calculation was one of the most brilliant in the records of
astronomy. In criticism it has been said that these were exhibitions
of skill rather than helps to a solution of the particular problem,
and that, in claiming to find the elements of the orbit within certain
limits, he was claiming what was, under the circumstances, impossible,
as the result proved.

In June, 1846, Le Verrier announced, in the _Comptes Rendus de
l'Academie des Sciences_, that the longitude of the disturbing planet,
for January 1st, 1847, was 325, and that the probable error did not
exceed 10 degrees.

This result agreed so well with Adams's (within 1 degrees) that Airy urged
Challis to apply the splendid Northumberland equatoreal, at Cambridge,
to the search. Challis, however, had already prepared an exhaustive
plan of attack which must in time settle the point. His first work
was to observe, and make a catalogue, or chart, of all stars near
Adams's position.

On August 31st, 1846, Le Verrier published the concluding
part of his labours.

On September 18th, 1846, Le Verrier communicated his results to the
Astronomers at Berlin, and asked them to assist in searching for the
planet. By good luck Dr. Bremiker had just completed a star-chart of
the very part of the heavens including Le Verrier's position; thus
eliminating all of Challis's preliminary work. The letter was received
in Berlin on September 23rd; and the same evening Galle found the new
planet, of the eighth magnitude, the size of its disc agreeing with Le
Verrier's prediction, and the heliocentric longitude agreeing within