_Biela’s Comet._—This comet was discovered on Feb. 27, 1826, by Wilhelm von Biela, an Austrian officer, at Josephstadt in Bohemia, and ten days later by Gambart at Marseilles. It was found to be revolving in an orbit of short period, and its elements presented an agreement with those of the comet of 1772 (Montaigne) and 1806 I. (Pons). Identity was inferred, and the next return was fixed for Nov. 27, 1832, when the object reappeared with great punctuality. At the end of 1845 this comet displayed some startling phenomena; for it divided into two portions, apparently quite disconnected, and which travelled side by side, separated by an interval of more than 150,000 miles! The double comet was observed again in 1852, when the interval separating them had, however, increased eightfold, for the dark space between measured 1,250,000 miles. This instance of a divided comet is by no means unique. The great comet of 1882 underwent a process of disruption, by throwing off small masses of nebulosity, which, however, survived the separation only a few days. Brooks’s Comet (1889 V.) was found by Barnard, on Aug. 1, 1889, to be divided into four parts! Two of these had a brief existence; but one of the minor fragments retained a very distinct appearance near the parent mass during the ensuing months of September and October. The phenomena of Biela’s Comet found an excellent counterpart here.
(10-inch reflector, power 60. W. F. Denning.) ]
Since 1852 Biela’s Comet has been lost. The most assiduous observations have failed to recover it, and the conclusion seems irresistible that further disintegrations have occurred and that its material has been dispersed beyond recognition. The great meteoric storms of Nov. 27, 1872 and 1885, were derived from this comet, and there is little reason to hope that _as a comet_ it will ever be seen again.
_Brorsen’s Comet._—A small comet was discovered in Pisces by Theodor Brorsen, at Kiel, on the evening of Feb. 26, 1846, Its observed path soon gave traces of an elliptical orbit; and the period was found to be about 5·58 years. The comet was re-observed at its return to perihelion in 1857, 1868, 1873, and 1879; but in 1884 it was looked for in vain. This comet was expected in February 1890, and several observers swept for it diligently, but to no purpose. Are we, therefore, to regard this as another lost member of our system? Has the comet of Brorsen, like that of Biela, suffered dispersion in such degree as to be no longer within the reach of our powerful telescopes? Should negative results again attend observers in 1895, when the comet ought to return, there will be no reason to doubt its actual disappearance. It may be mentioned that owing to planetary perturbations, the period of this body has rapidly become shorter since 1846. It was then 2034 days, but in 1879 was reduced to 1995 days.