ating that the planes of the orbits of all the planets, and the
lines connecting their apsides, passed through the Sun, was enabled to
assign the orb his true position with regard to those bodies.

JOHN KEPLER was born at Weil, in the Duchy of Wurtemberg, December 21,
1571. His parents, though of noble family, lived in reduced
circumstances, owing to causes for which they were themselves chiefly
responsible. In his youth Kepler suffered so much from ill-health that
his education had to be neglected. In 1586 he was sent to a monastic
school at Maulbronn, which had been established at the Reformation, and
was under the patronage of the Duke of Wurtemberg. Afterwards he studied
at the University of Tubingen, where he distinguished himself and took a
degree. Kepler devoted his attention chiefly to science and mathematics,
but paid no particular attention to the study of astronomy. Maestlin,
the professor of mathematics, whose lectures he attended, upheld the
Copernican theory, and Kepler, who adopted the views of his teacher,
wrote an essay in favour of the diurnal rotation of the Earth, in which
he supported the more recent astronomical doctrines. In 1594, a vacancy
having occurred in the professorship of astronomy at Gratz consequent
upon the death of George Stadt, Kepler was appointed his successor. He
did not seek this office, as he felt no particular desire to take up the
study of astronomy, but was recommended by his tutors as a man well
fitted for the post. He was thus in a manner compelled to devote his
time and talents to the science of astronomy. Kepler directed his
attention to three subjects--viz. 'the number, the size, and the motion
of the orbits of the planets.' He endeavoured to ascertain if any
regular proportion existed between the sizes of the planetary orbits, or
in the difference of their sizes, but in this he was unsuccessful. He
then thought that, by imagining the existence of a planet between Mars
and Jupiter, and another between Venus and Mercury, he might be able to
attain his object; but he found that this assumption afforded him no
assistance. Kepler then imagined that as there were five regular
geometrical solids, and five planets, the distances of the latter were
regulated by the size of the solids described round one another. The
discovery afterwards of two additional planets testified to the
absurdity of this speculation. A description of these extraordinary
researches was published, in 1596,