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.
Brooks’s double Comet, Sept. 17, 1889.
(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.
Faye’s Comet.—First seen at the Paris Observatory on the night of Nov. 22, 1843, when it was near the star Bellatrix in Orion. The observations clearly proved the comet to be moving in an elliptical path, and Dr. Goldschmidt of Göttingen determined its period as 7½ years. It was re-observed in 1851, and also during each of its five subsequent returns, the last of which occurred in August 1888. The orbit of this body approaches nearer to the circular form than that of any other known comet, except Tempel’s of 1867. Its perihelion distance is considerable, for it never comes within the orbit of Mars. Prof. Möller, of Lund, has investigated the path with all the critical acumen of a profound mathematician, and, chiefly owing to his labours, it is now regarded as one of the best known members of our system.
D’Arrest’s Comet.—Discovered at the Leipsic Observatory on June 27, 1851. M. Villarceau discussed the orbit, and announced it as an elliptic one with a periodic time of about 6½ years. The comet was redetected at its return in 1857-8, 1870, 1877, and 1890. It is a very faint object.
Pons-Winnecke’s Comet.—Discovered at Bonn on March 8, 1858, and on the elements being computed they were found nearly coincident with those of Pons’s Comet, 1819 III. Encke had assigned a period of 5·62 years for the latter, but it managed to escape observation during the six returns that occurred in the 39 years between 1819 and 1858. Its identity was fully established in 1869, when it was again observed.
Tuttle’s Comet.—A faint, diffused comet was discovered in the northern part of Hercules by H. P. Tuttle, of Cambridge, U.S.A., on Jan. 4, 1858. Its elements on being calculated were found by Pape to be similar to those of a comet discovered by Mechain on Jan. 9, 1790, and an elliptic orbit with a period of 13·66 years was derived from the new observations. On the assumption that the two bodies were one and the same there must have occurred four unobserved returns to perihelion between 1790 and 1858. The year 1871 was awaited in settlement of the question. When it came the comet returned, and the predictions received exact verification. Thus the comets of Mechain and Tuttle were placed in the inseverable bonds of identity.