Page:Heroes of the telegraph (IA cu31924031222494).djvu/21

 systematic researches, discovered the magnetism of the earth, and laid the foundations of the modern science of electricity and magnetism. Otto von Guericke, burgomaster of Magdeburg, invented the electrical machine for generating large quantities of the electric fire. Stephen Gray, a pensioner of the Charterhouse, conveyed the fire to a distance along a line of pack thread, and showed that some bodies conducted electricity, while others insulated it. Dufay proved that there were two qualities of electricity, now called positive and negative, and that each kind repelled the like, but attracted the unlike. Von Kleist, a cathedral dean of Kamm, in Pomerania, or at all events Cuneus, a burgher, and Muschenbroek, a professor of Leyden, discovered the Leyden jar for holding a charge of electricity; and Franklin demonstrated the identity of electricity and lightning.

The charge from a Leyden jar was frequently sent through a chain of persons clasping hands, or a length of wire with the earth as part of the circuit. This experiment was made by Joseph Franz, of Vienna, in 1746, and Dr. Watson, of London, in 1747; while Franklin ignited spirits by a spark which had been sent across the Schuylkill river by the same means. But none of these men seem to have grasped the idea of employing the fleet fire as a telegraph.

The first suggestion of an electric telegraph on record is that published by one 'C. M.' in the Scots Magazine for February 17, 1753. The device consisted in running a number of insulated wires between two places, one for each letter of the alphabet. The wires were to be charged with electricity from a machine one at a time, according to the letter it represented. At its far end the charged wire was to attract a disc of paper marked with the corresponding letter, and so the message would be spelt. 'C. M.'