Bouvard himself appears to have believed in the existence of a planet exterior to Uranus whose attraction was producing these disturbances, but he died in 1843 before any progress had been made with the solution of the enigma. In 1834 Hussey approached Airy, the Astronomer Royal, with the suggestion that he might sweep for the supposed exterior planet if some mathematician would help him as to the most likely region to investigate. Airy, however, returned a sufficiently discouraging answer, and Hussey apparently was deterred by it from carrying out a search which might very possibly have been rewarded by success. Bessel, the great German mathematician, had marked the problem for his own, and would doubtless have succeeded in solving it, but shortly after he had begun the gathering of material for his researches, he was seized with the illness which ultimately proved fatal to him. The question was thus practically untouched when in 1841, John Couch Adams, then an undergraduate of St. John's College, Cambridge, jotted down a memorandum in which he indicated his resolve to attack it and attempt the discovery of the perturbing planet, 'as soon as possible after taking my degree.' The half-sheet of notepaper on which the memorandum was made is still extant, and forms part of the volume of manuscripts on the subject preserved in the library of St. John's College. On October 21, 1845, Adams, who had taken his degree (Senior Wrangler) in 1843, communicated to Airy the results of his sixth and final attempt at the solution of the problem, and furnished him with the elements and mass of the perturbing planet, and an indication of its approximate place in the heavens. Airy, whose record in the matter reads very strangely, was little more inclined to give encouragement to Adams than to Hussey. He replied by propounding to the young investigator a question which he considered 'a question of vast importance, an _experimentum crucis_,' which Adams seemingly considered of so little moment, that strangely enough he never troubled to answer it. Then the matter dropped out of sight, though, had the planet been sought for when Adams's results were first communicated to the Astronomer Royal, it would have been found within 3-1/2 lunar diameters of the place assigned to it.