tly the moon next to
the earth. But he differed from Aristotle, who conceived that the earth
revolves in an orbit around the centre of the planetary system, and
turns upon its axis,--two ideas in common with the doctrines which
Copernicus afterward unfolded. But even Ptolemy did not conceive the
heliocentric theory,--the sun the centre of our system. Archimedes and
Hipparchus both rejected this theory.

In regard to the practical value of the speculations of the ancient
astronomers, it may be said that had they possessed clocks and
telescopes, their scientific methods would have sufficed for all
practical purposes. The greatness of modern discoveries lies in the
great stretch of the perceptive powers, and the magnificent field they
afford for sublime contemplation. "But," as Sir G. Cornewall Lewis
remarks, "modern astronomy is a science of pure curiosity, and is
directed exclusively to the extension of knowledge in a field which
human interests can never enter. The periodic time of Uranus, the nature
of Saturn's ring, and the occultation of Jupiter's satellites are as far
removed from the concerns of mankind as the heliacal rising of Sirius,
or the northern position of the Great Bear." This may seem to be a
utilitarian view, with which those philosophers who have cultivated
science for its own sake, finding in the same a sufficient reward, can
have no sympathy.

The upshot of the scientific attainments of the ancients, in the
magnificent realm of the heavenly bodies, would seem to be that they
laid the foundation of all the definite knowledge which is useful to
mankind; while in the field of abstract calculation they evinced
reasoning and mathematical powers that have never been surpassed.
Eratosthenes, Archimedes, and Hipparchus were geniuses worthy to be
placed by the side of Kepler, Newton, and La Place, and all ages will
reverence their efforts and their memory. It is truly surprising that
with their imperfect instruments, and the absence of definite data,
they reached a height so sublime and grand. They explained the doctrine
of the sphere and the apparent motions of the planets, but they had no
instruments capable of measuring angular distances. The ingenious
epicycles of Ptolemy prepared the way for the elliptic orbits and laws
of Kepler, which in turn conducted Newton to the discovery of the law of
gravitation,--the grandest scientific discovery in the annals of
our race.

Closely connected with astronomical