1 94 The Planet Saturn. 



THE PLANET SATURN". 



(continued.) 

 BY THE EEV. T. W. WEBB, A.M., E.E.A.S. 



Eeom an early period, irregularities have been remarked, in 

 the form of the shadows which the globe and ring mutually 

 cast upon each other. As far back as 1792, Dec. 26, when 

 Schroter was first trying his 1 3 ft. reflector, he noticed a jagged 

 outline to each of these shadows, which was confirmed, Jan. 18. 

 — Next we find Lassell, during an "unequalled view," 1849, 

 Aug. 3, describing the shadow on the ball as " evidently 

 knotted or notched," as though there were mountains on the 

 ring intercepting portions of the shadow, and " almost breaking 

 it up into a line of dots : " an appearance which he again 

 noticed with a similar opening of the ring, 1 861. He had also 

 seen it serrated, 1850, Nov. 21. So did DelaKue, repeatedly 

 in the spring of 1861, and very distinctly April 7, with his 

 13 in. reflector and a very fine 4-i- in. achromatic; the " very 

 irregular " outline was however figured by him as belonging 

 to the edge of the shadow, not of the ring, as Lassell. So did. 

 Jacob several times, 1861, especially May 19, with 3-^ in. ; he 

 thought it might be an illusion from the apparent projection of 

 parts of the shadow darker than the rest ; an idea even more 

 unintelligible than the difficulty which it professes to remedy. 

 Lassell also at Malta, 1862, Jan., found the shadow a, rough 

 line. The little roughnesses, it is true, which Huggins 

 suspected, 1862, especially May 18, on the S. edge of the dark 

 side of the ring, always entirely disappeared, leaving a per- 

 fectly smooth edge, under powers of 600 to 950. But this, 

 though it suggests caution, does not negative the previous 

 testimony. The fact is sufficiently clear, and sufficiently per- 

 plexing. Such irregularities could only, it would seem, be 

 occasioned either, 1, by corresponding unevennesscs on the 

 ring; or, 2, by a fretted and honeycombed structure of the 

 surface of the globe ; or, 3, by very great irregularity of refrac- 

 tion through the ring's atmosphere (that of the ball not being 

 distant enough) . Now, if the ring were studded with mountains 

 of sufficient size, they would be very visible in its edgewise 

 projection upon the sky, and, unless rotation is given up, 

 would be distinguishable by their rapid motion from the lucid, 

 points so often mentioned. If a highly irregular suiimv of the 

 globe were suggested, still our eye is never sufficiently far 

 removed from the direction of illumination to sec any marked 

 effect in the form of the shadow; and the supposition of 



