GALILEO 31 failed to interest his understanding, and he was soon permitted to abandon a study so distasteful to him. A document published by M. Selini in 1864 proves that he was at this time so far attracted towards a religious life as to have joined the novitiate of the order; but his father, who had other designs for him, seized the opportunity of an attack of ophtlialinia to withdraw him permanently from the care of the monks. Having had personal experience of the’uiiremunerative character both of music and of mathe- matics, he desired that his son should apply himself to the more profitable study of medicine, and, not without some straining of his slender resources, placed him, before he had completed his eighteenth year, at the university of Pisa. He accordingly matriculated, November 5, 1581, and im- mediately entered upon attendance at the lectures of the celebrated physician and botanist, Andrea Cesalpino. The natural gifts of the young student, not less multi- farious than those of an earlier Tuscan prodig , Leonardo da Vii;-ci, seemed at this time equally ready to develop in any direction towards which choice or hazard might incline them. In musical skill and invention he already vied with the best professors of the art in Italy ; his personal taste would have led him to choose painting as his profession, and one of the most eminent artists of his day, Lodovico Cigoli, owned that to his judgment and counsel he was mainly indebted for the success of his works ; his wit and eloquence gave promise that he_ would one day add to the literary glories of his country ; while his mathematical and mechanical genius only awaited a suitable opportunity for full display and development. In 1583, while watching the vibrations of the great bronze lamp still to be seen swinging from the roof of the cathedral of Pisa, he observed that, whatever the range of its oscillations, they were invariably executed in equal times. The experimental verification of this fact led him to the important discovery of the isochronism of the pendulum. He at first applied the new principle to pulse-nieasuremeiit, and more than fifty years later turned it to account in the construction of an astrononiical clock. Up to this time he was entirely ignorant of mathematics, his father having carefully held him aloof from a study which he rightly apprehended would lead to his total alienation from that of medicine. Acci- dent, however, frustrated this purpose. A lesson in geometry, given by Ostilio Ricei to the pages of the grand- ducal court, then temporarily resident at Pisa, chanced to have Galileo for an unseen listener ; his attention was riveted, his dormant genius was roused, and he threw all his energies into the new pursuit thus unexpectedly pre- sented to him. With Ricci’s assistance, he rapidly mastered the elements of the science, and eventually extorted his father’s reluctant permission to exchange Hippocrates and Galen fer Euclid and Archimedes. In 1586 he was with- drawn from the university, through lack of means, before he had taken a degree, and returned to Florence, where his family habitually resided. VVe next hear of him as lectur- ing before the Florentine Academy on the site and dimen- sions of Dante’s Inferno; and he shortly afterwards pub- lislied an essay descriptive of his invention of the hydro- statical balance, which rapidly made his name known throughout Italy. IIis first patron was the Marchese Guidiibaldo del iIonte of Pesaro, a man eminent for his scientific attainments, as well as influential by his family connexions. At his request he wrote, in 1588, a treatise on the centre of gravity in solids, which obtained for him, together with the title of “the Archimedes of his time,” the honourable though not lucrative post of mathematical lecture!‘ at the Pisan university. During the ensuing two years1589—9l) he carried on that remarkable series of experiments, by which he established the first principles of dynamical science, and by which he earned for himself the undying hostility of the bigoted Aristotelians of that day. From the leaning tower of Pisa he afforded to all the pro- fessors and students of the iiiiiveisity ocular demonstration of the falsehood of the Peripatetic dictum that heavy bodies fall with velocities proportional to their weights, and with unanswerable logic demolished all the time-lionoured maxims of the schools regarding the motion of projectiles, and elemental weight or levity. But while he convinced, he failed to conciliate his adversaries. The keen_ sarcasm of his polished rhetoric was not calculated to soothe the susceptibilities of men already sniarting under the depriva- tion of their most cherished illusions. He seems, in addi- tion, to have compromised his position with the grand-ducal family by the imprudent caiidour with which he condemned a machine for clearing the port of Leghorn, invented by Giovanni de’ Medici, an illegitimate son of Cosmo I. Princely favour being withdrawn, private rancoiir was free to show itself. He was publicly hissed at his lecture, and found it prudent to resign his professorship and withdraw to Florence in 1591. Through the death of his father in July of that year family cares and responsibilities devolved upon him as eldest son, and thus his nomination to the chair of mathematics at the university of Pa.diia, secured by the in- lluence of the )IarcheseGuidubaldo with theVeiietian senate, was welcome, as affording a relief from pecuniary embarrass- ment, no less than as opening a field for scientific distinction. His residence at Padua, which extended over a period of eighteen years, from 1592 to 1610, was a course of unin- terrupted prosperity. His appointment was three times renewed, on each occasion with expressions of the highest esteem on the part of the governing body, and his yearly salary was progressively raised from 180 to 1000 florins. His lcctures were attended by persons of the highest dis- tinction from all parts of Europe, a.nd such was the charm of his demonstrations that a hall capable of containing 2000 people had eventually to be assigned for the accommodation of the overflowing audiences which they attracted. His ingenious invention of the proportional compasses—aii instrument still used in geometrical rlrawing—-—dates from 1597; and about the same time he constructed the first therinometer, consisting of a bulb and tube filled with air and water, and terminating in a vessel of water. In this instrument, the results of varying atmospheric pressure were not distinguishable from the expansive and contractive effects of heat and cold, and it became an etficient measure of temperature only when Rinieri, in 1646, introduced the improvement of hermetically sealing the liquid in glass. The substitution, in 1670, of mercury for water completed the Inodern thermometer. Galileo seems, at an early period of his life, to have adopted the Copernican theory of the solar system, and was deterred from avowing his opinions—as is proved by his letter to Kepler of August 4, l597—by the fear of ridicule rather than of persecution. The appearance, in September 1604, of a new star in the constellation Serpentarius, afforded him indeed an opportunity, of which he eagerly availed himself, for making an onslaught upon the Aristo- telian axiom of the incorruptibility of the heavens 3 but he continued to conform his public teachings in the main to Ptoleniaic principles, until the discovery of a novel and potent implement of research placed at his command start- ling and hitherto unsuspected evidence as to the constitu- tion and mutual relations of the heavenly bodies. Galileo was not the original inventor of the telescope.‘ That 1 The word telescope, from 'r'7)}, far, o-rcoiréw, to view, was invented by Demiscianus, an eminent Greek scholar, at the request of Prince Cesi, president of the Lyncean Academy. It was used by Galileo as early as 1612, but was not introduced into English until much later. In 1655 the word telescope was inserted in Bagwell’s Jllystcrics. Qf Astronomy, as a term requiring explanation, trzmk or cylinder being
commonly used instead.