Page:Popular Science Monthly Volume 14.djvu/571

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MARCH, 1879.


By Professor JOHN TYNDALL.

THE subject of this evening's discourse was proposed by our late honorary secretary.[2] That word "late" has for me its own connotations. 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

  1. A discourse delivered at the Royal Institution of Great Britain on Friday, January 17, 1879.
  2. Mr. William Spottiswoode, now President of the Royal Society.