SHEILA TERRY / SCIENCE PHOTO LIBRARY SHEILA TERRY / SCIENCE PHOTO LIBRARY
Visual telegraph system. Coloured artwork of the demonstration, in 1791, of the Synchronised System by the French inventors, the brothers Chappe. This was an early telegraph, a system to send messages quickly over long distances. On 2 March 1791, the brothers transmitted a message from Brulon (about 16 kilometres away, centre left) to an identical set-up at Parce (foreground). A system of pendulum weights rotated a pointer on a clock face at each location. Flipping a large black and white card synchronised the pointers and indicated when the pointer moved over the symbol to be transmitted. A group of officials watched the demonstration. From La Telegraphie Historique (Alexis Belloc, 1888).
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