How Can You Send Messages Fast Without Electricity?

In the midst of the French Revolution, a former priest turned engineer built a signalling system based on visible signs that could be seen at a considerable distance. Claude Chappe’s invention consisted of a series of poles placed on rooftops or towers. Upon each pole a moveable crosswise beam was fastened that held two moveable arms. Signalmen used ropes to adjust the apparatus in no less than 196 positions that someone far off with a telescope could distinguish. Each position represented an upper case or lower case letter, a punctuation mark, or a numeral.

The first semaphore line of 22 stations went into service in 1794 linking Paris with Lille, a distance of more than 240 kilometers. It took from two to six minutes to transmit a brief message. The alternative, a rider on a horse, would have taken 30 hours.

Over the years the semaphore system changed. In 1850 the British railways began using metal arms in daylight and rows of lights in fog or darkness to signal trains. The U.S. Navy, among others, uses flags, half red, half yellow, divided diagonally, that a semaphore operator extends at different angles to indicate letters of the alphabet, numerals, or commands, the 30 positions of the International Standard Semaphore Code.

This spells MEDIA HISTORY