First signs of the doubling of Biela's comet, in the month of January 1840–Observations of the twin comets in America and Europe–Gradual separation and approach of the fragments–The two comets return and are observed in 1852; their distances found to have increased–Elements of the orbits of the two comets.

We now come to transformations still more singular in the outward appearance of cometary nebulosities, and more radical in their nature.

The second return of Biela's comet (period 6¾ years) since the epoch of its discovery as a periodical comet in 1826, or the eleventh of its returns since it was first observed in 1772, was marked by a memorable event, viz. its duplication and division into two distinct and separate comets. We here subjoin a few details on the subject of this event.

On December 21, 1845, the comet was observed by Encke at Berlin; on the 25th of the same month it was seen by M. Valz at Marseilles. Neither of these two astronomers perceived the slightest trace of separation. On the 19th, however, Mr. Hind remarked towards the north of the nucleus what appeared to be a kind of protuberance : was this a premonitory sign of the doubling of the comet? However this may be, it appears certain that the comet was first seen to be double on Janunry 13,1846, at Washington.