TEL 



146 



TEL 



lour necessary letters of the alphabet are, according to 

 this plan, which he give* on thv authority ol Joachimiu 

 Fort i us, to be divided into three clmxi of eight letters 

 eech. The first class ia represented by one torch, the 

 second by two, and the third In three . u'nd the, number of 

 the letter by the number of times which the torches are 

 elevated or discovered. Thus one torch raised once would 

 represent a. or raised eight time*. A ; two torches raised 

 one* would indicate i, raised twi. > . A : or eight times, o j 

 and three torches raised from oner mi--, would 



give thu remaining . "in r to jr. Similar to this, 



but itill eahirr of application. is tin- night -telegraph con- 

 trived by the Rev. .hum Brcmiicr. nf tin- Shetland Inlands, 

 and rewarded by the Society of Arts in 181B. A single 

 light constitutes ill.- whole apparatus in this plan, ami thu 

 whole operation consist* in its alternate exhibition and 

 concealment. The alphabet is divided into four classes 

 or divisions, of six letters each; and the number of ob- 

 scurations is to indicate, first, the number of the division. 

 and secondly, the number of the letter in that division; a 

 pause. being made betw ecn the obscurations which indicate 

 the number of the division and those which show the 

 number of the letter in that division ; and a longer pause 

 between the double set of movements thus required lor 

 every letter. Two lights, one to represent the division, 

 and th other the number of the letter, might in some 

 eases b used; but Mr. Brcmner conceives that, especially 

 in long distances, one is preferable, as affording less risk 

 of env.r. His plan had been found suitable tor distances 

 of twenty miles and upwards, and had been successfully 

 put in operation between the lighthouse on Copeland 

 Island and Port Patrick on the opposite side of the lii-h 

 Channel. Further particulars respecting this, and a de- 

 scription of another telegraph for clay-service, by the same 

 author, are given in the thirty-fourth volume of the So- 

 ciety's Transactions,' pp. IUHMF- Tedious as Mr. Brem- 

 ner's method may appear, it is stated that, supposing the 

 whole alphaoet to be used, sixty letters might easily be 

 eiven in five minutes; while the communication might 

 be effected more rapidly if, as in some telegraphic systems, 

 only sixteen letters were used. In addition to the alpha- 

 betic systems which depend merely upon the number or 

 alternate display and concealment of lights, Bishop Wil- 

 kins describes one which depends upon the relative posi- 

 tions of two lights attached to long poles, and which, he 

 says, ' for its quickness and speed is much to be preferred 

 before any ol the rest.' It will thus be perceived that 

 that ingenious writer came very near to the principle upon 

 which many of the modem telegraphic systems depend. 

 In suggesting the use of extended lines of telegraphic 

 communication, he further hints at the application of the 

 telescope (or, as he styles it, ' Galileus his perspective'), to 

 the deciphering of distant signals. 



Among the scientific writers who seem to have had 

 some notion of the modern telegraph are Kircher, Schottus, 

 and Ke-slt-r: the latter of whom proposed to cut out such 

 character* a> it was desired to show in the ends of 8 cask, 

 which was to be. ele\ated with a light enclosed in it. The 

 Marquis of Worcester also, in his -Century of Inventions,' 

 lout, announces, ' How at a window, as far as the eye can 

 ver black from white, a man may hold discourse with 

 his correspondent, without noise, made or notice taken,' 

 &c. ; and again, ' A way to do it by night as well as by 

 day, though as dark as pitch is black.' The cm-lie.-,! well- 

 defined plan of telegraphic communication appears how- 

 ever to be that de-cribed in :i paper addressed to the 

 Royal Society in 1<>H4. by Dr. Kobeit Hooke, and pub- 

 lished in I72Q>nDerham'i collection of his ' Philosophical 

 Experiments and Observations' pp. M--li)<). 'showing I 

 way how to communicate one's mind at great distances.' 

 Hooke states that he had discoursed on the subject some 

 years before, but that the then recent siege of Vienna bj 

 the Turks had revived the matter in his mind. His scheme 

 will be readily understood by the annexed cut. Fig. 1. 

 which represent* an elevated frame-work supporting a 

 panel or screen, a, behind which were to be suspended a 

 number of symbols or device*, formed of deal plank, of the 

 various shape* represented by the small black figures. 

 The firt twenty-four of these, which consist entirely of 

 straight linen, were to Htand for alphabetic characters : and 

 the mx il. -vii -es consisting of cuned lines were to be used 

 a* arbitrary signals. Whenever it was derired to display 

 ny of Oi*e characters, they were to be drawn from be- 



hind the screen by a .r pulleys in the 



frame-work, and so rendered visible in the open p; 



j. TheM telegraphs were to be erected upon elevated 







.1. 



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TJTVAXVA^ 



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stations, so chosen that, if possible, there might be no re- 

 fraction of the atmospbeie to impede vision, and so that 

 no intervening objects or disturbed background might 

 interfere with the clearness of the prospect ; and tele- 

 scopes were to be used by the observers. The older of 

 connection between the signs employed and the lett 

 the alphabet might, it is explained, be infinitely varied. 

 for the sake of secrecy ; and none of the parties einp!. 

 excepting those at the terminal stations, need h:\v . 

 knowledge of the message commnnie lie further 



proposed a scheme for night communication by means of 

 lights disposed in a ecitain older. About twi-ntv 

 after the date of Hooke's paper, Amontons brought for- 

 ward a very similar plan in France, and made public trial 

 of his contrivance before several persons of rank. ^ 

 other individuals subsequently devised similar scb. 

 but nothing was effected in the practical application of 

 telegraphic communication until the war of the French 

 revolution. Macdonald states that. 'Following the prin- 

 ciples laid down by Dr. Hooke, in 1684, Dupuis, in France, 

 invented the French telegraph, which Don Gnaltier. a 

 monk of the order of Citeaux, in 1781, modified, and pro- 

 posed to Condorcet, Milli, and Dr. Franklin, who recom- 

 mended it to the French government.' The telegraph 

 brought into use in 1793 or 1794, by M. Chappe, \\ 

 will be seen by Fig. 2, a very superior machine to that 

 of Dr. Hooke. 



Fig. 2. 



Chappe's telegraph, which, from its position when at 

 rest, is sometimes called the T telegraph, consisted of an 

 upright pole or jxist. at the top of which was pivoted, by 

 ntre, a transverse beam, which, by means of ropes 

 worked in the chamber below, that served also for an ob- 

 servatory, 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 anv required 

 angle with it ; and these arms also were worked liv 

 which were conducted through the axis of the beam, in 

 order that the necessary degree of tension might not be 

 disturbed by the action of the machine. By this 

 trivancc, without the use of any m i l"" 



'which might be indistinct when vie-.- 

 tance, 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. (.'happe 

 communicated his intelligence letter by letter, and sim- 

 plified the movements by using an alphabet of only six- 

 teen letters. The small figures in the cut show some' ol 

 the different positions assumed by the beam and ;, 

 and, as the connection between these and the letters they 

 were made to represent was quite arbitrary, their signifies- 



