Torches, mirrors, and smoke signals have been used to send coded messages over extended distances for at least 2,500 years. The first big improvement was the semaphore system invented in France by Claude Chappe in 1792. Similar systems were soon developed in several other countries, and military and business leaders demanded even more elaborate methods for sending complex information quickly.
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In Sweden, Abraham Edelcrantz designed signal towers that were constructed in and around Stockholm and Gothenberg starting in 1794. When completed, the system consisted of some 40 towers and could send messages over water to nearby islands. The panels were set in patterns that indicated letters, which could be seen by telescope from the next tower. |
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Edelcrantz tower (model) scale 1:10 National Museum of American History | |
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| Inside an Edelcrantz tower, Furusund, Sweden Courtesy of Telemuseum, Stockholm |
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Alexis Belloc begins his historical survey of telegraphy, La Télégraphie Historique, by describing optical signaling systems in ancient Greece, Rome, Egypt, and Persia. He also devotes many pages to the role of the Chappe semaphore in the Napoleonic wars of the early 1800s. |
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Alexis Belloc, La Télégraphie Historique … [Historical telegraphy] (Paris, 1888) Smithsonian Institution Libraries | |
| Among the communications techniques of the ancient world, John Gamble, in An Essay on the Different Modes of Communication by Signals, lists torches, smoke signals, and long chains of soldiers relaying messages by voice. |
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John Gamble, An Essay on the Different Modes of Communication by Signals (London, 1797) Smithsonian Institution Libraries | |
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Like the Chappe semaphore, this used a number code to transmit messages. |
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Portuguese version of the semaphore, early 1800s National Museum of American History | |
