Mr. Edison’s electric light[18] requires something more than a passing notice, and we will therefore endeavour to give a sketch of the general subject. Now that the electric light has been made available for domestic purposes, and the very simple lamp (consisting of an exhausted glass globe, two platinum wires, and a piece of charred paper) can be obtained, people will no doubt soon largely adopt electric lighting in their houses. The light has found a success at the theatre, in the streets, and in the train; there is no reason why it should not be adopted generally, being more economical and more healthy than gas.
[Illustration: Fig. 271. Electric candle.]
If we sever an electric wire, and bring the ends, tipped with carbon, into juxtaposition, we obtain a brilliant light. This is the Voltaic arc we have already mentioned, produced by the incandescence of finely-divided matter; it was the first method of illuminating by electricity, and was discovered by Sir Humphrey Davy, who obtained a very brilliant light, but at great expense—about a guinea a minute! But the Daniell and Grove batteries and generators, and modern improvements in 1860, brought the use of the electric light into prominence. Faraday lighted a lighthouse with its assistance.
But when the GRAMME GENERATOR was invented the needed impetus was applied. The Jablochkoff candles followed, and now we have the electric light in full operation. So far we have sketched the history of illumination by the Voltaic arc, and descriptions of the various apparatus will be found at the end of this chapter. But the method of lighting with an incandescent solid was introduced in 1845 by Starr and Peabody, who took out a patent for the use of platinum. Later on Drs. Draper and Despretz made experiments with platinum and carbon. The latter gentleman sealed the carbon in an exhausted globe, and then introduced nitrogen in place of the air. But the method died out and was forgotten, and in 1873 a medal was actually given by the Academy of St. Petersburg for the “discovery” to Messrs. Sawyer and Mann.
In 1878 Paris was lighted with the electric candles of Jablochkoff. This application of electricity stirred up our transatlantic cousins, and Mr. Edison was requested—backed up by many influential persons—to make the investigation whether the light could be produced for domestic purposes. The celebrated electrician undertook the commission, and certainly came unprejudiced to the encounter, for he had not at that time even seen an electric light.