i6 2 TRAVELS TO DISCOVER' 



Wc cannot miitake this, if we obferve liow anxioufly thcy- 

 liave varied the figure of the top, or point of each obeliik; 

 fometimes it is a very iharp one ; fometimes a portion of 

 a circle, to try to get rid of the great impediment that per- 

 plexed them, the penumbra. 



The projection of* the pavements, conftantly to the norths 

 ward, fo diligently levelled, and made into exact planes by 

 large ilabs of granite, mod artificially joined, have been fo 

 Substantially fecured, that they might ferve for the observa- 

 tion to this day ; and it is probable, the pofition of this city 

 and the well were coeval, the remit of intention, and both 

 the works of thefe firfb aftronomers, immediately after the 

 building of Thebes. If this was the cafe, we may conclude, 

 that the fact of the fun illuminating the bottom of the well 

 in Eratoilhenes's time was a fuppofed one, from the uniform 

 tradition, that once it had been fo, the periodical change 

 of the quantity of the angle, made by the equator and 

 ecliptic, not being then known, and therefore that the 

 quantity of the celeftial arch, comprehended between Alex- 

 andria and Syene, might be as erroneous from another 

 caufe, as the bafe had been by affirming a wrong diftance 

 on the earth, in place of one exactly meafured. 



There is at Axum an obelifk erected by Ptolemy Everge- 

 tes, the very prince who was patron to Eratofthencs, with- 

 out hieroglyphics, directly facing the fouth, with its top 

 firft cut into a narrow neck, then fpread out like a fan in 

 a femicircular form, with a pavement curioufly levelled to 

 receive the fhade, and make the Separation of the true fha-- 

 dow from the penumbra as dillinct as poSiible. 



This- 



