460 



INDEX TO VOLUME II. 



ELECTRIC PYEOMETEE. 



Association, 166) ; cost of, 126; 

 difficulties to be overcome in con- 

 struction of, 167 ; indicates too 

 low, at temperatures above white 

 heat, 166 ; pipe-clay cylinder for, 

 164 ; pipe-clay cylinder, insulation 

 of, 165 ; and platinum ball pyro- 

 meter, comparative results of, 150 ; 

 precautions requisite in using, 

 166 ; protecting case for, 164 ; 

 smelting operations, used in, 167 ; 

 Weinhold's, Prof., test of, 266. 



Electric pyrometer and differential 

 voltameter connected, 170 ; con- 

 stant resistance of instrument, 

 determination of, 172 ; constant 

 resistance should be small com- 

 pared with resistances to be 

 measured, 173 ; current, direction 

 of, from copper and zinc of battery 

 respectively, 171 ; reversing com- 

 mutator for, to prevent polariza- 

 tion of electrodes, 171, 172 ; total 

 resistance of, of what comprised, 

 172 ; volumes of gases in volta- 

 meters, inversely proportional to 

 resistances, 171. 



Electric railway, application of, 

 limits of, 264 ; aerial conductors 

 for, 264, 265 ; with' central con- 

 ductor, 264 ; losses in transmission, 

 265 ; with rails, insulated, acting 

 as conductors, and wheels insulated 

 from one another, 264. 



Electric resistance, of carbon varies 

 inversely with pressure, discovered 

 by Count de Moncel, 204, 212 ; 

 dependence of, on temperature, 

 142 ; diagram of, law of, 148 ; 

 due to vibration of particles con- 

 ductive in themselves requiring 

 pressure to produce conductive 

 continuity, 197 ; at high tempera- 

 ture compared by means of plati- 

 num ball pyrometer, 150 ; (in- 

 crease of, with temperature, 

 early experiments of Arndsten 



ELECTRIC TELEGEAPH. 

 and Siemens, Werner, 142 ; experi- 

 ments of Matthiesen, arithmeti- 

 cal within narrow limits, 142, 



146 ; Siemens, 0. W., law of, as 

 square root of heat communicated 

 or temperature, 147); measured by 

 Wheatstone balance.168 ; measure- 

 ment of temperature by, 1 58 ; 

 measuring, simple method of, 168 ; 

 microphone due to variation in, 

 196 ; of platinum, description 

 of experiments on, 143 ; pro- 

 portional to absolute temperature, 

 Glausius's law, 146 ; proportional 

 to velocity of vibrating atoms, 



147 ; variable with physical pres- 

 sure,197 ; variation of, with tempe- 

 rature. Siemens's, C. W., Bakerian 

 lecture on, 265, 266. 



Electrical science, rapid progress of, 

 Grove, W. R., on, 37. 



Electric signals first made by Gray, 

 S., in 1728, 16. 



Electric telegraph, appliances and 

 batteries, Highton, E., on, 42 ; 

 chemical, Davy, E., Morse. Bain, 

 Bakewell, 18 ; comprises battery, 

 conductor and receiving instru- 

 ment, 137 ; established by conti- 

 nental governments, 22 ; first 

 commercially useful, established 

 in 1838, by Wheatstone and Cooke, 

 20 ; first galvanic multiple wire 

 of Scemmering, 17, 18 ; first gal- 

 vanic single wire of Schweigger, 

 18 ; first static multiple wire 

 of Le Sage, 17 ; first static single 

 wire of Lomond, 17 ; galvanic 

 current applicable for, 17 ; Gauss 

 and Weber's method of working, 

 32 ; improved, 3 ; modern, elements 

 of, comprised in Franklin's appa- 

 ratus, 16 ; Morse's recording in- 

 strument, 21 ; progress of, paper 

 on, by Siemens, C. W., 1637; 

 Siemens, Werner, A. B. C. or dial 

 and printing or type instruments, 



