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Optical Telegraphs
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Since the late 1500s, Europe had been a breeding ground for
fantastical rumours of the existence of a magical communication
machine. Such an invention, whereby messages could be sent instantly
over long distances, was but a dream in those days. Until a
generation of amateur inventors developed several methods of sending
instant messages, no one could produce evidence that such a
communications device was possible.
Claude Chappe was among these pioneers. When his ecclesiastical
ambition became a casualty of the French Revolution in 1789, Chappe
turned his attention to the sciences, and began tinkering with the
idea of an electric messaging system. He and his four brothers,
Ignace, Pierre, René, and Abraham set up a shop in Brûlon, France to
continue work on telegraph technology. When their initial endeavours
failed—the electric telegraph being still decades away—Chappe turned
his attention instead to simpler methods of distance communication.
The earliest of these experiments relied on the transmission of
sound through striking a metal dish. However, Chappe reasoned that
sight messages could be sent much further and more quickly.
Before this breakthrough, the world had relied upon messengers,
even as it had for thousands of years. Beyond this, developments
were of a low-tech variety, limited to communicating through visual
means using flags and smoke signals.
Chappe merely enhanced these visual methods by creating his first
optical telegraph. His "far writer" consisted of a long pivoting
board, which was painted black on one side and white on the other.
By using synchronized clocks and a simple telescope, Chappe and his
brother René exchanged messages by flipping the board from black to
white and back again at set times in accordance with the letters
they wished to convey.
In 1791, he enlisted his brothers René and Pierre to help him
conduct experiments using several varieties of the tachygraphe that
he had invented. These early versions of an optical telegraph were
tested by sending messages between Brûlon and the town of
Parsé—about 16 kilometres away. On 2 March of that year, he
demonstrated the invention in the presence of local officials, and
while initially it was met with great enthusiasm, that quickly waned
in the face of the Napoleonic Wars. His second official
demonstration, in Belleville in 1792, ended in disaster when a mob
attacked him on the belief that he was sending coded messages to the
Royalists.
Chappe had better luck with his second optical telegraph—or
semaphore—system, which consisted of two black wooden arms joined by
a crossbar and mounted atop a tower. By using a pair of ropes and a
system of pulleys and levers, each counterweighted arm was capable
of seven different positions, whereas the crossbar could move into
four different positions, for a total of 196 different positions in
combination.
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