ;*oS 272 In&ulat'irs, 8, 27 inten:»uy of current, 179 ai earth's magnetic force, 138, 325a ol magnetic field, 312 of magnetisation, 3x3 Inverse Squares, Law of, 16, 117, 235, 245 Inversion, Thermo-electric, 382 Ions, 210 Isoclinic lines, X39 Isogomc lines, 139 Jacohi, Moritz Hermann, on local action, x62 discovers galvanoplastic pro- cess, 420 his boat propelled by electricity, theory of electromotors, 377 Jahlochko^^ Paul^ his battery, 183 electric candle, 373 Jar, Leyden, 51 ^ capacity of, 50, 267, £77 „ cascade arrangement cf, 279 „ cUscharge of, 51, 293 „ discovery of, 52 „ energy of charge of, cjS „ seat of charge of, 55 „ spark of, 289, 296 „ theory of, 267 Unit, 259 Jenkin, Fleeming, on cable as con- denser, 2;^4 on retardation in cables, 296 Joule^ James Prescott^ on effects of magnetisation. 1x3 Law of Heat of Current, 367 Mechanical equivalent of Heatj 255, 414 on atmospheric electricity, 306 on lifting - power of electro- magnet, 32b /^^/if-efFect, the, 380, 367 Rathodb, ao7 Kation, 210 Keeper, loi AVrr, Dr* John, Electro - optic dis- coveries, 273, 386 Magneto-optic discoveries, ixa, 388. Kinnersley, Elijah^ Electric Ther- mometer, 288 Kirihhoff, Gustav^ Laws of Branched Circuits, 353 Kite, the electric, 302 Kohlrausch, F,, on residual charge, 272 on electro-chemical equivalent, 211 ijbotnpte) Lambllar magnetisation, 107 492 INDEX, Laminated magnets, 95 Law of Inverse squares, x6, 1x7, 235, 245 Leakage, rate of, 299 Leclanchi*s Battery,^ 173 Le Baillif on diaroagnetism of antimony, 33^ Lemonnier discovers atmospheric electricity, 306 Length of spark, 291 Lenses Law, 396 alcohol calorimeter, 367 Leyden Jar (see Jar) Lichtenher^s figures, 297 Lifting-power of magnets, 103 of electromagnets, 328 Light affects resistance, 389 ' Electric, 371 Electromagnetic theory of, 365, 390 polarised, rotated by magnet, 114, 387, 388 Lightnmg, 9, 302, 304 conductors, 32, 305 duration of, 296, 304 Lines-of-force, electric, 243 due to currents, 191, 329, 334 magnetic, 89, 108, 310, 312 Lippmann^ G., Capillary Electro- meter, 225, 265 Liquids as conductors, 205 resistance of, 348 ** Local Action " in batteries, 161 Lodestone, 76, 340 ** Long-coil instruments, 352 Loss of Charge, 15, 259 Lffuis XV, electrifies 700 monks, 226 LullirHs experiment, 285 Luminous effects of spark, 289, 400 M Machine, Alternate-current, 411 Electric, 38 Compound- wound, 411 convection-induction, 45 cylinder, 39 dynamo-electric, 408 Holts^s, 46 , hydro-electrical, 44 invention of, 38 magneto-electric, 407 plate, 44 Winters, 40 Magne-crystallic action, 343 Magnet, breaking a, 106 Magnets, natural and artificial, 76, 77* 326 Magnetic actions of current, 18^; 318, 326, 329, 334 Magnetic attraction and repulsion, 80, no cage, 84 curves, 108, 191 field, 105, 191, 312, 327^ figures, 108, 109, izo,i9z „ theory of, 126 fluids, allegea, 91 force, 83, 310 (e) „ measurement of, 118 . 325a mduction, 89 „ coefficient of, 342 iron ore, 76 lines-of-force, 89, zoS, Z09, zzo» ^ 316 lines-of-force of current, zgz, 320, 329 maps, 139 meridian, Z36 metals, 86, 339 moment, Z23 {footnote^ 3Z3, 325a needle, 79, Z34 oxide of iron, 76, 172 [Jootno*^) paradox, a, Z28 pole, unit, X25 potential, 3x0, 314, '3 'j proof-plane, 402 saturation, 102, 330 „ BeetZf on, 11$ screen, 84 shell, 107, 192, 31X (>^) „ ^ force due to, 127 „ * potential due t^o, 127, 3:^ storms, X45, 309. substances, 85, 339 units, 32X writing, xxi Magnetisation, coefficient of (or sus- ceptibility), 89, 3x3 intensity of, 3x3 lamellar, 107 mechanical effects of, 1x3 methods of, 92-98, 327 solenoidal, X07 sound of, X 1 3, 434 time needed for, 330 Magnetism, ^6 action of, on light, X14, 387 caused by heat, 98 destruction of, 99 distribution of xq4 of gases, 339, 387 lamellar, X07 laws of, 8x, 1x6, 3x0, 330 permanent, 90, 3x3 residual, Z02 INDEXo 493 Magnetism, solenoidal, 107, 314 temporary, 90, 102, 313 terrestrial. 88, 135 theories of, 91, 115, 338 unit of, 125 Magnetite, 76 Magneto-electricity, 74, 391 Magneto-electric induction, 391 machines, 407 Magnetographs, 146 Magnetometer, 124 self- registering, 146 Magneto-optic Rotations, 387 Magnets, artificial, 77 compound, 95 forms of, loi lamellar, 107 laminated, 95 methods of making, 92 98 natural, 76, 101 power of, 103 Mance s method, 361 Maps, magnetic, 139 Mariner's Compass, 134 Marked pole, 8a Afascart, £., on self -registering apparatus, 288 on atmospheric electricity, 308 Matteuccu Cottlo, on physiological effects, 68, 230 on electromotive • force^ in muscle, 231 Maynooth Battery (see CallatCs Battery) Maxw //, James Clerks Electro- magnetic theory of Ligll^ 337. 365, 390 on Electric Images, 250 on protection from Lightning^ 32, 305 on residual charge of jar, 272 on self-repulsidn of circuit, 334 rule for action of current on magnet, 103, 317 Theorem of equivalent Mag- netic shell, 192, JJ18 Theory of Magnetism, 115 Measurements, electrical, 355-363 magnetic, 118, 325a Mechanical effects of Discharge, 284, ^3 ,. effects of magnetisation, 113 ,, in aielectric, 272 Medical Applications of Electricitv, 232, 369 Megohm, 323 Meidinger^s Battery, I75v Meridian, Magnetic, 136 Metallo-c^omv, 43a Microfarad condenser, 276 Microphone, the, 437 Milli -ampere, 323 Mimosa, the, electric behaviour of, 230 Minottds Battery, 176 Mirror Galvanometer, 203 ^loisture,' effect of, i, 8, 2op Molecular theory of Electric action, 6 actions of current, 221 Moment of Couple, 123 of inertia, 325a magnetic, 123 (footnote), 325a Morse Telegraph instrument, 425 Mouse-mill (see Re^/enisher) Mullery JohanneSy on strength of electromagnets, 330 Multiplier, Schweiggen^ s, iSg Muscular contractions, 229, 231 Mtcsschenbroeky Peter van, dis- covery of Ley den Jar, 52 on Magnetic Figures, no Mutual Induction, coefficient of, 320, 397 Mutual Potential^ coefficient of, 320 N Napoleon II.Vs Battery, 182 Needle, magnetic, 79 Needle "telegraph, 424 Negative electrification, 4, 300 Newton, Sir Isaac, observations on action and reaction, 83 bis lodestone, 103 suggests electric origin of light- ning, 9, 302 suggests glass ist electric machines, 38 Niaudefs Battery, 173 Nobili, Leopoldo, on muscular con- tractions, 68 on currents of animal electricity, 231 discovers NobilVs rings, ^2 Non-conductors, 8 Non-electrics, 2 North and south, 81, 135 North magnetic pole, Uie, 81, 135 Null methods, 263 Oerstedt, Hans Christian^ discovers magnetic action of current, 1849 - 185, 191 Ohm, Dr, G. S., 179 " Ohm's Law,r i«o, 345 494 INDEX- Ohm, the, or imit of resistance, 323 ,, determination* of, 364 One-fluid theory of electricity, 6 Optical strain, electrostatic, 386 „ electromagnetic, 387 Oscillations, electric, 295 method of (for electrostatics), 120 {footnote), 235 method of (for magnetic mea- surement), 120, 121, 122, 325a Osmose, electric, 222 Other sources of electricity than fric- tion, 10, 57 Ozone, 208, 298, 302 (Jbotncte) Page, Charles G., discovers ma;jnetic sounds, 113 Parallel currents, laws of, 332 Paramagnetic, 339^ " Passive" state of iron, 172 {fooinoie) Peltier i At^uinasei \nz elcctrcmctcr^ 260, 307 heating effect at junctions, 380 theory of thunderstorms, 303 Penetrative power of discharge, 2S4 , Periodicity of aurora and magnetic storms, 144, 145, 309 Perry and Ayrton (see Ayrton and Perry) Pile, Voltaic, 150 Pith-bail electroscope, 2, 3 Phosphorescence caused by dicchargs, 292 Photo -voltaic property of selenium, 589. 495 Redistrit)Ution of charge, 36 Reflecting galvanometer, 202 Registering magnetographs and elec- trometers, 146, 307 /?m, Philips invention of telephone, 434 Relation between currents and mag- nets, 184, 318, 326, 391 between current and enerp^y, 378 between current and heat and light, 366 Relays, 426 Replenisher, 45, 261, 262 Repulsion and attraction of electrified bodies, i, 3, 18, 20, 66, 236 and attraction, experiments on, 43 and attraction of currents, 331 and attraction of magnets, 76, 80 Repulsion electrometers, 260 Residual charge of Leyden jar, 53, 272 ,, of cable, 274, 430 „ of Voltameter, 272, 415 magnetism, 102 Resinous electricity, 4 Resistance, 27, 158, 179, 346 absolute unit of, 363, 364 affected by temperature, 349 light, 389 ,, ^ sound, 436 as a velocity, 363 bridge or balance, 358 coils, 359 internal, of cell, 181, 350 ,, „ measurement of, 361 laws of, 347 measurement of, 356 cf gases, 158, 348 of liquids, 158, 349 specific, 348 Retardation of currents through cables, 274, 296, 430 Retentivity (magnetic), 90, 313 Return shock or stroke, 26, 304 Reyfnond, Du Bois^ his galvanometer, 231 on animal electricity, 231 unpolarisahle electrodes, 231 Rheocord, 356 Rheostat, 356 Rheometer, \ Rheoscope, > su footnote to \Cji. Rhectrope, ) RUss^ Peter, on electric distribution, 3S Riess^ Peter, on length of spark, 291 electric thermometer, 7.Z%{f9ot* note)_ Ritchie* s electromotor, 375 Ritter^ Johann Wilhebny on action of current on sight, 228 his secondary pile, 415 on subjective galvanic sounds, 230 on the sensitive plant {Mimosa^ 230 Rolling friction, 10 Romagnosi, Dr,, discovers magnetic action of current, 184 Romas^ De^ his electric kite, 302 Ronalds^ Sir Francis^ invented a telegraph, 423 Rotations, electromagnetic, 335 Arago^Sy 401 Rowland, Henry A ., on magnetic effect of electric convection, 337 on intensity of magnetisation, 313 Ruhmkorff's induction coil, 398 commutator, 399 electromagnet, 339 s St. Siemens t Carl Wilhelm, his dynamo- electric machine, 409 hi?* loixgitudinal armature, 407 Sight affected by current, 228 Silurui, the, 68 Sine galvanometer, 201 Single touch, 92 Single-fluid cells, 169 Siphon-recorder, 431 Sfnee's Battery, 165, 169 Soap-bubble, electrified, 3 Solenoid, 329 magnet, 314 Solid angles, 133 Solidification, 6i Sgund of magnetisation, 113 Sounder, the, 42^ Sources of electnciiy, 10, 57 Spark, 9, 43, 281 duration of, 296 length of, 44, 291, 302 Specific resistance, 348 inductive cajQcity, 21, 49, 268, 272 Speed of signalling, 274, 275, 256, 430 Sphere, distribution of charge over 35 (4» 248, 249 S/foUiswGode, IVillmnZf on stris, 2^4 Ste^itrt^ Balfour^ on atmo'-pheric electricity, 308 OB magnetic storms, 144 Storms, magnetic, 145 Standards of resistance (see ResUt- ance Coils) Sts^in, dielectric, $6 Strength of current, 158, 179 „ in magnetic nxea- sure, 195, rrj Strei^gth of magnet pole, 102 of nagnetic shell, 315 Stri^ in vacuum tubes, 292, 294 Sturgeon, IV, , invents the electro- magnet, 326 Submarine telegraphs, 429 SulzeT^s experiment, 227 Sjmmery on two kinds of electiifica- tion, 4 Surface-density of charge, 35, 248 limit of, 248 of magnetism, 127, 311 Swemifnerda7?^ s frog experiment, 229 S^'ans electric lamp, ^^4 Tait, Peter Gutkriei electrification by evaporation of sulphate of copper solution, 63 Taii, Peter Guthrie, thermo-elec: diagram, 383 Tar:;ent galvanometer, 199 Taste affected by cmrent, 227 Telegraph, electric, 423 Bairns chemical, 218 Morse* s instrument, 425 needle instrument, 424 Telegraphy, diplex, 428 duplex, 428 quadruplex, 428 subraanne, 429 Telephone, Philip Reiis^ 434 currents of 229 Dolbear^s^ 436 Edison's (carbon), 436 Graliam Bell's (articulatmg), 435 Varle^s (condenser), 272 Temperature affects resistance, 183 affected by resistance, 369 Tension of electrostatic forces, 248 (^footnote) Ter quern, A,, parrot-cage experi- ment, 31 Terrestrial Magnetism, 88, 135 Test for weak currents (chemica^), 218, 286. for weak currents (physiologi* cal), 229 Testing for faults, 427 Tetanisation produced by interrupted currents, 230 Theories of Electricity, 6, 300, and preface, ix. Theories of Magnetism, 91, 115 „ Amperes, 338 „ I4^'Vwgll*Si IIS Theory of Electrolysis, Joule s^ 414 Grotth)css*s and Clansius's, 41S Thermo-electric currents, ) Thermo-electricity, [ 70» 379 Thermo-electric Diagp-am, 383 Thermo-el&otromotive Series, 382 Thermo-pile, 384 'Thompson, Silvanus PhilUps^ on magnetic figures due to cur rents, 33^ on AlagTietic writing, iix on NobilVs rings, 422 on Positive and Negative ^'States, 300 on opacity of Tourmaline, 390 ( footnote) ' Thomson, Joseph /., on Contact Electricity, 73 ; value of "x^," 365 Thomson, Sir IVilliam, the Re- plenisher (or MoUse-Mill), 45, 26 1. 263 INDEX. 497 Thomson^ Sir William^ Proof of Contact Electricity, 71 Attracted - disc Electrometers, 261 Divided-ring Electrometer, 71 Electric convection of Heat (the " Thamson-^^^Qt "), 383 Mirror Galvanometer, 202, 431 Modified DanieiVi Battery, 176 on atmospheric electricity, 306 on Electric Images, 250 on length of spark, 291 on nomenclature of Magnet Poles, 81 {footnote) on sounds in condensers, 272 predicts electric oscillations 295 {^footnote) Quadrant Electrometer, 262 Siphon Recorder, 431 Thermo-electric Diagram, 383 Wat«»r-dropping Collector, 307 Thunder, 9, 304 Thimderstorms, 302 Theory of, 303 Tinfoil Condensers, 47, 275 Tongs, Discharging-, 51 Torpedo (electric fish), 68, 218 Torpedoes, fuzes for firing, 2&6, 370 Torsion affected by magnetisation, 11 ^ Torsion Balance, or ) {Coulotfib^s) Torsion Electrometer f 15, 119 Total action of magnet, 325a Tourmaline, 66, 297, 390 {Jbotftote) Transformers, 400 [37^ Transmission of P^wer by Electricity Tubes of force, 243, 311 Two-fluid cells, 170 Two-fluid theory, 6 Two kinds of Electrification, 4, 5 „ Magnetic poles, 81 Tyndall^ Jokn^ on diamagnetic polar- ity, 342 on magne-crystallic action, 343 Unit Jar, 259 Unit (Electrostatic) of Electricity, 17, 236 (Electrostatic) of Capacity, 247 Magnetic Pole, 125 of difference of potential, 242 322, 323 of Electromotive-force, 323^ 323 of Resistance, 322, 323 . of Strength of Currenti 196, 323, 333 Units, Fundamental and Derived. .2541 255 dimensions of, 258, 32^ Electrical (Electrostatic), 357 Electromagnetic. 322, 323 Magnetic, 321 Physical Dimensions of, 2581 T. 324, 351 Practical, 323 Universal Discharger, 54 Ure^ Dr,f on Animal Electricity, 229 "z^," values of, 365, 390 Vacuum, induction takes place through, 50, 84, 89 partial, spark in, 9, 292 spark wUl not pass through, 291 Vacuum-tubes, 292 "Variation," the (see Declinution) Variation of Declination and Dip, secular, 141 ; annual, 143 ; diurnal, 14? ; geographical, 136 Varley, C Z''., his Telephone, 273 Vegetables. Electricity of, 09 carnivorous, sensitiveness of; 235> Velocity uf Discharge, 206 of Electricity (alleged), 296 ^ of Liffht, 365, 390 Verdet^s Constant, 387 Vibration produces Electrification, r^ Vitreous electricity, 4 Volt, the, 323 Volta^ AlessandrOy his Electrophori:-, 22 Condensing Electroscope, 7:, 149 Contact Series, 72 Crown of Cups, 151 on Atmospheric Electricity, 307 on Contact Electricity, 71, 148 on Electric Expansion, 273 on Electrification due to com- bustion, 62 Subjective Sounds due to Current. 228 Volta*s Law, 72, 148, 156 Voltaic Pile, 150 Voltaic Electricity (see Current Elec- tricity) Arc, 371 Battery, 154, 167; Pile, 150 Cell, simple, 152 Voltameter, 214, 215, 216 Voltmeter, 360 {,d) 49S INDEX. W Water, Electrolysis of, 206, 413 Weber, the 323 Weber ^ IVilkelnty. the Electro-dyna- mometer, 3;j6 on diamagnetic polarity, 342 Wheat stone ^ Sir Charles ^ on the brush discharge, 290 Automatic Telegraph, ^23 Dynamo -electric Machmes, 4c3 on supposed velocity of elec- tricity, 296 Wheats ton^s Bridge or Bal- ance, 358 Wiedcntann^ Gustav^ on effect of mapmetisxn on torsion, 113 Wiedemanfty Gnstavy en diamag* netism of platinum, 339 Wilde, Henry ^ Electric Candle, 373 Magneto-electric Machine, 40J Wind, Electric, 43 WdhUf's Cell, 182 WollastotCs Battery, 169 Wminer on dielectric capacity, 270 Zanr&onVs Dry Pile, 13, 182, 264 ZanotHy experiment on grasshoppo 229 Zero Potential, 37, «3<) INDEX TO CHAPTERS XIII-XV. Adjustable Vacuum Tube, 460 Alternate Currents, 476 Alternators, 479 Anode in Vacuum Tube, 450 Antennae, 448 Attuning of Waves, 442, 446 B Bianodic Focus Tube, 459 Block and Wave, 442 Bombardment in Vacuum Tube, 45i Branly^s Coherer, 444 Brush Arc-Lighting Machine, 481 Bus Bars, 468 Cathode in Vacuum Tube, 450 Cathode Kays, 451 Central Station, 466 Choking Coil, 477 Coherer, 444, 448 Compound Wound Dynamo, 481 Counter Electromotive Force, 474 Coupled Alternators. 479 Crookes^s Tube, 449 Cathode Rays by a Dynamo and Deflection of Magnet, 453 Difference between Motor. 473 Di-phase Currents, 480 Dislocation of Hip. 464, 465 Distributors. 468 Dynan-,o and Motor. 473 Dynamos, ClnSFes of 4^1 E Elasticity of Ether, 443 Electric Egg, 449 Ether. 442 Ether Waves, 440, 442 Exhaustion of Vacuum Tube, 461 F Feeders, 468 Five-Wire System, 469, 472 Fluorescence, 450 Focus Tube. 459 Frequency of Alternations, 476 Gerssler Tube, 449 Hard and Soft Vacuum Tubes, 456 Hertzian Waves, 441 Hertz's Wave Detector. 441 High Frequency Currents, 478 High Pressure System, 470 Impedance, 477 Induction Coils in Wireless Teieg raphy,446, 447 Induction Coil of X-Ray Apparatus, 462 Inertia of Ether, 443 Kathode, see Cathode INDEX. 499 Lag and Lead, 477 Lodge'' s Coherer, 444 Lorenz. Dr., of Vienna, 465 Low Pressure System, 468 Luxations, Congenital, 465 M Marconi" s Silver Coherer, 444 MarconVs System of Wireless Teleg- raphy. 445 Medium Pressure System, 469 Motor Dynamo, 469 Motors, Modern, 482 N Numberof Vibrations of Sound, Light, and Electric Waves, 433 Occlusion of Air in Metal Film, 459 Omnibus Bars, 468 OnestVs Coherer, 444 Oscillatory Nature of a Leyden Jar Discharge, 441, 443 Phase, 477 Plates for Radiography, 463 Polyphase Currents, 480 Propelling Drag in a Motor, 474 Radiant State, 451 Radium, 457 Railway Motor, 48$ Receiver of Wireless Message, 447 Reflection and Refraction of Electro- magnetic Waves, 441 Relay in Wireless Receiving Station, 448 Resistance of Vacuum Tube, 456 Roentgen's Discovery, 454 Rotor, 480 Series Wound Dynamo, 481 Shunt Wound Dynamo, 481 Sine Wave, 476 Slaby's System of Wireless Teleg- raphy, 448 Striation in Vacuum Tube, 450 Switchboard, 471 Synchroniser, 479 Synchronising of Waves, 442, 446 Synchronous Motors, 480 Testa's Polyphase Motor, 484 Tesla's High Frequency, 444 Thomson-Houston Stationary Motor, 483 Time of Exposure in Radiography, 464 Toepler's Pumps, 461 Transformation, 467 Transmitter of Wireless Message, 446 Transparency to X-Rays, 452 Transverse Vibrations of Ether, 4S2 Trembler Magnet, 448 Tri-phase Currents, 480 Torque, 475 Types of Dynamos and Motors Used on Various Circuits, 486 Uses of X-Rays, 465 Vacuum Tube, 449, 450 Velocity of Electric and Light Waves, 441 Vertical Wire in Marconi System, 446, 447, 448 W Wire Gauge Table, 487 X-Ray Apparatus, 458 X-Rays, 449 X-Rays, Discovery of, 454 X-Rays, Nature of, 456 X-Rays, Properties of, 4S5 X-Rays, Source of, 457 X-Rays, Uses of, 465 II 28^ ^^ LBD .V ^^-^^^ V ^-^^^^ J?-^^^ Cw ^h "-^^o^ ;. 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