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. 
t 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. 
Koy. Inst.," vol. i., p. 166). 
