The Semaphore Machine

Communication over the years has not always been easy. Before mail service, the people sent messages via horse and riders, called post riders. I’m sure that messages were only sent in this way when the message was really important, because it would be silly to pay someone to send a simple letter, or notes like our text messages of today. Just imagine that cost if the messages went back and forth as much as texts do. Nevertheless, post riders were the only way to get a message out in 1791. Inventions happen at a time when they are least expected, and just because it was 1791, doesn’t mean that the next year couldn’t bring something amazing. In this case, that is exactly what happened.

After seeing the problems there were with communications, Claude Chappe of France invented a system of communication that he called the Semaphore Machine. In reality it was an early form of the telegraph system we all know about. The machine was used until the nineteenth century when the telegraph was invented. The Semaphore system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed. The system worked by conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the shutters. It is read when the shutter is in a fixed position. The lines were a precursor to the electrical telegraph. It was also considered more private, which seems odd to me. How could a message relayed from the top of a tower be private? Of course, not everyone knew how to read the messages, but it would seem like there would be a few people who learned the codes and so could read the messages. Still, I suppose that the people who translated the messages were sworn to secrecy.

The system did have its drawbacks. The distance that this optical telegraph could bridge was limited by geography and weather. It could not be seen in rain or snow, and could not be seen over a hill. That limited its practical use. The solution was to use relay stations to reach longer distances. Of course, the system couldn’t cross expanses of water, unless a convenient island could be used for a relay station. While the system had its problems, it did serve a useful purpose in its time. In some forms, it is still used today. One modern version of the semaphore system is a flag semaphore, or a flag relay system. Another is the heliograph, which is an optical telegraph using mirror-directed sunlight reflections. I think anyone who has watched a movie about ships might recognize that one. It was how they signaled from one ship to another. Maybe the Semaphore Telegraph system wasn’t so antiquated after all.