Linvention of the telegraph dates from the end of the 18th century, with the development of the telegraph of Chappe, a French. This system of transmission of messages, initially optical, will become electric a few decades later. For many years, the telegram, printed on paper strips, will be the fastest way to spread information. Although of limited circulation, it is considered "the internet" of the twentieth century.
The invention of the telegraph by Chappe
Thetelegraph is invented in France during the French Revolution by Claude Chappe. The machine then consists of a mobile mast carrying articulated arms. It was an optical telegraphy system. Communication is done using signals emitted by the arms and reproduced by each operator to the destination. Establishing a code allowing complex messages to be transmitted, Chappe had the ambition to cover the entire French territory with this network.
Morse system and electric telegraph
In the nineteenth century, the development of electricity will allow an American named Samuel Morse to invent a new system to transmit messages, which will replace Chappe's everywhere in the world. Yet nothing could have suggested that Morse would achieve such a technological advance. Painter by training, Samuel Finley Morse has always been interested in electricity about which we do not know much at the time.
In 1829, he went to Europe to complete his artistic education and stayed there for three years. On the boat bringing him back to the United States, he overhears a conversation about the electromagnet that André-Marie Ampère has just invented. He then had the idea of making an electric telegraph using a simple code. As soon as he got back, he began to work on a prototype, which was completed in 1835. Two years later, Morse joined forces with the mechanic Alfred Vail and managed to operate his electric telegraph. In 1838, Morse developed the famous “Morse code”, made up of lines and dots separated by spaces. After several attempts, he finally manages to gain the support of the United States Congress, which allocates him $ 30,000 to build an experimental telegraph line between Washington and Baltimore.
The first telegram
On May 24, 1844, Morse sent his first telegram from the US Supreme Court. The message then transmitted is: "What hatli God wrought". Shortly afterwards, the system developed by Samuel Morse gained recognition around the world. In 1866, the laying of a submarine cable in the North Atlantic reduced the communication distance between London and New York by a few hours.
From the 1850s, devices were designed that used the characters of the alphabet, and no longer a code of particular signs. The Hughes system, patented in the United States in 1855 and produced in Paris, allowed a message to be written on a 28-key keyboard. The message was printed directly by the receiver, thanks to a clockwork movement synchronized with the transmitter keypad. The Hughes Telegraph had an average speed of 45 words per minute. The most efficient system was developed in France by Émile Baudot in 1874. The inventor imagined a 5-key keyboard, allowing faster typing. He thus increased the average speed to 60 words per minute. The Hughes system and its improvements were very successful and were used until the early 1950s.
The development of transoceanic telegraph lines
In the mid-19th century, engineers attempted to make telegraph lines crossing the oceans. The first submarine link was the Dover-Calais line, opened in November 1852. On the other hand, crossing the Atlantic proved more difficult. After an unsuccessful attempt in 1858, the first line was put into service in 1866. It was then the beginning of progress that never slowed down. The United Kingdom thus developed an extremely extensive intercontinental network, which at the beginning of the 20th century included nearly 250,000 km of telegraph lines.
It was in the British Empire that the telegraph will experience its heyday. As early as 1838, the first commercial electric telegraph line had been laid along a railway line. Deployed throughout the empire of Queen Victoria, and especially in India, the telegraph is essential as a diplomatic and strategic tool by accelerating communications over long distances. Its operation remains expensive and will never become domestic, unlike the "talking telegraph" which will succeed it, the telephone.
- History of telecommunications in France, by Catherine Bertho. Eres, 1984..
- The fabulous history of inventions - From mastery of fire to immortality. Dunod, 2018.