This is a convenient place at which to offer a brief explanation of the changes of appearance as regards the ball and rings which Saturn undergoes. These changes depend jointly on Saturn’s motion in its orbit round the Sun, and on the corresponding motion of the Earth in its orbit. Neither Saturn nor the Earth revolve round the Sun exactly in the ecliptic, and this want of coincidence results in the fact, that twice in the 29½ years occupied by Saturn in journeying round the Sun, the plane of its ring is seen edgeways by us on the Earth; whilst at two other periods intermediate but equi-distant the ring is seen opened out to the widest possible extent; that is, so far as we on the Earth can by any possibility have a chance of seeing it. [Illustration: Fig. 17.—Phases of Saturn’s Rings at specified dates.] The appearances presented by the rings when undergoing the transformations to which they are subject, will be readily understood by an inspection of the annexed engravings. Fig. 17, indicates the actual appearances in the years specified, and these years may be considered as carried forward and brought up to date by substituting 1877 for 1848, 1885 for 1855, 1891 for 1862, and 1898 for 1869. Adverting to fig. 16, it will suffice to remark that the two central phases of the rings, opened wide, are to be deemed co-related, or indeed identical in a geometrical sense (so to speak) the difference being that one of them is to be deemed to show the northern side of the ring (which is now in view and will continue in view till 1907) whilst the other represents the southern side, which was in view from 1877 till 1891. The foregoing is a brief statement of the general principle involved in the changes which take place, but the motions of the two planets introduce certain technical complications into the details which would be seen by an observer using a large telescope; with these, however, the ordinary reader will not care to concern himself, and need not do so.