se hands they continued for many years. In 1773
they were offered for 4000 francs, and sometime afterwards M. De Murr
purchased them for the Imperial Academy of Sciences at St Petersburg, in
whose library they still remain. Euler, Lexell, and Kraft undertook the
task of examining them, and selecting those that were best fitted for
publication, but we believe that no steps have yet been taken for
executing this task, nor are we aware that science would derive any
advantage from its completion.

Although, in drawing his own character, Kepler describes himself as
"troublesome and choleric in politics and domestic matters," yet the
general events of his life indicate a more peaceful disposition than
might have been expected from the peculiarities of his mind and the
ardour of his temperament. On one occasion, indeed, he wrote a violent
and reproachful letter to Tycho, who had given him no just ground of
offence; but the state of Kepler's health at that moment, and the
necessitous circumstances in which he had been placed, present some
palliation of his conduct. But, independent of this apology, his
subsequent conduct was so truly noble as to reconcile even Tycho to his
penitent friend. Kepler quickly saw the error which he committed; he
lamented it with genuine contrition, and was anxious to remove any
unfavourable impression which he might have given of his friend, by the
most public confession of his error, and by the warmest acknowledgments
of the kindness of Tycho.

In his relations with the scientific men of his own times, Kepler
conducted himself with that candour and love of truth which should
always distinguish the philosopher. He was never actuated by any mean
jealousy of his rivals. He never scrupled to acknowledge their high
merits; and when the discoveries made by the telescope established
beyond a doubt the errors of some of Kepler's views, he willingly avowed
his mistake, and never joined in the opposition which was made by many
of his friends to the discoveries of Galileo. A striking example of this
was exhibited in reference to his supposed discovery of Mercury on the
sun's disc. In the year 1607,[50] Kepler observed upon the face of the
sun a dark spot, which he mistook for Mercury; but the day proving
cloudy, he had not the means of determining by subsequent observations
whether or not this opinion was well founded. As spots on the sun were
at that time unknown, Kepler did not hesitate to publish the fact