1880.] on Applications of the Dynamo-Electric Current. 337 



Tlic electric \v^\\i was tliereforc no novelty ; but the interest 

 attaching to it at the present time was entirely due to the eom])ai-a- 

 tively cheap rate at which the electric current could be produced by 

 the expenditure of mechanical energy resulting from the combustion of 

 coal, whereas formerly zinc had to be consumed or burnt in tlie gal- 

 vanic battery. Much ingenuity had been displayed of late in devising 

 electric lamps and electric candles, the various devices proposed 

 having for their object to produce a steady action. These might be 

 divided into two classes — the gloio lights, and the regulators of the 

 electric arc. It was shown that glow lights furnished the most 

 simple solution of the problem, but could never rival the arc in 

 economy of result, because the intensity of the latter could be made 

 to approach that of solar liuht, whereas glow lights were limited 

 in intensity to the fusing or dispersing point of the conductor cm- 

 ployed. 



It had been proved that even in the electric arc the major portion 

 of the rays emitted were heat rays, but in the best glow light pro- 

 bably not more than 2 or 3 jier cent, were rays of high luminosity, 

 all the rest being lost as regards the effect to be produced. It was also 

 shown that greater efficiency could be obtained from a powerful arc 

 than from divided arcs, and that therefore the development of electric 

 lighting should be sought in the direction of creating powerful centres 

 of light, and not in its subdivision. 



Electric light, properly applied, was much cheaper than gas light, 

 but was not likely to supplant the latter for purposes where great 

 subdivision was indispensable ; besides which, gas was essentially 

 a heating agent, and would find ever-increasing application in that 

 direction. 



The sensitiveness of gas shares to the announcements of mere 

 varieties of glow lights showed that the principles upon which electric 

 lighting depended were not sufficiently appreciated. The regulation 

 of the electric arc to the varying conditions of current and to imper- 

 fections in the carbons was, however, a matter of j^ractical difficulty, 

 which admitted of an almost unlimited number of solutions. The 

 question was which practical combination was at the same time the 

 most simple and efficient. The lecturer had himself worked out 

 several solutions, one of which recommended itself by its absence 

 of all clockwork arrangement in making the advancing carbons abut 

 against a fixed metallic stop. Other solutions might, however, 

 have their particular advantages, but it was not the purpose of 

 his present lecture to enter upon a consideration of such details of 

 arrangement. 



The electric light, if properly carried into effect, was a cheap light. 

 By burning, for instance, a thousand cubic feet of gas in burners, and 

 consuming the same quantity in a gas engine, giving motion to a 

 dynamo-electric machine feeding an electric light, it could be shown, 

 as the lecturer had done before the House of Commons Committee 

 on Lighting by Electricity, that about twenty times the luminous effect 



Vol. IX. (No. 72.) 2 a 



