3H On the Invention of the Telegraph. 



of the laft century, and that he gave the firft complete dc 

 fcription of fuch a machine, as appears by the following ex- 

 tract from a paper of his, read before the Royal Society on 

 the 2 1 ft of May 1684*. " I propofed (fays he) fome year* 

 fince, a method of difcourfing at a diftance, not by found, 

 but by fight. I fay that it is pofiible to convey intelligence 

 from any one high and eminent place to any other that lies 

 within fight of it, though 3c or 4.0 miles diftant, in as fhort 

 a time almoft, as a man can write what he would have fent; 

 and as fuddenly to receive an anfwer as he that receives it 

 hath a mind to return it, or can write it down on paper. 

 Nay, by the help of 3, 4, or more of fuch eminent places, 

 vifible to each other, lying next in a ftraightline, 'tis poflible 

 to convey intelligence almoft in a moment, to twice, thrice, 

 or more times that d:ftance, with as great a certainty as by 

 writing. 



11 For the performance of this, we muft be beholden to a 

 late invention, which we do not find any of the ancients 

 knew; that is, the eye muft be afllfted with telefcopes, that 

 whatever characters are expofed at one ftaion, may be made 

 plain and diftinguifhible at the other. 



" lft, For the ilations: if they be far diftant, it will benc- 

 ceffary that they fhould be high, and lie expofed to the fky, 

 that there be .no higher hill, or part of the earth beyond 

 them, that may hinder the diftinctnefs of the characters, 

 which arc to appear dark, the ficy beyond them appearing 

 white. By which means, alfo, the vapours near the ground 

 will be puffed over and avoided. 



" Next, in chufing of thefe ftations, care muft be taken, as 

 near as may be. that there be no hijl that interpofes between 

 them, that is almoft high enough to touch the vifible ray; 

 becaufe, in fur 7 ! cafes, the refraction of the air of that hill 

 will be very apt to diilurb the clear appearance of the object. 



f The whole paper may be feen in " Philofophical Experiments and 

 Obfervations of the late eminent Dr. Robert Hooke," publilhed by Mr, 

 perham. London, 1726. 



"The 



