Chappe telegraph - Wikipedia
The system was composed of towers placed every 5 to 15 kilometers. Coded messages were sent from tower to tower, with transmission being handled by tower operators using specially designed telescopes. The messages were decoded once they reached their destination city. By the mid 19th century, the network spanned several hundred kilometres and covered most major French cities as well as Venice, Mainz and Amsterdam.
The system was dismantled after the introduction of the electric telegraph. Today, about twenty Chappe towers remain, in varying states of repair.
The Chappe telegraph system embodied varying designs, with the variation partly due to technological improvements made as the system was used.[1]
The typical tower's signaling mechanism was visible through specially designed telescopes from a neighboring tower, 5 to 15 km away. The mechanism consisted of:[2]
Two telescopes were used in each tower to see the signals up- and downstream from that tower. They had magnifications between 30× and 65×, depending on the arrangement of the towers. Each telescope was mounted in a wooden housing that kept it fixed and focused on one of the neighbouring towers.[6] This avoided the need to adjust the telescope for each message.
