1874, July.—Coggia’s Comet: a fine object in the northern sky. On July 14 the tail was 35° long, and it remained visible several days after the nucleus had disappeared below the horizon. The nucleus was about equal to a star of the 1st mag. Orbit probably elliptical, with a period of about 5711 years.
1880 I., Jan.-Feb.—A southern comet, with a long narrow tail, variously estimated from 30° to 40° in length. It passed very near to the Sun, and presents an orbital resemblance to the fine comets of 1680 and 1843.
1881 III., June-July.—This large comet appeared in the northern heavens on June 22, and became generally visible to observers in England. On the 27th it had a tail 15° long. Its period of visibility extended over nine months.
1881 IV., Aug.—This comet is scarcely entitled to rank as one of exceptional character; but it was a conspicuous object for several weeks in August, and had a tail 6° long on the 19th.
1882 III., Oct.—Well visible in the morning sky, with a tail 22° long. The nucleus underwent remarkable changes, and on Oct. 23 it showed four or five bright points or nuclei, looking like “a string of beads.” The comet threw off several small condensations, which were observed as separate comets near the parent mass. At perihelion this comet passed very close to the Sun, like the comets of 1680, 1843, and 1880; and these bodies were suspected to have an intimate relation, if not an absolute identity. But subsequent inquiries disproved this startling supposition; for the comet of 1882 was shown to have a period of about 718 years.
1887 I., Jan.—A fine southern comet, presenting many points of resemblance to that of 1880 I. On Jan. 22, as observed at Adelaide, the comet had a long narrow tail of about 30°, but no well-defined nucleus. On the same date, at the Cape of Good Hope, the tail appeared as a narrow ribbon of light, quite straight, and of nearly uniform brightness throughout its length. It was visible in the same region of the sky as the comet 1880 I., and came into view with equal suddenness.
Periodical Comets.—On page [235] is a list of the periodical comets as at present known. Some of these, marked with an asterisk, have only been observed at one return, and therefore await complete confirmation.
Many other comets have shown indications of pursuing elliptical orbits. Amongst those of short period may be mentioned 1743 I., 1766 II., 1783 I., 1819 IV., 1844 I., and 1873 VII. The following are examples of longer periods:—
| Comet. | Period. | |
|---|---|---|
| 1862 III. | 121 | years. |
| 1857 IV. | 234 | ” |
| 1861 I. | 415 | ” |
| 1860 III. | 1089 | ” |
| 1889 IV. | 5100 | ” |
| 1877 II. | 8393 | ” |
| 1847 III. | 13918 | ” |
| 1877 III. | 28,000 | ” |
| 1850 I. | 29,000 | ” |
| 1780 I. | 75,314 | ” |
| 1844 II. | 102,050 | ” |
| 1744 | 122,683 | ” |
| 1849 I. | 382,801 | ” |
| 1882 I. | 400,000 | ” |
These figures are to be regarded as approximations only.