106 Prof. Peirce on the Constitution of Saturn^ s Ring. 



Art. XV. — On the Constitution of Saturn^ s Ring ; by Prof. 



B. Peirce of Harvard University. 



. Abstract of a paper read before the Anieriran Association for the Advancement of 



Science, at the meetinj^ at Cincinnati. 



A MEMOIR upon Saturn's Ring, by Mr. George P. Bondj was read 

 to the American Academy of Arts and Sciences, upon the 15th of 

 April, and was the occasion of the present investigation. Since 

 Mr. Bond's paper is still unpnbHshed, I shall be obliged to make 

 constant reference to it, and even recapitulate some parts of it, 

 in order that the proper relcilion of the two paths of research 

 may be correctly understood. 



1. The author of the Mecanique Celeste proved that Saturn's 

 ringj regarded as soHd, would not be sustained about the pri- 

 mary, unless it had decided irregularities in its structure. But 

 the observations of Herschel and others have failed to detect any 

 indications of such irregularity, and a laborious series of observa- 

 tions have finally convinced Mr. Bond of the utter improbability 

 of any important irregularities, and he has, therefore^ adopted the 

 conclusion that Satuni's ring is not solid hut fluid, Mr. Bond's 

 argument is chiefly derived from observation ; whereas a new in- 

 vestigation of the mechanical conditions of the problem has led 

 me one step further. I am now convinced that there is no con- 

 ceivable form of irregularity and no combiiiation of irregularis 

 tieSj consistent with an actual ring, which would permit the ring 

 to he permanently maintained hy the primary if it were solid* 

 Hence it follows, independently of observation, that Saturn^s 

 ring is not solid. And^ now it is worthy of remark that if we 

 adopt, as the basis of calculation, the mass of the ring which 

 was determined by Bessel, the thickness from Bond and the other 

 dimensions from Struve, we shall find the density to be about 

 one-fourth more than water. So that the ring consists of a 



stream, or of streams of a fluid rather denser than water, flowing 

 around the primary. 



2. Mr. Bond next undertook a series of very ingenious and 

 novel computations, in order to determine from theoretical con- 

 siderations alone whether the ring was one or many, and arrived 

 at the remarkable result that neither of these hypotheses was ten- 

 able. He is, therefore, disposed to reconcile the discrepancies of 

 observation in this respect by supposing the constitution of the 

 ring to be variable; and that, althoug*h the principal division, 

 which has beeti always ot)served, is permanent, the other divis- 

 ions are constantly annihilated by the mutual concussions of the 

 rings, and again reproduced by some process which he does not 

 nndertake to define. This bold theory is fully sustained by my 

 own analytical investigations^ and not only do my researches ex- 



