TRANSACTIONS OF SECTION G. 773 



But -whatever may be the future of electricity as a prime mover, either in a 

 •dominant or subordinate relation to heat, it is certain to be largely used for 

 mechanical purposes in a secondary capacity, that is to say, as the offspring instead 

 of the parent of motive power. The most distinctive characteristic of electricity 

 is that which we express by the word ' current,' and this gives it gi-eat value in 

 •cases where power is required in a transmissible form. The term may be objected 

 to as implying a motion of translation analogous to the flow of a liquid through 

 a pipe, whereas the passage of electricity through a conductor must be regarded 

 as a wave-like action communicated from particle to particle. In the case of a 

 fluid current through a pipe, the resistance to the flow increases as tlie square of 

 the velocity, while in the case of an electric current the resistance through a given 

 conductor is a constant proportion of the energy transmitted. So far, therefore, 

 as resistance is concerned, electricity has a great advantage over water for the 

 transmission of power. The cost of the conductor will, however, be a grave 

 consideration where the length is gi'eat, because its section must be increased in 

 proportion to the length to keep the resistance the same. It must also be large 

 enough in section to prevent heating, which not only represents loss, but impairs 

 conductivity. To work advantageously on this system, a high electro-motive force 

 must be used, and this will involve loss by imperfect insulation, increasing in 

 amount with the length of the line. For these reasons there will be a limit to 

 the distance to which electricity may be profitably conveyed, but within that limit 

 there will be wide scope for its employment transmissively. Whenever the time 

 arrives for utilizing the power of great waterfalls the ti-ansmission of power by 

 electricity will become a system of vast importance. Even now small streams of 

 water inconveniently situated for direct appUcation may, by the adoption of this 

 principle, be brought into useful operation. 



For locomotive purposes also we find the dynamo-electric principle to be 

 available, as instanced in the very interesting example presented in Siemens' electric 

 railway, which has already attained that degree of success which generally 

 foreshadows an important future. It forms a combined fixed engine and 

 •locomotive system of traction, the fixed engine being the generator of the power 

 .and the electric engine representing the locomotive. 



Steam power may both be transmitted and distributed, by the intervention of 

 ' electricity, but it will labour under great disadvantage when thus applied, until 

 a thoroughly effective electric accumulator be provided, capable of giving out 

 electric energy with almost unlimited rapidity. How far the secondary battery 

 of M. Faiu-e will fulfil the necessaiy conditions remains to be seen, and it is to be 

 hoped that the discussions which may be expected to take place at this meeting 

 of the British Association will enable a just estimate of its capabilities to be 

 formed. The introduction of the Faure battery is at any rate a very important 

 step in electrical progi-ess. It will enable motors of small power, whatever their 

 natiu-e may be, to accomplish, by uninterrupted action, the effect of much larger 

 machines acting for short periods, and by this means the value of very small 

 streams of water will be greatly enhanced. This will be especially the case where 

 the power of the stream is required for electric lighting, which, in summer, when 

 the springs are low, will only be required during the brief hours of darkness, 

 while in winter the long nights will be met by a more abundant supply of water. 

 Even the fitful power of wind, now so little used, will probably acquire new life 

 when aided by a system which will not only collect, but equalize, the variable and 

 .uncertain power exerted by the air. 



It would greatly add to the utility of the Faure battery if its weight and size 

 could be considerably reduced, for in that case it might be applicable to many 

 pm-poses of locomotion. We may easily conceive its becoming available in a 

 lighter form for all sorts of carriages on common roads, thereby sa%-ing to a vast 

 extent the labour of horses. Even the nobler animal that strides a bicycle, or the 

 one of fainter courage that prefers the safer seat of a tricycle, may ere long be 

 spared the labour of propulsion, and the time may not be distant when an electric 

 horse, far more amenable to discipline than the living one, may be added to the 

 iounteous gifts which science has bestowed on ci^■ilized man. 



