"The earliest instance of applying Electricity to the production of light was in 1810, by Sir Humphrey Davy, who found that when the points of two carbon rods whose other ends were connected by wires with a powerful primary battery were brought into contact, and then drawn a little way apart, the Electric current still continued to jump across the gap, forming what is now termed an Electric Arc. ... Various contrivances have been devised for automatically regulating the position of the two carbons. As early as 1847, a lamp was patented by Staite, in which the carbon rods were fed together by clockwork. ... Similar devices were produced by Foucault and others, but the first really successful arc lamp was Serrin's, patented in 1857, which has not only itself survived until the present day, but has had its main features reproduced in many other lamps. ... The Jablochkoff Candle (1876), in which the arc was formed between the ends of a pair of carbon rods placed side by side, and separated by a layer of insulating material, which slowly consumed as the carbons burnt down, did good service in accustoming the public to the new illuminant. Since then the inventions by Brush, Thomson-Houston, and others have done much to bring about its adoption for lighting large rooms, streets, and spaces out of doors." _J. B. Verity, Electricity up to Date for Light, Power, and Traction, chapter 3._ ELECTRICITY: A. D. 1820-1825. Oersted, Ampere, and the discovery of the Electro-Magnet. "There is little chance ... that the discoverer of the magnet, or the discoverer and inventor of the magnetic needle, will ever be known by name, or that even the locality and date of the discovery will ever be determined [see COMPASS]. ... The magnet and magnetism received their first scientific treatment at the hands of Dr. Gilbert. During the two centuries succeeding the publication of his work, the science of magnetism was much cultivated. ... The development of the science went along parallel with that of the science of electricity ... although the latter was more fruitful in novel discoveries and unexpected applications than the former. It is not to be imagined that the many close resemblances of the two classes of phenomena were allowed to pass unnoticed. ... There was enough resemblance to suggest an intimate relation; and the connecting link was sought for by many eminent philosophers during the last years of the eighteenth and the earlier years of the present century." _T. C. Mendenhall, A Century of Electricity, chapter 3._