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interior would pass to us between the clouds of his deep atmosphere.

This corresponds closely with the facts observed in the case of Saturn as of his brother giant Jupiter. Both these planets shine much more brightly than they would do if their surfaces consisted of any known kind of earth. This has not only been shown by careful measurement of the light received from these planets, but by yet more satisfactory evidence obtained by photographing them. Lying so much farther from the sun than our moon does, much less light falls upon each square mile of their surface, and if they were opaque, and of the same reflective power as the moon, Jupiter would require about twenty-five times the period which is required to photograph the full moon, and Saturn about ninety times. But Dr. De La Rue, the eminent English photographer, finds that the photographic power of the moon exceeds Jupiter's only about as 3 to 2, and exceeds Saturn's only as about 15 to 1. This, indeed, would imply that a considerable part of each planet's light is inherent, a result which agrees with the estimates of their brightness obtained by Professor Bond of America. But we may be content to accept the lower estimate of Zöllner, the German astronomer, who found that Jupiter shines as if he were a globe of white cloud, and Saturn as though nearly of the same reflective capacity. This is sufficient to show that these two planets are quite unlike the earth. Combining with the reasoning based on Saturn's low mean density, the cloud-encompassed

condition of his atmosphere, and his relative brightness, suggestive of some degree of inherent luminosity, we seem justified in arriving at the conclusion that, like Jupiter the Prince of Planets, Ring-girdled Saturn is not a fit abode for living creatures.

But if, in Jupiter's case, we could turn from the primary planet to a scheme of dependent orbs, and regard these as the habitable worlds and their primary as a subsidiary sun, much more is this the case with Saturn. For, in truth, the scheme over which Saturn bears sway is a miniature, and no contemptible miniature, of the solar system itself. Within an extreme span of upwards of four millions of miles (two millions on either side of Saturn's globe) there circle eight worlds, the least of which is probably at least a thousand miles in diameter, while the largest, appropriately called Titan, is certainly larger than Mercury, and probably as large as Mars. Then within the path of the innermost of these bodies-these moons, as astronomers term them-there is the wonderful ring-system of Saturn. The span of this system of rings amounts to about 176,000 miles-that is, its outermost edge lies about 88,000 miles (more than eleven times the earth's diameter) from Saturn's centre. The complete system has a breadth of about 37,600 miles; but the innermost part, to a breadth of nearly 9,000 miles, is dark. Through this dark ring, where it crosses the planet, the outline of Saturn's disc can be clearly perceived. In fact, this wonderful dark ring is transparent. The bright parts

of the system form two rings, separated from each other by a dark, but not perfectly black, circular division, about 1,700 miles broad; but it is supposed that each of these two rings is subdivided into a great number of rings, and a circular mark, as though the outermost were divided into two connective rings of nearly equal width, has been seen by several observers.

Such is the wonderful system over which Saturn bears sway, his mighty mass guiding his eight satellites on their paths around him precisely as the sun's mass guides his eight planet-dependants on their course. It has been shown, too, that the ring-system consists of multitudes of small satellites, guided also by the attraction of Saturn, even as the thousands of bodies in the ring of asteroids are guided by the attraction of the sun.

It seems to me that, apart from the reasoning already adduced, we have to choose between two views of the Saturnian system. Either the scheme of satellites and the system of rings are intended to subserve some useful purpose with respect to Saturn, or Saturn subserves some useful purpose with respect to these systems. Now, the satellites can supply very little light to Saturn. All together (if they could be all full together) they would supply but a sixteenth part of the light which we receive from our moon when she is full. How so insignificant a supply of reflected light can make up to Saturnians for the fact that the direct supply of solar heat is but oneninetieth of that which we receive, I leave the believers in

Saturn's habitability to explain. But the ring-system, which also has been spoken of as supplementing the deficiency of solar light, does just the reverse. It deprives the Saturnians for long periods together, in some regions for several successive years, of the light they would otherwise receive. And this it does in the winter of those places. At this time, also, it reflects no light to them during the night. In summer the rings do not cut off any of the sun's light, and they shine at night with a considerable degree of brightness, marred only by the circumstance that at midnight the great shadow of the planet falls on nearly the whole of the visible part of the ring. But no supply of reflected light during the summer nights can compensate for the deprivation of the whole of the sun's direct light in winter for several of our years together.

We seem compelled, then, to adopt the view that Saturn subserves useful purposes to the worlds which circle round him. To these he certainly supplies much reflected light, and possibly a considerable proportion of inherent light. He probably warms them in a much greater degree. And it seems no unworthy thought respecting him that even as he sways them by his attractive energy, so he nourishes them as a subordinate sun by the heat with which his great mass is instinct. If our sun, so far surpassing all his dependent worlds in mass, yet acts as their servant in such respects, we may reasonably believe that Saturn and Jupiter act a similar part towards the orbs which circle round them.

NEWTON AND THE LAW OF THE UNIVERSE.

WHILE the study of astronomy affords many wonderful subjects for meditation in the celestial glories which it reveals to us, it also gives food for profitable reflection in the lessons which it affords us respecting the mental powers given to man by his Creator.

It is, for instance, a strange and suggestive circumstance, that man insignificant in his dimensions and in all his physical powers, when viewed in comparison even with the earth on which he lives, and compelled to remain always upon that orb, which is utterly insignificant compared with the solar system, should yet dare to raise his thoughts beyond the earth and beyond the solar system, to contemplate boldly those amazing depths amidst which the stellar glories are strewn.

That he should undertake to measure the scale on which the universe is built, to rate the stars as with swift yet stately motion they career through space, to test and analyse their very substance, to form a judgment as to processes taking place upon and around them, though not one star in all the heavens can be magnified into more than the merest point-all this affords noble conceptions of the qualities which the Almighty has implanted in the

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