founding of National
Observatories, accuracy hitherto undreamt of was possible, why not
attack the problem anew? This, then, he did, watching the stars with
great care to see if in six months they showed any change in absolute
position with reference to the pole of the heavens; any known secular
motion of the pole, such as precession, being allowed for. Already he
thought he detected a slight parallax for several stars near the pole,
and the subject was exciting much interest.

Bradley determined to attempt the same investigation. He was not
destined to succeed in it. Not till the present century was success in
that most difficult observation achieved; and even now it cannot be done
by the absolute methods then attempted; but, as so often happens,
Bradley, in attempting one thing, hit upon another, and, as it happened,
one of still greater brilliance and importance. Let us trace the stages
of his discovery.

Atmospheric refraction made horizon observations useless for the
delicacy of his purpose, so he chose stars near the zenith, particularly
one--[gamma] Draconis. This he observed very carefully at different
seasons of the year by means of an instrument specially adapted for
zenith observations, viz. a zenith sector. The observations were made in
conjunction with a friend of his, an amateur astronomer named Molyneux,
and they were made at Kew. Molyneux was shortly made First Lord of the
Admiralty, or something important of that sort, and gave up frivolous
pursuits. So Bradley observed alone. They observed the star accurately
early in the month of December, and then intended to wait six months.
But from curiosity Bradley observed it again only about a week later. To
his surprise, he found that it had already changed its position. He
recorded his observation on the back of an old envelope: it was his wont
thus to use up odd scraps of paper--he was not, I regret to say, a tidy
or methodical person--and this odd piece of paper turned up long
afterwards among his manuscripts. It has been photographed and preserved
as an historical relic.

Again and again he repeated the observation of the star, and continually
found it moving still a little further and further south, an excessively
small motion, but still an appreciable one--not to be set down to errors
of observation. So it went on till March. It then waited, and after a
bit longer began to return, until June. By September it was displaced as
much to the north as it h