in 1884, 1888, 1891, 1895, 1898, 1901, 1905, and 1908. It does not seem necessary to refer to these returns in detail unless it be to say that in 1895 (that is, at the end of 1894) and in 1898 the comet was very faint and observed with difficulty, whilst in 1904 it was found traced on a photographic plate as early as Sept. 11, though not generally seen till October and later months, when it was observed under very favourable circumstances at many Northern observatories. In 1908 it was not visually seen at all, but left a record of itself on a photographic plate. The only other remark which is worth making is, that comparing these recent returns as a whole it does not appear that the average brilliancy of the comet under average circumstances has varied much or at all during the 122 years that have elapsed since its first discovery. Berberich has written an interesting paper on the brightness of this comet at its many successive apparitions.[1] Perhaps it may be well to add that in 1888, 1898, and 1908 it was observed only or chiefly in the Southern hemisphere.
The period of Encke's comet is 3⋅315 years, so that it returns to the Sun 30 times in a century. The shortness of its period suggested to Miss Clerke that it might naturally be expected to wear out quickly, but there is not a tittle of evidence to justify this rash forecast.
(2.) Tempel's Second Periodical Comet (1873, ii.).
On July 3, 1873, Tempel at Milan discovered a faint comet fully 2' in diameter, somewhat elongated in shape, with an eccentric condensation of light, and a granular appearance. When its orbit came to be calculated it soon became evident that the comet moved in an elliptic orbit with a period of rather more than 5 years. Hind pointed out that soon after passing its ascending node and when near aphelion the comet passes close to the orbit of Jupiter, to which fact is due its periodicity; and it is now to be regarded as, after Encke's, the comet which leads the group known as "Jupiter Comets".[2]
