442 



INDEX. 



Ohm, the, or unit of resistance, 323 



,, determination of, 364 

 One-fluid theory of electricity, 6 

 Optical strain, electrostatic, 386 



electromagnetic, 387 



Oscillations, electric, 255., 

 method of (for elect! 



rostatics), 



120 (footnote), 235 

 method of (for magnetic mea- 

 surement), 120, 121, 122, 32$a 

 Osmose, electric, 222 

 Other sources of electricity than fric- 

 tion, jo, 57 

 Ozone, 208, 298, 302 (footnote) 



Page, Charles G., discovers magnetic 



sounds, 113 



Parallel currents, laws of, 332 

 Paramagnetic, 339 ^ 

 " Passive" state of iron, Tj2( footnote] 

 Peltier, Athanase^ his electrometer, 



260, 307 



heating effect at junctions, 380 

 theory of thunderstorms, 303 

 Penetrative power of discharge, 284 

 Periodicity of aurora and magnetic 



storms, 144, 145, 309 

 Perry and Ayrton (see Ayrton and 



Perry) 



Pile, Voltaic, 150 

 Pith-ball electroscope, 2, 3 

 Phosphorescence caused by discharge, 



292 

 Photo -voltaic property of selenium, 



3 8 9 



Photophone, 389 

 Physiological actions, 226, 287 

 Plane, the proof-, 29 



,, for magnetism, 402 I 



Plante, Gaston, his secondary bat- j 



teries, 415 ^ 



on globular lightning, 304 

 Plants, electricity of, 69, 230 

 Plate condenser, 48, 268, 277 

 electrical machine, 40 

 Plilcker, Juli-us, on magne-crystallic ; 



action, 343 



P6%gtndorff,J. C., his battery, 165 | 

 Points, density of charge on, 35, 249 j 



discharge at, 39, 42, 43, 249 

 Polarity, diamagnetic, 342 



magnetic, 82, 106, 115 

 Polarisation (electrolytic) in battery 



cells, 163, 414 



of Voltameter, 272, 413, 415 

 remedies for, 165 



Polarised light rotated by magnetic 



forces, 387 

 relay, 428 

 Poles of magnets, 78, 122 



of pyroelectric crystals, 66 

 of Voltaic battery, 154 

 Porrefs phenomenon, 222 

 Portable electrometer, 261 

 Portative force, 103 

 Positive and negative electrification, 



4> 3p 

 Potential, electric, 37, 237 



zero, 37, 239 

 magnetic, 310, 314, 315 



N due to current, 318 ( 

 mutual, of two circuits, 319, ) 



320 



Pouillet, Claude S. M., sine galvan- 

 ometer, 201 



tangent galvanometer, 199^ 

 Power, transmission of, 376 

 Practical Units, 323 

 Preece, William Henry, on space 



protected from lightning, 305 

 Pressure produces electrification, 65 

 Priestley, Joseph, on electric expan- 

 sion, 273 



Prime conductor, 39 

 Printing telegraphs, 423 

 Proof-plane, 29 



,, (magnetic), 402 

 Poisson on magnetism in crystals 



Protoplasm, electric property of, 231 

 Pyroelectricity, 66 



Q, 



Quadrant electrometer (Sir W. 



Thomson's), 262 

 electroscope (Henley's), 14 

 Quadruplex telegraphy, 428 

 "Quantity" arrangement of cells, 



etc., 181 



of electricity, unit of, 17, 236 

 Qiietelet, E., on atmospheric elec- 

 tricity, 308 



Quincke, Georg, on diaphragm cur- 

 rents, 224 



on electric expansion, 273 

 on electro - optic phenomena, 

 386 



Ray, electric (torpedo), 68 

 Recovery, elastic, 272 



