Page:Popular Science Monthly Volume 1.djvu/350

338 It is proper to remark, however, that Newton's period of the meteors exceeds Oppolzer's period of the comet by twenty-seven days, and that each is liable to some uncertainty. But for the authority of the distinguished French astronomer, the writer would have fixed upon the year 43 as the probable epoch at which the cometary mass was thrown into its present orbit. Be this as it may, it undoubtedly suffered considerable perturbation about 126.

The question of the planetary disturbance of the meteor-streams is one of great interest. The November group has its perihelion at the orbit of the earth; its aphelion at that of Uranus. Both planets, therefore, at each encounter with the current not only appropriate a portion of the meteoric matter, but entirely change the orbits of a large number of meteors. In regard to the devastation produced by the earth in passing through the cluster, it is sufficient to state that, according to Weiss, the meteor orbits resulting from the disturbance will have all possible periods from 21 months to 390 years. It may be regarded, therefore, as an additional evidence of the recent introduction of this meteor-stream into the solar system that the comet of 1866, which constitutes a part of the cluster, has not been deflected from the meteoric orbit by either the earth or Uranus. It is, moreover, interesting to remark that the comet and Uranus will be in close proximity about the year 1983; perhaps so close as to throw the former into a new orbit.

As the comets 1862, III., and 1866, I., were doubtless more brilliant in ancient than in modern times, and as the former was conspicuously visible to the naked eye, it seems not improbable that they may have been formerly observed. The epochs of their ancient returns agree in several instances with those of comets of which the recorded observations are insufficient to determine their elements.

The writer as long since as 1861 suggested the probable disintegration of Biela's comet and the distribution of its matter around the orbit. The earth crosses the path of these cometary fragments about the 29th or 30th of November—a well-known aërolitic epoch. It is also worthy of notice that an extraordinary number of shooting-stars was observed by M. Heis, at Aix-la-Chapelle, on the 29th of November, 1850.

From the fact that the earth, about the 20th of April, very nearly crosses the orbit of the comet 1861, I., a connection between the latter and the meteors of that epoch has been suggested by some astronomers. The period of the comet is, according to Oppolzer, 415 years. The first recorded shower of the April meteors occurred in the year 687 b. c.; the last great display in 1803 a. d. The interval is equal to six periods of 415 years. It is evident, however, that, if these meteors and the first comet of 1861 originally constituted a single group,