counted for, by supposing it composed of the finer particles. The precipitate is, however, constantly receiving new accessions, so that it is always becoming more conspicuous, and its recent detection may be due to its increasing density. The middle portion of the system we would expect to be the most dense; and we do find the inner bright ring to be the brightest. The outermost we would expect to be fainter, as from it the lower strata are supplied with additional matter, while it has, itself, no superior source from which to draw. We, accordingly, find, that while the inner bright ring shines like burnished silver, the outer is faint like tarnished silver. This hypothesis of the collision and union of meteoric bodies, receives countenance from the phenomena of the asteroids. We have seen that some of the minor planets have been discovered in regions which were, shortly before, diligently searched, though in vain; so that the surmise is probable, that they have become conspicuous from the union of two bodies, each of which would be invisible when separate. This concentration of matter would necessarily take place to the largest extent in the middle of the system of rings, where we actually find the greatest lustre.
The extreme thinness of the rings can also be accounted for in the same manner. If, at one time, the rings were thicker, but with a concentration in the middle of the thickness, the tendency would be to condense still further the outlying bodies. In cross-
