so as never to threaten any violent change from such mechanical causes, so far, at least, as the power of attraction is concerned. This is highly satisfactory, as a demonstration against the atheistical doctrine, which would exclude from the universe the operation of a Designing Cause. It does not, however, prove the absolute permanency of the system, and we know, from the "more sure word of prophecy," that it is not destined to last for ever.

f

There is, indeed, another element to be taken into consideration, which the French philosophers, already alluded to, have overlooked or rejected, but which bears directly upon the question of inherent stability,-I mean the question regarding a resisting medium. All their calculations have been founded on the two simple powers of attraction and inertia, under the supposition that these powers acted in empty space, without the existence of any impeding force. If it be found, therefore, that a resisting medium actually exists in the system; that is, that there is some fluid matter, however rare, in which the celestial bodies move, then this one fact will overturn the conclusion as to the absolute and inherent permanency of the present system of things, so far as mechanical powers are concerned. Nor will this discovery invalidate the reasoning in the preceding paper; for it will still remain a truth, worthy of the deepest admiration, that the plan was adopted, which, of all others, is best calculated to balance and counteract disturbing forces, even although other considerations should prove that the system was not intended to be eternal. It is this principle which secures the equal and salutary working of the system while it lasts, and which bestows upon it properties suited for the habitation of organized existences, during that period; and this is the whole extent of the view for which we have been contending.

Is there, then, a resisting medium,-a fluid in which our system floats? or are our planetary spheres wheeled in empty space? The diffusion of light throughout the universe, might, of itself, form a powerful argument for the existence of such a medium, on whatever theory its

properties are accounted for. Light is either an emanation from the great central body, and then that emanation must be something material; or it is an exciting cause of vibratory motion; and in that case, the vibrations must apparently be conveyed through some material substance. In either case, the theory of an absolute vacuum seems to be untenable. But, independent of this view, some facts have been very recently discovered, which cannot well be accounted for, but on the supposition of a resisting medium. I allude to certain circumstances occurring in the motion of one of the comets belonging to our solar system, to which the importance of Encke's observations have justly caused that astronomer's name to be attached. The revolution of this body round the sun, is found to be completed in a period of about three years. and four months, while its orbit is so eccentric and elongated, that it is more than ten times nearer the sun in one part of its course, than in another. The materials of which it is composed, seem to be exceedingly thin and transparent; so much so, indeed, that the stars may be seen through the most condensed part of its nucleus, without any apparent diminution of their brilliancy. In 1786, this comet was first observed; but it was not till 1822, that its periods were accurately determined; and then Encke, on comparing the calculated with the observed places, perceived a difference, which he attributed to the effect of a resisting medium. It was again the subject of observation in 1825, in 1828, and still more recently; and the conclusion has become general, that the obvious and constant disturbance of its course, arises from no other cause than that of its being affected by its motion in an ethereal fluid.

This fluid, however, must be of inconceivable rarity, and would probably not produce any apparent effect in its velocity, were it not from the small quantity of matter contained in the vapory sphere, which, as will easily be perceived, must increase the power of resistance of the medium through which it moves. Light and loose, however, as the body is, it has been found to be acted on by the solar and planetary attraction, in the same manner

with the other heavenly bodies; and the result having been accurately calculated, what Sir J. Herschel calls a residual phenomenon, has been discovered, which has given rise to the inference of a resisting medium.

The effect, however, though something very discernible, is yet but trifling; and, what may appear strange, this retardation of the motion, causes the body to perform its revolutions round the sun more quickly. The reason is, that the increasing slowness of the motion has the effect of augmenting the relative power of the sun's attraction, thus drawing the comet nearer to himself, and shortening its orbit. Within the last fifty years, in which its course has been observed, it has been found, that, while it has advanced about ten days farther in its path, than would otherwise have been the case, the time of its revolution has been diminished by about two days.

Now, the very same power of resistance, which acts so perceptibly on this unsubstantial body, must act also on every other body which passes through the same medium; and, however small the effect produced may be, it must be something, which, though not, perhaps, sufficient to produce any sensible effect on those more solid bodies, for many centuries, must yet, in reference to a period of eternal duration, be sufficient to derange, and finally to destroy, the whole system. As yet, no retardation of the planetary bodies has been observed, which could be referred to the existence of a resisting medium, because our observations extend to a period too limited; but this may only prove the extreme remoteness of the final catastrophe. "It may be millions of millions of years," says the distinguished author, whom we chiefly follow in this part of our work, "before the earth's retardation may perceptibly affect the apparent motion of the sun; but still the day will come (if the same Providence which formed the system, should permit it to continue so long,) when this cause will entirely change the length of the year, and the course of our seasons, and finally stop the earth's motion round the sun altogether. The smallness of the resistance, however small we choose to suppose it, does not allow us to escape this certainty.

There is a resisting medium; and therefore the movements of the solar system cannot go on for ever. The moment such a fluid is known to exist, the eternity of the movements of the planets becomes as impossible as a perpetual motion on the earth."*

The obvious use to be made of the fact now stated is, that our present system of things, which must have an end, must also have had a beginning. There must have been a period in which the impulse, now proceeding, originated. A period of commencement implies a cause; the order and regularity of the system implies an Intelligent Cause; and thus the idea of a Creator is forced upon us; and, instead of an eternal operation of mechanical powers, and an eternal succession of organized existences, which is the dream of the atheist, we see a system, glorious with the impress of a Divine hand, and rejoicing in the smile of a present Deity.

An ingenious living writer, after attributing the resisting medium to the remains of the nebulous matter out of which, according to Laplace's theory, the whole universe has originally been formed, concludes his account of the disturbing effects of that medium with the following striking observations:

"The idea of the ultimate dissolution of the solar system has usually been felt as painful, and forcibly resisted by philosophers. When Newton saw no end to the deranging effect of the common planetary perturbations, he called for the special interference of the Almighty to avert the catastrophe; and great was the rejoicing when a recent analyst descried a memorable power of conservation in our system's constituent phenomena. But, after all, why should it be painful? Absolute permanence is visible nowhere around us; and the fact of change merely intimates, that, in the exhaustless womb of the future, unevolved wonders are in store. The phenomena referred to, would simply point to the close of one mighty cycle in the history of the solar orb,-the passing away of arrangements which have fulfilled their objects, that

I.

* Whewell's Bridgewater Treatise, p. 200.

10

VII.

Thus is the periodic

they might be changed into new. death of a plant perhaps the essential to its prolonged life, and when the individual dies and disappears, fresh and vigorous forms spring from the elements which composed it. Mark the chrysalis! It is the grave of the worm, but the cradle of the sunborn insect. The broken bowl will yet be healed and beautified by the potter; and a voice of joyful note will awaken, one day, even the silence of the urn.

"Nay, what though all should pass! What though the close of this epoch in the history of the solar orb, should be accompanied, as some, by a strange fondness, have imagined, by the dissolution and disappearing of all these shining spheres? Then would our universe not have failed in its functions, but only been gathered up and rolled away, these functions being complete. That gorgeous material framework wherewith the Eternal hath adorned and varied the abysses of space, is only an instrument by which the myriads of spirits borne upon its orbs, may be told of their origin, and educated for more exalted being; and a time may come, when the veil can be drawn aside,—when spirit shall converse directly with spirit, and the creature gaze without hinderance on the effulgent face of the Creator."'*

FIFTH WEEK-SUNDAY.

DIVINE AND HUMAN KNOWLEDGE COMPARED.

WHEN the philosopher compares his knowledge of external nature with that of his fellow-men not conversant with such high studies, there is danger of his becoming

*Dr. Nichol, On the Architecture of the Heavens,' pp. 189-192, a work containing a beautiful popular view of the recent discoveries of the two Herschels, and other modern astronomers, published in June,

1837.