The Semaphore Telegraph
The word telegraph, which comes from Greek and means distance writing, usually raises the image of messages transmitted and received in code by electrical transmission over wires or radio waves. In fact the word was first used to describe a system developed by Claude Chappe of France during the Napoleonic Era. A system of towers scattered across the French Empire allowed messages to be transmitted from Paris to Venice, Amsterdam, Mainz, Strasbourg, and throughout metropolitan France in the shortest amount of time yet achieved, and led to other nations copying it to improve communications internally and with each other.
Throughout the French system, which consisted of 534 stations at its peak, messages could be sent and received in minutes and hours, rather than days and weeks. The system relied on visual communication between the towers on which the semaphores were installed, and were thus subject to interruption based on the weather. By 1794 the telegraph could transmit a message from Paris to Lille, a distance of over 140 miles, in just over a half hour, through fifteen stations which connected to two cities. As the French Empire grew following the French Revolutionary Wars, Napoleon could keep track of events in Paris and the rest of the Empire in a manner of hours.
The system used a crossbar on either end of which were attached movable wooden bars painted black. The angle of the crossbar and the corresponding changeable angles of the wooden bars determined the letter or number represented. The operator changed letters by moving the wooden bars and the angle of the crossbar in relation to the center of the tower. The transmission of a single letter required three separate movements. The first centered the black bars with the crossbar, the second displayed the letter being transmitted, and the third returned the crossbar to the center position. About three letters or numbers per minute could be transmitted.
The French system was so successful that both during and following the Napoleonic Wars other countries installed systems of their own, with modifications befitting their own needs. The first system in North America was begun in Canada in 1800. In the United States a system was built connecting Martha’s Vineyard with Boston for the purpose of transmitting shipping information. In several cities in the English speaking world, hills upon which semaphore towers were erected came to be called Telegraph Hill. France’s telegraph system became so extensive and successful that Samuel Morse was at first unsuccessful in selling his electric telegraph there.
In most countries the semaphore telegraph system came under the operation of the national postal system, and were used extensively to communicate trade news and other business considerations. In areas where there were sufficiently close islands in chains, semaphores were built to transfer information across bodies of water, such as the English Channel at the Pas de Calais, and across the Great Belt Strait in Denmark. By the mid-nineteenth century the semaphore telegraph was obsolete, unable to compete with the speed of the electric telegraph, and most of the towers were abandoned or demolished, though across Europe many remain.