TELECOMMUNICATIONS SYSTEMS BASED ON SOUND, WRITING OR LIGHT (IN DIRECT VISION)

The first telegraph to be built, following the scheme of 24 wires per letters of the alphabet, was made by George-Louis LE SAGE (1724-1803). To produce electrical discharges, the “Leyden bottle” was used, invented in that city by the Dutchman Pieter Van MUSSCHENBROEK in 1746 (a bottle of water with a metal rod attached to the cap, which, when brought close to an electric machine with its own hand, what it achieves is to act as a condenser plate, while the inner water acted as another, in such a way that it accumulated positive electricity on the inner wall of the bottle and negative on the outer part in contact with the hand, receiving a powerful electric shock). The Leyden jar turned out to be a powerful condenser of electricity due to sudden and not gradual discharges. (This would later be discovered with the invention of the electric cell and battery.)