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147 



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tion might be changed as often as was necessary for the 

 purpose of secresy ; it being only necessary 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 commencing at the Louvre, in 

 Paris, and proceeding by Montmartre and other elevated 

 points to Lisle, in order to communicate between the Com- 

 mittee of Public Welfare and the combined armies in the 

 Low Countries. Telescopes were used at each station, 

 and the signals displayed 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 Con- 

 M-ntion, on the 17th of August, 1794, stated 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 that place. (Annual Register, 1794, p. 51.) 



The advantages of such extraordinary celerity of com- 

 munication 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, who states 

 that he had made experiments as early as 1767, when he 

 proposed to use the sails of a windmill as a means of con- 

 veying intelligence by signals. The report of Chappf's 

 telegraph revived the matter with him, and late in 1794 

 he, with some friends, tried experiments with a numerical 

 telegraph (or a telegraph expressing numbers, which num- 

 bers refer to letters, words, or sentences, in a dictionary^, on 

 the principle shown in the culFig. 3. An index, or pointer, 

 in the form of an isosceles triangle, was so mounted upon 

 a post, or on a portable triangular stand, that it might be 



Fig. 3. 



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, mount eel 

 side by side by side, as in the lower part of the figure, 

 afford power for expressing any number from 1 to 7777, 

 excepting H, !). IS, lit, 2H. 29, and all others in which the 

 numerals S and 9 are required : the first pointer represent- 

 ing 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, expres-,, collectively, the number 2774. The 

 numerical system affords at least equal facilities with the 

 alphabetic or lettering plan for secrecy in the communica- 

 tince the connection between the numbers expressed 

 and the sentences to which they refer may be changed at 

 pismire, and none of the perso'm employed in transmit- 

 ting the intelligence need to possess the dictionary, the 

 niiiiilirr being all that they require to know. In reference 

 to this distinctive feature of his plan, Kdgeworth observes 

 that, while ' telegraph is a proper name for a machine 

 which describes at a distance, trMnt*ruj>h, or, contractedly, 

 lr/.'n!fi-'i/i/;, is a proper name for a machine which de- 

 scribes wordt at a distance ;' and therefore he uses the 

 latter term. In his ' Essay on the Art of Conveying 

 Secret and Swift Intelligence,' published in the sixth 

 volume of the 'Transactions of the Royal Irish Academy,' 

 in which the details of his plan are fully given, Edgeworth 

 notice* the great advantages derivable from the applica- 

 tion of telegraphic communication to commercial and 

 's, as, for instance, to the speedy announce- 

 ment of market-prices at a distance; and even hints at the 

 possibility of a line of telegraphs between Europe and the 



East Indies. 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. 



Another of the individuals whose attention was directed 

 to this subject by Chappe's telegraph, was the Rev. J. 

 Gamble, then chaplain to the Duke of York. He issued 

 a thin quarto pamphlet, without date, entitled ' Observa- 

 tions on Telegraphic Experiments,' in which, after noticing 

 several suggestions which had been made for effecting 

 rapid communication, he propounds another, of which he 

 believed himself to be the inventor. The apparatus which 

 he proposed consisted 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 present 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 submitted to the Admiralty in 1795, by 

 Lord George Murray, was adopted in the first government 

 line of telegraphs established in England, in 1790, 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 tele- 

 graph, which was continued in use by the Admiralty until 

 the year 1816, is illustrated by Fig. 4, in which A repre- 

 scnt.-, a square frame-work with six octagonal shutter*, 

 1,2, 3, 4, 5, and 0, arranged in two vertical columns, or 



Fig. 4. 



L.J 



1 2 



sets, and turned into a vertical position, so as to display 

 their broad surfaces completely, and B represents the 

 same apparatus with the boards or shutters placed horizon- 

 tally, or turned one-quarter round upon their respective 

 axes, so as to present nothing but their ederes to Hie eye. 

 The central space between the two columns of shutters 

 serves to render them more distinct to a distant obsvn i r, 

 and affords room for the ropes and pulleys by which the. 

 telegraph is worked, and winch are managed by persons 

 in the observatory below. As shown by the following 

 table, the six-shutter telegraph is capable of express! ni; 

 sixty-three different signals, by closing one, two, three, or 

 more of the shutters, according to the Arabic numerals in 

 the table, which refer to the numbers inserted in the cut 

 l-'i f. I. A. The position of the apparatus shown in Fig. 4, B, 

 is not counted as a signal ; it being the position of rest. 



Table qf the Separate or Dittinct Si finals given by the 

 N; i -thutier Telegraph. 



1 23 124 23fi 1215 3456 



2 24 125 '21.') 12 Hi 12315 



3 25 l.'li 240 1250 123-iO 



4 26 131 250 1345 12350 



5 :!l 135 3-t5 13 Hi 12-451! 

 35 130 340 135B 13450 



12 3<i 145 :',.-,(; I I5(i 23450 



13 15 140 450 2345 123450 



14 40 150 12.'14 2310 



15 (56 234 1235 2350 



16 123 235 1236 2150 



These signals affords the means of expressing each letter 

 of the alphabet, and each of the Arabic numerals, by a 

 distinct and simple sign, and still leave several siens un- 

 appropriated, which may be applied to words or sentences 

 of common use, or to arbitrary signals ; and the connec- 



U2 



