INDEX TO VOLUME II. 



457 



DYNAMO-ELECTRIC PRINCIPLE. 



Dynamo -electric or accumulative 

 principle of action, 120; conccp- 

 ii of, by Siemens, Werner, and 

 Wht'utstone, Charles, 214 ; illustra- 

 tion of, 120 ; machine, illustrative 

 of, cxliiliiicil at Royal Society in 

 1867, 214 ; papers by Siemens, C. 

 W., and Wheatstone, C., before 

 Royal Society, on, 214 ; production 

 of dynamo-electric currents on, 

 mechanical arrangement best 

 suited for, 121 ; residuary magne- 

 tism of electro-magnetic arrange- 

 ments sufficient to start machine on, 

 121 ; Siemens, W., brought before 

 Berlin Academy. 199 ; Siemens, 

 C.W., and Wheatstone, C., brought 

 before Royal Society and Varley, 

 S. A., also worked in same direc- 

 tion, 199 ; tension and power of 

 current, how increased on. 120. 



Dynamo machine, Siemens, C. W., 

 wound, advantages of, 218, 219 ; 

 efficiency, 53 per cent, as compared 

 with 45 per cent., 218 ; electro- 

 motive force increasing with 

 increasing resistance, 218 ; helices 

 not injured by heat, 219; maxi- 

 mum current, that habitually 

 used, 219. 



Dynamometer, adjustment of brake- 

 power in, 116 ; brake of self- 

 adjusting, 117 ; description of, 116, 

 140 ; direct and absolute measure- 

 ment of work expended, 190 ; 

 effect of varying pressure on, 186, 

 187; importance of , for measuring 

 strain on cable, 115 ; plan of 

 loading brake of, by hydraulic 

 pressure, 116; for testing power 

 consumed by dynamo-electric 

 machines, 189. 



EARTH'S conducting power, dis- 

 covery of. for galvanic currents, by 



i:l l.c TUIC CUBBENT. 



Krman, Basse and Aldini, 20 ; for 

 static currents by Franklin, 20. 



Earth currents, faults in submarine 

 cables affected by, 88, 183 ; suc- 

 cessfully dealt with by Varley, 

 183. 



Edison, telephone with carbon con- 

 tact, 197, 204. 



Efficiency, of dynamo - electric 

 machine very high, 190, 250 ; of 

 electric furnace high, 226. 



Electric arc, capable of larger effects, 

 222 ; produced by Sir H. Davy in 

 1810, 222 ; rays emanating from, 

 greater number non-luminous, 247; 

 application of, to recent research, 

 by Huggins,W. ; and Lockyer, J. N., 

 to astronomy ; and by Dewar, J., 

 to chemistry, 222 ; richness of, in 

 highly refrangible invisible rays 

 discovered by Stokes, G. G., 255 ; 

 " sunstroke " and blistering effects 

 of, 227. 



Electric candle, description of, 191. 



Electric charge, neutralisation of, by 

 second insulated wire in cable, 

 13 ; first observed by Siemens, 

 Wer., memoir to French Academy 

 in 1849 by, 44. 



Electric condition, of sub-marine 

 conductor, 29 ; previous, of exist- 

 ing cables unknown, 61. 



Electric conductor, improvement in 

 process of covering, 48 ; strand of 

 several copper wires for, 28 ; sus- 

 pended, for dynamo-electric loco- 

 motion, 249. 



Electric current, distribution of, to 

 branch circuits, 210 ; (measurer, 

 action of, principle of, 205, 212 ; 

 diagram produced by, process of 

 determining value of, in webers 

 or other units, 206, 213 ; descrip- 

 tion of, 204, 212; formula for 

 variations and very small varia- 

 tions of current in, 205, 206, 213) ; 

 measuring and recording passage 



