NEWTON S PRINCIPIA. 133 



that a number of masses of a fluid revolve round E at 

 equal distances from it by the same laws of attraction by 

 which M moves round E, and that these masses are thus 

 formed into a ring ; then it follows that the portions of this 

 ring will move quicker in syzygy than in quadrature, that 

 is, quicker at A and B than at C and D ; also, that the 

 nodes of the ring, or the intersections of its plane with the 

 plane S E, will be at rest in syzygy, and move quickest in 

 quadrature, and that the ring s axis will oscillate as it re 

 volves, and its inclination will vary, returning to its first 

 position, unless so far as the precession of the nodes carries 

 it forward. Suppose now E to be a solid body with a 

 hollow channel on its surface, and that E increased in 

 diameter until it meets the ring, which now fills that 

 channel, and suppose E to revolve round its own axis 

 the motion of the fluid, alternately accelerated and re 

 tarded (as we have shown), will differ from the equable 

 rotatory motion of the solid on its axis, being quicker than 

 the globe s motion in syzygy, and slower in quadrature. 

 If S exerts no force, the fluid will not have any ebbs and 

 flows, but move as round a centre that is at rest; but 

 if the varying attraction of S operates, being greater 

 when the distance is less, the disturbing force acting in the 



direction S L, and being as ,. 2 , will raise the fluid in A 



and B, or in syzygy, and from thence to quadrature, C 

 and D, while the force L N will depress it in quadrature, 

 C and D, and from thence to syzygy, A and B, If we 

 now suppose the ring to become solid, and the size of E 

 to be again reduced, the inclination of the ring will vary, 

 and oscillate ; and the precession of its nodes will continue 

 the same and so would the globe, if, without any ring 

 at all, it had an accumulation of matter in the equator, 

 or had matter of greater density there than elsewhere, and 



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