6 journal, r. a. s. (ceylon). [Vol, VII., Ft. I. 



orbits from the combined effect of their centrifugal and centri- 

 petal forces. 



In the verses referred to just now the following descrip- 

 tion is given: — " The so-called apex, when in the half 

 orbit in front of the planet, draws the planet forward ; in like 

 manner, when in the half orbit behind the planet it draws it 

 backward. Being drawn away, forward and backward, they 

 proceed by a varying motion." 



The accelerated motion and retarded motion are conveyed 

 by the terms " siyhrockcham" and " mandochcham" which 

 mean respectively u swiftness" and " slowness." 



Thus, it will be seen that the European and Hindu sciences, 

 although the expressions are different, agree as to the causes 

 of the motion of planets in circular or oval orbits. 



X. — Though the motions of planets and the figure of 

 their orbits had been determined by Copernicus and other 

 astronomers, yet the cause, or power, which carries them in 

 their orbits, was unknown at that time. The discovery of this 

 cause was made by Sir Isaac Newton. 



The principle on which the planetary revolution is founded is 

 gravitation. The laws of gravitation were known to the Hindus 

 long before Sir Isaac Newton's time. Thus, the 6th ; 7th, and 

 9th verses of the 3rd chapter of Slddhdnta Siromani state : — 



(6th.) " The property of attraction is inherent in the earth. 

 By this property the earth attracts any unsupported heavy 

 thing towards it. The thing appears falling, but it is in a 

 state of being drawn to the earth. The ethereal expanse being 

 equally outspread all around, where can the earth fall? " 



(7th.) " Observing the revolution of the constellations, the 

 Buddhas thought that the earth had no support ; and as no 

 heavy body is seen stationary in the air, they asserted that the 

 earth goes eternally downwards in space. " 



(9th.) "Observing, as you do, Buddha, that every heavy 



