THE PLANET SATURN.
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opened-out. Many such, by the Messrs. Bond in 1848, arerecorded in the second volume of the “ Annals of the HarvardCollege Observatory,” to which we have already referred. It isthere stated, that at such times some of the satellites of theplanet, of which we shall have more to say presently, mayoccasionally be seen to be apparently threaded, like heads ona needle, on the fine line of light to which the rings arereduced, while carried backwards and forwards along it bytheir orbital motions, which are nearly in the same planewith it.
It is believed that in this way an important proof may he
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obtained of the extreme thinness of the rings. It is said thateven so small a satellite as the 7th, whose probable diameteris considerably less than 1,000 miles, has been seen, when thussituated, to extend upon either side beyond the thickness ofthe line of light of the rings. Other reasons also indicate thatthe thickness at any rate of the rings a and b, does not exceedat the most 100, or perhaps 200 miles, and may very possiblyfall short of 50 miles.
At the times to which we have just referred, there is, how-ever, an appearance of a greater thickness in the ring-systemfor about one-third of the distance to which their light extendsupon each side of the disc. Thus far a fainter hazy light ofsomewhat greater breadth is seen, and was at one time