ASTRONOMY of the BRAHMINS. 175 



the rule defcribed in it, for rinding the difference between the 

 true and apparent conjunction, at the time of a folar eclipfe, 

 contains the calculation of the moon's parallax, but fubftitutes 

 the parallax in right afcenfion for the parallax in longitude * ; 

 an error which the authors of this aflronomy would probably 

 have avoided, had they derived their knowledge from the 

 writings of Ptolemy. From this fuppofed parallax in longi- 

 tude, they next derive the parallax in latitude, where we may 

 obferve an application of the doctrine of fimilar triangles ; for 

 they fuppofe the firft of thefe to be to the laft in the conflant 

 ratio of 25 to 2, or nearly as the radius to the tangent of the 

 inclination of the moon's orbit to the plane of the ecliptic. 

 We have here, therefore, the application of another geometrical 

 theorem, and that too proceeding on the fuppofition, that a 

 fmall portion of the fphere, on each fide of the point which the 

 fun occupies at the middle of the eclipfe, may be held to coin- 

 cide with a plane touching it in that point. 



51. The remit which the Brahmins thus obtain will be al- 

 lowed to have great accuracy, if it be confidered how fimple 

 their rules are, and how long it mufl be fince their tables were 

 corrected by obfervations. In two eclipfes of the moon, 

 calculated in India by their method, and likewife obferved 

 there by M. le Gentil, the error, in neither cafe, exceeded 

 23' of time, (correfponding to one of 13' of a degree, in 

 the place of the moon) ; and in the duration and magni- 

 tude of the eclipfe, their calculation came flill nearer to the 

 truth f- 



52. Since 



* Hift. Acad. II. P. 109. Ibid. Mem. 253,-256. 



•j- In the language, however, of their rules, we may trace fbme marks of a fabulous 

 and ignorant age, from which indeed even the altronomy of Europe is not altogether 

 free. The place of the moon's afcending node, is with them the place of the Dragon or 

 the Serpent ; the moon's diftance from the node, is literally tranflated by M. le Gentil, 



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