ete manner, allowing greater
accuracy of observations.

GALILEO

Dialogues on the System of the World

Galileo Galilei, famous as an astronomer and as an experimental
physicist, was born at Pisa, in Italy, Feb. 18, 1564. His talents
were most multifarious and remarkable; but his mathematical and
mechanical genius was dominant from the first. As a child he
constructed mechanical toys, and as a young man he made one of his
most important discoveries, which was that of the pendulum as an
agent in the measurement of time, and invented the hydrostatic
balance, by which the specific gravity of solid bodies might be
ascertained. At the age of 24 a learned treatise on the centre of
gravity of solids led to a lectureship at Pisa University. Driven
from Pisa by the enmity of Aristotelians, he went to Padua
University, where he invented a kind of thermometer, a proportional
compass, a microscope, and a telescope. The last invention bore
fruit in astronomical discoveries, and in 1610 he discovered four
of the moons of Jupiter. His promulgation of the Copernican
doctrine led to renewed attacks by the Aristotelians, and to
censure by the Inquisition. (See Religion, vol. xiii.)
Notwithstanding this censure, he published in 1632 his "Dialogues
on the System of the World." The interlocutors in the "Dialogues,"
with the exception of Salviatus, who expounds the views of the
author himself, represent two of Galileo's early friends. For the
"Dialogues" he was sentenced by the Inquisition to incarceration at
its pleasure, and enjoined to recite penitential psalms once a week
for three years. His life thereafter was full of sorrow, and in
1637 blindness added to his woes; but the fire of his genius still
burnt on till his death on January 8, 1642.

_Does the Earth Move_

SALVIATUS: Now, let Simplicius propound those doubts which dissuade him
from believing that the earth may move, as the other planets, round a
fixed centre.

SIMPLICIUS: The first and greatest difficulty is that it is impossible
both to be in a centre and to be far from it. If the earth move in a
circle it cannot remain in the centre of the zodiac; but Aristotle,
Ptolemy and others have proved that it is in the centre of the zodiac.

SALVIATUS: There is no question that the earth cannot be in the centre
of a circle round whose circu