THE 



POPULAR SCIENCE 

 MONTHLY. 



MARCH, 1879. 



THE ELECTKIC LIGHT.' 



By Peofessob JOHN TYNDALL. 



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

 honorary secretary.'^ That word " late " has for me its own con- 

 notations. 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 ardor 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 



' A discourse delivered at the Royal Institution of Great Britain on Friday, January 

 17, 1879. 



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

 VOL. XIV. — 36 



