PHYSICAL AND LITERARY. 207 



formerly were confidered as feas, but, be- 

 caufe of cavities difcovered in them with 

 better telefcopes, are fufpedled by many 

 to be only large planes, fome decifion of 

 this queflion might be obtained. Water 

 is of too great importance, in natural 0- 

 perations, to fuppofe haflily any planet 

 to be deprived of it; though we muft 

 alfo allow that the variety of nature is not 

 to be limited by our conceptions. 



T H E o R . I. 



The gravity towards an oblate fpheroid 

 in the axis produced, decreafes in a lels 

 proportion than that in which the fquarc 

 of the diftance from the centre increafes: 

 But the gravity in the plane of the equa-^ 

 tor decreafes in a higher proportion than 

 that in which the I'quare of the diftance 

 increafes. 



The OR. II. 



Let b denote the femidiameter of the 

 equator, c the diftance of the focus of the 



generating 



