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Mining order telegraph. Historical illustration of an order telegraph as used in a mine. This was a simple form of electrical telegraphy, with the movement of the lever to a new position used to ring a bell at the other end of the system, in this case in a lift used in a mine shaft. Moving the corresponding lever to the new position acknowledged the order. The orders (in French) are a series of instructions for raising and lowering the lift at different speeds and to different levels. Similar systems are used on ships to communicate with the engine room. Artwork from 'Electricite' (1911) by Max de Nansouty, part of the 'Les merveilles de la science' series of 1867-1891 by Louis Figuier.
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