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Wheatstone telegraph dial. Historical illustration of the dial used the telegraph invented by British physicist Charles Wheatstone (1802-1875). This was the first practical public telegraph system that did not require knowledge of Morse code. The user sent each letter by holding down the relevant button and cranking a handle. Up to 15 words per minute were possible. Wheatstone's first telegraph (with Cooke) was patented in 1837. This single-needle refinement was developed in around 1845. 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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