IS opal ilnstitution of (Great 



WEEKLY EVENING MEETING, ^<i7jr'^'''^"y^ 



Friday, January 17, 1879. 

 Sir W. FiiKDERiCK Pollock, Bart. M.A. Vice-President, in tlie Cliair. 



Professor Tyndall, D.C.L. LL.D. F.E.S. 



The Electric LigJit. 



The subject of this evening's discourse was proposed by our late 

 Honorary Secretary.* That word "late" has for me its own connota- 

 tions. It implies, among other things, the loss of a comrade by whose 

 side I have worked for thirteen years. On the other hand, regret is 

 not without its opposite in the feeling with which I have seen him 

 rise by sheer intrinsic merit, moral and intellectual, to the highest 

 official position which it is in the power of English science to bestow. 

 Well, he, whose constant desire and practice were to promote the 

 interests and extend the usefulness of this Institution, thought that at 

 a time when the electric light occupied so much of public attention, a 

 few sound notions regarding it, on the more purely scientific side, 

 might, to use his own pithy expression, be " planted " in the public 

 mind. I am here to-night with the view of trying, to the best of my 

 ability, to realize the idea of our friend. 



In the year 1800, Volta announced his immortal discovery of the 

 pile. Whetted to eagerness by the previous conflict between him and 

 Galvani, the scientific men of the age flung themselves with ardour 

 upon the new discovery, repeating Volta's experiments, and extending 

 them in many ways. The light and heat of the Voltaic circuit 

 attracted marked attention, and in the innumerable tests and trials to 

 which this question was subjected, the utility of platinum and charcoal, 

 as means of exalting the light, was on all hands recognized. Mr. 

 Children, with a battery surpassing in strength all its predecessors, 

 fused platinum wires eighteen inches long, while " points of charcoal 

 produced a light so vivid that the sunshine, compared with it, 

 appeared feeble."f Such efi'ects reached their culmination when, in 

 1808, through the liberality of a few members of the Eoyal Institu- 

 tion, Davy was enabled to construct a battery of 2000 pairs of plates, 

 with which he afterwards obtained calorific and luminous efi'ects far 

 transcending anything previously observed. The arc of flame between 



* Mr. William Spottiswoode, now President of the Royal Society, 

 t Davy: 'Chemical Philosophy,' p. 110. 



Vol. IX. (No. 70.) b 



