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XIII. Fig. 104 gives, according to H. A. Newton, the positions of Biela's Comet in its orbit relatively to the Earth at the times of the occurrence of the great meteor showers known to have been manifested when the Earth was near this comet's orbit. The line of the nodes, or the place of the Earth's nearest approach to the comet's track, being at N, it appears that in 1798, when the Earth encountered at that point the great meteor shower of Dec. 6 of that year, observed by Brandes, Biela's Comet was at B, somewhat nearer to the Earth than in 1838 on the next occasion when a similar display was witnessed. In the last-named year the comet was at A, about 300 millions of miles distant along its orbit from the Earth. At the recurrence of the great meteor shower of Nov. 27, 1872, the comet must have been near C, or about 200 millions of miles along its path from the node N. From this it would seem that the meteoric particles must be thickly distributed over a stretch of at least 500 millions of miles of the comet's orbit, preceding the comet "to a distance of 300 millions of miles, and following it to a distance of 200 millions of miles, as in 1872 ."

If Biela's Comet had maintained its existence it would have reappeared in 1879, 1886, 1892, 1899, and 1906. It has been suggested that in the years in which it would have been due the Andromedes meteors were more pronounced than in ordinary years, but I have not found sufficient evidence to support this idea.

One case of a meteor shower pairing off with a comet in the way above described might have been a mere coincidence; but four clear cases set astronomers thinking that there was something important in the background. That something is that all meteor showers are manifestations of broken-up comets. This may be the case, but it is premature at present to assert this dogmatically. Probably it may be safely assumed that the more scattered a meteor shower is the longer