Will be evening star during the month, rising at 1:35 p. m. on the
1st and at 11:36 a. m. on the 31st, and setting at 3:09 a. m. on the
2d, and at 1:10 a. m. on the 1st of February. On the 8th, at 1:02 a.
m., it is 6′ south of the moon. On the 28th, at 3:00 p. m., it is
stationary. From the 1st to the 28th its motion will be 12½ seconds
of arc retrograde, and from the latter date to the end of the month
8.7 seconds of arc direct. Its diameter equals 1.6 seconds. Will be
found in the constellation _Aries_. Neptune is so far away that really
little is known in regard to it. Its peculiar interest to us centers
in the fact developed in its discovery, namely, that notwithstanding
comparatively little is definitely settled in astronomical science,
a wonderful degree of exactness has been attained in the computation
of the places of the heavenly bodies. In 1820, astronomer Bouvard, of
Paris, made a new and improved set of tables which formed the basis of
the calculations made on the motions of Jupiter, Saturn and Uranus.
In a few years it was found by observations that Uranus failed to
occupy the place assigned him by the tables. In twenty-four years the
disagreement amounted to two minutes of arc (a slight error, one would
think, but not to be overlooked, and easily measured). The discrepancy
led Mr. John C. Adams, an English student, in 1843, and M. Leverrier, a
Frenchman, in 1845, each without the knowledge of the other, to attempt
to reckon the elements of an unknown planet that would cause the
disturbance. Adams, in October, 1845, communicated the results of his
efforts to Prof. Airy, Astronomer Royal, who, however, for some reason
not very clear, failed to make any search in the quarter directed. In
1846, the result of Leverrier’s calculations were published, and bore
such a striking similarity to those of Mr. Adams, that Prof. Challis,
of Cambridge Observatory, immediately began a very thorough search,
and had made considerable progress, when Leverrier in September, 1846,
wrote to Dr. Galle, of Berlin Observatory, giving him the elements, and
asking him to direct his telescope to a certain portion of the heavens.
This the Doctor did, and the result was that on the 23d of September,
1846, the planet afterward called Neptune, was found within a very
short distance from the point indicated by both M. Leverrier and Mr.
Adams.