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form au exception to that family law, which, however, prevails again with respect to the remoter planets, it was long suspected that some planet might have a place between Jupiter and Mars, and the early part of the present century was in fact distinguished by the discovery of Ceres, Pallas, and Juno. The small and irregular figures of these planets, and the close approximation of their mean distances, led to a conjecture that they might be the fragments of a large planet which at some remote period occupied the interval in question. If so, it was not improbable that other fragments of the same body were still in existence, and that the most likely place to detect them would be near the nodes of those already observed ; and to this profound reasoning we are indebted for the discovery of Vesta. The realization of an inference of this description, legitimately founded on principles previously announced, would seem to entitle astronomy to a higher appellation than that of a mere theory of probabilities.

The reader may have been startled by the familiarity with which we have alluded to the existence of intelligent beings, on the myriads of orbs that are supposed to circulate round the stars. That the Stars are Suns is a matter which admits of no doubt. That some of them are periodically eclipsed by opaque bodies, which apparently are members of their planetary family, we have already seen. Positive knowledge assures us that the Earth is inhabited; and analogy urges us to the inference, that if an opaque sphere, such as the Earth is, revolve round Algol, it must be for the purpose of receiving from its orbit round that central Sun, light, heat, variety of seasons, day and night,—so many gifts, which it is preposterous to suppose the Deity would bestow, without any purpose, upon a mere collection of matter.

The analogies which thus display a family likeness throughout all the systems of the universe will perhaps be more easily comprehended, if we advert for a moment to the other planets of our own system, which are more immediately within the sphere of our observation. Mercury and Venus both have atmospheres much loaded with clouds, which are manifestly a provision serving to mitigate the intense heat and glare of the sun. We shall see presently the intimate connexion which subsists, not only between the vegetation of our Earth, but also the subsistence of animal life, the transmission of sound and light, nay, all the arts that tend to civilize society, and the existence of the atmosphere which we possess. Wherever an atmosphere is found encircling a sphere, and supporting upon it clouds of vapour, we may infer that upon such spheres there are water and dry land, vegetation, animal life, intelligent beings, and civilization. This inference becomes the

more more inevitable when we find that, according to the best observations, both those planets have their day and night of nearly the same length as our own. In Mars, the outlines of continents and seas have been discerned with perfect distinctness: it has also its atmosphere and clouds, and brilliant white spots at its poles, which are supposed, with a great deal of probability, to be snow. The general fiery aspect of its appearance is conjectured to arise from an ochrey tinge in the soil, not unlike our red sandstone districts. Its day and night differ from ours by little more than half an hour. These are all analogies to Earth, which render the idea of those three planets being mere blanks in the solar system, altogether inconsistent with what we actually know of the fecundity which teems with life, wherever air, water, heat, and light are combined. We shall extract a singular illustration of the activity with which these elements pursue their appointed duties, from the manuscript diary of a friend, who has been, for upwards of twenty years, an enthusiastic, though silent, observer of nature :—

'I have often taken up a drop of water on the head of a common pin, and placed it on a glass slide, which stands edgewise in the instrument (a solar microscope): consequently, if there had been a full drop, it would have run down the surface of the glass slide ; yet, little as there was of it, it more than covered the side of the room in which I stood, and was twelve feet in diameter as its parts were successively brought in view on a screen placed five feet from the lens. By using another lens I could, of course, have extended the twelve feet to twenty-four. The little drop of water thus magnified appeared filled with several species of animalcula, of all sizes between one-sixteenth of an inch and thirteen inches! They often appear in such numbers that I cannot find one unoccupied spot on the screen which the head of a pencil would cover in the space of twelve feet. Frequently the screen appears to be one sheet of minor living animals just coming into life, each not larger than the head of a pin, or at most a pea, while the larger and more perfect are sporting amongst them. Sometimes they are so numerous as to form an opaque moving- mass, and I am obliged to wipe oft" a part and dilate the remainder with pure spring water, in order to make them appear separately, and to observe their movements. What myriads there must be! and no doubt living upon animals still less than themselves, which not even the solar microscope can detect I

'With a common microscope I have often seen a great number of animalcula, called gluttons, feeding within the transparent shell of a small dead wheel * animal, both the shell and its numerous contents being invisible to the unassisted eye. This little creature resembles

* We are convinced from observation, that the wheel is an optical deception. The whole of the head of this animakulum is fringed with feelers, which it throws out and retracts with a rapidity that at the angles gives the appearance of circular motion.

the the Brachionus Bakiri; the females cany their eggs in the same way its shell has six teeth.'

If a portion of water not so large as a drop be thus peopled with a countless host of animalcules of various races, would it not be unphilosophical in the extreme to suppose that light and heat, air and water, vegetation, day and night, seasons and climates, are bestowed on Mercury, Venus, and Mars, without any view to animal life, without any purpose of administering to the maintenance and happiness of intelligent beings capable of appreciating the blessings of existence? The argument applies with still more force to Jupiter, Saturn, and Uranus; with respect to each of which, machinery of the most complex description has been devised, manifestly (amongst others) for the purpose of making up the great deficiency of solar light, which they would otherwise experience, owing to their vast distance from the centre of our common system. We are all of one family with reference to matter and motion. Is it not incumbent upon us to conclude that the family resemblance extends to the individual character, as well as to the countenance and conduct?

We speak here only of the planets, not of their satellites, which are evidently used only as auxiliaries to their primaries for the reflection of light, the balancing of their waters, and perhaps the due regulation of their motions respectively. Our Moon, for instance, does not appear to us capable of supporting animal life. We find its surface, at least that part of it which is seen from Earth, occupied by volcanic craters, some of them of prodigious magnitude; we can discern upon it no indication of vapour; therefore it can have no water, unless the element be hid in caverns, inaccessible to the rays of the sun. Without clouds and atmosphere the animal system cannot be supported. But whether this reasoning be right or wrong, it will appear, that not only the moon but the earth, of which it is the handmaid, and the planets, with their attendants, are all proceeding, by slow but inevitable steps, to a period when they shall cease to exist, however remote that period may be from the time in which we happen to live. If this be so, the argument drawn from the mortal character of Me stars is equally sustained by the particular system of which our habitation forms so small a part.

The reader need hardly be reminded that the diameter of the real globe of the Sun, without reference to the luminous element by which it is surrounded, has been calculated at eight hundred and eighty-two thousand miles. But he has not perhaps much considered the striking fact, that if the eleven planets by which that orb is surrounded at various distances in space, together with their eighteen satellites, as well as the two rings of Saturn, were fused into one sphere, the bulk of that sphere would hardly be one threehundredth part of the magnitude of the Sun. The apple which falls from the tree to the earth, the return to the earth of a stone thrown inlo the air, demonstrate the irresistible power which a large mass of matter exercises over a smaller. It is by the operation of the same law that the sun attracts Mercury, for instance, at the distance of thirty-seven millions of miles. But the force of that attraction is in some degree counteracted by that of Venus, as well as by the attraction of all the other planets and their satellites; and the precision with which all these complicated forces, resulting from the power of the sun over all, and from the individual power of each planet with respect to the other, have been adjusted, is of itself a proof that nothing less than a divine intelligence could have framed and combined this splendid machinery. The magnet and the piece of sealing-wax made warm by friction attract other bodies, by means of the electric fluid with which the one is permanently, the other temporarily, charged. But the celestial motions are regulated by the influence with which every one particle of matter is endowed in relation to every other in the universe.

These mutual gravitations of the planets towards each other in their career round the sun are the causes of certain perturbations in the system, which, though very minute in each particular case, become considerable in the lapse of ages. It is, for example, one of their consequences, that the moon performs her monthly revolution round the earth in a shorter interval now than she did formerly, as appears from the record of an eclipse observed by the Chaldeans at Babylon seven hundred and twenty-one years before the Christian a?ra. These perturbations are, however, restrained within certain points of oscillation, beyond which they cannot pass. The stability of the solar system is therefore so far secured; for it would be scarcely worthy of the Great Architect that any damage should be done to it by a palpable defect in the machinery. Neither is it likely that any material change would occur in our system, if it be true, as we cannot doubt, that it is in movement, together with the stars and their planets, round the centre of ihe universe, the sovereign sun of all things, the position of which no earthly vision can ever discover. A remove of this description would be to us utterly imperceptible. 'The development of such an alteration,' observes M. Poinset, ' is similar to an enormous curve, of which we see so small an arc that we imagine it to be a straight line.' Upon this supposition the true equatorial plane of all the suns, and of the worlds which they illumine, would pass through the centre of gravity of the universe, and in that centre we shall, therefore, find the uncreated and only abode of absolute

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lute and eternal repose—the throne of the Omnipotent. It is not given to the imagination to picture, until it shall actually witness, the grandeur of such a procession, composed of innumerable orbs clothed in light, encircled by their planets teeming with every order of intelligence, and moving round the great Mind which has fashioned the whole, veiling but not eclipsing the radiance of H is glory.

Whether it be ordained that as one system perishes another shall supply its place in eternal succession, thus manifesting to all ages the presence of an ever-active Omnipotence, it is not for us to conjecture. But the agency of destruction has been proved from its effect in particular instances in the firmament of the stars; and as to our system, a similar agency is found in a resisting medium, which, though extremely rare, and hitherto of imperceptible influence, so far as our globe is concerned, nevertheless must at length modify the forms of the planetary orbits, and involve them in disorder and ruin. The supposition of the presence and power of such an ethereal fluid was a favourite notion among the Cartesians, who, without perceiving the whole of the consequences of their theory, concluded from mere abstract reasoning that all space was full of some species of matter. The calculations of Newton, on the contrary, have been made upon the hypothesis that all the heavenly bodies move in a perfect vacuum. A remarkable recent discovery shows that the doctrine of the Cartesians is right, although it does not substantially affect the calculations of our own great astronomer, so very rare is the fluid in question, and so protracted are its final results.

We owe this discovery to the observations that have been made upon a body now generally called Encke's comet, which moves with extraordinary rapidity in an exceedingly eccentric orbit round the sun. That orbit it completes in about three years and four months, or, more accurately speaking, in twelve hundred and eight days. Jt is a body of extreme apparent tenuity: when in our sky it looks like a speck of mere vapour. The stars shine through it without any diminution of their brightness. Nevertheless, slight as this wreath of vapour may seem to us to be, it extends over an immense tract in space, and observation has proved that it is acted upon by exactly the same force of solar attraction which influences the other bodies of the system. It might easily have been conceived, that if the parts of space unoccupied by denser matter were filled with a resisting fluid, however rare, its effect upon such a body as Encke's comet would probably be capable of actual perception and calculation, and so in fact it has turned out. This comet wasfirstseen in 1786; it was again discovered in 1795, 1805, and 1819- Astronomers at first supposed that they had in these instances

Vol. L. No. xcix. c seen

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