t Pisa. Read Bruno and became smitten with the
Copernican theory. Controverted the Aristotelians concerning falling
bodies, at Pisa. Hence became unpopular and accepted a chair at Padua,
1592. Invented a thermometer. Wrote on astronomy, adopting the Ptolemaic
system provisionally, and so opened up a correspondence with Kepler,
with whom he formed a friendship. Lectured on the new star of 1604, and
publicly renounced the old systems of astronomy. Invented a calculating
compass or "Gunter's scale." In 1609 invented a telescope, after hearing
of a Dutch optician's discovery. Invented the microscope soon after.
Rapidly completed a better telescope and began a survey of the heavens.
On the 8th of January, 1610, discovered Jupiter's satellites. Observed
the mountains in the moon, and roughly measured their height. Explained
the visibility of the new moon by _earth-shine_. Was invited to the
Grand Ducal Court of Tuscany by Cosmo de Medici, and appointed
philosopher to that personage. Discovered innumerable new stars, and the
nebulae. Observed a triple appearance of Saturn. Discovered the phases
of Venus predicted by Copernicus, and spots on the sun. Wrote on
floating bodies. Tried to get his satellites utilized for determining
longitude at sea.

Went to Rome to defend the Copernican system, then under official
discussion, and as a result was formally forbidden ever to teach it. On
the accession of Pope Urban VIII. in 1623, Galileo again visited Rome to
pay his respects, and was well received. In 1632 appeared his
"Dialogues" on the Ptolemaic and Copernican systems. Summoned to Rome,
practically imprisoned, and "rigorously questioned." Was made to recant
22nd of June, 1633. Forbidden evermore to publish anything, or to teach,
or receive friends. Retired to Arcetri in broken down health. Death of
his favourite daughter, Sister Maria Celeste. Wrote and meditated on the
laws of motion. Discovered the moon's libration. In 1637 he became
blind. The rigour was then slightly relaxed and many visited him: among
them John Milton. Died 8th of January, 1642, aged 78. As a prisoner of
the Inquisition his right to make a will or to be buried in consecrated
ground was disputed. Many of his manuscripts were destroyed.

Galileo, besides being a singularly clear-headed thinker and
experimental genius, was also something of a musician, a poet, and an
artist. He was full of humour as well as of solid common-sense, and his
literary style is brill