nearly half a mile across; Saturn, a small orange, on a circle of four-fifths of a mile; and Uranus, a full-sized cherry or small plum, upon the circumference of a circle more than a mile and a half in diameter. As to getting correct notions on this subject by drawing circles on paper, or, still worse, from those very childish toys called orreries, it is out of the question. To imitate the motions of the planets in the above-mentioned orbits, Mercury must describe its own diameter in 41 seconds; Venus in 4m. 4s.; the earth in 7m.; Mars in 4m. 48s. ; Jupiter in 2h. 56m.; Saturn in 3h. 13m.; Uranus in 2h. 16m.; and Neptune in 3h. 30m. IS THE SUN INHABITED? If (says Arago) this question were simply proposed to me, Is the Sun inhabited? I should reply, that I know nothing about the matter. But let any one ask of me if the sun can be inhabited by beings organised in a manner analogous to those which people our globe, and I hesitate not to reply in the affirmative. The existence in the sun of a central obscure nucleus, enveloped in an opaque atmosphere far beyond which the luminous atmosphere exists is by no means opposed, in effect, to such a conception. Sir William Herschel thought the sun to be inhabited. According to him, if the depth of the solar atmosphere in which the luminous chemical action operates should amount to a million of leagues, it is not necessary that the brightness at each point should surpass that of an ordinary aurora borealis. In any case, the arguments upon which the great astronomer relies, in order to prove that the solar nucleus may not be very hot, notwithstanding the incandescence of the atmosphere, are neither the only, nor the best, that might be adduced. The direct observation, made by Father Secchi, of the depression of temperature which the points of the solar disc experience wherein the spots appear, is in this respect more important than any reasoning whatever. Dr. Elliott maintained, as early as the year 1787, that the light of the sun arose from what he called a dense and universal twilight. He further believed, with certain ancient philosophers, that the sun might be inhabited. When the Doctor was brought before the Old Bailey for having occasioned the death of Miss Boydell, his friends, Dr. Simmons among others, maintained that he was mad, and thought that they could prove it abundantly by showing the writings wherein the opinions which we have just cited were found developed. The conceptions of a madman are in the present day generally adopted.--Arago's Popular Astronomy, vol. i. book xiv. chap. 29. Sir John Herschel concludes that the sun is a planet abundantly stored with inhabitants; his inference being drawn from the following arguments: On the tops of mountains of a sufficient height, at an altitude where clouds can very seldom reach to shelter them from the direct rays of the sun, we always find regions of ice and snow. Now, if the solar rays themselves conveyed all the heat we find on this globe, it ought to be hottest where their course is least interrupted. Again, our aeronauts all confirm the coldness of the upper regions of the atmosphere. Since, therefore, even on our earth, the heat of any situation depends upon the aptness of the medium to yield to the impression of the solar rays, we have only to admit that, on the sun itself, the elastic fluids composing its atmosphere, and the matter on its surface, are of such a nature as not to be capable of any excessive affection from its own rays. Indeed, this seems to be proved by the copious emission of them; for if the elastic fluids of the atmosphere, or the matter contained on the surface of the sun, were of such a nature as to admit of an easy chemical combination with its rays, their emission would be much impeded. Another well-known fact is, that the solar focus of the largest lens thrown into the air will occasion no sensible heat in the place where it has been kept for a considerable time, although its power of exciting combustion, when proper bodies are exposed, should be sufficient to fuse the most refractory substances. COMPARATIVE LIGHT OF THE SUN AND THE FIXED STARS. Dr. Wollaston has inferred, from observations made by him, that the direct light of the Sun is about one million times more intense than that of the full Moon; and therefore very many million times greater than that of all the fixed stars taken collectively. In order to compare the light of the sun with that of a star, he took, as an intermediate object of comparison, the light of a candle reflected from a small bulb, about a quarter of an inch in diameter, filled with quicksilver, and seen, by one eye, through a lens of two inches focus; at the same time that the star or the sun's image, placed at a proper distance, was viewed by the other eye through a telescope. The mean of various trials seemed to show that the light of Sirius is equal to that of the sun seen in a glass bulb one-tenth of an inch in diameter, at the distance of 210 feet, or that they are in the proportion of one to ten thousand millions; but, as nearly onehalf of the light is lost by reflection, the real proportion between the light from Sirius and the sun is not greater than that of one to twenty thousand millions. THE SUN'S LIGHT COMPARED WITH TERRESTRIAL LIGHTS. When we place the flame of a wax-candle so that it is projected upon the regions of the atmosphere nearest the Sun's disc, it totally disappears, and we see merely the wick under the form of a black spot. This effect is still more strongly marked, as it ought to be, when the flame is projected upon the disc itself of the body. Whence we may deduce the con clusion, that the brightness of this flame is less that of a corresponding portion of the sun than that of a corresponding portion of the surrounding atmosphere, and that it does not form even 1-30th of the latter. Now, the intensity of the atmospheric light being 1-500th of the light of the sun in the vicinity of that body, we see that the intensity of the flame of a wax-candle is only 1-30th x 1-500th, or the 15,000th part of the solar light. The brightest light which man has been enabled to produce is that which has been named the electric light, which is engendered by the aid of the galvanic battery, the magnificent invention of Volta. It is no exaggeration to assert that the electric light is comparable to the solar light; for if we project upon the sun's disc the light which is obtained by rendering incandescent two pieces of charcoal placed in communication with the two poles of a galvanic battery, we do not arrive at all at the result which is furnished by a wax-candle, or even a Carcel lamp. The electric light is not effaced in presence of that of the sun. According to the energy of the battery employed, we find that the electric light varies from the fifth part to the fourth of that of the sun; or, in other words, that it is equivalent to that diffused by a number of wax-candles varying between 3000 and 3750. Let us add, that a Carcel lamp gives as much light as seven wax-candles and that the light of a jet of gas is equal to that of nine wax-candles. : The reader will be pleased to remark, that we speak only of the brightness of the sun at the surface of the earth, and not of the intensity of the light of that body near its surface.Arago's Popular Astronomy, vol. i. book xiv. chap. 25. THE NEARER THE SUN THE GREATER THE COLD. This phenomenon is explained by the sunbeams bringing to the earth both light and heat as they descend to warm the hottest valleys or plains, and passing through the upper strata of the atmosphere, but leaving them always of a temperature much below freezing. This low temperature is proved by the fact, that all lofty mountains, even under the equator, are capped with never-melting snows; and that the higher the peaks are, though, therefore, the nearer to the sun, the colder they are. Thus aeronauts, in their balloon-car, if they mounted very high, would be frozen to death if not protected by very warm clothing. Another fact of the very same kind is, that a glass globe full of cold water, or even a ball of ice, will, in the sun's rays, act as a burning lens.-Dr. Neil Arnott. THE EARTH TRAVELLING ROUND THE SUN. Mr. Samuel Warren thus illustrates our rate of transit through space in our journey round our central luminary, computed by one of our best practical astronomers: "While I was journeying from London to Hull, some 200 miles, the planet, on which we were creeping by steam-power, had travelled some 410,000 miles through space! So that we are, while I am speaking, whirling along, without being in the least physically sensible of it, at the rate of upwards of 68,000 miles an hour; more than a thousand miles a minute, and nineteen miles between two beats of a pendulum, or in a second of time.* MAGNETIC RELATION BETWEEN THE EARTH AND THE SUN. Mr. Faraday has demonstrated this by the remarkable fact that there is an exact coincidence between the variation of the Sun's spots and that of the Earth's magnetism,-a decennial change, the existence of which had been established by Colonel Sabine, in conformity with the results of careful observation made by MM. Swabe and Lamart on the corresponding variations of the Sun's spots and the magnetic needle.—Samuel Warren, D.C.L. COMPARATIVE LIGHT OF THE SUN AND MOON. The splendour of Solar Light is more than 300,000 times that of the Full Moon: in other words, if the firmament were paved with 300,000 full moons, their united splendour would be inferior to that of the sun. ECCENTRICITY OF THE MOON. An eminent German astrologer concludes, from long study, that the centre of gravity of the Moon is sixty miles on one side of the centre; the effect of which would be, that the side visible to us may be regarded as a vast mountain sixty miles aigh, while the other side-that which we do not see-may have all the water and all the atmosphere. Hence our satellite may not be so devoid of these two elements as is commonly believed. The very irregularities of the moon were, in Galileo's opinion, a proof of Divine wisdom; for, had its surface been absolutely smooth, it would have been "but a vast and unblessed solitude, void of animals, of plants, of cities, and of men, the abode of silence and inaction, senseless, lifeless, soulless, and stripped of all those ornaments which now render it so varied and so beautiful."-Sir David Brewster. At the time of the death of Jesus Christ it was very near full moon. Now, when the moon eclipses the sun, it is neces While the earth moves 68,305 miles an hour, Mercury moves more than 100,000 miles; whence chemists use his symbol to denote quicksilver. While we are disposed to regard this as a rapid motion round the sun, what must the inhabitants of Neptune, who travel only three and a half miles a second, think of us, who are whirling round the sun at six times the speed of Neptune! sarily new. The Eclipse of the Passion, then, was the effect of a miracle.-Arago. HEAT FROM THE MOON. M. Melloni has proved, beyond doubt, that the rays of the Moon give out a slight degree of Heat. He concentrated the rays with a lens, over three feet diameter, upon his thermoscopic pile, when the needle was found to deviate from 0° 6' to 4° 8', according to the phase of the moon.-Letter from Melloni to Arago. THE HARVEST MOON. In Olmsted's Mechanism of the Heavens, p. 169, are these remarks upon this phenomenon: "About the time of the autumnal equinox, the Moon, when near her full, rises about sunset a number of nights in succession. This occasions a remarkable number of brilliant moonlight evenings; and as this in England the period of Harvest, the phenomenon is called the Harvest Moon. The sun being then in Libra, and the moon, when full, being, of course, opposite to the sun, or in Aries, and moving eastwards in or near the ecliptic at the rate of about 13° per day, would descend but a small distance below the horizon for four or six days in succession,-that is, for two or three days before, and the same number of days after, the full; and would, consequently, rise during all these evenings nearly at the same time, namely, a little before or a little after sunset, so as to afford a remarkable succession of fine moonlight evenings." AGE OF OUR PLANET. It is supposed that the plants of the coal period required a temperature of 22° Reaumur; the mean now is 8°, or 14° less. By experiments on the rate of cooling lavas and melted basalt, it is calculated that 9,000,000 of years are required in the earth to lose 14° Reaumur. M. Hibbert puts the period at 5,000,000. But, supposing the whole to have been in a molten state, the time that must have elapsed in passing from a liquid to a solid state is fixed at 350,000,000 years.-M. Boué. PLURALITY OF WORLDS. The idea occurred even to Copernicus, that our heavy mundane sphere, which affords convenient and substantial support to the footsteps of man, might possibly be not the only body of this kind contained within the wide realms of universal space. He knew that, if he could get far enough away from its sunlit form, he must see it dwindle down to a shining point or star. He perceived that the transparent regions surrounding the earth are crowded with such shining points, which become visible when the observer is protected from the glare of the sun by the nocturnal shadow of the globe. He watched these shiuing star-points night after night, until he ascertained that some |