tion,
was permitted to pursue his studies unmolested for the remainder of his
days.

Galileo died at Arcetri on January 8, 1642, when in the seventy-eighth
year of his age.

Though not the inventor, he was the first to construct a refracting
telescope and apply it to astronomical research. With this instrument
he made a number of important discoveries which tended to confirm his
belief in the truthfulness of the Copernican theory.

On directing his telescope to the Sun, he discovered movable spots on
his disc, and concluded from his observation of them that the orb
rotated on his axis in about twenty-eight days. He also ascertained that
the Moon's illumination is due to reflected sunlight, and that her
surface is diversified by mountains, valleys, and plains.

On the night of January 7, 1610, Galileo discovered the four moons of
Jupiter. This discovery may be regarded as one of his most brilliant
achievements with the telescope; and, notwithstanding the improvement in
construction and size of modern instruments, no other satellite was
discovered until near midnight on September 9, 1892, when Mr. E. E.
Barnard, with the splendid telescope of the Lick Observatory, added
'another gem to the diadem of Jupiter.'

The phases of Venus and Mars, the triple form of Saturn, and the
constitution of the Milky Way, which he found to consist of a countless
multitude of stars, were additional discoveries for our knowledge of
which we are indebted to Galileo and his telescope. Galileo made many
other important discoveries in mechanical and physical science. He
detected the law of falling bodies in their accelerated motion towards
the Earth, determined the parabolic law of projectiles, and
demonstrated that matter, even if invisible, possessed the property of
weight.

In these pages a short historical description is given of the progress
made in astronomical science from an early period to the time in which
Milton lived. The discoveries of Copernicus, Kepler, and Galileo had
raised it to a position of lofty eminence, though the law of
gravitation, which accounts for the form and permanency of the planetary
orbits, still remained undiscovered. Theories formerly obscure or
conjectural were either rejected or elucidated with accuracy and
precision, and the solar system, having the Sun as its centre, with his
attendant family of planets and their satellites revolving in majestic
orbits around him, presented an impressive spectacle o