TELEGRAPH. 



ters, which are to appear dark againft the (ky, beyond thfm 

 appearing white, by which means ;iiio the vapours near the 

 ground will be pafled over and avoided. Next, in clioofing 

 thefe ftations, care muft be taken, as near as may be, that 

 there be no hill that interpofes between them, that is almotl 

 high enough to touch the vifible ray, becaufe in fnch cafes 

 the refraftion of the air of that hill will be very apt to dif- 

 turb the clear appearance of the objctl. The (lations being 

 found convenient, the next thing to be confidered is, what 

 telefcopcs will be neceflary for each ftation. One of thefe 

 telefcopes muft be fixed at each extreme ftation, and two of 

 them in each ' intermediate ftation ; fo that a man for each 

 glafs, fitting and looking through them, may plainly dif- 

 cover what is done in the next adjoining ftation, and with 

 his pen write down on a paper the charafters there expofed, 

 in their due order ; fo that there ought to be two perfons at 

 each extreme ftation, and three at each intermediate one, that 

 intelligence may be conveyed backwards and forwards at the 

 fame time. Next there muft be certain times agreed on, 

 when the correfpondents are to expeft it ; or elfe there muft 

 be fet at the top of a pole, in the morning, the hour ap- 

 pointed by either of the correfpondents for afting that 

 day. 



" Next there muft be convenient apparatus of charafters, 

 confifting of at leaft as many diftinft charafters as there are 

 secefTary letters in the alphabet, (to be made ufe of as is ex- 

 prefled in Plate Telegraph, fg. I.) And thefe muft be either 

 day charafters or night charafters. If they are to be made 

 ufe of in the day-time, they may all be made of deals, and 

 of a fize convenient for the feveral diftances, any one of 

 which charafters may fignify any one letter of the alphabet, 

 and the whole alphabet maybe varied io,ooo ways, fo that 

 none but the two extreme correfpondents fhall be able to dif- 

 cover the information conveyed. If the charafters are for 

 the night, then they may be made with links, or lights dif- 

 pofed in a certain order, which may be covered or un- 

 covered, according to the method agreed on. There will be 

 alfo requifite feveral other charafters, which may for expe- 

 dition exprefs a whole fentence, fuch as ' I am ready to 

 communicate ;' ' I am ready to obferve.' I could inftance 

 a hundred ways of facilitating the method of performing the 

 defign with the more dexterity and quickncfs, and with little 

 change, but that I think will, be needlefs at prefcnt, fince, 

 whenfoever fuch a way of correfpondence . ftiall be put in 

 praftice, thofe and many more than I can think of at pre- 

 fent will of themfelves occur, fo that I do not in tlie leaft 

 doubt but that with a little praftice dl things may be made 

 fo convenient, that the fame charafter may be feen at Paris, 

 within a minute after it hath been expofed in London ; and 

 that the charafters may be expofed fo quick after one ano- 

 ther, that a compofer ftiall not much exceed the expofer in 

 fwiftnefs, and this not only at the diftance of one ftation, 

 but of an hundred ; for fuppofing all things ready at all of 

 thofe feveral ftations for obferving and expofing as fail as the 

 fecond obferver doth read the charafters of the firft expofer, 

 the fecond expofer will difplay them to the obferver of the 

 third ftation, whofe expofer will likewife difplay them for 

 the fourth obferver, as faft as his obferver doth name them 

 to him or write them down. There may be many objeftions 

 brought againft this way of communication, becaufe it has 

 not yet been put in praftice, but hardly any that may not be 

 eafily anfwered and obviated." 



Dr. Hooke illuftrates his invention thus : Let ABC 

 (^jig. 2.) reprefent three very long mafts or poles erefted, E 

 the top piece that joins them together, D a fcrecn, behind 

 which all the deal-board charafters hang upon certain rods 

 or line8, and may, by the help of fniall lines connefted with 



each of them, be expofed at 1"', or drawn back at D, at 

 occafion may require. 



This propofal of our ingenious countryman it very com- 

 plete and well ftndied ; it would be Icfs convenient and expe- 

 ditious than the modern telegraphs, but would certamly have 

 anfwered very ufifiil purpolee, with the advantage of being 

 very free from the uncertainties and errors of more complete 

 machines, which, at the fame time that they admit of mak- 

 ing a greater variety of figns than the letters of the alphabet, 

 are for the fame reafon more liable to miftakes in exhibiting 

 as well as in reading or tranflating them. The only obvious 

 improvement on Dr. Hooke's telegraph is, that, inilcad of 

 concealing the charafters behind the fcreen D, they (hould 

 be kept down below in the houfe on which the machine 

 is to be erefted, and be hoifted up into tlie frame when they 

 are to be exhibited. 



M. Amontons, an ingenious French academician who ftu. 

 died mechanics, was born at Paris in 1663, and died in 1 705, 

 at the age of forty-two. He propofed the following method : 

 Let there be people placed in l^L'veral ftations, and at fuch 

 a diftance from each other, that by the help of a telcfcope, a 

 man at one ftation may fee a fignal made in the next before 

 him : he muft immediately repeat the fame fignal, that it 

 may be feen by perfons in tlie ftation next after him, who 

 are to communicate it to thofe in the following ftation, and 

 fo on. Thefe fignals may be as letters of tlie alphabet, or 

 as a cipher, underftood only by the two perfons who are in, 

 the diftant places, and not by tliofe who make the fignals. 

 The perfon in the fecond ftation making the fignal to the 

 perfon in the third the very moment he fees it in the firft, 

 the news may be carried to the greateft diftance in as little 

 time as is neceftary to make the fignals in the firft ftation. 

 The diftance of the feveral ftations, which muft be as few 

 as poftible, is meafured by the reach of a telefcope. M. 

 Amontons is faid to have tried this method on a fmall traft 

 of land, before feveral perfons of the highefl rank at the 

 court of France ; but we are not acquainted with the kind of 

 apparatus he employed ; all that we know of his method is 

 precifely the fame as Dr. Hooke's. 



Guyat, a long time after Dr. Hooke, propofed tables, 

 with letters cut out in them : and Paiihan, in his Diftionnaire 

 de Phyfique, defcribes a tranfparent figure, confilling of 

 one perpendicular and three Iiorizontal ftripes, forming ten 

 compartments, each of which can be rendered vifible or in- 

 vifible at pleafure, by blinds or ftiutters moveable from 

 behind. 



Mr. Richard LovcU Edgeworth, in a memoir which he 

 prefented to the Royal Society of Ireland (fee their Tranf- 

 aftions, vol. vi. p. 125.), adduces proof, that in 1767 he tried 

 an experiment of tlie prafticabllity of communicating intel- 

 ligence by a fwift and unfufpefted mode ; and for this pur- 

 pofe he employed a common windmill, and arranged a fyf- 

 tem of fignals, which could be made by the different pofitions 

 of the arms of its fails, the canvas being removed fr^i" °n*' 

 or more arms, as was required. Thefe fignals were made to 

 denote numbers, and both parties were provided with voca- 

 bularies, in which all the words were numbered. 



French Telegraph Akhough the telegraph was thm 



fully explained in 1684, it does not appear that this valuable 

 invention was at all praftifed or applied to any ufcful pur- 

 pofe until 1793 or 1794, \\hen the events of the French re- 

 volution had direfted all the energies of that ingenious people 

 to the improvement of the art of war. A report made by 

 Barrere to the fitting of the French Convention in Auguft 

 1794, attributes the invention of the telegrapli which they 

 ufed to citizen Chappe. 



" The new invented telegraphic language of fignals is an 



artful 



