5o8 



ILLUSTRATIONS OF THE 



principle extremely like that which is the halls 

 of all the foregoing reafonings, led one of the 

 greateft philofophers of the prefent age to dif- 

 cover the revolution of Saturn's ring on its axis, 



r 



and even to determine the velocity of that revolu- 

 tion, fach as it has been fmce found by obferva- 

 tion. La. Place, laying it down as a maxim, that 

 nothing in nature can exift, where there are cau- 

 fes of change, not balanced or compenfated bj 



aufe 



ded, that the parts of th 



ring muft be held from falling down to the body 

 of the planet by fome other force than their mere 

 cohefion to one another. Were it otherwife, every 

 particle detached from the ring, by any means. 



uft defcend in a ftraight 1 

 dicular to the furface of S 



almoft perpen 

 and the final 



deftrudion of the ring mufl: be inevitable 



Th 





ly force that could balanc 



th 



fFed of gra 



vitation, feemed to be a centrifugal fo 



ari- 



g 



fmg from the rotation of 

 paffing through its centre, and perpendicular to 

 its plane. La Place proceeded to inquire what 

 celerity of rotation 



was adeauate to this effed: 



d found that one of 



hours and a quarter 



4 



would be required, which is almoft preeifely 

 the time afterwards determined by Dr Her- 



with this 

 rotation, 



SCHEL 



from adual obft 



If. 



mm 



•r^ 



* La Place, uBi/u^ra, p. 242 



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