my wife, 'but not
so nice and well dressed as this of mine is.'"

[45] See the Life of Tycho, page 137.

CHAPTER II.

_Kepler's Pecuniary Embarrassments--His Inquiries respecting the
Law of Refraction--His Supplement to Vitellio--His Researches on
Vision--His Treatise on Dioptrics--His Commentaries on Mars--He
discovers that the orbit of Mars is an Ellipse, with the Sun in one
focus--And extends this discovery to all the other Planets--He
establishes the two first laws of Physical Astronomy--His Family
Distresses--Death of his Wife--He is appointed Professor of
Mathematics at Linz--His Method of Choosing a Second Wife--Her
Character, as given by Himself--Origin of his Treatise on
Gauging--He goes to Ratisbon to give his Opinion to the Diet on the
change of Style--He refuses the Mathematical Chair at Bologna._

Although Kepler now filled one of the most honourable situations to
which a philosopher could aspire, and possessed a large salary fitted to
supply his most reasonable wants, yet, as the imperial treasury was
drained by the demands of an expensive war, his salary was always in
arrear. Owing to this cause he was constantly involved in pecuniary
difficulties, and, as he himself described his situation, he was
perpetually begging his bread from the Emperor at Prague. His increasing
family rendered the want of money still more distressing, and he was
driven to the painful alternative of drawing his income from casting
nativities. From the same cause he was obliged to abandon his plan of
publishing the Rudolphine Tables, and to devote himself to works of a
less expensive kind, and which were more likely to yield some pecuniary
advantages.

In spite of these embarrassments, and the occupation of his time in the
practice of astrology, Kepler found leisure for his favourite pursuits.
No adverse circumstances were capable of extinguishing his scientific
ardour, and whenever he directed his vigorous mind to the investigation
of phenomena, he never failed to obtain interesting and original
results. Since the death of Tycho, his attention had been much occupied
with the subject of refraction and vision; and, in 1606, he published
the result of his researches in a work, entitled "A Supplement to
Vitellio, in which the optical part of astronomy is treated, but
chiefly on the artificial observation and estimation of diameters, and
of the eclipses of the S