The Story of the Semaphore Part III
This third article in a series deals with “Semaphore Machines”, the devices used to transmit messages visually across long distances before the invention of the electric telegraph. All relied on a system of moveable arms or shutters, whose position indicated specific numbers or letters. Beginning with the French Chappe system first deployed in 1794, over the next 50 years dozens of semaphore systems were proposed, and a number were implemented in Britain, continental Europe and India. Such devices were used both for military purposes, and to transmit urgent commercial information to and from ports.