French semaphore line superseded by the telegraph

Background. The Chappe telegraph, invented in the early 1790s, utilized towers spaced 5 to 15 kilometers apart. Claude Chappe determined that moving angles were more discernible at distance than other signal characteristics. The system expanded from the initial Paris-Lille line to cover major French cities, with Paris serving as the central node. This infrastructure facilitated political unification and commercial communication, notably for stock exchange information.

Transition to Electric Telegraph. The decline of the optical system began with the establishment of the first electric telegraph line in 1845. In 1846, a decision was made to replace the optical telegraph with the Foy–Breguet electrical telegraph following a successful trial on the Rouen line. The French optical system remained in use for many years after other countries had switched to the electrical telegraph, and the conversion to electrical telegraphy was slower and more difficult than in other countries.

Final Operations. Despite the 1846 decision, the French optical system remained in use for many years. The last signal from a Chappe telegraph was sent in 1854. The transition was not immediate, reflecting the persistence of optical infrastructure even as electrical alternatives gained prominence. No supplied passage ties a specific 1853 use to the French Chappe system, so no such claim is made here.