HISTORICAL VIEW OP THE

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Sir W. Herschel had succeeded beyond any previousartist in forming and polishing large metallic speculafor telescopes; and, with his gigantic instruments, hadthe satisfaction of soon adding a new planet to our sys-tem. The discovery of Uranus took place in 1781, andwas immediately recognised by astronomers throughoutEurope . The same eminent observer continued to de-vote himself to the minute examination of the heavens ;and added immensely to our knowledge of the nebulae,the appearances and probable physical nature of the sun ;and, lastly, of double stars; which, by comparison of ob-servations at considerable intervals, he found, were, inseveral instances, composed of two bodies, revolvinground their common centre of gravity. This discoverywas announced in 1803, and has been since abundantlyconfirmed by the joint labours of his highly distinguishedson and Sir J. South; as well as of M. Struve, ofDorpat. Thus is an unlimited extension given to thedominion of the great law of gravitation; even the el-liptic forms of the orbits having been, in several in-stances, ascertained.

Another series of brilliant discoveries were those ofthe four small planets between the orbits of Mars andJupiter: Ceres , discovered by Piazzi, in 1801, Pallas,by Olbers , in 1802 ; Juno, by Harding, in 1804 ; andVesta; by Olbers , in 1807.

The establishment of the periods of two very remark-able comets has also marked the present century. Oneobserved in 1819 and 1822 was found to resembleprevious appearances. Encke calculated the orbit, andpredicted its return in 1825, which was fully verified;and again in 1828 and 1832. It is thus shown to be asmall nebulous body, belonging to our system, of a na-ture, in some sense, intermediate to a comet and aplanet. Another body, of a similar nature, was in likemanner shown to be a periodical comet by Biela, in1825.

The last-mentioned discoveries are all of continentalorigin; and there are numerous other important researches