In 1789, Claude Chappe, a priest, arrived in Paris showing his optical telegraph invention, which he called a 'semaphore'. This invention drew the attention of physics and mechanics fan G. Romm, stressing its importance before the war, its cheapness, convenience and speed. The Order released money to build such a telegraph 210 km long between Lille and Paris. In 1794, its construction was complete. 20 intermediate stations were established between the two cities.
Each of them was equipped with a vertical mast resembling a railway semaphore. Movable rulers were fastened to the end of the mast. With the help of cords and blocks, rulers could take 196 different positions, representing not only all the letters, but the most commonly used words. Each station was serviced by one or two employees. They watched the neighbor through a telescope and reproduced at its mast those signals that they recieved from the neighbor. Then the signals were passed on. So, letter by letter, word by word, dispatches were transmitted from one station to another along the line.
Similar telegraph lines were introduced by Nicholas I in Russia. A message was transferred from Brest to Paris in seven minutes using an optical telegraph. The only drawback of this telegraph was that during poor visibility it was impossible to send messages. In addition, stations had to be built close to each other. The optical telegraph existed in Russia in the 1860s