THE SOURCE OF T HE NILE. e0$ 



On tile day of the fummer folilice, at the moment the 

 fim was ftationary in the meridian of Syene, he placed a ftyle' 

 perpendicularly in the bottom of a half -concave fphere,- 

 whichhe expofed in open air to the fun at Alexandria. Now,, 

 if that ftyle had call no made at Alexandria, it would have 

 been precifely in the fame circumitance with a ftyle in the 

 well in Syene ; and the reafon of its not calling the made 

 would have been, that the fun was directly vertical to it. 

 But he found, on the contrary, this ftyle at Alexandria did 

 cart a fhadow ; and by meafuring the diflance of the top of" 

 this fhadow from the foot of. the ftyle, he found, that, when, 

 the fun call no fhadow at Syene, by being in the zenith, at: 

 Alexandria he projected a fhadow ; which mewed he was 

 diftant from the vertical .point, or zenith, jj-0=y° 1 2 7 , which, 

 was yVth of the. circumference of the whole heavens, or of 

 a great circle,-. 



This being fettled, the concltifion was, that Alexandria 

 and Syene mufl be diftant from each other by the 50th part- 

 of the circumference of the whole earth. 



Now 5000 ftades was the diftance already affirmed be-* 

 tween Alexandria and- the well of Syene ; and all that was 

 to be done was to repeat 5000 ftades fifty times, or multiply 

 5000 ftades by 50, and the anfwer was 250,000 ftades, which 

 was the total of the earth's circumference. This, admitting' 

 the French contents of the Egyptian ftadiurn to be juft, will 

 amount to 1 1,403 leagues for the circumference of the earth 

 fought ; and as our prefent account fixes it to be 9000, 

 the error will be 2403 leagues in excefs, or more. than one- 

 fourth of the whole mm required. 



Thi9 



