102 BSERVATIONS on the 



fcience of thofe eaftern nations, of being drawn up by one who 

 was more deeply verfed in the fubjedl than may be at firft ima- 

 gined, and who knew much more than he thought it necefTary to 

 communicate. It is probably a compendium, formed by fome 

 ancient adept in geometry, for the ufe of others who were mere- 

 ly pradlical calculators. 



II. If we were not already acquainted with the high anti- 

 quity of the aftronomy of Indoftan, nothing could appear more 

 fingular, than to find a fyftem of trigonometry, fo perfedl in its 

 principles, in a book fo ancient as the Surya Siddhanta. The 

 antiquity of that book, the oldefl of the Saftras, can fcarce be 

 accounted lefs than 2000 years before our aera, even if we fol- 

 low the very moderate fyftem of Indian chronology laid down 

 by Sir William Jones *. Now, if we fuppofe its antiquity to 

 be no higher than this, though it bears in itfelf internal marks of 

 an age ftill more remote f , yet it will fufficiently excite our won- 

 der, to find it contain the principles of a fcience, of which the firft 



rudiments 



ference. It is remarkable that tlie Hindoos fliould have been thus led, at fo early 

 a period, to put in praftice a method, the fame in the moft material point, with one 

 which has been but lately fuggefted in Europe as an important improvement in tri- 

 gonometrical calculation. In the Phil. Tranf. for 1783, Dr Hutton of Woolwich 

 propofed to divide the circumference, not into degrees, as is ufually done, but into 

 decimals of the radius ; and he has pointed out how the prefent trigonometrical ta- 

 bles might be accommodated to this new divifion, with the leaft pofllble labour, in a 

 paper which difplays that intimate acquaintance with the refources, both of the nu- 

 merical and algebraic calculus, for which he is fo much diftinguiflied. His plan is, 

 in one refpeft, the fame with the Hindoo method, for it ufes the fame unit to exprefs 

 both the circumference and the diameter ; in another refpeft it differs from it, vi%. 

 in making the radius the unit, while the other alTumes for an unit the 360th part 

 of the circumference. Dr Hutton 's plan has never been executed, though it cer- 

 tainly would be of advantage to have, befides the ordinary trigonometrical tables, 

 others conftru£ted according to that plan. 



* Afiatic Refearches, vol. II. p. 1 11, iSc. 



f The obliquity of the ecliptic is flated at 24^ in the Surya Siddhanta, as in all 

 the other aftronomical tables of the Hindoos which we are yet acquainted with. 



(Tranf. 



