closer to us, had a disc so small
that it was observed nearly a score of times without particular notice,
though it did not escape the eagle glance of Herschel. There remained
then only one available method of finding Neptune. It was to construct a
chart of the heavens in the neighbourhood indicated, and then to compare
this chart night after night with the stars in the heavens. Before
recommending the commencement of a labour so onerous, the
Astronomer-Royal thought it right to submit Mr. Adams's researches to a
crucial preliminary test. Mr. Adams had shown how his theory rendered an
exact account of the perturbations of Uranus in longitude. The
Astronomer-Royal asked Mr. Adams whether he was able to give an equally
clear explanation of the notable variations in the distance of Uranus.
There can be no doubt that his theory would have rendered a satisfactory
account of these variations also; but, unfortunately, Mr. Adams seems
not to have thought the matter of sufficient importance to give the
Astronomer-Royal any speedy reply, and hence it happened that no less
than nine months elapsed between the time when Mr. Adams first
communicated his results to the Astronomer-Royal and the time when the
telescopic search for the planet was systematically commenced. Up to
this time no account of Mr. Adams's researches had been published. His
labours were known to but few besides the Astronomer-Royal and Professor
Challis of Cambridge, to whom the duty of making the search was
afterwards entrusted.

In the meantime the attention of Le Verrier, the great French
mathematician and astronomer, had been specially directed by Arago to
the problem of the perturbations of Uranus. With exhaustive analysis Le
Verrier investigated every possible known source of disturbance. The
influences of the older planets were estimated once more with every
precision, but only to confirm the conclusion already arrived at as to
their inadequacy to account for the perturbations. Le Verrier then
commenced the search for the unknown planet by the aid of mathematical
investigation, in complete ignorance of the labours of Adams. In
November, 1845, and again on the 1st of June, 1846, portions of the
French astronomer's results were announced. The Astronomer-Royal then
perceived that his calculations coincided practically with those of
Adams, insomuch that the places assigned to the unknown planet by the
two astronomers were not more than a degree apart! This was