GALILEE, or GALu.so, in biography, b. most excellent philosopher, mathema tician and astronomer, was the son of a Florentine nobleman, and born at Pisa, in the year 1564. The earliest subjects of his studies were, poetry, music, and draw ing ; but his genius soon led him to the cultivation of sublimer sciences, by his proficiency in which he has immortalized his name. His father, though a noble, possessed but a limited fortune, and was therefore desirous of educating him a physician, that he might secure greater means of independence from the profits of his profession, than he could derive from his paternal estate. With this view he entered him as a student in philosophy and medicine at the university of Pisa ; but Galileo became soon dissatisfied with the obscurity of the Aristotelian system then taught in the schools, and conceiv ed an unconquerable dislike to medical studies.
He now betook himself to the study of the mathematics, and, without the assist ance of a tutor, made a rapid progress in those sciences, commencing with Euclid, and afterwards making himself master of the works of Archimedes, and of other ancient mathematicians. When his father perceived which way his inclination tend ed, and that his improvement indicated uncommon talents for mathematical pur suits, he prudently suffered him*to follow the natural bias of his mind without any restraint. So great was the reputation he acquired as a mathematician, that, in the year 1589, the Duke of Tuscany ap pointed him to the mathematical chair an the University of Pisa. He discharg ed the duties of this appointment, for about three years, with the applause and admiration of the liberal and more en lightened; but not without exciting the jealousy and opposition of the violent Aristotelians, who, because he ventured to question some of the hypothetical maxims of their master, held him out in the odious light of a visionary and dan gerous innovator. Becoming disgusted with the obstructions which their igno rance and bigotry threw in the way of his promoting just principles of science, in the year 1592 he resigned his profes sorship at Pisa, and accepted with plea sure of an invitation that was sent him to fill the mathematical chair in the univer sity of Padua. In this seminary he con tinued for eighteen years, esteemed and cherished by the Paduans and Vene tians, raising the credit of the university as a school of sound philosophy, and admired by all the learned, who had sufficient liberality and spirit to emanci pate themselves from the fetters of an.
cient prejudices.
By degrees Tuscany felt an increasing ardour for improvement, and no sooner was it known that Galileo's patriotism inclined him to devote his services to his native country, than Cosmo II. Grand Duke, sent for him to Pisa in the year 1611, where he made him professor of mathematics, with a very considerable stipend. Afterwards he invited him to Florence, and gave him the title of prin cipal mathematician and philosopher to his highness, continuing to him the salary annexed to his professorship, without any obligation to a residence at Pisa. With the study of mathematics, Galileo united that of physics, particularly the doc trines of mechanics and optics. Before he had settled at Padua, he had written his " Mechanics," or treatise on the bene fits derived from that science, and its in struments ; and also his " Balance," for finding the proportion of alloy or mixed metals. These he had introduced into his lectures at that university.
Being informed at Venice, in the year 1609, that Jansen, a Dutchman, had in. vented a glass, by means of which dis tant objects appeared as if they were near, he turned his attention to this sub ject, and from the imperfect accounts he had received, and his own reflections on the nature of refraction, discovered the construction of that instrument. The next day after he had solved the pro. blem of its construction, he made such an instrument, and, by the attention which he paid to its perfection and improve ment, may justly be considered as the second inventor of the telescope. He now turned his instrument towards the heavens, and discovered unheard of won ders. He perceived the surface of the moon not to be smooth, but rough, and full of prominences and cavities. The milky way he found to be an assemblage of fixed stars, invisible to the naked eye. Venus he found to vary in its phases like the moon. The figure of Saturn he observed to be oblong, and imagined that it consisted of three distinct parts, one spllierical in the midst, and two lesser ones on the sides, which afterwards ap peared to be only the answ, or extreme parts of Saturn's ring. Jupiter he saw surrounded with four moons, which, in honour of the Duke de Medici, he called Medicean stars, and soon perceived that, by means of their frequent eclipses, geo graphical longitudes might be found On the sun's disk he perceived spots, from the motion of which he inferred that the sun revolved on its axis.