Semaphore Telegraph, or optical telegraph, was the "first practical system of long-distance telegraphic communication" (Bray 35). Typically, it is described as a communications medium which required the use of manual movable arms or closeable apertures mounted in towers (on hilltops) that were in line-of-sight.
Messages Letter by Letter
transmission measured by words per minute
Semaphores were installed in various countries, including:
- Denmark (1802) - England - France - Prussia (1832)'
In 1794, French engineer Claude Chappe invented the semaphore telegraph. Chappe's semaphore had movable arms and handles to operate them.
A "Telegraph Hill" is a site where a semaphore station was installed between London, Deal,and Portsmouth. These semaphore stations were developed by Lord George Murray "using holes closed manually by movable wooden shutters" (Bray 37).
"The first use of flag signals at sea is often credited to the Duke of York, later James II, in the wars with the Dutch in the seventeenth century, and from Nelson's famous signal we realize that a highly sophisticated system had been perfected by the time of Trafalgar." (45
It was important because during battle there's no other way to send messages. On land, one could send a messenger on a different route to avoid the battlefield and get the message out.
"One of the early characteristics of the early non-electrical systems was that they were capable of transmitting ver little information; for example, if you had previously agree that lighting a signal fire means 'The city has fallen', you have no means of sendind an alternative message such as 'Clytemnestra has twins', although it may be of equal importance. In a very limited sense the information is coded, that is the occurrence of fire means a certain message and no other" (Beck 45).
dependence on light disruption by bad weather
The system "may be regarded as a precursor of present-day microwave radio, relay systems which often use hilltop sites" (Bray 37).
- Beauchamp, K. G. History of Telegraphy.
- Beck, A. H. W. Words and Waves: An Introduction to Electrical Communications. New York: McGraw-Hill Book Company, 1967.
- Bray, John. The Communications Miracle: The Telecommunication Pioneers from Morse to the Information Superhighway. New York: Plenum Press, 1995.
or Bray, John. Innovation and the Communications Revolution: from the Victorian pioneers to broadband Internet. London: The Insitutition of Electrical Engineers, 2002. p. 31.
- Coe, Lewis. The Telegraph: A History of Morse's Invention and Its Predecessors in the United States. Jefferson, NC: McFarland & Company, Inc., Publishers, 1993.
- Friedman, Ken. The Wealth and Poverty of Networks.
- Holzmann, Gerard J. The Early History of Data Networks.
- Lubrano, Annteresa. The Telegraph: How Technology Innovation Caused Social Change.
- Lucy, N.
- Shiers, George. The Electric Telegraph: An Historical Anthology.
- Winston, Brian. Media, Technology, and Society.