Disc, distribution of charge on, 55 - by Bunsen's flame, 48 energy of, 150; in the cascade arrange. examples in, 159 various forms of, 98, 377 et seq. in secondary circuit of induction coil, Distribution of electric charge, 55 laws of, illustrated by the ice-pail, 57 Dots and dashes, Morse signals, 420 apparatus for printing, 421 Dynamo, work done upon, in relation to Dynamos, various forms of, 38; et seq. as motors, 402 EARTH, magnetic fie'd of, modified by the presence of iron, 30 magnetic elements of the, 30; how to action of, on a magnetic needle, 28 Earth's field, observation of changes in action of, on mobile currents, 311 Ebonite, a good 'electric.' 43 how to prevent it deteriorating, 63 Eddies in the ether about lines or mag. Eddy currents due to induction, 363 Eel, electric, 169 Efficiency, dynamo-electric, 408 Electricity, atmospheric, 113 distribution of, on conductors, 55 - electrostatic induction machines for, 'fluid' theories of, 48 frictional, machines for, 60 measurable as a quantity, 65 specific heat of, 265 practical applications of, 416 et seq. statical, phenomena of, 42 et seq. -'current'; in what sense to be under- FOR E.M.F., reverse, of an electro-motor, 402 of currents in arc-lighting, 442 - practical unit of, 221, 298 absolute electro magnetic unit of, 297 in relation to heats of combination, 240 in electrostatic discharges, 150 degradation of, 238 instrument for measuring, 449 - of an electrostatic charge resides in the of battery-cell, transformations of, 238 per second [see Activity '], 239, 298 potential, 128 radiant, 341 Engravings reproduced by electrolysis, 193 Equivalents, electro-chemical, 191 table of, 192 Erg, definition of, 127 Ether, the, 340 electrostatic phenomena possibly due to HEAT, absorption and evolution of, at junctions of thermo-electric pair, 263 converted into electric energy by thermo- - distribution of, in the circuit, 244 evolved in a circuit, relation of, to evolution of, according to cell arrange- - evolved in a circuit, formulæ for measur- - tendency of energy to take the form of, unit of, 239 Heats of combination in relation to Helmholtz's modification of Gaugain's Holtz induction machine, 108 Hughes's investigation of the molecular invention of the microphone, 431 173 - film on copper plate of voltaic cell, means of getting rid of, 176 CE-PAIL, Faraday's, 57, ICE Incandescence, electric lighting by, Swan's lamp, 434 India-rubber, specific inductive capacity Induction, phenomena of, accompanying electromagnetic, 343 et seq. vel city of propagation of, 342 in the earth's field, 366 disturbance of telephone lines by, 430 illustrated by experiments with the examined from a 'potential' point of -machines, 100 magnetic, 7 along lines of force, 19, 331 its influence on magnetic measure- Insulating st nds, 53 stool, 64 field-, 387 hollow, contrasted with solenoid, 327 Mariner's compas, 29 Mass, as distinguished from weight, 13 Maxwell's (Clerk) electro-magnetic theory Mechanics, preliminary knowledge of, Megohm, multiple of ohm, 235 Mercury, use in amalgamating zinc piate cups for connecting wires, 175 - specific resistances of, 236 Meters for total current' supplied, 443 Microhm, fraction of ohm, 235 Microphones, 431 Molecular theory of magnetism, 3 Molecules, interchanges between, in elec. Moment, magnetic, of a needle, 15 how measured, 17, 26, 40 Moments of single forces and couples, 14 system of telegraphy, 421 Motor [see Flectro-motor] Mutual potential of two circuits, 359 RES Poles, magnetic, mutual attraction and - action of currents on, 294 action of element of current on, 296 - potentials on, 316, 323 -- of the voltaic cell, 172 Pole-strength, dimensions' of, 300, 301 at a point in the atmosphere, 117 curve of, round the axis of the difference ot, 66, 131 distribution of, in the circuit of a how to measure by work, 67, 131 measurement of, 131, 153 of an isolated sphere, 141 of thunder-clouds, 115 fall of, through the circuit, 215 magnetic, due to circuits, 316, 322 due to magnetic shells, 304 - mutual, of two circuits, 359 Power, transmission of, from a distance, |