GALILEI VINCENTIO, a noble Florentine, and father of the illustrious Galileo Galilei, was born in the early half of the sixteenth century, and studied music under Zarlino, though he did not hesitate to attack the opinions of his master, in a Discorso intorno all' Opere del Zarlino,' and afterwards in his great work, the 'Dialogo della Nusica entice a moderns,' a folio volume, printed at Florence in 1581.
This work, which displays vast erudition and laborious research, has afforded much assistance to the musical historians of later days; but the author occasionally betrays a hardiness in assertion, of which his more philosophic son was never guilty. He was an exquisite per former on the lute, an instrument, he tells us, that was better manufactured in Englsnd than in any other part of Europe. He was a rigid Aristoxenian, and his prejudices in favour of the ancients were strong ; nevertheless his 'Dialogo' is well worth the notice of the curious inquirer lute musical history.
GALILE'l, GALILE'0, who is most commonly known under the latter, which was his Christian name, was the son of Vincentio Galilei. He was born at Pisa, in Tuscany, on the 15th of February 1564.
Having acquired, during his boyhood, and under adverse circum stances, the rudiments of classical and polite literature, he was placed by his father at the University of Pisa in his nineteenth year. Galilei was designed for the medical profession, but that genius for experi ment and demonstration, of which he exhibited the symptoms in his earlier youth, having found a more ample scope in the university under the kind auspices of Guido Ubaldi, with whom he had become acquainted through his first essay on the Hydrostatic Balance, he determined to renounce the study of medicine and pursue geometry and experimental philosophy. This resolntion, to which his father reluctantly agreed, was highly approved by those who bad witnessed his extraordinary talents, and was perseveringly followed up by him through the rest of his life.
His first important discovery was the isochronism of the vibrations of a simple pendulum sustained by a fixed poiut. This property is not rigorously true where the arcs of oscillation are considerable and unequal, nur does Galilei ever seem to have adopted any contrivance similar to a fly-wheel, by which these arcs may bo rendered equal. His knowledge too of the force of gravity, of the decomposition of forces, and of atmospheric resistance, was too imperfect to conduct him to any valuable improvement of the ;instrument, and hence the fair claims of his successor, Huyghens, so well supported by his treatise De Horologic, Oscillatorio,' cannot with any justice be transferred to Galilei, whose merits are sufficiently abundant and conspicuous to need no borrowed attributes. This equality or near equality of the time of
vibrations Galilei recognised by counting the corresponding number of his own pulsations, and having thus perceived that the pendulum oscillated more slowly or rapidly according to Unless or greater length, he immediately applied it to the medical purpose of discovering the state of the pulse; and the practice was adopted by many Italian physicians for a considerable time.
Through the good offices of Ubaldi, who admired his talents and foresaw their future development, Galilei became introduced to tho grand-duke Ferdinand I. de' Medici, who appointed him mathematical lecturer at Pisa (1589), though at an inconsiderable salary. Here ho commenced a series of experiments on motion, which however were not published until long after, and then only a scanty portion. This circumstance is probably not much to be regretted, since his infer ences on the relation of velocity to space were incorrect at first; but he had learned enough from his experimental course to perceive that most of the scholastic assumed laws of motion were untenable.
The mind of Galilei becoming thus unfettered from tho chain of authority, he resolved to examine the rival systems of astronomy— the Ptolemaic, with its cumbrous machinery of cycles and epicycles, eccentrics and primum mobile, and the Copernican, which, from its simplicity and gradually-discovered accordance with phtenomena, was silently gaining proselytes amongst the ablest observers and mathe maticians. He soon discovered and proved the futile nature of the objections then usually made against it, which were founded on a com plete ignorance of the laws of mechanics, or on some misapplied quota tions from Aristotle, the Bible, and the Fathers; and having also observed, that many who had at first believed the former system, had changed in favour of the latter, while none of those attached to the latter changed to the Ptolemaic) hypothesis—that the former required almost daily some new emendation, some additional crystalline sphere, to accommodate itself to the varying aspects of the celestial plirouo rnena—that the appearance and disappearance of new stars contradicted the pretender] incorruptibility of the heavenly bodies, together with other reflections which he has collected in his dialogues,—he became a convert to the Copernican system, and in his old age its most con epic-none martyr. So strong however were the religious prejudices on the subject of the quiescence of the earth, that Galilei thought it prudent to continue to lecture on the hypothesis of Ptolemy, until time should afford a favourable opportunity to destroy the visionary fabric by Incontestable facts.