18 
connecting the ends of larger wires through which a strong 
current was passing became red hot. And the Arc light was 
discovered in 1810, when Sir H. Davy, experimenting with a 
very strong battery, happened to place two pieces of charcoal at 
tlie connexion of the wires, and was startled by the appearance 
of the most brilliant light known to man, though the Lime-light, 
produced by heating a cone of lime in a jet of hydrogen (or even 
common coal gas) mixed with oxygen, is intensely brilliant, as 
is also the light produced by burning magnesium wire. 
No real use of either the Incandescent or the Are light was, 
however, possible till the invention of the Hlectro-Magnet by 
Stringer in 1825, followed in 1832, ky Faraday’s great discovery 
of Electro-Magnetic induction. At the same time rods of 
charcoal suitable for electric lighting were being prepared. 
These are now usually made of powdered coke pressed and 
baked. In 1847 W. E. Straite attempted to regulate 
automatically the distance between the pair of charcoal rods as 
they were consumed, and this was fairly successfully accomplished 
by Serrin, in 1857. And in 1858, the South Foreland Lighthouse 
was temporarily illuminated with the Electric Arc by means of 
the Magneto-Hlectrie Apparatus of Holmes and Faraday, worked 
by a steam engine, and with Dubose’s modification of Serrin’s 
regulator. A few years later electric lighting was permanently 
established at the South Foreland and Dungeness Lighthouses. 
Wilde, in 1866, made an exceedingly powerful magneto-electric, 
and in 1866-7 Sir C. Wheatstone and Mr. Siemens (afterwards 
Sir W. Siemens), made the first true dynamo without permanent 
magnets. This, in 1870, Gramme greatly improved. These 
machines enabled electricity to be produced in unlimited quantity 
by the steam engine or other motive power. Since this time the 
march of progress has been rapid and continuous. 
In 1876, Jablochoff placed the pair of charcoal rods parallel to 
each other, and between them a non-conducting substance which 
was consumed with the rods. With this ‘‘ Jablochoff candle,”’ 
the Avenue de |’ Opéra at Paris, was illuminated in 1877, and the 
world was awakened to the powers of the new ‘‘ Child of Science.” 
In 1878 Edison succeeded in dividing the electric current and 
thus rendered the Incandescent light suitable for practical use. 
Before this, as early as 1845, King had taken out a patent 
for Incandescent light, and in 1873, Lodighim publicly and 
successfully shewed his Incandescent lights, which were in 
principle very similar to those of Edison. Meanwhile in 1860, 
Swan had still more closely approximated to Kdison’s invention, 
and after Edison’s trials and first failures, Swan carried on his 
own improvements side by side with those of Edison, so that 
now in America, there are 3 or 4 million Edison and Swan 
