94 HISTORY OF THE [1840-50 to do about Adams ? He was no novice in reading astronomical documents, and whatever importance he may have attached to an extra verification, he cannot, in my opinion, have been under any doubt of the significance of the brief paper of results which Adams had left with him in 1845 October, or have supposed that the explanation they offered could be explained away. Yet as for any spontaneous action of his own, then or later, until the force of circumstances had established Adams in a secure position, he seems to have been willing to let Adams's claim and achievement perish unknown. In excuse for judging so severely Airy's attitude, one must remember the peculiar eminence of his position ; he was the official guardian of British astronomy, and even of science in general, as no one else has ever been ; he deliberately made such a position for himself by cultivating connections at home and abroad, both within and without the borders of his science ; and he was at all times a man of rapid and effective action, never too busy to take up something new. Anyway, Airy came to the conclusion before the Greenwich Visitation in June, that the planet must be searched for, and that the Northumberland equatoreal, at Cambridge, should be set to the work. He mentioned it to the Visitors as a matter of necessary division of labour, and referred to Adams's confirmation of Le Verrier. Herschel was present, and seized the importance of the point at once. The idea was not a new one. Hansen and E. Bouvard had canvassed it. As long before as 1842, Bessel had been Herschel 's guest and had talked with him over the errors of Uranus. He was going to devote attention to it on his return home, and would consider the explanation offered by an exterior planet. He wrote to Herschel afterwards : "I announce to you (melde ich Ihnen) that Uranus is not forgotten," and in fact a young astronomer, Flemming, was engaged by him upon pre- liminary work at the time of his fatal illness. Herschel felt no doubt of the existence of the planet, and announced the im- pending discovery, as far as he felt entitled to do, at the meeting of the British Association in the course of the summer. Unfortunately the use of the Northumberland telescope meant Challis's direction of operations. It may be admitted that Challis was a man of no imagination. The Athenaeum, in one of its com- ments on the event, speaks of " the wise men who never believe until the thing is done, the sober men to whom everything that is to be is a figment in the brain of a visionary, the practical men who are not quite sure there is a future until it runs by them in the shape of time present." Challis was one of them. The search had no attraction for him. One might suppose he did not want to dis- cover the planet, for when his eye lighted actually upon it in the
