Optical telegraph

The optical telegraphs precede the electrical telegraph. It is faster than riding couriers for bringing a message over long distances. Types of optical telegraphs are the semaphore, [ship flags]?, smoke signals, and beacons. The distance that an optical telegraph can bridge is limited by geography, the shape of the earth, and the sharpness of the human eye. In practical use, most optical telegraphs used relay leagues to bridge longer distances.

There has been in France at the end of the XVIII^e century a complete and working installation of optical telegraph. During the Revolution period, a french inventor, Claude Chappe (1763-1805), convinced the deputies to set up a hudge network between major cities. It has been used for army and national communications till the years 1850s.

Throughout Chinese history, smoke signals were used as communication tool during war time. Until these days, the Chinese phrase (烽火 feng1 huo3) is still used as a synonym for war.

/Talk