eproaches. On the plea of being occupied with his daughter's marriage,
Tycho requested Ericksen, one of his assistants, to reply to Kepler's
letter; and he did this with so much effect, that Kepler saw his
mistake, and in the noblest and most generous manner supplicated the
forgiveness of his friend. Tycho exhibited the same good feeling; and
the kindness of Hoffman, President of the States of Styria, completed
the reconciliation of the two astronomers.

On his return to Prague in 1601, he was presented by Tycho to the
Emperor, who conferred upon him the title of Imperial Mathematician, on
the condition that he would assist Tycho in his calculations. This
connexion was peculiarly valuable to Kepler, as the observations of his
colleague were the only ones made in the world which could enable him to
carry on his own theoretical inquiries. These two astronomers now
undertook to compute, from Tycho's observations, a new set of
astronomical tables, to be called the Rudolphine Tables, in honour of
the Emperor. This scheme flattered the vanity of their master, and he
pledged himself to pay all the expenses of the work. Longomontanus,
Tycho's principal assistant, took upon himself the labour of arranging
and discussing the observations on the stars, while Kepler devoted
himself to the more congenial task of examining those on the planet
Mars, with which Tycho was at that time particularly occupied. The
appointment of Longomontanus to a professorship in Denmark, and the
death of Tycho in October 1601, put a stop to these important schemes.

Kepler succeeded Tycho as principal mathematician to the Emperor, and
was provided with a handsome salary, which was partly charged on the
imperial treasury, and partly on the States of Silesia, and the first
instalment of which was to be paid in March 1602. The generosity of the
Emperor did not fail to excite the jealousy of ignorant individuals, who
were not aware of the value of science to the state; but the increasing
fame of Kepler, and the valuable works which he published, soon silenced
their opposition.

In September 1604, astronomers were surprised with the appearance of a
new star in the foot of Serpentarius. It was not seen before the 29th of
September, and Moestlin informs us that, on account of clouds, he did
not obtain a good view of it till the 6th of October. Like that of
1572,[45] it at first surpassed Jupiter in brightness, and rivalled even
Venus, but it afterwards became