roving and adding to those which were formerly known, and his
skill and assiduity as an observer, have given a character to his
labours, and a value to his observations, which will be appreciated to
the latest posterity. The appearance of the new star in 1572 led him to
form a catalogue of 777 stars, vastly superior in accuracy to those of
Hipparchus and Ulugh Beig. His improvements on the lunar theory were
still more valuable. He discovered the important inequality called the
_variation_, and also the annual inequality which depends on the
position of the earth in its orbit. He discovered, also, the inequality
in the inclination of the moon's orbit, and in the motion of her nodes.
He determined with new accuracy the astronomical refractions from an
altitude of 45 deg. down to the horizon, where he found it to be 34'; and he
made a vast collection of observations on the planets, which formed the
groundwork of Kepler's discoveries and the basis of the Rudolphine
Tables. Tycho's powers of observation were not equalled by his capacity
for general views. It was, perhaps, owing more to his veneration for the
Scriptures than to the vanity of giving his name to a new system that he
rejected the Copernican hypothesis. Hence he was led to propose a new
system, called the Tychonic, in which the earth is stationary in the
centre of the universe, while the sun, with all the other planets and
comets revolving round him, performs his daily revolution about the
earth. This arrangement of the planets afforded a sufficient explanation
of the various phenomena of the heavens; and as it was consistent with
the language of Scripture, and conformable to the indications of the
senses, it found many supporters, notwithstanding the physical absurdity
of making the whole system revolve round one of the smallest of the
planets.

It is a painful transition to pass from the astronomical labours of
Tycho to his astrological and chemical pursuits. That Tycho studied and
practised astrology has been universally admitted. He calculated the
nativity of the Emperor Rudolph, and foretold that his relations would
make some attempts upon his life. The credulous Emperor confided in the
prediction, and when the conduct of his brother seemed to justify his
belief, he confined himself to his palace, and fell a prey to the fear
which it inspired. Tycho, however, seems to have entirely renounced his
astrological faith in his latter days; and Kepler states,[43] in