GALILEI, GALILEO commonly called Galileo (gal-i-le'o), a distinguished Italian physicist; born in Pisa, Italy, Feb. 18, 1564. His father, Vincenzo Galilei, a nobleman of Florence, intended him for the medical profession; but his love of mathematical studies was so decided that he was allowed to pur sue them. At the age of 24 he was ap pointed mathematical professor at Pisa. There he was constantly engaged in as serting the laws of nature against the Scholastic philosophy, which raised up such a host of enemies against him that in 1592 he was obliged to resign his pro fessorship. He then went to Padua, where he lectured with unparalleled suc cess, and students flocked to hear him from all parts of Europe. After remain ing there 18 years, Cosmo III. invited him back to Pisa, and then to Florence, with the title of principal mathematician and philosopher to the grand-duke. Gali leo had heard of the invention of the telescope by Janson, and making one for himself. He found that the moon, like the earth, has an uneven surface, and he taught his scholars to measure the height of its mountains by their shadow.
His most remarkable discoveries were Jupiter's satellites, Saturn's ring, the Sun's spots, and the starry nature of the Milky Way. The result of his discoveries was his decided conviction of the truth of the Copernican system; though the blind conservatism of the monks charged him with heresy for it, and he was twice prosecuted by the Inquisition, first in 1615, and again in 1633. On both occa sions he was compelled to abjure the sys tem of Copernicus. In the following year, when he was 70 years old, and his health was declining, a very heavy blow fell on him by the death of his beloved daughter, Maria. Two years later he became blind. His latter years were spent near Flor ence, devoting himself to the perfecting of his telescope. His greatest work is the "Dialogue on the Copernican and Ptolemaic Systems." Among his others are "Dialogues on Motion," "Sidereus Nuncius," "Treatise on the Sphere, etc." He died in Arcetri, near Florence, Italy, Jan. 8, 1642. His remains were ultimate ly deposited in the Church of Santa Croce at Florence.