1854.] 



METEORS AND FALLING STARS. 



21! 



approach the regions of space through which the earth is moving, 

 they enter the atmosphere with great velocity, and in consequence 

 of the great resistance and friction which follow, are rendered 

 incandescent, and emit a light as long as they remain in it. As 

 there have thus been believers in the planetary origin of meteor- 

 ites, so some of the Greek philosophers thought they came from 

 the sun. This was the opinion of Diogenes Laertius regarding 

 the origin of the Aegos Potamos stone, about which Aristotle 

 held such an absurd idea. 



COSMICAL ORIGIN OF AEROLITES, ETC. 



The more general opinion now is that the greater portion of 

 meteors are of cosmical origin — -that is, bodies revolving in space, 

 independent of the earth's rotation, and subject to the same laws 

 as the other celestial bodies. " Shooting-stars, fire-balls, , and 

 meteoric stones are,'' says Humboldt, "with great probability, 

 regarded as small bodies moving with planetary velocity, and 

 revolving, in obedience to the laws of general gravity, in conic 

 sections round the sun. When these masses meet the earth in 

 their course, and are attracted by it, they enter within the limits 

 of our atmosphere in a luminous condition, and frequent]} - let fall 

 more or less strongly heated stony fragments, covered with a 

 shining black crust; but the formative power, and the nature of 

 the physical and chemical processes involved in these phenomena, 

 are questions all equally shrouded in mystery." 



The great argument in favor of this view of the character of 

 these bodies is derived from the divergence or point of departure 

 being generally stationary, and secondly, from their entirely plane- 

 tary velocity. These facts led Sir John Herschell to decide "that 

 a zone or zones of these bodies revolve about the sun, and are 

 intersected by the earth in its annual revolution." Capocci, of 

 Naples, regards the Aurora Borealis, shooting- stars, aerolites, and 

 comets as all having the same origin, and as resulting from the 

 aggregation of cosmical atoms, brought into union by magnetic 

 attraction. He supposes that in the planetary spaces there exist 

 bands or zones of nebulous particles, more or less fine, and endued 

 with magnetic forces, which the earth traverses in its annual revo- 

 lution ; that the smallest and most impalpable of these particles 

 are occasionally precipitated on the magnetic poles of our globe, 

 and form polar Auroras; that the particles a degree larger, in 

 which the force of gravitation begins to be manifested, are attracted 

 by the earth, and appear as shooting-stars; that the particles in 

 a more advanced state of concretion give rise in like manner to 

 the phenomena of fire balls, aerolites, etc. ; that the cornels which 

 are known to have very small masses are nothing else than the 

 largest of the aerolites, or rather uranolites, which, in course of 

 time, collect a sufficient quantity of matter to be visible from the 

 earth. 



After the great shower of stars in 1833, and the observed 

 periodicity of its character, Professor Olmsted, collecting all the 

 facts within reach, deduced from them the existence of a nebu- 

 lous cloud or mass of meteoric stars, approaching the earth at 

 particular periods of its revolution, under conditions as to time, 

 direction, and physical changes from proximity, which he has 

 fully detailed in Silliman's Journal of Science for 1834 and 

 1836. His speculation that this meteoric cloud might be part 

 of the solar nebula known as the Zodiacal Light, was taken up 

 and enlarged upon by Biot in a Memoir read by him in 1836. 

 He shows that on the 13th November the earth is in such a rela- 

 tive position that it must necessarily act by attraction or contact 

 upon the material particles of which this nebula is composed, 

 producing phenomena which we may reasonably consider to be 

 represented by these meteoric showers. He brings the same 



theory to explain the sporadic shooting-stars of ordinary nights. 

 He supposes that the habitual passage of Mercury and Venus 

 across the more central regions of this nebula must have dispersed 

 innumerable particles in orbits very little inclined to the ecliptic, 

 and so variously directed that the earth may encumber, attract, 

 and render them luminous in every part of its revolution. Sup- 

 posing, then, we admit that these meteors compose a closed ring 

 or zone, within which they all pursue one common orbit, how is 

 it that we so seldom witness such splendid spectacles as those 

 exhibited in the November showers of 1799 and 1833? "If," 

 says Humboldt, " in one of these rings, which we regard as the 

 orbit of a periodical stream, the asteroids should be so irregularly 

 distributed as to consist of but few groups sufficiently dense to 

 give rise to these phenomena, we may easily account for the 

 unfrequency of such glorious sights." Olbers has predicted, but 

 I know not upon what data, that the next appearance of the 

 phenomenon of shooting stars and fire-balls intermixed, falling 

 like flakes of snow, will not occur until between the 12th and 

 14th November, 1867. — [Cosmos, vol. i., p. 127.) Again: the 

 enormous swarm of falling-stars in November, 1799, was almost 

 exclusively seen in America — the swarms of 1831 and 1832 were 

 visible only in Europe, and those of 1833 and 1834 only in the 

 United States, and occasionally the November stream has been 

 visible in but a small portion of the earth. A very splendid 

 meteoric shower was seen in England in 1837, while a most 

 attentive and skillful observer at Braunzberg, in Prussia, only 

 saw on the same night, which was uninterruptedly clear, a few 

 sporadic shooting-stars, between 7 o'clock p. m. and sunrise the 

 next morning. Bessel explains, " that a dense group of the bodies 

 comprising the great ring may have reached that part of the 

 earth in which England is situated, while the more eastern dis- 

 tricts of the earth might be passing at the time through a part 

 of the meteoric ring proportionally less densely studded with 

 bodies." In the same way Humboldt accounts for the non- 

 appearance, during certain years, in any portion of the earth, of 

 the two great streams of August and November, to intervals 

 occurring between the asteroid groups. Poisson's account of this 

 is somewhat different. " If," says he, " the group of falling-stars 

 form an annul us around the sun, its velocity of circulation may 

 be very different from that of our earth ; and the displacements 

 it may experience in space, in consequence of the actions of the 

 various planets, may render the phenomenon of its intersecting 

 the planes of the ecliptic possible at some epochs, and altogether 

 impossible at others." The latest form of this hypothesis is that 

 adopted by M. M. Saigney and Gravier, in France, viz., that 

 meteors and their substances have their original abode in infinite 

 space ; that large groups of shooting-stars are situated in portions 

 of the heavens visited by our earth ; that, when our globe arrives 

 in the vicinity of these corpuscules, they are attracted by the 

 earth, and, bursting, leave the material of which they are com- 

 posed to fall upon the surface of our globe. 



Whilst this is now generally regarded as the most probable 

 hypothesis yet framed to account for the origin of these myste- 

 rious appearances, still, even by it, many things regarding meteors 

 are left unsolved. Many questions there are yet awaiting the 

 possible solution of the future, and this solution can only be the 

 result of more extended observation and experiment. It is the 

 duty, therefore, of all who desire the advancement of science, to 

 aid in adding at least to the number of recorded observations, 

 and thus to broaden the basis on which the astronomer and the 

 man of science are to build their hypotheses and their theories. 



In conclusion, it is remarkable to find that the opinions of some 

 of the Greek natural philosophers, particularly those of the Ionian 

 school, early assumed the cosmical origin of meteoric stones. 



