The planet which Herschel called after George III. (but which now goes under the more appropriate name of Uranus) was discovered by him March 13, 1781; not accidentally, but as one of the fruits of a laborious investigation, with a distinct and useful object. He was examining every star with one telescope, that he might obtain a definite idea of relative phenomena, which should enable him to distinguish changes actually taking place, from differences of appearance caused by the use of different telescopes: the whole being in furtherance of the design of “throwing some new light upon the organization of the celestial bodies.” The last words, which are part of the title of one of his subsequent papers, aptly express the line of astronomy to which Herschel devoted his life; and the discovery of the planet Uranus was not the chance work of a moment, but the consequence of sagacity strengthened by habit, the latter being formed with a perfect knowledge of what was wanted, as well as of what would be useful in supplying it. Had he been merely registering the places of the stars, he would probably (as others did before him) have passed the planet, perhaps with some remark upon its apparent _diskiness_: for though the stars have no well-defined discs, yet some have so much more of the appearance of discs than others, that a faint planet, viewed with a low power, might easily be taken for a star. But being engaged upon the stars, expressly with a view to trying how much of such a circumstance would be telescopic, and how much real, he was thereby led to try higher powers, and, eventually, other telescopes. The existence of the _planet_ was soon ascertained, and forms one of the two great features of Herschel’s reputation in the eyes of the world at large.