TELEGRAPH. 



TELEGRAPH. 



About twenty years after the date of Hooke's paper, Amontons brought 

 forward a similar plan in France. Some other individuals subsequently 

 devised similar schemes, but nothing was effected in the practical 

 application of telegraphic communication until the wars of the French 

 revolution. Macdonald states that, " Following the principles laid 

 down by Dr. Hooke, in 1684, Dupuis, in France, invented the French 

 telegraph, which Don Gualtier, a 'monk of the order of Citeaux, in 

 1781, modified, and proposed to Condorcet, Milli, and Dr. Franklin, 

 who recommended it to the French government." The telegraph 

 brought into use in 1793 or 1794, by M. Chappe, was, as will be seen 

 by fg. 2, a very superior machine to that of Dr. Hooke. 



Fig. 2. 



Chappe's telegraph, which, from its position when at rest, is some- 

 tunes called the T telegraph, consisted of an upright pole or post, at 

 the top of which was pivoted, by its centre, a transverse beam, which, 

 by means of ropes worked in the chamber below, that served also for 

 an observatory, might be made to assume any required angle with the 

 post. Each end of this moveable beam carried a short arm, that was 

 capable of assuming any required angle with it ; and these arms also 

 were worked by ropes, which were conducted through the axis of the 

 beam, in order that the necessary degree of tension might not be dis- 

 turbed by the action of the machine. By this contrivance, without 

 the use of any angles of less than 45 (which might be indistinct when 

 viewed from a great distance, or under the influence of a refractive 

 atmosphere), as many as 256 different signs might be made. A much 

 smaller number was however sufficient, as M. Chappe communicated 

 his intelligence letter by letter, and simplified the movements by using 

 an alphabet of only sixteen letters. The small figures in the cut show 

 some of the different positions assumed by the beam and arms ; and, 

 as the connection between these and the letters they were made to 

 represent, was quite arbitrary, their signification might be changed as 

 often as was necessary for the purposes of secrecy ; it being only neces- 

 n.iry that the key should be known to the parties sending and receiving 

 the message, although it might be transmitted through a great number 

 of intermediate stations. Such telegraphs were first erected on a line 

 < '.imnencing at the Louvre, in Paris, and proceeding by Montmartre 

 and other elevated points to Lisle, in order to communicate between 

 the Committee of Public Welfare and the combined armies in the Low 

 Countries. Telescopes were used at each station, and the signals dis- 

 played at one station were immediately repeated at the next ; four 

 seconds being found sufficient for effecting the required motions, and 

 sixteen seconds the time allowed for observing and noting down each 

 signal, during which the machine remained stationary. Barrere, in 

 announcing the invention of the telegraph to the Convention, on the 

 17th of August, 1794, utated that the news of the recapture of Lisle 

 had, by means of this machine, reached Paris in an hour after the 

 troops of the Republic had entered the place. (' Annual Register,' 



The advantages of such extraordinary celerity of communication 

 were so obvious, that in England and other countries many plans were 

 immediately brought forward, some of which differed materially from 

 that which had been successfully put in practice in France. Among 

 these was that contrived by Mr. R. L. Edgeworth. whose numerical 

 telegraph (or a telegraph expressing numbers, which numbers refer to 

 letters, words, or sentences, in a dictionary), will be understood by 



I i -. ::. 



means of fy. 3, in which an index or pointer, in the form of an isos- 

 celes triangle, was so mounted upon a post, or on a portable triangular 



ARTS AND SCI. DIV. VOL. VIII. 



stand, that it might be turned into any of the eight positions shown in 

 the upper part of the cut ; these positions indicating, respectively, 

 and the numerals 1 to 7. Four such pointers, mounted side by side, 

 as in the lower part of the figure, afford power for expressing any 

 number from 1 to 7777, excepting 8, 9, 18, 19, 28, 29, and all others 

 in which the numerals 8 and are required : the first pointer repre- 

 senting thousands, the second hundreds, the third tens, and the fourth 

 units. Thus, the four black pointers in the figure being, respectively, 

 in the positions indicating 2, 7, 7, and 4, express, collectively, the 

 number 2774. Further particulars of this method will be found in 

 Edgeworth's ' Essay on the Art of Conveying Secret and Swift Intelli- 

 gence,' published in the sixth volume of the ' Transactions of the Royal 

 Irish Academy.' He also published a pamphlet entitled ' A Letter to 

 the Right Honourable the Earl of Charlemont on the Tellograph, and 

 on the Defence of Ireland," which was reprinted at London in 1797. 



The Rev. J. Gamble, chaplain to the Duke of York, proposed a 

 shutter telegraph, consisting of a frame-work containing five boards, or 

 shutters, arranged vertically one above the other, and pivoted in such 

 a way that any or all of them might be closed, so as to present their 

 broad surfaces to the eye, or opened, so as to show merely a thin 

 edge, which would be invisible at a distance. The various signals 

 produced by closing one or more of these shutters may be applied 

 either to a numerical or an alphabetical system. A similar plan sub- 

 mitted to the Admiralty in 1795, by Lord George Murray, was adopted 

 in the first government line of telegraphs established in England, in 

 1796, between London and Dover. The 'Annual Register 'for that 

 year (p. 4 of the ' Chronicle ') mentions the erection of the telegraph 

 over the Admiralty on the 28th of January, and states that information 

 had been conveyed from Dover to London in seven minutes. The 

 action of this kind of telegraph, which was continued in use by the 

 Admiralty until the jear 1816, is illustrated by ,/?</. 4, in which A 



Fig. 4. 





L 



represents a square frame-work with six octagonal shutters, 1, 2, 3, 4, 5, 

 and 6, arranged in two vertical columns, or sets, and turned into a 

 vertical position, so as to display their broad surfaces completely, and 

 n represents the same apparatus with the boards or shutters placed 

 horizontally, or turned one-quarter round upon their respective axes, 

 so as to present nothing but their edges to the eye. The central space 

 between the two columns of shutters serves to render them more 

 distinct to a distant observer, and affords room for the ropes and 

 pulleys by which the telegraph is worked, and which are managed by 

 persons in the observatory below. A modification of this kind of 

 telegraph, intended for night as well as for day service, was submitted 

 to the Society of Arts, in 1805, by Mr. Joseph Davis. About the same 

 time that shutter-telegraphs were being introduced in England, the 

 Chevalier A.' N. Edelcranta, of Stockholm, was devising similar 

 machinery for use in Sweden. (See Nicholson's 'Journal/ 1803; 

 Society of Arts ' Transactions' for 1808.) Other modifications of the 

 shutter telegraph were put forward from time to time, but experience 

 established the superiority of telegraphs or semaphores with moveable 

 arms ; and these were greatly simplified, so as to avoid the objection 

 raised to the old French telegraph. Among the schemes proposed soon 

 after the first practical application of telegraphs, was one which consisted 

 in dividing a large circle into twenty four parts, for the letters of the 

 alphabet, and employing a traversing radius, or index, to point them 

 out ; wires being fixed before the object-glass of the telescope to enable 

 the distant observer to determine the position of the radius. This plan 

 could only be applied to short distances, because refraction might 

 render it difficult to distinguish between positions so little varying 

 from each other. The same radiating principle was, however, adopted 

 in some machines of a more practical character ; among which was a 

 telegraph contrived by the Rev. J. Gamble, consisting of five beams or 

 arms pivoted at the top of a post, upon one axis, and capable of pro- 

 ducing many different combinations without using angles of less than 

 45. On a similar principle were constructed the French coast 

 telegraphs adopted in 1803, to which the name of semaphore was first 

 applied, and from which it has been given to other telegraphic machines, 

 the action of which is dependent upon the motion of arms around 

 pivots placed at or near their extremities. These French semaphores, 

 or, as they were sometimes called, signal-posts, consisted of upright 

 posts with two or three moveable arms, turning upon separate pivots, 

 one above the other. Before they were much known in this country, 

 Captain Pasley had been led to observe the inferiority of the common 

 land-telegraph to that used at sea, which consisted of coloured flags, 



F 



