Many possibilities had to be guarded against. It was, for instance, possible that the object was really a star which, by some mischance, eluded the careful eye of the astronomer who constructed the map. It was even possible that the star might be one of the large class of variables which alternate in brightness, and it might have been conceivable that it was too faint to be seen when the chart was made. Even if neither of these explanations would answer, it was still necessary to show that the object was now moving, and moving with that particular velocity and in that particular direction which the theory of Leverrier indicated. The lapse of a single day was sufficient to dissipate all doubts. The next night the object was again observed. It had moved, and when its motion was measured it was found to accord precisely with what Leverrier had foretold. Indeed, as if no circumstance in the confirmation should be wanting, it was ascertained that the diameter of the planet, as measured by the micrometers at Berlin, was practically coincident with that anticipated by Leverrier. The world speedily rang with the news of this splendid achievement. Instantly the name of Leverrier rose to a pinnacle hardly surpassed by that of any astronomer of any age or country. For a moment it seemed as if the French nation were to enjoy the undivided honor of this splendid triumph. But in the midst of the pæans of triumph with which the enthusiastic French nation hailed the discovery of Leverrier, there appeared a letter from Sir John Herschel in the _Athenæum_ for 3d October, 1846, in which he announced the researches made by Adams, and claimed for him a participation in the glory of the discovery. Subsequent inquiry has shown that this claim was a just one, and it is now universally admitted by all independent authorities. This, however, was of slight comparative importance. The truly wonderful part of the matter was, that these two men could have so reasoned that, from the movements of one lately-discovered planet, they could point out the exact spot where a yet more distant planet ought to be, and that close to this very spot the planet was found. For when, both in England and in Germany, powerful telescopes were pointed in the direction named--_there the planet was_. No doubt about the matter. Not a star, but a real new planet in the far distance, wandering slowly round the sun.