صور الصفحة
PDF
النشر الإلكتروني

meantime, of so great a number of Comets in our system, all moving round the sun in eccentric orbits (that is, in paths or orbits which cross the paths or orbits of the planets), and yet striking against no planet; offers a fresh and most magnificent testimony to the amazing order, or refined organization, amid which the system of the universe performs its work: for, under this notion, how much greater than otherwise would be the number of chances (if chance had the least share in the question) that some Comet or other should cross the path or orbit of a planet, at the very moment when the planet was in that precise point of its orbit! Again, if it be really true, that any one of the Comets of our system makes a revolution of nearly six hundred of our years, as to duration of time; what must be the extent of that revolution as to space; or, into space, how far must not that Comet travel from our sun, yet belonging, all the while, to its system, and never approaching so near to any other fixed star or sun, as to fall into its attraction, and be prevented from returning to the point whence it set out? If it is to be believed (as is asserted by the philosophy of our day), that light is a body, and travels at the rate of more than four hundred miles in a second of time; and if you listen also to what is described concerning the velocity of the motion of a Comet, tell me, I beseech you, how many miles would a Comet run into space, in a period of three hundred of our years, or about the time required for its journey out; and, to assist, at least in a small degree, the powers of your imagination upon so vast a subject, it will be well to remember, in company with the foregoing, that some astronomers estimate the distance of space, between the earth and the most conspicuous

(and, therefore, as they say, the nearest) of the fixed stars, as being equivalent to (if not exceeding) two hundred thousand times the diameter of the earth; and that, taking, in round numbers, this diameter at eight thousand miles, the most moderate calculation makes the distance of such a star, one thousand six hundred millions of miles; or, nearly thirty thousand times the distance of the moon. Many other questions, however, concerning Comets, appear to me to be suggested by this last; but with none of these will I now trouble you."

“But let us suppose, for an instant,” said Mowbray, " the possibility of the earth's receiving a blow from a Comet; and, in such an event, what would you imagine to be the consequence?”

“ The consequence, or consequences, in that case,” said Mr. Gubbins,“would much depend both upon the size and the material in which a Comet really consists. If the Comet which should strike the earth were much smaller than itself, I need not say, that the effect of the blow might be proportionably small; but if it were as large, or even larger, and yet not so hard nor so heavy as the earth, still the effect of the blow would be proportionably small. Many estimates and calculations of these effects have been made upon the supposition that the density of the body of a Comet is equal to the density of the body of the earth; notwithstanding that astronomers are generally agreed that the real densities are by no means equal; and that in truth, the body of a Comet consists in some very thin or rare substance. Now, you know, that if a ball of wool were struck against a much smaller ball of lead, the ball of lead would neither be split, nor flattened, nor show any mark or impression upon its surface, nor even be put out of its place; unless the impelling force of the ball of wool exceeded the resisting force which had previously kept the leaden ball where it stood. I mean, that the impelling force of a Comet could make no alteration in the figure, place or motion of the earth, unless its substance were harder and more dense, than the substance of the earth, and its force greater than the force with which the present place and motions of the earth are maintained ;truths from which I am disposed to infer, that in the absence of any thing like real knowledge upon those subjects, modern astronomy, in its speculations upon the horrors of the imagined catastrophe, is almost as childish as the ancient, when, from the appearance of a Comet, even without supposing a blow, it yet trembled for a variety of evils !"

“I think so, too,” said Mowbray; "and, though the mind will be busy, at times, and invent we know not what unfounded notions, to explain the past, the present, or the future; yet I see neither use nor ground for the contemplation of these imaginary disasters from the operation of Comets, any more than from the other bodies in the heavens! What think you, neighbour Gubbins; whether it is not a great deal more likely that Comets have been made to sustain things, than to destroy them?”

“ Much more likely, certainly; but this notion, of one heavenly body striking against another, and thereby occasioning fractures and disruptions, is a favourite with modern astronomy; and I recollect one particular theory of the kind, offered with a basis of mathematical demonstration, and so beautiful as taken by itself, and so easily separable from the . more particular notion of such celestial catastrophes as those of which we have been speaking, that I will not omit to mention it; and in truth, I shall be disappointed, if the suggestion of it does not afford as much pleasure to you, as it does, and has afforded to me. You are aware that the planets of our system, of which the earth is one, are very unequal, both in their magnitudes, and in their distances from the sun; in the degree that seems to invite an idea of the absence of all symmetry, and, if I may so say, of all method, in their formation and disposition; leaving it to be conceived that they are severally held in their places, and enabled to perform their evolutions, only because it so happens that they are so formed, and so arranged, as to effect those objects. But the astronomer to whom I refer, suggests, and offers what he considers mathe. matical demonstration of the truth of his theory, that the magnitudes and distances in question are such, that these actual magnitudes and distances, and no other, could give the solar system its completeness and operation; going so far as to insist that the masses or magnitudes of the numerous small planets only lately discovered to exist, and to belong to the system, amount collectively to the precise quantity and weight of matter, and fill the precise point of space, in which ought, upon theory, to be found, either a very large planet, or else many small ones, composing, together, a mass, exactly equivalent to that imaginary planet, and to the collective masses of the small planets really and recently discovered. The small planets actually existing, my astronomer is speedily tempted to derive from an assumed breaking into fragments of the ideal planet which he supposes, but the place and office of which they thoroughly supply; because, collectively, they still amount to the same mass, and travel in the

same orbit, that is, move at the same indispensable distances from the sun, and from their sister planets, as those assigned to their vastly larger original. Buffon, before this philosopher, had already imagined that our own planet might have been anciently no more than an irregular fragment, struck off from the body of the sun, and rolled into roundness by the mere effect of the motion in which it has ever since been kept. But, without lending ourselves too readily to this description of hypothesis, hy which the shattering of old worlds, and the structure of new ones from their broken pieces, is so familiarly and readily explained; what I stop at is, the beautiful order which the first part of the astronomer's theory infers, in the composition and arrangement of the solar system, in place of that disorder which, as I have remarked, the apparently irregular magnitudes, both of the planets and their orbits, might suggest upon slighter inspection; an order and a beauty of which the system is thus made to display a new example, among the myriads which the whole universe, in every part, presents; and of which examples the universe itself is only the most stupendous !"

Mr. Gubbins's astronomy, sublime as was the speculation upon which he had now entered, fell by no means in waste upon his company; for, with the help of a few marbles, a few peas, and a morsel of chalk, he readily erected a planetarium sufficient for the assistance of the eye; and besides, his efforts were powerfully helped by that general eagerness for knowledge which is so common to the human mind, in persons gifted with their portion of mind, whatever be their age or their condition; by the intelligent curiosity so early springing to life in by far the greater part of children; and by a share of that affecting eagerness so often dis

« السابقةمتابعة »