We know not that Dr. Murray is more successful, when he insinuates, in one passage, that these bodies spring from the thunder storm, and when he resorts, in another, to the solvent agency of hydrogen, and the changes produced on different substances by the influ ence of the electiic fluid. That truly philosophic tra veller and observer, Humboldt, who studied the pre sent subject with much attention, is decidedly of opi nion, that meteorites are foreign to the confines of our atmosphere.
The romantic notion, that they are the products of lunar volcanos, has derived sonic countenance from the speculations of the celebrated La Place, Poisson, Dr.
Hutton, and others, who bate demonstrated the abstract proposition, that a heavy body, projected with a velocity of about 6000 feet in a second, may be driven beyond the sphere of the moon's attraction into that of the earth. But the existence of any such volcanic force in the moon is purely hypothetical ; nay, the existence of volcanos at all in our satellite, begins to be very seriously ques tioned. Overlooking these considerations, however, as well as the combustion of sub lunar substances without the contact of atmospherical air, the occasional arrival of fragments of such lava on the surface of the earth would, on a fair computation of chances, imply such a copious discharge of volcanic matters, that the moon, by this time, should consist of hardly any thing else. Further, if we may be allowed to reason Irom analogy, we should ex pect the volcanic productions of the moon to exhibit varieties of aspect and composition, and not a definite and precise number of the same ingredients. The re sistance which a body falling fecim our satellite would experience in its transit through our atmosphere, com bined with the two-fold motion of the earth, may suffi ciently obviate the ordinary objection derived from the comparatively moderate impulse with which meteorites usually impinge on the earth's surface, but affords no solution of the more formidable difficulty, deduced from the want of coincidence, in point of time, between the descent of these stones and the moon's position, she being as often in their nadir as in their zenith.
Dr. Chladni, who, for years, has devoted much of his attention to the history of meteoric stones, long since intimated his belief, that they are cosmical bodies, or fragments of planetary matter. As earthy, metallic, and other particles, form the principal component parts of our planet, among which iron is the prevailing ingredi ent, other planetary bodies, he affirms, may consist of similar, or, perhaps, of the same component parts, though combined and modified in a very different manner. There may also be dense matters, accumulated in small er masses, disp.:rsed throughout infinite space, and which, being impelled either by some projecting power or attraction, continue to move until they approach the earth, or sonic other body, when, being overcome by gravitating force, they immediately fall down. By their exceeding great velocity, and the violent friction in the atmosphere, a strong electricity and heat must necessa rily be excited, by which means they arc reduced to a flaming and melted condition, and great quantities of va pour and different kinds of gases are thus disengaged, which distend the liquid mass, until, by a still further expansion of these elastic fluids, the whole at length ex plodes.
Our principal objection to this sort of reasoning is, that the leading idea of portions of cosmical matter be ing allowed to revolve in space, and to terminate their career on the surface of a planetary orb, is stated in terms too vague and gratuitous ; but it assumes some what of reason and consistency. %t hen propounded the particular development of which we have conceived it to be susceptible.
Although we ha% e now allotted to this curious sub ject as much space as our limits wi.I permit, we arc still far from having exhausted its details ; and we shall, therefore, conclude by recommending to the perusal of our inquisitive readers, Stepling de Pluvia lanidea Troili's Essay. already cited ; la tvo Lithoi.n;e. .117nos filiErique ; Bigot de INIorogues, Me/noires Ilistoriques e:: :NI••EoaoLoov may be defined that department of phy sical science which treats of atmospherical phenomena. This definition is immediately suggested by the origi nal impol t of the word, as derived from tc“EGlec4, mete ors ; and Xovos, a discourse. The word meteors, indeed, has, in our language, been almost exclusively confined to those luminous bodies, which are seen occasionally in our atmosphere, and whose appearance and motion have not hitherto been reduced to any definite law. In Greek, however, the word perrEays, (from FACTECJe05, high or c/c tned) was indiscriminately applied to ali bodies, whe ther luminous or opaque, that appeared in, or were de posited from the atmosphere ; and the term meteorology is still used in the same, or even a more extended ac ceptation. It denotes the investigation, not only of those atmospherical phenomena that are of comparatively rare occurrence, and may be more properly denominated meteors, hut of the various changes also, that are ob served to take place in the state of the atmosphere it self. But for this extended application of the the subject would be comparatively uninteresting, and could with little propriety be dignified with the appellation of a science. Bodies that appear only at irregular inter vals, at a considerable distance from the cal th, and per haps but for a few seconds at a time, though unques tionably deserving of being noticed and recorded, are not likely soon to be subjected to any thing like accu rate investigation, or ever to be interesting, otherwise than as objects of curiosity or conjecture. The case, however, is very different with those atmospherical phe nomena, which, from their frequency or vicinity to the earth, immediately affect the comfort and subsistence of its inhabitants. These must be at all times inlet csting, and in the progressive advancement of physical science they arc becoming every day more so, in consequence of the invention of various instruments, by which their effects may be mote accurately estimated ; and their causes, it is to be hoped, in due time unfolded and ex plained. It is chiefly to these last, therefore, as consti tuting the great principles of meteorological science, that we propose directing the attention of our readers in the present article, and shall purposely avoid dwelling, at any great length, on the state of meteorology previous to the invention of those instruments, by which, in mo dern times, this department of science has been enrich ed, or on such phenomena as have not yet been made the subject of any thing like direct experiment.