Episode 2 of 3

Public Demonstration between Brûlon and Parcé

When: 2 March 1791
Where: Brûlon–Parcé line
Part of: Demonstration of the Mechanical Telegraph by Claude Chappe

Chappe's first public demonstration of the optical system took place on 2 March 1791 across a 16-kilometre line.

Chappe settled on an optical system, and the first public demonstration occurred on 2 March 1791 between Brûlon and Parcé, a distance of 16 kilometres (9.9 mi). The demonstration used the semaphore principle in which an operator in a tower moved pivoted arms through a sequence of positions spelling out text messages in semaphore code.

Sources

Optical telegraph Wikipedia, revision of 2026-06-11
Claude Chappe Wikipedia, revision of 2026-05-16

Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.