Télégraphe de Chappe
Semaphore, also called télégraphe de Chappe.
A few pages about communication by means of semaphores:
IEEE Global History Network The Telegraph of Claude Chappe - an optical telecommunication network for the XVIIIth century (pdf).
Wikipedia Semaphore line.
BBC News How Napoleon's semaphore telegraph changed the world.
Now the French use chinese modems.