"Semaphore telegraph" redirects here. For signalling by hand-held flags, see Flag semaphore. For other uses, see Semaphore (disambiguation).
A replica of one of Chappe's semaphore towers in Nalbach, GermanyIllustration of signalling by semaphore in 18th-century France. The operators would move the semaphore arms to successive positions to spell out text messages in semaphore code, and the people in the next tower would read them.
An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals (a form of optical communication). There are two main types of such systems; the semaphore telegraph which uses pivoted indicator arms and conveys information according to the direction the indicators point, and the shutter telegraph which uses panels that can be rotated to block or pass the light from the sky behind to convey information.
The most widely used system was the Chappe telegraph, which was invented in France in 1792 by Claude Chappe. It was popular in the late eighteenth to early nineteenth centuries.[1][2][3] Chappe used the term "télégraphe" to describe the mechanism he had invented – that is the origin of the English word "telegraph".[4] Lines of relay towers with a semaphore rig at the top were built within line of sight of each other, at separations of 5–20 miles (8–32 km). Operators at each tower would watch the neighboring tower through a telescope, and when the semaphore arms began to move spelling out a message, they would pass the message on to the next tower. This system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed. Half a century later, semaphore lines were replaced by the electrical telegraph, which was cheaper, faster, and more private. The line-of-sight distance between relay stations was limited by geography and weather, and prevented the optical telegraph from crossing wide expanses of water, unless a convenient island could be used for a relay station. A modern derivative of the semaphore system is flag semaphore, signalling with hand-held flags.
^Burns 2004, Chapter 2: Semaphore Signalling
^"Telegraph". Encyclopædia Britannica. Vol. 10 (6th ed.). 1824. pp. 645–651.
^David Brewster, ed. (1832). "Telegraph". The Edinburgh Encyclopaedia. Vol. 17. pp. 664–667.
^Axon, William (1880). "On the History of the word Telegraph". Proceedings of the Literary and Philosophical Society of Manchester. 19: 183. Retrieved 10 June 2023.
An opticaltelegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals (a form of optical...
systems are thus not true telegraphs. The earliest true telegraph put into widespread use was the Chappe telegraph, an opticaltelegraph invented by Claude Chappe...
bells and three-position needle telegraph instruments. In the 1840s, the electrical telegraph superseded opticaltelegraph systems, becoming the standard...
introduction to different forms of optical communication. Visual techniques such as smoke signals, beacon fires, hydraulic telegraphs, ship flags and semaphore...
Dilhac, "The Telegraph of Claude Chappe: An Optical Telecommunication Network for the XVIIIrd Century."" (PDF). "How Napoleon's semaphore telegraph changed...
3 March 1791, Chappe tested an opticaltelegraph with a system of synchronized pendulums and a white and black optical panel between the cities of Brûlon...
Telegraphy usually refers to the electrical telegraph, but telegraph systems using the opticaltelegraph were in use before that. A code consists of a...
as opticaltelegraphs. However, they could only utilize a very limited range of pre-determined messages, and as with all such opticaltelegraphs could...
the Foy-Breguet electrical telegraph, also descended from the French opticaltelegraph. Although based on the opticaltelegraph, by the time flag semaphore...
writings. From 1838 on he joined the opticaltelegraph of Johann Ludwig Schmidt, who established a private telegraph line between Hamburg and Cuxhaven....
An optical fiber, or optical fibre, is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers find wide usage...
of opticaltelegraphs, radio telegraph stations, or riding couriers. Early 19th century methods of this type evolved into the electrical telegraph networks...
A telegraph hill is a hill or other natural elevation that is chosen as part of an opticaltelegraph system. Telegraph Hill may also refer to: A high point...
Sigismund Gottfried Huth in 1796. Huth proposed an alternative to the opticaltelegraph of Claude Chappe in which the operators in the signaling towers would...
Hertzian waves could be used (instead of light) in systems akin to opticaltelegraph: for example, Richard Threlfall and John Perry suggested that in 1890...
packet – Formatted unit of data carried by a packet-switched network Opticaltelegraph – Tower-based signaling network Pioneer plaque – Plaques on the Pioneer...
third-highest escarpment. From 1789 to 1847 Child's Hill hosted an opticaltelegraph station. The area has long given its name to a ward of the United...
for a private two-needle telegraph on this line to connect it to its base in Portsmouth, finally replacing the opticaltelegraph. In September 1845 the...
A telegraph hill is a hill or other natural elevation, chosen as part of an opticaltelegraph system because of the relatively great distance between...
systems using semaphore codes and telescopes. The latter form of opticaltelegraph came into use in Japan, Britain, France, and Germany from the 1790s...
Napoleonic Wars. The telegraph station was closed in 1814 following the end of the war, along with nearly all of the other opticaltelegraph stations in Denmark...
Gustaf III. He is known for his experiment with the opticaltelegraph. He inaugurated his telegraph with a poem dedicated to the Swedish King on his birthday...
has made skywriting possible. Polybius square Opticaltelegraph Ivan, Djordjevic (2010). Coding for Optical Channels. Springer US. p. 2. ISBN 978-1-4419-5569-2...
order to alert defenses. As signals, beacons are an ancient form of opticaltelegraph and were part of a relay league. Systems of this kind have existed...
These early cables used copper wires in their cores, but modern cables use optical fiber technology to carry digital data, which includes telephone, Internet...
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