114 ON THE RINGS OF SATURN. 



vious observers. Two reflectors of the Newtonian form were used, of between six and 

 seven inches' aperture. 



At Berlin, on the 25th of April, 1837, the outer ring was seen by Professor Encke, 

 with perfect distinctness, divided into two nearly equal parts, and several divisions were 

 recognized on the inner edge of the inner ring. The great equatorial of the Berlin Ob- 

 servatory was used with an achromatic eye-piece. 



On the 28th of May, the place of the outer secondary interval was determined. The 

 great optical capacity of the telescope, and the eminence of Professor Encke as an ob- 

 server, gives the highest value to these observations. They are found in the Astro- 

 nomische Nachrichten, No. 338. No. 357 of the same volume has a notice of several 

 divisions on both rings, seen by De Vico, at Rome, with the equatorial of the Roman 

 College, the object-glass of six inches, by Cauchoix. A letter from M. Decuppis, 

 Comptes Reiidus, Vol. VII., gives a description of several divisions seen at Rome, in 

 May, June, and July, 1838. 



On the 7th of September, 1843, a division of the outer ring was detected by Messrs. 

 Lassell and Dawes, at Starfield. They employed a Newtonian reflector of nine inches' 

 aperture ; the details are to be found in Vol. VI. of the Monthly Notices of the Royal 

 Astronomical Society. 



The newly discovered inner ring of Saturn cannot properly bo classed with the sub- 

 divisions of the old ring, as it lies within its inner edge. 



We have, then, the best assurance, in the number and reputation of those who have 

 described the phenomena in question, that to set aside these appearances by referring them 

 to some optical deception on the part of the observer, or to some defect in his instrument, 

 is an explanation altogether insufficient and unsatisfactory. On the other hand, we know 

 that some of the best telescopes in the world, in the hands of Struve, Bessel, Sir John 

 Herschel, and others, have given no indication of more than one division, when the 

 planet has appeared under the most perfect definition. The fact, also, that the divisions 

 on both rings have not usually been visible together, and that the telescopes which have 

 shown distinctly several intervals in the old ring have failed to reveal the new inner ring, 

 while the latter is now seen, but not the former, may be taken as some evidence that the 

 difference is not probably owing to any extraordinary tranquillity or purity of the atmos- 

 phere, nor to any peculiarly favorable condition of the eye or instrument, but rather to 

 some real alterations in the disposition of the material of the rings. 



Admitting this, the idea that they are in a fluid state, and within certain limits 

 change their form and position in obedience to the laws of equilibrium of rotating bodies, 

 naturally suggests itself There are considerations to be drawn from the state of the 



