+1 credit
| Version | Summary | Created by | Modification | Content Size | Created at | Operation |
|---|---|---|---|---|---|---|
| 1 | Dean Liu | -- | 3472 | 2022-10-20 01:47:31 |
Video Upload Options
A semaphore telegraph 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 most widely used system was invented in 1792 in France by Claude Chappe, and was popular in the late eighteenth to early nineteenth centuries. Lines of relay towers with a semaphore rig at the top were built within line-of-sight of each other, at separations of 5 to 20 miles. Operators at each tower would watch the neighboring tower through a spyglass, 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. Semaphore lines were a precursor of the electrical telegraph, which would replace them half a century later, and would also be 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. Modern derivatives of the semaphore system include flag semaphore (a flag relay system) and the heliograph (optical telegraphy using mirror-directed sunlight reflections).
References
- Groundbreaking Scientific Experiments, Inventions & Discoveries of the 18th Century, Jonathan Shectman, p. 172
- Oxford English Dictionary.
- Webster's Unabridged Dictionary.
- 500 Years of New Words, Bill Sherk
- "The Origin of the Railway Semaphore". Mysite.du.edu. http://mysite.du.edu/~jcalvert/railway/semaphor/semhist.htm. Retrieved 2013-06-17.
- "History of the Telephone part2". Ilt.columbia.edu. http://www.ilt.columbia.edu/projects/bluetelephone/html/part2.html. Retrieved 2013-06-17.
- http://www.ieeeghn.org/wiki/images/1/17/Dilhac.pdf
- Holzmann, Gerard J.; Pehrson, Bjorn (2003). The Early History of Data Networks.
- https://web.archive.org/web/20140202183712/http://chappe.ec-lyon.fr/message.html
- Chapter 2: Semaphore Signalling ISBN:978-0-86341-327-8 Communications: an international history of the formative years R. W. Burns, 2004 https://books.google.com/books?id=7eUUy8-VvwoC&pg=PA29
- Adrian James Kirwan, 'R.L. Edgeworth and Optical Telegraphy in Ireland, c. 1790-1805' in Proceedings of the Royal Irish Academy (2017). https://www.jstor.org/stable/10.3318/priac.2017.117.02?seq=1#page_scan_tab_contents
- https://www.inc.com/magazine/19990915/13554.html
- Telegraph, Volume 17 of The Edinburgh Encyclopaedia, pp. 664–667, 1832 David Brewster, ed. https://books.google.com/books?id=VhEbAQAAMAAJ&pg=PA657
- Lieutenant Watson's Telegraph Mechanics' magazine, Volume 8 No. 222, Knight and Lacey, 1828, pages 294-299 https://books.google.com/books?id=rNZQAAAAYAAJ&pg=PA298
- F.B. Wrixon (2005), ISBN:978-1-57912-485-4 Codes, Ciphers, Secrets and Cryptic Communication pp. 444-445 cover Murray's shutter telegraph in the U.K., with codes.
- Military Signals from the South Coast, John Goodwin, 2000
- Telegraph Vol 10, Encyclopædia Britannica, 6th Edition, 1824 pp. 645–651 https://books.google.com/books?id=MsYnAAAAMAAJ&pg=PA645
- Faster Than The Wind, The Liverpool to Holyhead Telegraph, Frank Large, an avid publication ISBN:0-9521020-9-9
- Raddall, Thomas H. (1971), Warden of the North, Toronto, Canada: McClelland and Stewart Limited, http://www.ourroots.ca/toc.aspx?id=6183&qryID=8cbb8294-7361-4fdc-ac50-78627a229b5f
- Rens, Jean-Guy (2001), The invisible empire: A history of the telecommunications industry in Canada, Montreal, Canada: McGill-Queen's University Press, https://books.google.ca/books?id=8kUmt-Q7ySMC&pg=PA7&lpg=PA7&dq=nova+scotia+semaphore+line#v=onepage&q=nova%20scotia%20semaphore%20line&f=false
- The Age of Invention 1849–1920, Post & Tele Museum Danmark, website visited on May 8, 2010. http://www.ptt-museum.dk/en/exhibitions/the_permanent_exhibition/the_age_of_invention/
- "Semaphore Tower". Archived from the original on 4 March 2016. https://web.archive.org/web/20160304094408/http://gharghur.gov.mt/semaphore-tower/.
- Holzmann, Gerard. "Data Communications: The First 2,500 Years". http://spinroot.com/gerard/pdf/hamburg94b.pdf. Retrieved 28 June 2011.
- Page 84 in http://www.ebooksgratuits.com/pdf/dumas_monte_cristo_3.pdf
- See second paragraph in http://www.inlibroveritas.net/lire/oeuvre23495.html#page_163
