Davy probably never imagined that his brilliant experiment would soon play so important a part in the future lighting of the world. He may never have regarded it as of any practical value. In fact, many years elapsed before any further attempt was made to utilize the light of the electric arc. The reason for this is not difficult to discover. The batteries in existence were crude and gave only their full power for a very short time after the circuit was closed. They were subject to the very serious defect of rapid polarization, whereby the activity was at once reduced. A long period elapsed before this defect was removed. Davy in his experiments had also noted the very intense heat of the electric arc, and found that but few substances escaped fusion or volatilization when placed in the heated stream between the carbon electrodes. Here again he was pioneer in very important and quite recent electric work, employing the electric furnace, which has already given rise to several new and valuable industries. The conduction of electricity along wires naturally led to efforts to employ it in signalling. As early as 1774 attempts were made by Le Sage, of Geneva, to apply frictional electricity to telegraphy. His work was followed before the close of the century by other similar proposals. Volta’s discovery soon gave a renewed impetus to these efforts. It was easy enough to stop and start a current in a line of wire connecting two points, but something more than that was requisite. A good receiver, or means for recognizing the presence or absence of current in the wire or circuit, did not exist. The art had to wait for the discovery of the effects of electric current upon magnets and the production of magnetism by such currents. Curiously, even in 1802 the fact that a wire conveying a current would deflect a compass needle was observed by Romagnosi, of Trente, but it was afterwards forgotten, and not until 1819 was any real advance made.