Science in Short Chapters

by W. Mattieu Williams

Mr. Slinto, in a letter to the Times, estimates the number seen at Suez as reaching at least 30,000, while in Italy and Athens about 200 per minute were observed. They were not, however, the Leonides, that is, they did not radiate from a point in the constellation Leo, but from the region of Andromeda. Therefore they were distinct from that system of small wanderers usually designated the “November meteors,” were not connected with Tempel’s comet (comet 1, 1866), but belong to quite another set.

The question now discussed by astronomers is whether they are connected with any other comet, and, if so, with which comet?

In the “Monthly Notices” of the Royal Astronomical Society, published October 24th last, is a very interesting paper by Professor Herschel, on “Observations of Meteor Showers,” supposed to be connected with “Biela’s comet,” in which he recommends that “a watch should be kept during the last week in November and the first week in December,” in order to verify “the ingenious suggestions of Dr. Weiss,” which, popularly stated, amount to this, viz., that a meteoric cloud is revolving in the same orbit as Biela’s comet, and that in 1772 the earth dashed through this meteoric orbit on December 10th. In 1826 it did the same, on December 4th; in 1852 the earth passed through the node on November 28th, and there are reasons for expecting a repetition at about the same date in 1872.

The magnificent display of the 27th has afforded an important verification of these anticipations, which become especially interesting in connection with the curious history of Biela’s comet, which receives its name from M. Biela, of Josephstadt, who observed it in 1826, calculated its orbit, and considered it identical with the comets of 1772, 1805, etc. It travels in a long eccentric ellipse, and completes its orbit in 2410 days—about 6¾ years. It appeared again, as predicted, in 1832 and 1846.

Its orbit very nearly intersects that of the earth, and thus affords a remote possibility of that sort of collision which has excited so much terror in the minds of many people, but which an enthusiastic astronomer of the present generation would anticipate with something like the sensational interest which stirs the soul of a London street-boy when he is madly struggling to keep pace with a fire-engine.

The calculations for 1832 showed that this comet should cross the earth’s orbit a little before the time of the earth’s arrival at the same place; but as such a comet, traveling in such an orbit, is liable to possible retardations, the calculations could only be approximately accurate, and thus the sensational astronomer was not altogether without hope. This time, however, he was disappointed; the comet was punctual, and crossed the critical node about a month before the earth reached it.

As though to compensate for this disappointment, the comet at its next appearance exhibited some entirely new phenomena. It split itself into two comets, in such a manner that the performance was visible to the telescopic observer. Both of these comets had nuclei and short tails, and they alternately varied in brightness, sometimes one, then the other, having the advantage. They traveled on at a distance of about 156,000 miles from each other, with parallel tails, and with a sort of friendly communication in the form of a faint arc of light, which extended as a kind of bridge, from one to the other. Besides this, the one which was first the brighter, then the fainter, and finally the brighter again, threw out two additional tails, one of which extended lovingly towards its companion.

The time of return in 1852 was of course anxiously expected by astronomers, and careful watch was kept for the wanderers. They came again at the calculated time, still separated as before.

They were again due in 1859, in 1866, and, finally, at about the end of last November, or the beginning of the present month. Though eagerly looked for by astronomers in all parts of the civilized world, they have been seen no more since 1852.

What, then, has become of them? Have they further subdivided? Have they crumbled into meteoric dust? Have they blazed or boiled into thin air? or have they been dragged by some interfering gravitation into another orbit? The last supposition is the most improbable, as none of the visible inhabitants of space have come near enough to disturb them.