OUTLINES OF NATURAL PHILOSOPHY. 



. The centre of the Sun is never distant by 

 so much as his own diameter from the centre 

 of gravity of the system. 



The diameter of the Sun is equal nearly to .009 of 

 the radius of the Earth's orbit. Now, if we sup- 

 pose the Sun, and all the great planets of the sys- 

 tem, Jupiter, Saturn and Uranus, to be in a 

 straight line, and the planets all on one side of the 

 Sun, the centre of the Sun will be nearly the far- 

 thest possible from the centre of gravity of the 

 whole; yet we shall find on computation, that the 

 distance is not greater than .0085 of the radius of 

 the Earth's orbit. NEWTONI Princip. lib. in. 

 prop. 12. 



. In the preceding propositions the ex- 

 istence of the principle of gravitation, has been 

 established by induction from the laws of KEP- 

 LER ; and from that principle, by reasoning 

 downward, conclusions have been obtained con- 

 cerning the quantity of matter in the planets, 

 to which observation, without the assistance of 

 theory, never could have reached. 



It yet remains to be shewn, that the same force 

 which occasions the descent of heavy bodies on 

 the Earth's surface, at the rate of 16.09 feet per 

 second, when diminished in the inverse ratio of 

 the square of the distance, is just sufficient to re- 

 tain the Moon in her orbit. 



The 



