3(38

THE PLANET SATURN.

century later, Sir W. Herscliel, after more than ten yearsof careful observation, was convinced that, whether viewedfrom the one side or from the other, the division between thetwo rings was seen exactly in the same position ; and that itwas a real break through which the dark background of theheavens was visible, and not simply a dusky shading upon thering-surface. The two rings, thus divided from one another,are those which, as we have already mentioned, are nowgenerally named a and b ; the outer being a, the inner b.

But in the year 1850 a wonderful extension of the systemwas discovered, inasmuch as Professor Bond, of the CambridgeObservatory, U.S., and Messrs. Dawes and Lassell, in England,detected a third ring, closer to the planet than the other two,and of a most remarkable character. It is that which isnow called the ring c ; its chief peculiarity being, that it has adusky and obscure, although transparent, appearance, almostlike that of gauze or crape, and such that the body of theplanet can be seen through a : considerable portion of it. Sometime after its discovery in 1850, it was found that it had beennoticed, so early as in 1838, to resemble a shadow where it

their observation, which is to be found in vol. i. of the “ PhilosophicalTransactions, ” does not confirm their right to the credit of the discovery.They only noticed an apparent depression, or deformation, in the portionsof the ansae which appeared joined to the planet, which possibly suggestedthe idea that the two ansae might be two independent appendages ; butthey saw no division in the breadth of the ring, the first indication ofwhich is due to Cassini, whose drawing clearly indicates a shading in thering where subsequent observations have conclusively proved that theprincipal division exists. We must therefore assign the discovery of theduplicity of the ring to Cassini. At the same time, we have no wish todetract from the reputation of William Ball as a skilful observer.Huyghens refers to his observations some years before the above date(having heard of them from Dr. Wallis) as confirming his own, in evi-dence of the appearance of a dark line seen across the planet at certaintimes (viz., when the rings are viewed edgewise), w r hich proved the realform of the appendage, which had seemed so enigmatical, to be that of awide and flat, but very thin, concentric ring surrounding the planet.Minehead (or, as it is in the “Philosophical Transactions, ” “Mainhead”)is doubtless a misprint for Mamhead, a village a few miles south-west ofExeter.