Galileo did not get everything right. He thought that the
tides were not related to the moon, as Johannes Kepler had
claimed, and he misinterpreted the rings of Saturn. In his
defense, one must realize that his best telescope magnified the
size of objects only 30 times.
Because falling objects moved too fast to accurately time,
instead of dropping metal balls from the Tower of Pisa, Galileo
studied pendulums and bronze balls rolling down inclined grooves.
He timed these by collecting water released from a reservoir and
carefully weighing it.
Isaac Newton incorporated Galileo’s law of horizontal
motion, the principle of inertia, into his first law of motion.
Although Christiaan Huygens is credited with inventing the
pendulum clock in the 1650s, Galileo realized that a pendulum
would provide a more accurate clock and invented an escapement
mechanism for it in 1642.
See also in The book of science:
Readings on wikipedia: