1858.] and the Figure of the Earth. 213 



to these objections; and several competent judges have pronounced 

 the hypothesis to be untenable : I therefore regard it as abandoned. 



It is in this direction, however, I fully believe, that a counteract- 

 ing cause is to be found, if there be any, to modify the large disturb- 

 ing effect of the Himalaya Mountains. I have recently been con- 

 sidering this subject again, and purpose communicating a paper to 

 the Eoyal Society on the subject shortly, if my hopes are verified 

 by further examination. This cannot, however, diminish the import- 

 ance of ascertaining the true amount of deflexion from mountain- 

 attraction, as every disturbing cause should be fully examined 

 and estimated. 



14. The present position of the problem of Himalayan attrac- 

 tion is this. The data which I assume in the six tables in pages 78 

 to 83 of the Philosophical Transactions for 1855 should be examined, 

 to see whether the values of h are tolerably correct representatives 

 of the average heights of the masses standing on the several "com- 

 partments" to which they appertain. This the gentlemen of the 

 survey can best do. I have written to Colonel "Waugh, the Surveyor 

 General, (who first called my attention to this subject) for corrections 

 of these heights ; but, having received no corrections, I conclude the 

 data are rightly assumed. 



I am, your obedient servant, 



Calcutta, July 6th, 1858. J. H. Pratt. 



Bhdskaras knowledge of the Differential Calculus. — By Baptt Deva 

 Shastri, Professor of Mathematics and Astronomy in the Govern- 

 ment Sanskrit College, Benares. 



To the Editor of the Asiatic Society's Journal. 



Sir, — It appears to be generally believed that the principle of 

 the Differential Calculus was unknown to the ancient Hindu 

 mathematicians. Allow me to correct this impression by the fol- 

 lowing statement regarding what Bhaskaracharya has written on 

 the subject. 



