Galileo

(gal-e-lē'o,) (properly GALILEI,) a renowned Italian mathematician and natural philosopher, B. at Pisa, 1564, early evinced abilities of the first order. After studying medicine, he turned his attention to the exact sciences, and discovered in 1584 the isochronism of the vibrations of a pendulum. Four years later he filled the chair of Mathematics at Pisa, and discovered the law by which the velocity of falling bodies is determined. 1592-8 G. held the profe orial chair of mathematics at Padua, invented a thermometer, and gave in his adhesion to the Copernican system of astronomy. In 1609 he invented the telescope,discovered by it the satellites of Jupiter, and deciphered the luminous neb ulæ of the Milky Way. Denounced as a heretic, G. repaired to Rome in 1616, where Pope Paul V. interdicted him from pursuing further his researches into the doctrine of the earth's motion. In 1632 his great work-Dialogues on the Ptolemaic and Copernican Systems-appeared, and subjected its author to renewed persecution. Summoned before the Inquisition, G. was incarcerated in prison for several years. This great philosopher D. at Florence, 1642. [s. 392]