ht enough to be seen by its disc, ultimately reached
Professor Challis, it naturally gave him an entirely different view of the
possibilities; he immediately began to compare the observations already
made, and found that he had observed the planet early in August. But it
was now too late to be first in the field, for Galle had already made his
announcement of discovery. Writing to Airy on October 12, Challis could
only lament that after four days' observing the planet was in his grasp,
_if_ only he had examined or mapped the observations, and _if_ he had not
delayed doing so until he had more observations to reduce, and _if_ he had
not been very busy with some comet observations. Oh! these terrible _ifs_
which come so often between a man and success! The third of them is a
peculiarly distressing one, for it represents that eternal conflict
between one duty and another, which is so constantly recurring in
scientific work. Shall we finish one piece of work now well under way, or
shall we attend to something more novel and more attractive? Challis
thought his duty lay in steadily completing the comet observations already
begun. We saw in the last lecture how the steady pursuit of the discovery
of minor planets, a duty which had become tedious and apparently led
nowhere, suddenly resulted in the important discovery of Eros. But
Challis was not so fortunate in electing to plod along the beaten track;
he would have done _better_ to leave it. There is no golden rule for the
answer; we must be guided in each case by the special circumstances, and
the dilemma is consequently a new one on every occasion, and perhaps the
more trying with each repetition.

[Sidenote: Sensation caused by the discovery.]

[Sidenote: Not all _national_ jealousy.]

Such are briefly the events which led to the discovery of Neptune, which
was made in Germany by direction from France, when it might have been made
in Cambridge alone. The incidents created a great stir at the time. The
"Account" of them, as read by Airy to the Royal Astronomical Society on
November 13, 1846, straightforward and interesting though it was, making
clear where he had himself been at fault, nevertheless stirred up angry
passions in many quarters, and chiefly directed against Airy himself.
Cambridge was furious at Airy's negligence, which it considered
responsible for costing the University a great discovery; and others were
equally irate at his attempting to claim for Adams som