Map of the optical telegraphy network designed by the Chappé brothers. On this map the La Rochette-Paris line and Paris are marked. The optical telegraph in France had a network of 4,800 km and 556 stations that connected about 30 cities. With this telegraphy system, a message could be sent between any of the cities that belonged to the network, which in turn were linked to the capital, Paris. (1794-1852) These types of maps were part of the technological design of the first telecommunication lines, hence the importance of their conservation as historical documents.