This Day In History
Saturday, February 22, 2020
On This Day

March 2, 1791

Long-distance communication speeds up...
Long-distance communication speeds up with the unveiling of a semaphore machine in Paris. A semaphore telegraph, optical telegraph, shutter telegraph chain, Chappe telegraph, or Napoleonic semaphore 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. These systems were popular in the late 18th to early 19th century. In modern usage, "semaphore line" and "optical telegraph" may refer to a relay system using flag semaphore, and "optical telegraph" may refer to a heliograph (optical telegraphy using mirror-directed sunlight reflections).
semaphore,semaphore line,Paris
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