Optical Telegraph: The Email of the 18th Century

Email, SMS, and apps like WhatsApp—with their near-instant message transmission—are now part of our daily lives. A very large percentage of people in developed countries use these services daily. However, humanity managed quite well for centuries communicating without electronics.

But we often forget that most of the communication methods we use today require electrical energy to function. A phone call, an SMS, sending an email, or a videoconference all need this form of energy. If the power supply is cut for any reason, we become isolated.

However, there are other ways to communicate. Although they may seem extremely rudimentary, communication over relatively large distances using signals made with flags or lights works perfectly well. And it's possible to send messages at a more than acceptable speed.

Claude Chappe's Optical Telegraphy

In fact, French inventor Claude Chappe is considered the first communications magnate. This wouldn't be particularly interesting if it weren't for the fact that Chappe was born in France in 1763, at a time when electricity was still something like magic. Nevertheless, the inventor created an optical telegraphy system that in 1792 allowed messages to be sent across France at speeds of over 1,000 kilometers per hour. And without using electricity!

Claude was born into a wealthy family, and was the grandson of a French baron. But the French Revolution transformed his life, and together with his four brothers he took on the development of a system of telegraph stations. It was an idea that had been attempted several times, but no one had managed to make it work in practice.

Chappe built a series of towers, separated from each other by 12 to 25 kilometers. In each tower there was a person responsible for receiving and retransmitting messages, using a pair of telescopes. These telescopes pointed one toward the immediately preceding tower, and another toward the following tower. The secret of the success of the system devised by the Frenchman was in what these operators observed.

After many trials, Chappe discovered that over long distances it was easier to distinguish angles on a rod than the presence or absence of flags or signals. So each tower included a mast that had at its upper end small pieces of shorter length called indicators. These arms, measuring 3 x 0.3 meters and black in color, had the appropriate counterweights to be operated effortlessly using two handles.

A 'dictionary' of valid positions for the arms was created, consisting of 196 possible positions. Each combination of angles and arms was assigned to a letter, word, or even a complete phrase, making it possible to transmit relatively long messages in very short times.

A trained operator could 'read' three or four symbols per minute and transmit them to the next tower. A message could travel about 1,380 kilometers in an hour, the same speed at which a passenger plane travels today. Two centuries ago, such speed was totally revolutionary.

Two hundred years before the arrival of the internet, in 1792, the first messages were successfully sent between the cities of Paris and Lille, 230 kilometers apart, using 15 towers built by Chappe. Two years later, Paris received via optical telegraph the news of the capture of Condé-sur-l'Escaut, less than an hour after the event occurred. This was completely unprecedented in a world that took days or weeks to learn of news.

This event was the trigger for the success of Chappe's system. Other lines were built, incorporating more French cities and also neighboring countries. In fact, the system was used by Napoleon to coordinate the empire and the army. It is estimated that by 1793 there were already more than 5,000 kilometers covered by these stations, the first to receive the name 'Telegraph'.

Only in 1846 did the French government adopt a new means of communication: the electric telegraph. Although many intellectuals of the time warned of the weakness of the new system, since a telegraph cable could be sabotaged simply by cutting it, the use of electricity in communications would never be abandoned.

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