Semaphore
To meet the need for swift communication between Napoleon's (1769-1821) far-flung armies in the 1790s, the Frenchman Claude Chappe (1763-1805) invented an optical-relay system of visual telegraphs that he called the semaphore. His system consisted of tall vertical posts, each of which supported a movable crossbar with movable arms at each end. Using a system of pulleys and ropes, the semaphore operator would move the crossbeam and its indicator arms into a variety of positions that represented numbers and the different letters of the alphabet. Chappe installed his signalling mechanisms on hilltop towers which allowed an unobstructed view. While such a system would have been possible many centuries earlier, Chappe's made use of both a signalling code and the recently invented telescope to read signals across distances much greater than would previously have been possible.
Giving the name telegraph to his signalling system, Chappe secured a commission from the French government as Ingénieur-Télégraphe in 1793 and installed a line of semaphore towers from Paris, France, to Lille, France. With each tower was approximately 6 miles (10 km) apart, the distance covered totaled 144 miles (231.7 km).
Messages could be sent 90 times faster with the Chappe semaphore than by horse-riding couriers. The new telegraphy achieved wide popularity when it was used to bring news of victories on the Napoleonic battlefields in 1794. Soon Chappe semaphores covered most of France, and were only supplanted by the electric telegraph in the 1850s.
In England, George Murray and John Gamble had built an optical signaling system in 1795, consisting of a tower-mounted box with six movable shutters that opened and closed to produce coded messages. Chains of these shutter telegraphs were built in Britain in the early 1800s, but they were gradually replaced between 1811 and 1814 with the Chappe semaphore system. In the United States, Jonathan Grout built the first commercial semaphore system in 1800 between Boston, Massachusetts, and Martha's Vineyard to send news about ship and cargo arrivals. Various telegraph and signal hills can still be found on maps of Cape Cod. Proposals in the United States Congress to award $30,000 to build a semaphore telegraph system all along the Atlantic Coast led to Samuel Morse's successful application for government support of his electric telegraph. Once the electric telegraph was perfected, the semaphore was doomed by its inherent limitations: it was unusable at night or when bad weather reduced visibility, and was restricted in its speed of transmission by the manual demands it put on the operator.
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