METEORS. The whole subject of meteors was treated in the body of the work under the head of MatoLvrEs. The subject, however, has since occupied a great deal of attention, and there is at present a tendency on the part of astronomers and physicists. to separate that class of meteors known as " shooting-stars" from the group of meteoro lites (which includes airo-siderites, or masses of meteoric iron; siderolites, which are conglomerates of iron and stone; and aerolites, which are wholly of stone), on the grounds that the most prominent appearances of the former are periodic, while the latter seem to occur at irregular intervals, and that the former have hitherto not been proved to leave any traces of their visit on the earth's surface. We are, however, hardly as yet in a position to decide as to the similmity or dissimilarity of the two classes of bodies.
Popular interest has been largely aroused respecting " shooting-stars," by reason of the brilliant display of them which took place on the night of Nov. 13,1866. This " star-shower," the grandest that has ever been observed in Britain, was confidently pre dicted, from the occurrence of a similar shower at the corresponding date in 1799,1883, and 1834; and the extremely favorable state of the atmosphere rewarded those who were on the watch with a complete view of one of nature's most magnificent displays. The shower commenced about ill P.m., with the appearance at brief intervals of single meteors; then they came in twos and threes, steadily and rapidly increasing in number till 1h. 13m. A.M. on Nov. 14, when no fewer than 57 appeared in one minute. From this time the intensity of the shower diminished gradually, wholly ceasino. about 4 A.m. The total number of meteors which at that time came within the limitsnof the earth's atmosphere was estimated at about 240,000, and the number seen at each of the several observatories in Britain averaged nearly 6,000. This star-shower, like those of 1833 and 1834, seemed to proceed from the region of the heavens marked by the stars and y in the constellation Leo; and it has been shown by astronomers that this was the point towards which the earth in her orbit was moving at the time; consequently, she had either overtaken the meteoric shower, or had "met" it proceeding in a contrary direction. The meteors on that occasion presented the usual variety of color, size, and duration; the great majority were white, with a bluish or yellowish tinge; a considerable number were red and orange; and a few were blue; many surpassed the fixed stars in luster, and soroe were even brighter than Venus (the most brilliant planet as seen from the earth) at her maxinium. Most of the meteors left trains of vivid green light 5° to 15° in
length, which rnarked their course through the heavens, and endured for 3' on an average, then becominff dissipated; though some of the trains were almost 40° in length, and remained in sighCfor several minutes. Prof. Airy observed that the direction of the meteors' flight was little influenced by the earth's attraction.
On the morning of Nov. 14,1867, a star-shower equal in magnitude to that of 1866. was observed in France and America, but was almost wholly invisible in Britain, on account of the cloudy state of the atmosphere.
The brilliant display of 1866 gave a vigorous impulse to the astronomical investiga tion of shooting-stars, and it is now generally agreed that the November meteors move in an orbit round the sun, inclined at about 7° to that of the earth, and that, in all proba bility, this orbit forms a ring or belt of innumerable small fragments of matter, distrib uted with very variable density of grouping along it, thus corresponding so far to the planetoid (q.v.) group between Mars and Jupiter. It is also agreed that the motion of this meteor ring round the sun is retrograde; that the earth's orbit at that point where she is situated on Nov. 13-14 intersects this ring; and that, probably, in 1799, 1833-34, and 1866-67, it is the same group of meteors which has been observed; and the last mentioned hypothesis has been made the foundation of a calculation of the probable orbit and periodic time of this meteor-ring. The fact that a November star-shower -generally occurs for two years in succession, and then recurs at an interval of 82 or 33 years, seems to indicate that though the earth may pass through the meteor-orbit every year, the meteors are so grouped at intervals along the ring, and their periodic time differs so much from that of the earth, that it requires 32-33 years before this accumu. lating difference amounts to a complete revolution of either the earth or the ring, and a repetition of the star-shower becomes possible.