How Napoleon’s semaphore telegraph changed the world

A BBC article from back in June this year that I happened to miss on the world’s first telegraph network.

Hugh Schofield recounts the wonderful description by Alexandre Dumas in The Count of Monte Cristo on one of these ‘Chappe stations’  (named after their creator, Claude Chappe):

The count sees the contraption “like the claws of an immense beetle” and feels wonder that “these various signs should be made to cleave the air with such precision as to convey to the distance of three hundred leagues the ideas and wishes of a man sitting at a table”.

The video at the top of the article also contains some information on the relay of messages. Telegraph operators, although mechanically involved, were not privy to the content of the messages sent. Only ‘superintendents’ were able to decode such commands. This was because a code book or vocabulary was required in order to parse the message and understand its sending.

The reason why this is so incredible is that semaphore lines required a line of sight. The mechanical arms of each station needed to be visible to other stations in order for messages to be received and decoded. In so being, anyone in the surrounding area and within the line of sight could indeed see the mechanical arms, but crucially for its deployment as a military technology, not actually read the message. To all without the code book the content of the message remained a mystery. For something so visible there is a startlingly secret dimension to its operation. Despite the possibility, as Dumas evocatively notes, to “convey…the ideas and wishes of a man sitting at a table” there were actually very few people to whom this transmission was deemed accessible, open and actable upon.