the perturbations which Professor Airy had noticed, and see whether he
could explain these also by his hypothesis. If he could, there might be
something in his theory. If he failed--well, there was an end of it. The
questions were not difficult. They concerned the error of the radius
vector. Adams could have answered them with perfect ease; but sad to
say, though a brilliant mathematician, he was not a man of business. He
did not answer Professor Airy's letter.

It may seem a pity to many that the Greenwich equatorial was not pointed
at the place, just to see whether any foreign object did happen to be in
that neighborhood; but it is no light matter to derange the work of an
observatory, and alter the plans laid out for the staff, into a sudden
sweep for a new planet on the strength of a mathematical investigation
just received by post. If observatories were conducted on these
unsystematic and spasmodic principles they would not be the calm,
accurate, satisfactory places they are.

Of course, if anyone had known that a new planet was to be found for the
looking, _any_ course would have been justified; but no one could know
this. I do not suppose that Adams himself felt an absolute confidence in
his attempted prediction. So there the matter dropped. Adams's
communication was pigeonholed, and remained in seclusion eight or nine
months.

Meanwhile, and quite independently, something of the same sort was going
on in France. A brilliant young mathematician, Urban Jean Joseph
Leverrier, born in Normandy in 1811, held the post of astronomical
professor at the École Polytechnique, founded by Napoleon. His first
published papers directed attention to his wonderful powers; and the
official head of astronomy in France, the famous Arago, suggested to him