Editing Telegraphy (section)

=== Optical telegraph ===

[[File:Construction-pruss-opt-tele.png|thumb|upright=0.7|right|Schematic of a Prussian optical telegraph (or [[Optical telegraph|semaphore]]) tower, {{Circa|1835}}]]
[[File:Chappe semaphore.jpg|thumb|upright|left|19th-century demonstration of the semaphore]]
{{main|Optical telegraph}}

An [[optical telegraph]] is a telegraph consisting of a line of stations in towers or natural high points which signal to each other by means of shutters or paddles. Signalling by means of indicator pointers was called ''semaphore''. Early proposals for an optical telegraph system were made to the [[Royal Society]] by [[Robert Hooke]] in 1684<ref>{{cite web|url=http://mysite.du.edu/~jcalvert/railway/semaphor/semhist.htm |title=The Origin of the Railway Semaphore |publisher=Mysite.du.edu |access-date=17 June 2013}}</ref> and were first implemented on an experimental level by Sir [[Richard Lovell Edgeworth]] in 1767.<ref>{{cite book |url=https://books.google.com/books?id=9eLCsHfKq1IC|title=Communications: An International History of the Formative Years |author=Burns, Francis W. |year=2004 |publisher=IET |isbn=978-0-86341-330-8}}</ref> The first successful optical telegraph network was invented by [[Claude Chappe]] and operated in France from 1793.<ref>{{Cite web|url=https://www.britannica.com/technology/semaphore|title=Semaphore &#124; communications|website=Encyclopedia Britannica}}</ref> The two most extensive systems were Chappe's in France, with branches into neighbouring countries, and the system of [[Abraham Niclas Edelcrantz]] in Sweden.<ref name=Holzmann>Gerard J. Holzmann; Björn Pehrson, ''The Early History of Data Networks'', IEEE Computer Society Press, 1995 {{isbn|0818667826}}.</ref>{{rp|ix–x, 47}}

During 1790–1795, at the height of the [[French Revolution]], France needed a swift and reliable communication system to thwart the war efforts of its enemies. In 1790, the Chappe brothers set about devising a system of communication that would allow the central government to receive intelligence and to transmit orders in the shortest possible time. On 2 March 1791, at 11 am, they sent the message "si vous réussissez, vous serez bientôt couverts de gloire" (If you succeed, you will soon bask in glory) between Brulon and Parce, a distance of {{convert|16|km|mi|frac=2}}. The first means used a combination of black and white panels, clocks, telescopes, and codebooks to send their message.

In 1792, Claude was appointed ''Ingénieur-Télégraphiste'' and charged with establishing a line of stations between Paris and [[Lille]], a distance of {{convert|230|km|mi}}. It was used to carry dispatches for the war between France and Austria. In 1794, it brought news of a French capture of [[Condé-sur-l'Escaut]] from the Austrians less than an hour after it occurred.<ref>[https://www.bbc.co.uk/news/magazine-22909590 How Napoleon's semaphore telegraph changed the world] {{Webarchive|url=https://web.archive.org/web/20190824001923/https://www.bbc.co.uk/news/magazine-22909590 |date=24 August 2019 }}, BBC News, Hugh Schofield, 16 June 2013</ref> A decision to replace the system with an electric telegraph was made in 1846, but it took a decade before it was fully taken out of service. The [[Siege of Sevastopol (1854–1855)|fall of Sevastopol]] was reported by Chappe telegraph in 1855.<ref name=Holzmann/>{{rp|92–94}}

The [[Prussian semaphore system|Prussian system]] was put into effect in the 1830s. However, they were highly dependent on good weather and daylight to work and even then could accommodate only about two words per minute. The last commercial semaphore link ceased operation in Sweden in 1880. As of 1895, France still operated coastal commercial semaphore telegraph stations, for ship-to-shore communication.<ref>"A Semaphore Telegraph Station", ''Scientific American Supplement'', 20 April 1895, page 16087.</ref>
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