ELECTRICAL ENERGY, STORAGE OF. 



267 



ates, the results of which were communicated 

 to the French Academy in March. The ex- 

 periments were undertaken to obtain 1. The 

 mechanical labor expended in charging the bat- 

 tery. 2. The quantity of electricity stored up 

 during the charge. 3. The quantity of elec- 

 tricity given out during the discharge. 4. The 

 electrical work actually eifected during the dis- 

 charge. And they showed that of the total 

 quantity of electricity introduced in the bat- 

 tery, 90 per cent was given out again, and 

 that 60 per cent of the total electrical work 

 spent in charging was recovered during the 

 discharge. The accumulator therefore absorbed 

 40 per cent of the electrical work that would 

 otherwise have been available in the lamps 

 through which the discharge was made. So 

 great a loss as this would place the accumula- 

 tor without the limits of commercial utility in 

 most cases, if further experience shows that 

 this is the utmost efficiency to be obtained. 

 The results of various other experimenters, 

 however, show the loss to be considerably less. 

 Sir William Thomson concluded from his ex- 

 periments that the probable loss in charging is 

 10, and in discharging 15 per cent, while Pro- 

 fessor Ayrton states that this loss, in a well- 

 constructed cell, properly charged and dis- 

 charged, need not exceed 18 per cent, and, 

 if the discharge be sufficiently slow, this may 

 be brought down to 10 per cent. If so high 

 an efficiency as 80 per cent can be ob- 

 tained in actual use, it is very probable that the 

 accumulator will be found a thoroughly practi- 

 cal apparatus, which can be used with advan- 

 tage in almost all the applications now made of 

 powerful electric currents. But whether its 

 efficiency reach this figure or not, it may still 

 be a valuable adjunct in many cases, for it 

 must be borne in mind that its real value in a 

 commercial sense is not determined solely by 

 its own efficiency. If by its use the efficiency 

 of other apparatus forming an element of an 

 electrical system can be raised, the gain might 

 in some cases be sufficient to nearly, if not 

 quite, neutralize the loss due to the accumula- 



tor itself. In the case of incandescent lighting 

 it is quite possible that the efficiency of these 

 lamps may be considerably increased, as there 

 is no danger of the lamps being destroyed by 

 a sudden increase of current, and they may 

 therefore be run nearer their breaking limit, 

 and consequently more economically. The life 

 of the lamp will probably also be found to be 

 greater than when run direct from the ma- 

 chine. The advantage of an apparatus in a sys- 

 tem of distribution which increases the reliabil- 

 ity of the supply is one of no small amount, 

 and may rightly be considered to have an eco- 

 nomic value. 



Too little is yet known, both of the first cost 

 of accumulators and of their depreciation, to 

 be able to judge whether their use will de- 

 crease the investment necessary, in a system of 

 distribution, below that required without them. 

 In this country the Brush Electric Light Com- 

 pany proposes to place accumulators in the 

 houses of consumers, and charge them with 

 the currents used for its arc-lamps. A large 

 number of local Brush Companies are now en- 

 gaged in furnishing arc-lamps, and have the 

 plant for the purpose. These lamps are in use 

 at the most from six o'clock in the evening 

 until six the next morning, so that the plant 

 is idle, or nearly so, twelve hours out of the 

 twenty-four. 



By using accumulators, this plant can be run 

 continuously, and a saving of course effected, 

 so far as machines and street conductors are 

 concerned. The company has as yet furnished 

 no figures as to the investment required for the 

 storage-batteries, and hence the economic feasi- 

 bility of the plan can not be determined, though 

 the company asserts that in this regard it is 

 entirely satisfactory. 



The only figures yet given of the price of 

 accumulators are those recently put forth by 

 the Electrical Power Storage Company, of Eng- 

 land, which has begun the manufacture and 

 sale of the Faure-Sellon-Volckmar and the Sel- 

 lon-Swan batteries. The company has issued 

 a circular in which information is given as to 



the proper rate of charge and discharge, the one, two, and five horse-power are at pres- 

 size of the cells, and their price. From this ent manufactured; the rates of economical 

 circular it appears that cells of three sizes charge and discharge of which are : 



