PHYSICAL ASTRONOMY. 283 



made an augmentation of 2h 48m nearly in the 

 length of the year. But it is certain, the same 

 author adds, that if an augmentation so great as 

 even two seconds in the length of the year, had 

 taken place at that time, it would have been dis- 

 covered from Dr MASKELYNE'S observations, 

 when compared by DE LAMBRE for the construc- 

 tion of the New Astronomical Tables. The mass 

 of the Comet, therefore, cannot have been T i^th 

 of the mass of the Earth. 



The same Comet passed through the midst of the 

 satellites of Jupiter without producing the smallest 

 effect. Mecanique Celeste, vol. iv. p. 250. 



It is reasonable, therefore, to think, that no mate- 

 rial, or even sensible alteration has ever been pro- 

 duced in our system by the action of a Comet. % 



SECT. 



