THE ELECTRIC LIGHT. 661 



practice were to promote the interests and extend the use- 

 fulness 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 dis- 

 covery 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 so vivid that the sunshine, com- 

 pared with it, appeared feeble."* Such effects reached 

 their culmination when, in 1808, through the liberality of 

 a few members of the Royal Institution, Davy was enabled 

 to construct a battery of two thousand pairs of plates, with 

 which he afterward obtained calorific and luminous effects 

 far transcending anything previously observed. The arc 

 of flame between the carbon terminals was four inches 

 long, and by its heat quartz, sapphire, magnesia, and lime, 

 were melted like wax in a candle flame; while fragments of 

 diamond and plumbago rapidly disappeared as if reduced 

 to vapor, f 



The first condition to be fulfilled in the development of 

 heat and light by the electric current is that it shall en- 



* Davy, "Chemical Philosophy," p. 110. 



} In the concluding lecture at the Royal Institution in June, 1810, 

 Davy showed the action of this battery! He then fused iridium, the 

 alloy of iridium and osmium, and other refractory substances. 

 Philosophical Magazine, vol. xxxv., p 463. Quetelet assigns the 

 first production of the spark between coal-points to Curtet in 1802. 

 Davy certainly in that year showed the carbon light with a battery of 

 150 pairs of plates in the theater of the Royal Institution (" Jour. 

 Hoy. Inst.," vol. i., p. 166). 



