ified
eclipses, and divided the day into twenty-four hours.

To the Greeks belongs the credit of having first studied astronomy in a
regular and systematic manner. THALES (640 B.C.) was one of the earliest
of Greek astronomers, and may be regarded as the founder of the science
among that people. He was born at Miletus, and afterwards repaired to
Egypt for the purpose of study. On his return to Greece he founded the
Ionian school, and taught the sphericity of the Earth, the obliquity of
the ecliptic, and the true causes of eclipses of the Sun and Moon. He
also directed the attention of mariners to the superiority of the Lesser
Bear, as a guide for the navigation of vessels, as compared with the
Great Bear, by which constellation they usually steered. Thales believed
the Earth to be the centre of the universe, and that the stars were
composed of fire; he also predicted the occurrence of a great solar
eclipse.

Thales had for his successors Anaximander, Anaximenes, and Anaxagoras,
who taught the doctrines of the Ionian school.

The next great astronomer that we read of is PYTHAGORAS, who was born at
Samos 590 B.C. He studied under Thales, and afterwards visited Egypt and
India, in order that he might make himself familiar with the scientific
theories adopted by those nations. On his return to Europe he founded
his school in Italy, and taught in a more extended form the doctrines of
the Ionian school. In his speculations with regard to the structure of
the universe he propounded the theory (though the reasons by which he
sustained it were fanciful) that the Sun is the centre of the planetary
system, and that the Earth revolves round him. This theory--the accuracy
of which has since been confirmed--received but little attention from
his successors, and it sank into oblivion until the time of Copernicus,
by whom it was revived. Pythagoras discovered that the Morning and
Evening Stars are one and the same planet.

Among the famous astronomers who lived about this period we find
recorded the names of Meton, who introduced the Metonic cycle into
Greece and erected the first sundial at Athens; Eudoxus, who persuaded
the Greeks to adopt the year of 365-1/4 days; and Nicetas, who taught
that the Earth completed a daily revolution on her axis.

The Alexandrian school, which flourished for three centuries prior to
the Christian era, produced men of eminence whose discoveries and
investigations, when arranged and classified, enab