an undiscovered planet beyond it, and if possible thence to determine
the elements of its orbit, &c., approximately, which would probably
lead to its discovery."

Accordingly, "as soon as possible after taking his degree" he embarked
upon the enterprise, and the first solution was made in the long vacation
of 1843, assuming the orbit of the unknown planet to be a circle with a
radius equal to twice the mean distance of Uranus from the sun (an
assumption which, as we have seen, was also made by Le Verrier). Having
satisfied himself that there was a good general agreement between his
results and the observations, Adams began a more complete solution; indeed
from first to last he made no less than six separate solutions, the one
which he announced to Airy in the above letter being the fourth. Hence he
had already done an enormous amount of work on the problem, and was in his
own mind so justly convinced of the correctness and value of his results
that he was liable to forget that others had not had the same opportunity
of judging of their completeness; and he was grievously disappointed when
his announcement was not received with full confidence.

[Sidenote: His disappointment at Greenwich, and at Airy's question.]

But perhaps it should first be stated that by a series of mischances Adams
had been already much disappointed at the failure of his attempts to see
the Astronomer Royal on his visits to Greenwich. This does not seem to
have been exactly Airy's fault; he was, as may well be supposed, an
extremely busy man, and was much occupied at the time on a question of
great practical importance, at the direct request of the Government,
namely, the settling of the proper gauge for railways throughout the
country. The first time Adams called to see him, he was actually in London
sitting on the Committee which dealt with this question, and Adams was
asked to call later; when the visit was repeated, Airy was unfortunately
at dinner (and it may be added that his hours for dinner were somewhat
peculiar), and the butler, acting somewhat in the manner of his kind,
protected his master's dinner by sending away one whom he doubtless
regarded as a troublesome visitor. There is, as I have said, little doubt
about any of the facts, and it seems well established that Airy himself
did not learn of Adams' visits until afterwards, and it would scarcely be
just to blame him for a servant's oversight. But Adams had left the p