PHYSICAL AND LITERARY. 20^ 



figure differs confide rably from a fphere; 

 9nd the gravitation towards him is not 

 inverfcly as the fquare of the diftance fronj. 

 his centre. Now, this variation from the 

 regular courfe of gravity may produce 

 fome inequalities in their motions. And, 

 ^n order to judge of thefe, I have com^ 

 puted the law of gravity towards luch a 

 fpheroid as Jupiter^ and will fubjoin fome 

 jtheorems on this fubje(5. 



It feems fomewhat jBxtraprdinary, that 

 in 1 30 years, iSnce Jupiter's fatellites were 

 difcovered by Galileo, no eclipfe of any 

 of thefe fatellites by one another has been 

 pbferved . Such an eclipfe could hold but 

 for a fmall time : But, as it is not diffi- 

 cult to compute nearly the time when they 

 ought to happen, it would be worth while 

 to look for them ; fince this might con- 

 tribute to render their theory more per* 

 fedl ; which is of fo miich ufe in afcer- 

 taining the longitudes of places. If it be 

 found to be a phaenomenon that paiTes 

 over quickly, becaufe of their fwifc mp* 

 tions, it may be the more ufefui, provi-* 

 ding it can be feen. 



Na 



