ied this
defect, and there is no point in science more certain than that the sun,
moon, and planets do not exercise any influence on the general state of
our atmosphere.

The philosophers in Kepler's day, who had studied the phenomena of the
tides, without having any idea of their cause, and who observed that
they were clearly related to the daily motions of the two great
luminaries, may be excused for the extravagance of their belief in
supposing that the planets exercised other influences over "sublunary
nature." Although Kepler, in his Commentaries on Mars, had considered it
probable that the waters of our ocean are attracted by the moon, as iron
is by a loadstone, yet this opinion seems to have been a very transient
one, as he long afterwards, in his System of Harmonies, stated his firm
belief that the earth is an enormous living animal, and enumerates even
the analogies between its habits and those of known animated beings. He
considered the tides as waves produced by the spouting out of water
through its gills, and he explains their relation to the solar and lunar
motions by supposing that the terrene monster has, like other animals,
its daily and nightly alternations of sleeping and waking.

From the consideration of Kepler's astrological opinions, it is an
agreeable transition to proceed to the examination of his high merits as
an astronomer and a philosopher. As an experimental philosopher, or as
an astronomical observer, Kepler does not lay claim to our admiration.
He himself acknowledges, "that for observations his sight was dull, and
for mechanical operations his hand was awkward." He suffered much from
weak eyes, and the delicacy of his constitution did not permit him to
expose himself to the night air. Notwithstanding these hindrances,
however, he added several observations to those of Tycho, which he made
with two instruments that were presented to him by his friend Hoffman,
the President of the States of Styria. These instruments were an iron
sextant, 2-1/2 feet in diameter, and a brass azimuthal quadrant 3-1/2 feet in
diameter, both of which were divided into single minutes of a degree.
They were very seldom used, and we must regard the circumstances which
disqualified Kepler for an observer, as highly favourable to the
developement of those great powers which he directed with undivided
energy to physical astronomy.

Even if Kepler had never turned his attention to the heavens, his
optical labours wo