After he had taken his degree, and had thus obtained a little
relaxation from the lines within which his studies had previously
been necessarily confined, Adams devoted himself to the study of the
perturbations of Uranus, in accordance with the resolve which we have
just seen that he formed while he was still an undergraduate. As a
first attempt he made the supposition that there might be a planet
exterior to Uranus, at a distance which was double that of Uranus
from the sun. Having completed his calculation as to the effect
which such a hypothetical planet might exercise upon the movement of
Uranus, he came to the conclusion that it would be quite possible to
account completely for the unexplained difficulties by the action of
an exterior planet, if only that planet were of adequate size and had
its orbit properly placed. It was necessary, however, to follow up
the problem more precisely, and accordingly an application was made
through Professor Challis, the Director of the Cambridge Observatory,
to the Astronomer Royal, with the object of obtaining from the
observations made at Greenwich Observatory more accurate values for
the disturbances suffered by Uranus. Basing his work on the more
precise materials thus available, Adams undertook his calculations
anew, and at last, with his completed results, he called at Greenwich
Observatory on October the 21st, 1845. He there left for the
Astronomer Royal a paper which contained the results at which he had
arrived for the mass and the mean distance of the hypothetical planet
as well as the other elements necessary for calculating its exact
position.

[PLATE: JOHN COUCH ADAMS.]

As we have seen in the preceding chapter, Le Verrier had been also