The _Electric Telegraph_ has had considerable antiquity claimed for it, but it is pretty certain that the discovery made by Doctor Watson, in 1747, that electricity would pass through wires, and that the earth would complete the circuit, gave the first impetus to the Electric Telegraph. Doctor Watson was enabled to transmit shocks across the Thames, and made experiments at Shooters Hill. Franklin did likewise across the Schuykill in 1748, and De Luc performed the same experiments on the Lake of Geneva. Both Lesage and Lomond caused pith balls to diverge at distant points, and in 1794 Reizen made use of the electric spark for transmitting signals, and made strips of foil show out certain letters when the spark passed. He had a wire and a return wire for each letter of the alphabet.
These were all slow advances, and subsequently many learned men in Europe sought to improve upon the ideas then promulgated. We read of telegraphs constructed at Madrid by Salvá and Betancourt in 1797 and 1798, one extending for more than twenty miles. The first-named gentleman finally proposed to substitute the Voltaic pile for the usual machine, and Ronalds and Dyar in England and New York respectively employed frictional electricity with some success. The latter sent charges of frictional electricity through a wire, and they were recorded by being made to pass through litmus paper. The distances between the discharges were intended to indicate the letters of the alphabet, but even if the experiment was fairly tried it failed, for little was heard of the result.
After the invention of Volta’s pile, which Salvá wished to adopt, Sömmering began his experiments. He used thirty-five wires, set up vertically at the bottom of a glass reservoir of water, and terminating in gold points. These wires ended in the opposite direction in brass plates attached to a bar of wood. At one end the points and at the other the plates bore the same letters respectively; hydrogen at one gold point, and oxygen at another, and two different letters were indicated when the current was sent through any two plates. This arrangement was afterwards improved upon, and only two wires retained.
It was not until electro-magnetism had been developed, however, that Œrstead found out the power of electricity to deflect the magnetised needle, and in 1820, Scheweigger added a “multiplier.” Then came Arago into the field with his discovery, that a “wire carrying a current could magnetise a steel rod.” Ampère substituted a helix for a straight wire, and Sturgeon used soft iron for steel, and developed the electro-magnet. Daniell’s battery, and Faraday’s discoveries of magneto-electricity and the induction coil were the means of putting a constant supply of electricity at the service of the telegraph and so on, till 1830 brought out a more practical method introduced by Schilling.