VII. 



On the Rings of Saturn. 

 Br G. P. BOND, 



ASSISTANT AT THE ASTRONOMICAI, OBSERVATORV OF HARVARD COU.EGE. 



Communicated April 15, 1851. 



The question of the multiple divisions of the ring of Saturn has engaged the attention 

 of astronomers from an early period. Cassini appears to have been the first to notice 

 the primary division, though he has placed it midway between the inner and the outer 

 edges. 



This interval is always visible with a good telescope, but much nearer to the outer 

 edge than Cassini describes it to be. Short, next, with a telescope of twelve feet focus, 

 probably a reflector, saw two or three divisions outside of the centre of the ring ; a figure 

 is given in Lalande's Astronomy. In June, 1780, Sir W. Herschel noticed, on four dif- 

 ferent nights, a division near the inner edge. From its never, either previously or sub- 

 sequently, having been seen by him, it is probable that the subdivisions are not perma- 

 nent ; otherwise they could scarcely have escaped detection under the scrutiny to which 

 he subjected every thing appertaining to the system of Saturn for thirty or forty years. 

 This inner division is figured and described in the Philosophical Transactions for 1792. 

 In Gruithuisen's Astron. Jahrbuch, for 1840, pp. 103-105, mention is made of lines 

 seen on both rings in 1813 and 1814. Quetelet, at Paris, with an achromatic of ten 

 inches' aperture, saw the outer ring divided in December, 1823. 



On the 17th of December, 1825, and on the 16th and 17th of January, 1826, at 

 least three divisions were seen on the outer ring by Captain Kater. A full account, 

 illustrated with engravings, has been published in Vol. IV. Part II. of the Memoirs of the 

 Royal Astronomical Society. This contains also a collection of the accounts of pre- 



