The Chappe telegraph, named for its inventor, Claude Chappe (1763-1805), was first tested in 1791 and improved in 1793, but the first functional line, which ran from Paris to Lille, opened in 1794.
This system allowed information to be transmitted through optical signals sent from a telegraph station. It was usually a tower especially built for this purpose on a hill or sometime a public building. The signals, watched and relayed from station to station, allowed messages to reach their destination at a speed unrivaled at the time. A special coding system ensured the confidentiality of communications.
The caption reads in the original French:
Télégraphe de chappe.