In January, 1867, M. Stephan, of Marseilles, discovered a new comet, the elements of which, after two months' observations, were computed by Mr. G. M. Searle, of Cambridge, Massachusetts. The perihelion of this body is near the orbit of Mars; its aphelion near that of Uranus,--the least distance of the orbits being about 2,000,000 miles. The present form of the cometary path is doubtless due to the disturbing action of Uranus. The comet completes its revolution in 33.62 years; consequently (as has been pointed out by Mr. J. R. Hind) five of its periods are almost exactly equal to two periods of Uranus. The next approximate appulse of the two bodies will occur in 1985, when the form of the comet's orbit may be sensibly modified. ELLIPTIC COMETS WHOSE APHELIA ARE AT A MUCH GREATER DISTANCE THAN NEPTUNE'S ORBIT. In October, 1097, a comet was seen both in Europe and China, which was noted for the fact of its having two distinct tails, making with each other an angle of about 40°. From a discussion of the Chinese observations (which extended through a longer period than the European), Laugier concluded that this body is identical with the third comet of 1840, which was discovered by Galle on the 6th of March. If, therefore, it has made no intermediate return without being observed, it must have a period of about 743 years. It is also highly probable, from the similarity of elements, that the comet which passed its perihelion on the 5th of June, 1845, was a reappearance of the comet of 1596,--the period of revolution being 249 years. The elements of the great comet of 1843 are somewhat uncertain. There is a probability, however, of the identity of this body with the comet of 1668. This would make the period 175 years. The third comet of 1862 is especially interesting from its connection with the August meteors. Its period, according to Dr. Oppolzer, is 121-1/2 years. THE GREAT COMET OF 1858 was one of the most remarkable in the nineteenth century. It was discovered on the 2d of June, by Donati, of Florence, and first became visible to the naked eye about the last of August. The comet attained its greatest brilliancy about the 10th of October, when its distance from the earth was 50,000,000 miles. The length of its tail somewhat exceeded this distance. If, therefore, the comet had been at that time directly between the sun and the earth, the latter must have been enveloped for a number of hours in the cometic matter. The observations of this comet during a period of five months enabled astronomers to determine the elements of its orbit within small limits of error. It completes a revolution, according to Newcomb, in 1854 years, in an orbit somewhat more eccentric than that of Halley's comet. It will not return before the 38th century, and will only reach its aphelion about the year 2800. Its motion per second when nearest the sun is 36 miles; when most remote, only 234 yards. CHAPTER IV. OTHER REMARKABLE COMETS.