First Demonstration of Semaphore Telegraph

Date: March 2, 1791 • Location: Paris, France

French inventor Claude Chappe and his brothers first demonstrated the semaphore telegraph, a system to convey information by means of visual signals, using towers with pivoting crossarms.

Claude Chappe was a French inventor who in 1792 demonstrated a practical semaphore system that eventually spanned all of France. His system consisted of a series of towers, each within line of sight of others, each supporting a wooden mast with two crossarms on pivots that could be placed in various positions. The operator in a tower moved the arms to a sequence of positions, spelling out text messages in semaphore code. The operator in the next tower read the message through a telescope, then passed it on to the next tower. This was the first practical telecommunications system of the industrial age, and was used until the 1850s when electric telegraph systems replaced it.