'V 



K 



G. P. Bond on the Rings of Saturn, 105 



erence to the ring outside it. The nearest sides commence mov- 

 ing together, until they come in contact. All the others must 

 follow. The consequence of such a conflict of these masses, 

 each urged by different velocities, corresponding to the different 



times of rotation of the several rings, must be fatal to the whole' 

 structure. 



It is therefore again necessary that the rings be not of regular 

 figure or density. 



But if these irregularities are small, there will be only a feeble 



resistance opposed to their tendency to fall upon the body of the 

 planet. 



On the other hand, if they be large, they will become the 

 source of mutual disturbances, which must end in their destruc- 

 tion, by causing them to fall upon each other. The smallness of 

 the intervals between them, and the near equality in the period 

 of rotation of two adjacent rings, will make the danger of the 

 latter event imminent, if not wholly unavoidable. 



The nearness of the rings will in any case render it impossi- 

 ble that they can assume a figure of equilibrium permanent or 

 nearly so. 



The hypothesis that the whole ring is in a fluid state, or at 

 \ least does not cohere strongly, presents fewer difficulties. 



J There being no longer an unyielding coherence between the 



particles of the inner and outer edges, they have not necessarily 

 the same period of rotation about Saturn. A continual ^ow of 

 the inner particles past the outer may be supposed, by which the 

 centrifugal force will be brought into equilibrium with the other 

 forces. And even should an accumulation of disturbances, of 

 ^hich the absence of inequalities lessens tTie probability, bring 

 the rings together, the velocities at the point of contact will be 

 Very nearly equal^ and the two will coalesce without disastrous 

 consequences. - % 



If in its normal condition the png has but one division, as is 

 commonly seen, under peculiar circumstances it might be antici- 

 pated that the preservation of their equilibrium would require a 

 separation in some regions of either the inner or outer ring; this 



• 



^ould explain the fact of occasional subdivisions being seen. 

 -Theu- being visible for a short time, jnd then disappearing, to 

 the most powerful telescopes, is accounted for by the removal of 

 the sources of disturbance, when the parts thrown off would 



reunite. 



Finally, a fluid rine, symmetrical in its dimensions, is not of 

 necessity in a state of^unstable equilibrium with reference either 

 to Saturn or to the oth 



er rings. 



Seco>,d Series, Vol. XII, No. 34.— July, 1 85 1. H 



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