144 REMARKS on the 



be 2°, 12'*, about t6' greater than it is determined, by the 

 modern aftronomy of Europe. This difference is very confi- 

 derable ; but we lhall find that it is not to be afcribed wholly 

 to error, and that there was a time when the inequality in que- 

 ftion was nearly of the magnitude here affigned to it. In the 

 other points of the fun's path, this inequality is diminifhed, 

 in proportion to the fine of the mean diftance from the apogee, 

 that is, nearly as in our own tables. The apogee is fuppofed 

 to be 8o° advanced beyond the beginning of the zodiac, and 

 to retain always the fame pofition among the fixed ftars, or to 

 move forward at the fame rate with them f. Though this 

 fuppofition is not accurate, as the apogee gains upon the 

 ftars about io" annually, it is much nearer the truth than the 

 fyftem of Ptolemy, where the fun's apogee is fuppofed abfo- 

 lutely at reft, fo as continually to fall back among the fixed 

 ftars, by the whole quantity of the preceffion of the equi- 

 noxes %. 



12. In thefe tables, the motions of the moon are deduced, 

 by certain intercalations, from a period of nineteen years, 

 in which fhe makes nearly 235 revolutions ; and it is curious 

 to find at Siam, the knowledge of that cycle, of which the in- 

 vention was thought to do fo much honour to the Athenian 

 Aftronomer Met on, and which makes fo great a figure in our 



modern 



* The equation of the fun, or what they call the chaiaa, is calculated in the Sia- 

 inefe tables only for every 15* of the matteiomme, or mean anomaly. Cassini, ubi 

 fupra, p. 299. 



f Aft. Ind. p. 9. 



% The error, however, with respect to the apogee, is lefs than it appears to be ; 

 for the motion of the Indian zodiac, being nearly 4' fwifter than the ftars, is but 6" 

 flower than the apogee. The velocity of the Indian zodiac is indeed neither the 

 fame with that of the ftars, nor of the fun's apogee, but nearly a mean between 

 them. 



