The construction of the machine was such, that each signal was uniformly giv en in precisely the same manlier at all times : It did not depend on the opera tor's manual skill ; and the position of the arm could never, for any one signal, be a degree higher or a degree lower, its movement being regulated mechanically. M. Chappe having received at the Louvre the sentence to be conveyed, gave a known signal to the second station, which was Mont Martre, to prepare. At each station there was a watch tower, where telescopes were fixed, and the per son on watch gave the signal of prepa ration which he had received, and this communicated successively through all the line, which brought them all into a state of readiness. The person at Mont '!Maitre then received, letter by letter, the sentence from the Louvre, which he repeated with his own machine ; and this was again repeated from the next height, with inconceivable rapidity, to the final station at Lisle.
Various experiments were in conse quence tried upon telegraphs in this country ; and one was soon after set up by government, in a chain of stations from the Admiralty office to the sea coast. It consists of six octagon boards, each of which is poised upon an'axis in a frame, in such a manner that it can be either placed vertically, so as to appear with its full size to the observer at the nearest station, or it becomes invisible to him by being placed horizontally, so that the narrow edge alone is exposed, which narrow edge is from a distance invisible. Six boards make thirty.six changes, by the most plain and simple mode of work ing ; and they will make many more, if more were necessary : but as the real su periority of the telegraph, over all other modes of making signals, consists in its making letters, we do not think that more changes than the letters of- the alphabet, and the arithmetical figures, are neces sary ; but, on the contrary, that those who work the telegraphs should avoid communicating by words or signs agreed upon to express sentences ; for that, is the sure method never to become expert at sending unexpected intelligence accu rately. This telegraph is, without doubt,
made up of the best number of combina tions possible ; five boards would be in sufficient, and seven would he useless. It has been objected to it, however, that its form is too clumsy to admit of its be ing raised to any considerable height above the building on which it stands ; and that it cannot be made to change its direction, and consequently cannot be seen but from one particular point. Seve ral other telegraphs have been proposed to remedy these defects, and perhaps others to which the instrument is still liable. The dial-plate of a clock would make an excellent telegraph, as it might exhibit one hundred and forty-four signs, so as to be visible at a great distance. A telegraph on this principle, with only six divisions instead of twelve, would be sim ple and cheap, and might be ridged, twen ty or thirty feet high above the building without any difficulty : it might be sup ported on one post, and therefore turn round ; and the contrast of colours would always be the same.