204 ESSAYS AND OBSERVATIONS 



fudden and great changes on his furface 

 are owing to tides analogous to thofc yvq 

 call fpring-tides. Further, the velocity 

 with which Jupiper revolves on his axis, 

 and the greatnefs of his body, muft con- 

 tribute to the greatnefs of thefe tides, and 

 of the inundations produced by them. 



In Jupiter's fyftem, the theory of gra- 

 vity difcovers itfelf in forne particulars 

 more manifeftly than in any other pare 

 of the general fyrtem. Jupiter is the only 

 body that is, to lenfe, fpheroidical ; the 

 axis being lefs than the diameter of the 

 equator byiV* Poiiibly we may, by far- 

 ther obfervations, difcover the efFe<5ls of 

 the tides likewife ; or rather may learn, 

 that effecfls already vifible and known 

 proceed from them. 



Th e adion of the fatellites upon one 

 another produces lome irregularities in 

 their motions ; and from this it is fup- 

 pofed that their eclipfes do not anfwer ac- 

 curately to the times computed from the 

 tables. But there is another fource, I be- 

 lieve, of their irregularities. Jupiter's 



figure 



