are apt to fall into, in the contracted notions, which we at first form of the extent and number of those objects, which surround us. The universe, at first, consisted of the sun, and moon, and a few stars, next the planets were added, and after many centuries some of these planets were found, very much to the surprize of every one, to be attended with satellites; at length we were compelled to admit another planet into the system, which had remained so long unaltered; and now, very lately, four more, and in the very place where they were wanted; that is, where there was the most room for them. But before going so far after arguments in support of this beautiful theory, we ought first to see how it will suit the circumstances of the case to be explained. There are difficulties respecting the production of light, heat, and sound, as Professor Day readily admits, which are not very satisfactorily solved by this hypothesis. Indeed we are unable to conceive how flame, or ignition, is kept up and sound propagated at elevations of fifty and an hundred miles, where the air must be, at the former height, at least sixteen thousand and at the latter more than two hundred million times rarer than at the surface of the earth. That the friction of a body, moving in a medium so rare, is sufficient to heat a gross compound of earth and metal to a red or white heat, or to collect electricity faster than it could fly off in an atmosphere so highly rarified, may, for aught we know, be true. But we know of no facts or principles to justify or countenance the supposition. These difficulties, it must be confessed, are not peculiar to the hypothesis under consideration, nor are they such as ought to be considered insuperable obstacles to its admission; if it could be fully made out, that the direction and velocity of meteors correspond to those of bodies revolving in regular orbits, and that they are in fact solid, gravitating masses, which, though they may somtimes send off a few fragments, continue on their course. This, as we have before mentioned, seems to be considered as a settled point by Professor Day, becanse "the luminous object," if it consisted "principally of flame or vapour, could not preserve a regular, globular figure, while moving through the atmosphere with a velocity twenty times as great as that of sound, but would be immediately dissipated;" and because the body of the meteor, after making ample allowance for exaggeration, surprize, &c. "will remain vastly larger than any, which has been known to fall to the earth." Now we acknowledge that very great weight is due to these arguments, and we should not hesitate to admit the conclusion, did it not involve us in greater difficulties than those we seek to avoid. The very great velocity and regular outline of meteors, we allow, seem altogether incompatable with the supposition that they are gaseous bodies. But is there no other alternative? How are we to account for the absence of large masses, in those cases, where meteors have actually fallen to the earth, of which we have several upon record? Mr. Barbham relates,* that riding out one morning in Jamaica, he saw a ball of fire, about the size of a bomb, swiftly falling down with a great blaze. "When I came to the place where it fell, says he, I found many people gathered together, admiring the ground's being strangely broken up and ploughed by the ball of fire, which they said had fallen down there. I observed there were many holes in the ground, one in the middle of the bigness of a man's head, and five or six smaller round it, and so deep as not to be fathomed by such implements as were at hand. All the green herbage was burnt up near the holes, and there continued a strong smell of sulphur near the place for some time," Upon search being made after ward, it is said by another, no stones were found. We give the following on the authority of Dr. Gregory.† "Admiral Chambers, on board the Montague, November 4, 1749, was taking an observation just before noon, when, on directing his eye to the windward, he observed a large ball of blue fire about three miles distance from them. They immediately lowered the topsails, but it came so fast upon them, that, before they could raise the main tack, they observed the ball rise almost perpendicularly, and not above forty or fifty yards from the main chains, when it went off with an explosion, as Phil. Trans. vol. xxx. p. 837. Gregory's Dict- Ark. Meteors, By this great as if hundreds of cannon had been discharged at the same time, leaving behind it a strong sulphurous smell. explosion, the main top-mast was shattered in pieces, and the main mast rent quite down to the keel. Five men were knocked down, and one of them much bruised. Just before the explosion, the ball seemed to be of the size of a large mill-stone." It is related that a meteor fell in Northhamptonshire and penetrated three feet into a gravelly soil, and that a man was killed, by what was called the lightning, and that his body exhibited marks of electricity. We have also an account of a large fire ball, which is said to have fallen lately in India, and to have burned five villages, destroying the crops, and killing some of the inhabitants.† These do not appear to be the effects of a solid compact body, heated and electrified by passing through the atmosphere. In some of these accounts, and particularly of that observed at sea, we could scarcely have failed to have learned something more, had the luminous object been a hard heavy mass. The rapidity of the motion, the light, colour, explosion, and sulphurous smell, seem to be strong indications of the presence of clectricity. We have been frequently reminded beside, in reading these accounts, of a remarkable phenomenon, which is sometimes observed during a thunder-storm; and in one instance, been accidentally imitated by artificial electricity. We speak of lightning descending upon houses and conductors in a globular form, and sometimes perforating timber and making holes in the ground. The experiment with an electrical apparatus is related by Cavallo,‡ as having been performed by Mr. Arden, with a good electrical machine, connected with a large jar. After turning sometime he perceived, as also another gentleman who was with him, a ball of fire much resembling a red hot bullet, and full three quarters of an inch in diameter, ascending up the side of a small glass tube, that was suspended in the jar, and turning§ on its axis; at the same time, having reached the top, it began to descend, till it was concealed by the top of the coating. Soon • Phil. Trans. vol. xxxiii. p. 367. † Phil. Mag. for 1811. Cavallo's complete treatise of Electricity, vol. ii. p. 225. after, the machine being continued in action, "a very great flash was seen, a large explosion was heard, and strong smell of sulphur was perceived; a round aperture was cut through the side of the jar, rather more than three quarters of an inch in diameter, and the coating torn off for three or four inches round the aperture." ! There are several other circumstances related of meteors, not very conformable to analogy, or to the laws of a revolving body. Without mentioning their changes of figure and variety of shapes, their separating into several parts and moving on near each other, and then uniting again, as asserted by observers; we would refer particularly to their moving in an irregular curve. This appears to have taken place in several of the most remarkable. "This dipping and rising," says Dr. Pringle,* “of the course of the meteor, is not more extraordinary than its lateral deviation from a straight line; for when observed in the shire of Ross, it was moving to the southward of east, in a direction nearly contrary to the first." Cavallot relates the following of a meteor, that appeared January 15, 1784. "At this moment the body of the meteor appeared of an oblong form, but it presently acquired a tail, and soon after it parted into several bodies, each having a tail, and all moving in the same direction at a small distance from each other, and very little behind the primitive body, the size of which was gradually reducod after the division.-Its course in this direction was very short, perhaps 50 or 6°, after which it turned itself toward the east." Its former course is described as "in an oblique direction toward the east." Of a meteor which appeared August 18, 1783, it is stated, by Alexander Aubert, Esq ‡ "that it moved at first almost in a vertical direction, changing its size and fig ure continually, having to me," says he, "all the appearances of successive inflamations, and not of a solid body. It was sometimes round, at others oval and oblong, with its longest diameter in the line of its motion. I recollect an appearance," he continues, "which confirms me in the idea I had of its not being a solid body. In its progress it did not describe as regIbid p. 113. • See p. 146. † Phil. Trans. vol. lxxiv, p. 108. ular a curve, as might have been expected from such a body, but seemed to move in somewhat of a waving line." We do not know what explanation is to be given of these phenomena, upon the supposition, that meteors are solid bodies. It will hardly be said, that the explosion on the surface is sufficient to change the direction of a heavy mass, a mile in diameter, and moving with a velocity forty or fifty times that of a cannon ball, and to give it an equal velocity in nearly a contrary direction. But there is another fact related of many of these meteors, which, if it is to be relied upon, seems to put the point beyond dispute, and this is the very great velocity, observed in so many instances, and so often remarked upon. "The velocity of the meteor," observes Mr. Day, "corrosponds with the motion of a terrestrial comet, passing through the atmosphere in an elliptical orbit. A body moving near the earth, with a velocity less than three hundred miles in a minute, must fall to its surface by the power of gravitation If it move in a direction parallel to the horizon, more than four hundred and thirty miles in a minute, it will fly off in the curve of an hyperbola; and will never return, unless disturbed in its motion by some other body besides the earth. Within these two limits of three hundred, miles on the one hand, and of four hundred and thirty on the other, (some allowance being made for the resistance of the air and the motion of the earth,) the body will revolve in an ellipsis returning in regular periods." We wish Mr. Day had furnished us with the particulars whence he draws the general conclusion, that this velocity "has generally been estimated to be rather more than three hundred miles in a minute." Mr. C. F. Fulda,* in a memoir read to the Physical Society of Gottingen, December 7, 1796, states a case, upon what he seems to consider as good authority, in which the velocity was esti mated at fifteen hundred and thirty feet per second; that is, less than eighteen miles per minute; and he considers the velocity as varying between this quantity and thirty miles per second, or eighteen hundred per minute. Dr. Youngt says, that the ve locity of these meteors is commonly twenty miles per second, • Phil. Mag. vol. iii. p. 66. † Lectures on Nat. Phil. vok i. p. 721. |