Let the small circle A, in the centre, represent the Earth, and the circle B C D E the orbit of the Sun, on the supposition that he moves round the Earth every 24 hours. The line A B will represent the distance of the Sun from the Earth, or 95 millions of miles; the line B D the diameter of the orbit he would describe; and the circle B C D E the circumference along which he would move every day, or 597 millions of miles, which is somewhat more than three times the diameter. If the line A F represent the distance of the nearest star, the circle F G H I will represent the circuit through which it would move every 24 hours, if the earth were at rest. It is obvious, from the figure, that since the stars are at a greater distance from the earth than the sun, the circle they would describe around the earth would be larger in proportion, and, consequently, their velocities would be proportionably more rapid; since they would move through their larger circles in the same time in which the sun moved through his narrower sphere. But the supposition that the earth is the

centre of all the celestial motions, and that the different stars are daily moving around it with different velocities, and the slowest of these motions is so inconceivably rapid—is so wild and extravagant, that it appears altogether inconsistent with the harmony of the universe-with the Wisdom and Intelligence of the Deity, and with all the other arrangements he has made in the system of nature.

No. II. p. 72.-Experimental Illustrations of the Pressure of the Atmosphere.

The pressure of the atmosphere is most strikingly illustrated by means of the air pump. But as few persons, comparatively, possess this instrument, the following experiments, which any person may perform at pleasure, are sufficiently convincing on this point. Take a common wine glass, and fill it with water; apply a piece of paper over the mouth of the glass; press the paper to the rim of the glass with the palm of the hand; turn the glass upside down; withdraw the hand from the paper, and the water will be supported by the pressure of the atmosphere. That it is the atmospherical pressure, and not the paper, which supports the water is evident; for the paper, instead of being pressed down by the weight of the water, is pressed upward by the pressure of the atmosphere, and appears concave, or hollow in the middle. If the flame of a candle be applied to the paper, it may be held, for an indefinite length of time, close to the paper, without setting fire to it. The same fact is proved by the following experiment :-Take a glass tube, of any length, and of a narrow bore; put one end of it in a basin of water; apply the mouth to the other end, and draw out the air by suction; the water will immediately rise toward the top of the tube; and if the finger or thumb be applied to the top of the tube, to prevent the admission of air, and the tube removed from the basin of water, the water in the tube will be supported by the pressure of the atmosphere on the lower end. Again :-Take, a wine glass, and burn a small bit of paper in it; and, when the paper is burning, press the palm of the hand upon the mouth of the glass, and it wil adhere to the hand with considerable force. In this case, the pressure of the atmosphere will be sensibly felt; for it will sometimes require considerable force to detach the glass from the hand.

The pressure of the atmosphere explains a variety of common phenomena. When we take a draught of water out of a

basin, or a running stream, we immerse our mouths in the water, and make a vacuum by drawing in the air; the pressure of the atmosphere upon the external surface of the water then forces it into the mouth. The same cause explains the process of a child sucking its mother's breasts-the action of a boy's sucker, in lifting large stones-the rise of water in pumps-the effects produced by cements—the firm adhesion of snails and periwinkles to rocks and stones-the scarcity of water in the time of hard frosts-and the fact that a cask will not run by the cock, unless a hole be opened in some other part of the cask.

No. III. p. 253.—On the means by which it may probably be ascertained whether the Moon be a habitable world.

ABOUT six years ago, the Author published, in the Monthly. Magazine, a few observations on the surface of the Moon, in which a few remarks were offered on this subject. The following is an extract from that communication:

"If we be ever to obtain an ocular demonstration of the habitability of any of the celestial orbs, the Moon is the only one, where we can expect to trace, by our telescopes, indications of the agency of sentient or intelligent beings; and I am pretty much convinced, that a long continued series of observations on this planet, by a number of individuals in different places, might completely set at rest the question, • Whether the Moon be a habitable world?' Were a vast

number of persons, in different parts of the world, to devote themselves to a particular survey of the Moon-were different portions of her surface allotted to different individuals, as the object of their particular research—were every mountain, hill, cavern, cliff, and plain accurately inspected—and every change and modification in the appearance of particular spots carefully marked and represented in a series of delineations, it might lead to some certain conclusions, both as to her physical constitution, and her ultimate destination. It can be demonstrated, that a telescope which magnifies 100 times, will show a spot on the Moon's surface, whose diameter is 1223 yards; and one which magnifies a thousand times, will, of course, enable us to perceive a portion of her surface, whose size is only 122 yards: and, consequently, an object, whether natural or artificial, of no greater extent than one of our large edifices, (for example, St. Paul's Church, London,) may, by such an instrument, be easily distinguished.

Now,

if every minute point on the Lunar surface were accurately marked by numerous observers, it might be ascertained whether any changes are taking place, either from physical causes, or from the operations of intelligent agents. If a large forest were cutting down-if a city were building in an open plain, or extending its former boundaries—if a barren waste were changing into a scene of vegetation—or, if an immense concourse of animated beings were occasionally assembled on a particular spot, or shifting from one place to another—such changes would be indicated by certain modifications of shade, color, or motion; and, consequently, would furnish a direct proof of the agency of intelligent beings analogous to man, and of the Moon being a habitable globe. For although we may never be able to distinguish the inhabitants of the Moon (if any exist) yet if we can trace those effects which can flow only from the operations of intelligent agents, it would form a complete demonstration of their existence, on the same ground on which a Navigator concludes an unknown island, to be inhabited, when he perceives human habitations, and cultivated fields.

"That changes occasionally happen on the lunar hemisphere next the earth, appears from the observations of Herschel and Schroeter, particularly from those of the latter. In the transactions of the Society of Natural Philosophy,' at Berlin, Schroeter relates, that on the 30th December, 1791, at 5 o'clock, p. m. with a 7 feet reflector, magnifying 161 times, he perceived the commencement of a small crater on the south-west declivity of the volcanic mountain in the Mare Crisium, having a shadow of at least 2" 5. On the 11th January, at 20 minutes past five, on looking at this place again, he could see neither the new crater nor its shadow. Again, on the 4th January, 1792, he perceived, in the eastern crater of Helicon, a central mountain, of a clear gray color, 3" in diameter, of which, during many years' observations, he had perceived no trace. • This appearance,' he adds, 'is remarkable, as probably from the time of Hevelius, the western part of Helicon has been forming into its present shape, and Nature seems, in that district, to be particularly active.'-In making such minute observations as those to which I allude, it would be proper, along with an inspection of the moon's luminous disk, to mark the appearances of different portions of her dark hemisphere, when it is partially enlightened by the reflected light from the earth, soon after the appearance of new moon. These researches would require a long-continued series of the most minute observations, by numerous

observers in different regions of the globe, which could be effected only by exciting, among the bulk of mankind, a general attention to such investigations. But were this object accomplished, and were numerous observations made from the tops of mountains, and in the serene sky of southern climes, where the powers of the telescope are not counteracted by dense vapors, there can be little doubt that direct proofs would be obtained that the Moon is a habitable world; or, at least, that the question in relation to this point would be completely set at rest."

No. IV.—Remarks on the late pretended discovery of a Lunar Fortification.

THE British Public was lately amused by the announcement of a discovery said to have been made by Professor Frauenhofer, of Munich. This gentleman was said to have discovered a fortification in the Moon, and to have distinguished several lines of road, supposed to be the work of the lunar inhabitants. It is scarcely necessary to say, that such announcements are obviously premature. To perceive distinctly the shape of an object in the Moon, which resembles a fortification, it is requisite, that that object be of a much larger size than our terrestrial ramparts. Besides, although an object resembling one of our fortifications were perceived on the surface of the moon, there would be no reason to conclude, that it served the same purpose as fortifications do among us. We are so much accustomed to war in our terrestrial system, and reflect so little on its diabolical nature, that we are apt to imagine that it must form a necessary employment even in other worlds. To be assured that a fortification existed in the Moon for the same purpose as with us, would indeed be dismal tidings from another world; for it would be a necessary conclusion, from such intelligence, that the inhabitants of that globe are actuated by the same principles of depravity, ambition, and revenge, which have infected the moral atmosphere of our sublunary world. With regard to the pretended discovery of the Lunar roads, it may not be improper to remark, that such roads behooved to be at least 400 feet broad, or ten times the breadth of ours, in order to be perceived as faint lines through a telescope which magnifies a thousand times; which is a higher power, I presume, than Frauenhofer can apply with distinctness to any of his tele