The telegraph (of the Greek τηλε têlé , far and γραφειν graphein , to write) is a system intended to transmit messages of a point to another at long distances, using codes for a fast and reliable transmission.
During the French revolution, Claude Chappe, engineer Lyons, invented, developed and succeeds in imposing at the French State its revolutionary system of transmission by semaphore S, in particular thanks to the support of Joseph Lakanal: the Turn of Cap.
Until now, the sites of telegraph of Cap, because of their sites, are very required to install hertzian relays of communications and, even under consideration for a type of optical telecommunications very different: the connections Laser.
Optical telegraph
The first telegraph was optical and completely handbook. The first uses of the telegraph of Cap were dedicated to the military communication. The Message S could be transmitted on a long distance via relays spaced of ten kilometers and located on heights.
These turns were provided with a system of hinged jibs actuated manually by an operator via a system of pulleys. The operator supervised through two glasses located in an opposite way the preceding tower and the following one. Thus, it observed the signals emitted by the preceding relay and retransmettait it with the following. In the first times, two people actuated the telegraph. Quickly, due to budgetary restriction, only one operator was charged to monitor the two glasses of the tower relay. That supposed a constant observation.
This system made it possible to transmit messages much more quickly than with the mail with horse, it connected Paris to Marseilles, or Brest, for example in a few hours by using a code formed of hundreds of words and sentences which accelerated the transmission and guaranteed a certain confidentiality. It had nevertheless to be counted 20 minutes so that a code is relayed from Paris to Brest. At a rate of 40 seconds approximately between each word or expression, a message of 10 words took one hour to make the voyage, and that by not counting the possibilities of paralyzes in court of road (a relay continued to repeat the sign as long as it was not transmitted, which obliged the whole of the chain to repeat the same signal as long as the relay was not done.)
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