Semaphore line  

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Train wreck at Montparnasse (October 22, 1895) by Studio Lévy and Sons.
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Train wreck at Montparnasse (October 22, 1895) by Studio Lévy and Sons.

A semaphore telegraph, optical telegraph, shutter telegraph chain, Chappe telegraph, or Napoleonic semaphore is a system of conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the mechanical elements; it is read when the shutter is in a fixed position.

The system was invented in 1792 in France by Claude Chappe, and was popular in the late 18th to early 19th century.

Semaphore lines were a precursor of the electrical telegraph. They were far faster than post riders for bringing a message over long distances, but far more expensive and less private than the electrical telegraph lines which would replace them. The distance that an optical telegraph can bridge is limited by geography and weather; thus, in practical use, most optical telegraphs used lines of relay stations to bridge longer distances.

Modern derivatives of the semaphore system include flag semaphore (a flag relay system) and the heliograph (optical telegraphy using mirror-directed sunlight reflections).

The Chappe telegraph in literature

  • In "Mister Pencil" (1831), comic strip by Rodolphe Töpffer, a dog fallen on a Chappe telegraph's arm and its master attempting to help provoke an international crisis by involuntarily transmitting disturbing messages.
  • In "Lucien Leuwen" (1834), Stendhal pictures a power struggle between Lucien Leuwen and the prefect M. de Séranville with the telegraph's director M. Lamorte.
  • In Chapter 60 ("The Telegraph") of Alexandre Dumas' The Count of Monte Cristo (1844), the title character describes with fascination the semaphore line's moving arms. "I had often seen one placed at the end of a road on a hillock, and in the light of the sun its black arms, bending in every direction, always reminded me of the claws of an immense beetle..." He later bribes a semaphore operator to relay a false message in order to manipulate the French financial market. Dumas also describes in details the functioning of a Chappe telegraph line.
  • In the Hector Malot's novel Romain Kalbris (1869), one of the characters—a girl named Dielette, describes her home in Paris as "...next to a church near which there was a clock tower. On top of the tower there were two large black arms, moving all day this way and that. [I was told later] that this was Saint-Eustache church and that these large black arms were a telegraph."
  • In chapter 10 of C. S. Forester's Hornblower and the Hotspur (1962), the destruction of a French semaphore tower and a shore battery is a key plot point. A similar event is also the focus of the seventh episode of the A&E Horatio Hornblower series.
  • In the young adult fiction book Death Cloud by Andy Lane (2010), Mycroft Holmes tells 14-year-old Sherlock Holmes about semaphore stations, commenting about his school beforehand, saying "All the Latin a boy can cram into his skull, but nothing of practical use."

Fictional semaphores in literature

  • In the alternative history novel, Lest Darkness Fall (1939), by L. Sprague de Camp, the protagonist, a 20th Century man who falls into Dark Age Rome, develops a semaphore system to warn of invasion. To make it practical he also invents the telescope.
  • Pavane (1968), an alternate history novel by Keith Roberts, features a society where long distance communication is by a network of semaphores operated by the powerful Guild of Signallers.
  • Terry Pratchett's Discworld novels (1983) describe a system of 8-shutter semaphore towers, known as Clacks. In the alternate universe of the Discworld, the semaphore system occupies a similar role to that of the Internet on Roundworld. Using advanced clacks coding it is possible not only to send very fast telegrams, but also to encode pictures and send them long-distance. Shopping and banking via the clacks is also mentioned, in a similar fashion to online shopping.
  • In David Weber's Safehold series (2007), a world-wide Semaphore system is used by the Church to help them maintain their dominion over the world.
  • In Alastair Reynolds' Terminal World (2010), the distant-future terrain is criss-crossed with semaphore lines relaying information between the one remaining city, Spearpoint, outlying communities and the airborne community Swarm.

See also




Unless indicated otherwise, the text in this article is either based on Wikipedia article "Semaphore line" or another language Wikipedia page thereof used under the terms of the GNU Free Documentation License; or on original research by Jahsonic and friends. See Art and Popular Culture's copyright notice.

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