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134 only 68° to be described during the time which would elapse before its next return to perihelion. Various attempts have been made, without any very definite measure of success, to identify this comet with others which have gone before; but this is a matter which belongs to a previous chapter.

The Comet of 1858 (vi.). On June 2 in that year G. B. Donati, of Florence, descried a faint nebulosity slowly advancing towards the North, and near the star λ Leonis. Owing to its immense distance from the Earth (something like 240,000,000 miles) great difficulty was experienced in laying down its orbit. By the middle of August, however its future course, and the great increase in its brightness which would take place in September and October, were clearly foreseen. Up to August it had remained a faint object, not discernible by the unaided eye. It was distinguished from ordinary telescopic comets only by the extreme slowness of its motion (in singular contrast to its subsequent career), and by the vivid light of its nucleus. It has well been said that "the latter peculiarity was of itself prophetic of a splendid destiny". Traces of a tail were noticed on August 20. and on August 29 the comet was faintly perceptible to a keen unaided eye, but it was not until Sept. 3 that I so saw it. For a few weeks the comet occupied a Northern position in the Heavens, and it was therefore seen both in the morning and in the evening. On Sept. 6 a slight curvature of the tail was noticed, which subsequently became one of its most striking features. On Sept. 17 the head equalled in brightness a star of the 2nd mag., the length of the tail being 4°. The comet passed its perihelion on Sept. 29, and was at its least distance from the Earth on Oct. 10. Its rapid passage to the Southern Hemisphere rendered it invisible in Europe after the end of October, but it was followed at the Santiago-de-Chili and Cape of Good Hope Observatories for some months afterwards, being last seen by Sir T. Maclear at the latter place on March 4, 1859." Its early discovery enabled Astronomers, while it was yet