INDEX TO VOLUMI: II. 



463 



GERMAN SILVER. 



magnetic observatory, 19 ; work i MI: 

 of, method of, 32. 



German silver resistances, 93. 



nan telegraph department, A. K. 

 C. instruments used by, 5. 



Glass, clear, non-interception of 

 luminous rays by, 255 ; highly 

 refrangible rays absorbed by, 255. 



Gramme's dynamo-electric machine, 

 experiments on, 215, 216. 



Grappling for cable in Atlantic, 117 ; 

 a delicate operation in deep water, 

 141. 



Gray, S., made electric signals in 

 1728. I-:. 



Grove, W. R., battery power, different 

 forms of, 38 ; (on gutta percha. 

 improving insulating power of , 38 ; 

 as an insulator, 38) ; on Oersted 

 and electro-magnetism, 46 ; rapid 

 progress of electric science, 37 ; 

 Ruhmkorff coil, reference to, 38 ; 

 submarine cable, necessity of 

 strength of, 38. 



Grove's gas battery, description of, 

 261 ; disadvantage of small sur- 

 face of contact of, 261 ; (Siemens, 

 C. W., carbon-lead electrodes used 

 in, by, 263 ; electrode of triple 

 contact for, 262 ; modification of, 

 in 1852, 261, 262 ; platinized retort 

 carbon tubes used in, by, 262). 



Gutta percha, cables of, effect of heat 

 on, 73, 74 ; (conductivity of, 66 ; 

 diminished by hydrostatic pres- 

 sure, 49 ; effect of temperature 

 on, 49) ; (covered underground 

 line wire, cost of, 9 ; weight of, 

 9) ; covered wire, faults how pro- 

 duced in, 73 ; destruction of, de- 

 pends on intensity and duration of 

 currents, 47 ; disintegrated by 

 electrolytic action, 47 ; dissolving 

 of, in water, 109 ; employed by 

 Siemens, Werner, in 1846, for in- 

 sulating purposes, 67 ; enemies to, 

 oxidation and animals, 9 ; exhi- 



HBLIX CIRCUIT. 



bited in 1844-45 by Montgomery 

 at the Society of Arts, 184 ; faults 

 after submersion, apt to develop 

 in, 99 ; history of introduction of, 

 as insulator, 11, 22 ; improvement 

 in, as insulating material, 61; (ami 

 india-rubber cable*, compared a* 

 to cost, 74 ; effects of temperature, 

 72 ; insulating ppwer, 67, 72, 83, 

 87, 99 ; solubility in water, 109 ; 

 specific non-conducting and in- 

 ductive power, 67 ;) inductive 

 capacity of, independent of con- 

 ductivity, 56 ; insulating proper- 

 ties of, important for submarine 

 cables, 26 ; insulation of, improved 

 by pressure, 92, 112 ; (as an insu- 

 lator, Grove, W. R., on, 38 ; sug- 

 gested use of by Siemens, C. W., 

 in 1845, 99 ; suitability of, 105 ; 

 used by Siemens, Werner, in 1847, 

 184) ; introduced first into this 

 country, 184 ; machine designed 

 in 1847 by Siemens, Werner, 184 ; 

 process for coating wire, criticism 

 of, 73 ; protected by lead, 9 ; puri- 

 fication of, Society of Arts Com- 

 mittee for, referred to by Highton, 

 B., 42 ; recent progress in manu- 

 facture of, 109 ; Siemens, C. W., 

 sent to Siemens, Werner, for ex- 

 perimenting, 22, 184 ; (under- 

 ground wire, 5, 9 ; 4,000 miles of, 

 in use in 1851, 9). 



HEAT (effect of, on non-conductors, 

 31 ; on resistance of wire, 125) ; 

 from electric light counteracts 

 night frost, 232 ; electric telegraph 

 cables, spontaneous generation of, 

 in, 92, 95, 158 ; generated by elec- 

 tricity, Joule's law regarding, 201, 

 213 ; proportional to square of 

 velocity of vibrating atoms, 147. 



Helix circuit and field circuit, ar- 

 rangement of, 218. 



