French optical telegraph system. 19th-century diagram of a dial to encode signals in the mechanical-optical semaphore telegraph system ('aerographe')

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French optical telegraph system. 19th-century diagram of a dial to encode signals in the mechanical-optical semaphore telegraph system ('aerographe') developed by French inventor Pessault Delatour. Mechanical-optical telegraphy had been invented by French engineer Claude Chappe in the 1790s. Later systems refined the concept but were largely abandoned following the development of electric telegraphy by Morse and others in the 1840s. This dial for encoding signals is from Delatour's 'Aerographe: systeme universel de communication d'idees au moyen de signaux sonores et visuels, mis a la portee de tout le monde' (1833).

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Size: 3387px × 5215px
Photo credit: © KING'S COLLEGE LONDON/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

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