426 



INDEX. 



379, 381 ; resistance of element, 314 ; 

 resistance of tubes, 319 ; rate of 

 working, 41 9; sine galvanometer, 24 ; 

 shunt circuits, 286 ; tangent gal- 

 vanometer, 238 ; voltameter, 234 ; 

 Wheatstone's balance, 290. 



Franklin's theory, 3. 



French railway telegraphs, 65. 



French telegraph bell, 68. 



Fused metals, 270. 



G-alvani, 15 ; hypothesis of, 15. 



Galvanism, discovery of, 13. 



Galvanic current, origin, 215 ; effects, 

 218 ; measurement, 232. 



Galvanic element, resistance, 313 ; con- 

 stants, 313 ; force of, 315. 



Galvanic batteries, 220 ; polarization, 

 278. 



Galvanometer, constants of, 303 ; dif- 

 ferential, 353*; Gaugain's, 240 ; mag- 

 netism of coils, 245 ; sine, 241 ; 

 sine and tangent, 247 ; tangent, 

 237 ; Thomson's, 249 ; Weber's, 247. 



Galvanised wire, 195. 



Gauss and Weber's telegraph, 27. 



German lightning-guard, 212. 



German silver wire, 268. 



Glass tubes, 328. 



Great Eastern, 349. 



Grey's experiments, 2. 



Grotthuss' theory, 215. 



Grove's element, 327. 



Gutta-percha, 357 ; conducting power, 

 280 ; inductive capacity, 384 ; under 

 pressure, 365 ; absorption of water 

 by, 386. 



Heating of cables, 373. 



Heat produced by current, 218. 



Heat and resistance, 266. 



High pressure tests, 365. 



Hooper's I. R. cable, 388. 



House's telegraph, 53. 



Hughes' telegraph, 55. 



Indian and Bed Sea cable, 343. 



India-rubber, 384 ; conducting power, 

 280 ; inductive capacity, 384 ; in- 

 sulation, 385 ; as insulator, 384 ; 

 Hooper's, 388 , absorption of water 

 by, 386 ; under pressure, 365. 



Induction in cables, 111. 

 Inductive capacity, 411. 

 Induced magnetism, 24. 

 Injection of poles, 185. 

 Insulation resistance, 299 ; under pres- 

 sure, 365. 



Insulation of G. P., 357 ; of I. R., 384 ; 

 of Wray's mixture, 388; of core, 

 356. 



Insulating materials, 280, 384. 



Insulators, line, 189 ; Bright' s, 189 ; 

 Chauvin's, 192; Clark's, 191; Sie- 

 mens', 190. 



Insulators, stretching, 193 ; Kohl's, 

 194 ; Siemens', 194 ; Varley's, 192. 



Intensity of current, 256. 



Intermediate commutator, 95. 



Jacobi's etalons, 328. 



Jar, Ley den, 3. 



John's telegraph, 120. 



Joints in line wires, 196 ; in core, 363 ; 



testing, 370 ; in cable, 371. 

 Joule, Dr., 331, 336. 



Kerckhoff's lightning-guard, 213. 

 Kirchhoff's laws, 285. 

 Kramer's telegraph, 70 ; alarm, 72 ; 

 battery, 224. 



Law, Ohm's, 256 ; Kirchhoff's, 285 ; 

 magnetic deflection, 21 ; electro- 

 magnetism, 24. 



Laying cable, 391. 



Lesage's telegraph, 8. 



Lever key, Morse, 42. . 



Leyden jar, discovery of, 3 ; construc- 

 tion of, 4. 



Light, 218. 



Lightning-guard, 205 ; Bianchi's, 213; 

 Breguet's, 209, 211 ; Fardley's, 210 ; 

 German, 212; Kerckhoff's, 213; 

 Meissner's, 207 ; Nottebohm's, 210; 

 Siemens', 208, 211. 



Lightning and electricity, 204. 



Lightning, stroke of, 204. 



Line insiilators, 189. 



Local circuits, Moore's, 42 ; Wheat- 

 stone's, 40. 



Lomond's telegraph, 9. 



Magnet, electro, 24; construction of, 

 24 ; laws of, 24; deflection of, 21. 



Magnetic effects of current, 220. 



Magnetism of coils, 245. 



Magneto -electricity, 25. 



Magneto-electric telegraphs, 21 ; Gauss 

 and Weber's, 28 ; Siemens', 75, 

 136, 166 ; Steinheil's, 33 ; Wheat- 

 stone's, 45. 



Magneto induction key, 126. 



Magnitudes, electrical, 333. 



Mallet's buckled plates, 189. 



Malta- Alexandria cable, 344. 



