2o8 Mi (cell arte a Curtofa. 



of Ptolemy, the Tropick faid to be obferv'd 

 by EuBemon and Meton, Junii 27. marie, An- 

 no 432. ante Chrifium, can no ways be re- 

 concile without fuppofing the Obfervation 

 made the next day, or June 28th in the 

 Morning. And Ptolemy^ own Tropick ob- 

 ferv'd in the third Year of Antoninus, Anno 

 Chriftt 140. was certainly on the 23th and 

 not the 24th day of June as will appear 

 to thofe that mall duly confider and com- 

 pare them with the length of the Year de- 

 duced from the diligent and concordant Ob- 

 fervations of thofe two great Aftronomical 

 Genii, Hifparchus and Albatdni ; eftablihVd 

 and confirm'd by the Concurrence of all the 

 Modern Accuracy. For thefe Obfervations 

 give the length of the Tropical Year, fuch 

 as to anticipate the Julian Account only one 

 day in 300 Years-, but we are now fecure 

 that the faid Period of the Sun's Revolu- 

 tion does anticipate very nearly three days 

 in 4Q0 Years *, fo that the Tables of Ptolemy 

 founded on that Suppofition, do err about a 

 whole day in the Sun's Place, for every 240 

 Years. Which principal Error hi fo Funda- 

 mental a Point, does vitiate the whole Su- 

 per ft ru dure of the Almagefi, and ferves to 

 convift its Author of want of Diligence, or 

 Fidelity, or both. 



But to return to our Method, the great 

 Advantage we have hereby, is, that any 

 very high Building ferves for an Inftrument, 

 or the Top of any high Tower or Steeple, 

 or even any high Wall whatfoever, that may 

 be fufficient to intercept the Sun, and caft a 

 true ihade : Nor is the Pofition of the Plane 



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