ing the stratum of meteoric matter, they would be caught in its meshes, and fixed in its plane.
It is plain, from the above observations, that, in one sense, the system of Saturn is not permanent, and a natural inquiry is suggested—Is the system of Saturn, in this respect, a type of the solar system? We have seen that the solar system is absolutely stable, but only on the supposition that the planetary bodies experience no resistance in passing through space. But have we ground for believing that there is no obstruction? So far from this, there is the most conclusive evidence that there is such obstruction. The effect upon the planets has not been detected, but the comets have proclaimed the fact, that there is an element of decay in the system. Encke's comet is narrowing its circle at every revolution, and is going down, as it were, a spiral staircase to its ultimate destiny—absorption in the sun. The comet is of a consistency so light, that it is exceedingly sensitive to the retarding influence, just as the light balloon at once feels the slightest breath of air. But the question is only one of degree. The comet has a rapid and gaining spiral, like the moth circling round the fatal light; but the densest planet has also to pursue a downward course, though incalculable ages may elapse before the close spiral shall reach the central furnace. It may be objected that, if the stamp of decay is upon the solar system, the argument from its stability falls to the ground, and all the resources of
