page_title: Fort de Valros
section_title: Telegraph tower
hierarchical_section_title: Fort de Valros / Telegraph tower
caption_attribution_description: English: Map showing Chappe chain of semaphore telegraphy in the Hérault département of France Français&#160;: Carte montrant la chaîne des tours du télégraphe Chappe dans le département de l'Hérault (France).
context_page_description: The Fort de Valros is a ruined small castle or fortress in the commune of Valros in the Hérault département of France. In the mid-19th century, the fort was the site of a semaphore station.
context_section_description: The small square tower nestled in the south west corner of the fortress (number 7 on the plan above) is a remnant of the aerial telegraphy invented at the end of the 18th century by the engineer Claude Chappe (1763-1805), using semaphore signals.
  The first semaphore telegraphy line was established in 1794 between Paris and Lille. The French network extended over 5,000 km with 534 stations serving 29 towns. Installed in 1834, the line linking Avignon to Narbonne, via Valros, was functioning until 1853. The semaphore network was then replaced by electric telegraphy. The tours de Chappe (Chappe towers), every 12 km or so, were built on high points. Each station was equipped with a mechanism for transmission and two telescopes to receive a message and to control its onward transmission. The mechanism consisted of a vertical mast supporting a 4.60 m long movable arm, the regulateur. At either end of the latter was a secondary arm, 2 m long, the indicateurs. The mast extended down into the interior of the tower into a tight room, 3 m by 3 m, sheltering the stationnaire, the solitary worker glued to his telescopes. For speed, and confidentiality, messages were encoded using a table where each figure signified a word or phrase. To transmit a message, the regulateur was placed either horizontally or vertically. The indicateurs were articulated every 45ᵒ, with 7 positions for each. This gave a total of 98 combinations (7 X 7 X 2), of which six were reserved for the service - the only ones whose meanings were known to the stationnaire. The total repertoire of messages was, therefore, 92 pages of 92 lines, a total of 8,464. Signals were sent in groups of two: the first number for the number of the page, the second for the number of the line on that page.
caption: The Chappe telegraph chain in l'Hérault
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