has been imagined, that the maculæ are occasioned by smoke and opaque matter thrown out by volcanos or burning mountains of immense magnitude; and that when the eruption is nearly ended, and the smoke dissipated, the fierce flames are exposed, and appear like faculæ or luminous spots. M. de la Hire imagined the Sun to be in a continual state of fusion, and that the spots which we observe, are only the eminences of large masses of opaque matter, which, by the irregular agitations of the fluid, sometimes swim upon the surface, and sometimes sink and disappear. Others have supposed them to be occasioned by a number of planets circulating round the sun, at a small distance from his surface. But Dr. Alexander Wilson, by attending particularly to the different phases presented by the umbra, or shady zone, of a spot of an extraordinary size, that ap peared upon the sun in November 1769, during its progress over the solar disk, was led to form a new and singular conjecture concerning the nature of these appearances: which he seems afterward to have confirmed and established by repeated observations. The results of these observations are, that the solar maculæ are cavities in the body of the sun; that the nucleus, as the middle or dark part has been usually called, is the bottom of the excavation; and that the umbra, or shady zone, usually surrounding it, is the shelving sides of the cavity. Dr. Wilson appears not only to have ascertained the reality of these immense excavations in the body of the sun, but to have pointed out a method of measuring the depth of them. He estimates, in particular, that the nucleus, or bottom of the large spot above-mentioned, was not less than a semidiameter of the earth, or about 4000 miles below the level of the sun's surface; while its other dimensions were of a much larger extent. From his observations it may be further inferred, that the body of the sun, in the depth of the nucleus, either emits no light, or emits so little as to appear dark, when seen at the same time, and compared with that resplendent, and probably, in some degree, fluid substance which covers his surface. This manner of considering these phenomena naturally gives rise to many curious speculations and inquiries. It is natural to inquire, for instance, by what great commotions this refulgent matter is thrown up on all sides, so as to expose to our view the darker part of the sun's body, which was before covered by it? What is the nature of this shining matter? And why, when the excavation is formed in it, is the lustre of this shining substance, which forms the shelving sides of the cavity, so far diminished, as to give the whole the appearance of a shady zone, or darkish atmosphere, surrounding the denuded part of the sun's body? But for a more ample detail of Dr. Wilson's observations on the whole subject, I must refer my readers to the Philosophical Transactions, vol. lxiv; as well as to Dr. Herschel's suggestions of a kindred theory, in different volumes of the same national work. : The motion of the macula is from east to west, and as they are observed to move quicker when they are near the central regions, than when they are near the limb, it follows that the sun must be spherical body, and that he revolves on his axis. The time in which he performs this revolution, as observed by Cassini, is 25 days, 14 hours, and 8 minutes. Beside the solar spots, the zodiacal light is a singular phenomenon which accompanies the sun, and is usually attributed to his atmosphere. It begins to appear a little before sunrise, and seems at first like a faint, whitish zone of light, resembling the milky way, with its borders ill terminated, and scarcely to be distinguished from the twilight, which is seen commencing near the horizon. It is then but little elevated, and its figure nearly agrees with that of a flat lenticular spheroid, seen in profile. As it rises above the horizon, it becomes brighter and larger to a certain point, after which the approach of day renders it gradually less apparent, till it becomes quite invisible. From this philosophical account of the sun, and the principal phenomena which he exhibits, the next and most obvious inquiry is into his pervading energy and essential importance in the creation, and particularly to our globe. But nothing can equal what Thomson has said upon this subject, in his beautiful Hymn to the Sun, at the commencement of his Summer: I refer my readers, therefore, to this, not only as a poetical illustration, but as the noblest account that has ever been given, of the dignity, use, and beauty of this resplendent orb. Dr. Herschel supposes that the spots in the sun are mountains on its surface, which, considering the great attraction exerted by the sun upon. bodies placed at its surface, and the slow revolution it has about its axis, he thinks may be more than 300 miles in height, and yet stand very firmly. He says that in 1792, he examined the sun with several powers from 90 to 500; and it evidently appeared, that the black spots are the opaque ground or body of the sun; and that the luminous part is an atmosphere, which being intercepted or broken, gives us a glimpse of the sun itself. Hence he concludes, that the sun has a very extensive atmosphere, which consists of elastic fluids that are more or less lucid and transparent, and of these the lucid ones furnish us with light. This atmosphere he imagines to be somewhere between 1800 and 2780 miles in height; and he supposes that the density of the luminous solar clouds need not be exceedingly more than that of our aurora borealis, in order to produce the effects with which we are acquainted. The sun, then, appears to be a very eminent, large, and lucid planet, the first and only primary one belonging to our system. Its similarity to the other globes of the solar system, with regard to its solidity; its atmosphere; its surface diversified with mountains and valleys; its rotation on its axis; and the fall of heavy bodies on its surface; lead us to conclude that it is most probably inhabited, like the other planets, by beings whose organs are adapted to the peculiar circumstances of the vast globe. By analogical reasoning, likewise, we infer that the moon and planets are the abodes of happiness to indefinite numbers of animated, and, perhaps, rational and intelligent creatures, who may speculate and reason upon our supposed existence as we do of theirs; who may be pursuing scientific knowledge in a way similar to our Newtons, Herschels, and Davys. To take the moon, for instance, and what is applicable to her may, unquestionably, be inferred of the superior planets, and of their moons or satellites also. The moon is a secondary planet of considerable magnitude; its surface is, as we have seen, diversified, like that of the earth, with hills and valleys. Its situation with respect to the sun, is much like that of the earth; and, by a rotation on its axis, it enjoys an agreeable variety of seasons, and of day and night. To the moon, our globe would appear a capital satellite, undergoing the same changes of illumination as the moon does to the earth. The sun, planets, and the starry constellations of the heavens, will rise and set there as they do here; and heavy bodies will fall on the moon as they do on the earth. There seems, then, only to be wanting, in order to complete the analogy, that it should be inhabited like the earth. It may be objected, that, in the moon, there are no large seas; and its atmosphere (the existence of which is doubted by many) is extremely rare, and unfit for the purposes of animal life; that its climates, its seasons, and the length of its days and nights, totally differ from ours; that without dense clouds, which the moon has not, there can be no rain, perhaps no rivers and lakes. In answer to this it may be observed, that the very difference between the two planets strengthens the argument. We find, even on our own globe, that there is a most striking dissimilarity in the situation of the creatures that live upon it. While man walks on the ground, the birds fly in the air, and the fishes swim in the water. We cannot, surely, object to the conveniences afforded by the moon, if those that are to inhabit its regions are fitted to their conditions as well as we on this globe of ours. The analogy already mentioned establishes a high probability that the moon is inhabited. Suppose, then, an inhabitant of the moon, who has not properly considered such analogical reasonings as might induce him to surmise that our earth is inhabited, were to give it as his opinion, that the use of that great body, which he sees in his neighbourhood, is to carry about his little globe, in order that it may be properly exposed to the light of the sun, so as to enjoy an agreeable and useful variety of illumination, as well as to give it light by reflection, when direct light cannot be had; should we not condemn his ignorance and want of reflection? The earth, it is true, not only performs those offices which have been named, for the inhabitants of the moon, but we know that it also affords magnificent dwellingplaces to numberless intelligent beings.-From experience, therefore, we affirm, that the performance of the most salutary offices to inferior planets is not inconsistent with the dignity of superior purposes; and in consequence of such analogical reasonings, |