456 



INDEX TO VOLUME II. 



DISTRIBUTION. 



exceeding, obtainable by electric 

 arc, 222. 



Distribution, of electric current to 

 branch circuits, 210 ; of light of 

 high intensity produced in a focus, 

 208. 



Diurnal repose, Darwin's opinion 

 regarding, 257 ; not probably 

 necessary to plant life, 230. 



Divided light less economical than 

 central, 247 ; and centralized light, 

 consideration of. 246, 247. 



Double needle instrument, 20 ; use 

 of in England, Clark, L., on, 41 ; 

 and Morse's compared by Clark, L., 

 41 ; Highton, E., on, 42. 



Double relay system, Siemens and 

 Halske's, 33. 



Double step by step or dial telegraph 

 of De Foy et Breguet fils, 22. 



Douglass, J. N., lighthouse illumina- 

 tion, electric light applied to, dis- 

 cussion of paper by, 206 209. 



Dover and Calais, submarine cables 

 between, 26. 



Draper, J. W., plant cultivation in 

 the solar spectrum, yellow ray 

 most efficacious in decomposition 

 of C0 2 in vegetable cell, 256. 



Dungeness, electric and oil light at, 

 207. 



Dynamical converted into electric 

 force without the aid of permanent 

 magnetism, 119. 



Dynamical expression of increase of 

 resistance with temperature, 147, 

 148. 



Dynamo-electric current (applica- 

 tion of, to fusion of refractory 

 materials, 221 ; to horticulture, 

 227 ; to locomotion, 241 ;) eco- 

 nomical means of transforming 

 electrical into mechanical energy 

 and vice versd, 220 ; means of 

 improving steadiness of, 214 ; and 

 magneto-electric, electric arc pro- 

 duced economically by, 222. 



DYNAMO-ELECTRIC MACHINE. 



Dynamo-electric locomotion,methods 

 available for various, 249 ; for 

 tunnels and elevated tramways, 

 243. 



Dynamo- electric locomotive, conduc- 

 tors for, 243, 244 ; difficulties of, 

 250 ; starting at high potential, 

 cause of, 242 ; starting, stopping, 

 and reversing of, effected by com- 

 mutator, 241 ; suitable for tram- 

 ways, mines, &c., and underground 

 railways, 251 ; suspended electric 

 conductors for, 249. 



Dynamo-electric machine, advan- 

 tages, principal of, 215 ; Alteneck, 

 von H.'s modification of, 215 ; 

 arranged so that portion of cur- 

 rent should excite, 248 ; cost of, 

 191 ; defect of, with increase of 

 work, power to overcome resistance 

 diminishes, 248 ; dynamometer for 

 testing power consumed by, 189 ; 

 economy of, 199 ; efficiency maxi- 

 mum of, 190 ; efficiency, theore- 

 tical maximum of, 250 ; electro 

 motive force diminishes with in- 

 creasing external resistance, 216 ; 

 with separate exciters, 248 ; ex- 

 ternal resistance should equal that 

 of machine for best effects, 192 ; 

 a generator on descending gra- 

 dient, 242 ; Gramme, Brash, 

 Wallace-Farmer, efficiency of, com- 

 pared, 216 ; Hopkinson, J., deter- 

 mination of efficiency and other 

 properties of, 216 ; and magneto- 

 electric machine, ratio of velocity 

 of on level, and on rising and 

 falling gradient, 242 ; maximum 

 results with, 250 ; original Siemens 

 experimental, still used to excite 

 permanent magnets, 21 5; for quan- 

 tity and intensity, 210 ; rationale 

 of, 199 ; scientific principles of, 

 187 ; Siemens's examined by J. 

 Hopkinson, 216 ; winding, various 

 modes of, 217, 218. 



