own atmospheric air; and, as our lungs are not adapted for the inhalation of any other kind of gas, the probable effect of the intermingling of our atmosphere with the substance of a comet would be at once to render the former utterly unfitted for the support of animal life. LAPLACE'S NEBULAR HYPOTHESIS. ནདད E have now completed our survey of the great system of which we ourselves form a part. Sun, planets, satellites, and comets-all the elements of the solar system-have successively passed before us; and the only heavenly orbs we have left to consider are the more distant stellar ones, which are SO far removed from our own immediate ken. But before we proceed to visit those distant realms, we must glance for a moment at Laplace's great theory of the origin of our system, one of the grandest and most magnificent speculations which it has ever entered into the heart of man to conceive. It is true that Newton's discovery of the law of gravitation furnished us with a key to much that was dark and inexplicable before; it reduced the motions of the planets to harmonious symmetry, and replaced the elaborate eccentrics, cycles, and epicycles of the ancients by simpler and more familiar curves. That law, as all our readers are aware, explains why the planets move in ellipses, and accounts for their different periods and ever-varying velocities; but there are questions which it does not answer-such as why all those elliptical orbits are SO nearly circular, and why the planets and satellites all revolve round their primaries and rotate on their axes in the same direction, namely, from east to west; all those orbits being moreover very nearly in the equatorial planes of the primaries.* On these points Newton's law throws no light; the solar system would be equally possible, and, with certain limitations, equally stable, and equally fitted for the support of life if this remarkable uniformity did not exist. To what then are we to attribute it? Is it likely to have been a direct and arbitrary exercise * These laws are indeed broken by the satellites of Uranus, but it is impossible to doubt that this single exception arises from accidental circumstances, and that the otherwise unbroken uniformity must be explained by some common cause. of the Creative will, or a less direct result means Were of that power, working by natural from some prior form of existence? the sun and planets called suddenly into being in their present forms and with their present motions, or were they developed by slow and gradual steps from some simpler original creation? Science tells us that both hypotheses would accord sufficiently well with known present facts; reverential thought pronounces neither of them inconsistent with the loftiest views of the Divine power and wisdom. But the latter is certainly the more interesting and attractive to us, and, we may perhaps add, apparently the more consonant with what we see of the Almighty's working in the lesser world around us. We see the perfect man developed from a helpless babe; we see the loftiest tree developed from a tiny bud; and there is nothing incongruous in supposing that our glorious system itself may have sprung from some vast but equally simple germ. This is a subject which must be handled with humility and diffidence; for we are leaving the regions of mathematics and entering upon those of uncertain speculation; we are treading on sacred ground in seeking to enter into the counsels of the Great Architect of the Universe. We are endeavouring to go deeper than the laws of nature will take us; we are seeking for a key to the mysteries of our system in the probable circumstances of its creation. For this it is that the bold and lofty speculation of Laplace seeks to do; it reaches back into the unfathomable ages of a past eternity, and takes its stand beside the Almighty Author of all things at the first exercise of His creative fiat, when the foundations of the earth and the heavens were laid, when the morningstars sang together, and all the sons of God shouted for joy. The Nebular Hypothesis is briefly and poetically summed up as follows by the Poet Laureate in "The Princess: "This world was once a fluid haze of light, Till toward the centre set the starry tides, |