" THE ELECTRIC STORAGE OF ENERGY:' 549 



batteries at the one place and conveying them to another, when he 

 wrote in one of his letters of "Professor Reynolds's disappointment 

 with M. Faure's practical realization of electric storage, because it does 

 not provide a method of porterage suj^erior to conduction through a 

 wire." This is " like being disappointed with an invention of improve- 

 ments in water-cans and water-reservoirs because the best that can be 

 done in the way of movable water-cans and fixed water-reservoirs 

 will never let the water-carrier supersede water-pipes wherever water- 

 pipes can be laid." If we may venture to extend the great electrician's 

 metaphor, it is like finding fault with the Great Eastern Railway 

 Company's service of sea-water brought to London in cans, on the 

 ground that it is just possible to obtain sea-water by a large main laid 

 down to the coast, and that such a scheme is now under consideration. 

 Another valuable property of the new battery is pointed out by Sir 

 William Thomson. If it were to be used either at a fixed station to 

 work an electric railway, such as the firm of Siemens have already 

 brought into practical use, or to be carried on an ordinary carriage to 

 drive it, the energy developed by the vehicle in running down-hill 

 would be stored up ready to be used for its propulsion when it again 

 reached a level or an ascending incline. 



In the course of the correspondence Professor Ayrton has again 

 mentioned the experiments which he and Professor Perry are carrying 

 out with the view of using coal or coal-gas instead of zinc in a primary 

 battery. Should he succeed in doing so, we should obtain a source of 

 energy about ten times cheaper in working than the best-known steam- 

 engine, and M. Faure's invention may very likely be the means of 

 making it a commercial success ; for, should Messrs. Ayrton and Perry, 

 or any other physicist, succeed in making a coal or coal-gas battery 

 giving a good proportion of the theoretical energy of the coal or gas, 

 should it have a high internal resistance, it would be difficult to use it 

 in practice ; but, by the aid of Faure's batteries, in cases where work 

 was only wanted to be done for a few hours a day, as in the case of 

 electric lighting, the comparatively feeble current of the primary bat- 

 tery might be collected and stored for fifteen or sixteen hours, and 

 then allowed to run out again in the eight or nine houi*s for which the 

 source of energy is practically wanted. 



The subject of this new secondary battery is one of great scientific 

 importance. As the writer of a leader in the " Times " points out, it is 

 by no means unlikely that a similar piece of apparatus may be made of 

 some metal, and its appropriate salt, which shall be cheaper and lighter 

 than one of M. Faure's form of similar powers ; at all events, the in- 

 vention and its results are pretty sure to turn the attention of invent- 

 ors and investigators toward batteries both secondary and primary 

 a branch of inquiry which has for so many years been quite thrown 

 aside in favor of endeavors to improve the dynamo-machine. Kow, a 

 primary battery is theoretically the most economical artificial source 



