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GALILEI, VINCENTIO. 



GALILEI, GALILEO. 





Consulate and the Empire,' and of late years his name has been little 

 heard of in connection with politics. Galiano has been twice married. 

 His first marriage, which took place at the age of nineteen, was very 

 unfortunate, and exercised a prejudicial influence on part of his early 

 career. 



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 ' Diseorso intorno all' Opere 

 del Zarlino,' and afterwards in his great work, the 'Dialogo della 

 Musica antica e moderna,' a folio volume, printed at Florence in 1581. 

 This work, which displays vast erudition and laborious research, has 

 nflbrded 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 England 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 into musical history. 



GALILE'I, GALILE'O, who is most commonly known under the 

 laiter, which was Lie Christian name, was the son of Vincentio Galilei. 

 He was born at Pisa, in Tuscany, on the 15th of February 1561. 



Having acquired, during his boyhood, and under adverse circum- 

 stances, the rudiments of classical aud polite literature, he was placed 

 by his father at the University of Pisa in his nineteenth year. Galilei 

 v as designed for the medical profession, but that genius for experi- 

 ment aud demonstration, of which he exhibited the symptoms iu his 

 i irlii-r youth, having fouud 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 

 .i ti-ruiiued to renounce the study of medicine and pursue geometry 

 aud experimental philosophy. This resolution, to which bis father 

 reluctantly agreed, was highly approved by those who had witnessed 

 his extraordinary talents, and was perseveringly followed up by him 

 through the rest of his life. 



His first important discovery was the isochrouism of the vibrations 

 of a simple pendulum sustained by a fixed point. This property is 

 not rigorously true where the arcs of oscillation are considerable aud 

 unequal, nor does Galilei ever seeui to have adopted any contrivance 

 similar to a fly-wheel, by which these arcs may be 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 

 ' l)e Horologio Oscillatorio,' cannot with any justice be transferred to 

 Galilei, whose merits are sufficiently abundant and conspicuous to need 

 no borrowed attribute*. This equality or near equality of the time ol 

 vibrations Galilei recognised by counting the corresponding number 

 of his own pulsations, aud having thus perceived that the pendulum 

 oscillated more slowly or rapidly according to its less 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 the 

 grand-duke Ferdinand I. de' Medici, who appointed him mathematical 

 lecturer at Pisa (1589), though at an inconsiderable salary. Here he 

 commenced a series of experiments on motion, which however were 

 not published until long alter, 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 ; bm 

 he had learned enough from his experimental course to perceive tha ( 

 most of the scholastic assumed laws of motion were untenable. 



The mind of Galilei becoming thus unfettered from the chain o 

 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 phenomena, was 

 silently gaining proselytes amongst the ablest observers and mathe 

 maticiaus. 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 pheno- 

 mena that .the appearance and disappearance of new stars contradicted 

 the pretended 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- 

 spicuous 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 fact*. 



One of the false doctrines which he first combated was that bodies 

 if unequal weights would fall through the same altitude in unequal 

 Imes : thus, if one body were ten times as heavy as another, it should 

 all through 100 yards while the lighter had only fallen through ten. 

 Jut though the experiment was performed from the leauing tower 

 at Pisa, and both bodies reached the ground at almost the same 

 nstant (the small difference, as Galilei rightly observed, being attri- 

 >utable to the unequal resistances of the air), the witnesses of this 

 >xperiuient were not convinced, so inveterately were they prejudiced 

 n favour of the doctrines in which they had been taught to place 

 mplicit belief. 



Instead of making converts by his experiments, Galilei discovered 

 ;hat he had made many secret aud sorne open enemies; he therefore 

 .eft Pisa and removed to the university of Padua (1592), where he 

 was appointed to a professor's chair for the limited period of six 

 years. Here he invented an imperfect species of thermometer, 

 depending on the expansion of the air which remained after a portion 

 was expelled by heat from a narrow glass tube, which was then 

 .nverted and immersed in water. His correspondence with Kepler 

 commenced about the same period, and continued with the greatest 

 mutual friendship aud regard until his death. A treatise on the 

 Sphere,' after the Ptolemaic system, which is attributed to Galilei, 

 appeared about the same time. (Afterwards published at Rome, lb'6o.) 



On his reappointment to the professorship at Padua his salary was 

 doubled, his fame increased, and his lectures were crowded; but these 

 flattering events were overbalanced by a disagreeable intermittent 

 disease to which he then first became subject, aud which pursued him 

 for the remainder of his life. A new star, almost as brilliant as that 

 which directed Tycho BrahiS's miud to the study of astronomy, having 

 appeared iu 1604, in the constellation of Ophiuchus, he made it the 

 subject of his lectures, which it may be presumed were less explana- 

 tory of its cause, than intended as an attack upon the Ptolemaic 

 system. The conjecture now most generally adopted relative to 

 these remarkable phaeuomena is, that luminosity is not essential to 

 the central body or sun of a planetary system, consequently the star 

 may be quite opaque or partially luminous, and therefore would be 

 either absolutely invisible or only seen when the luminous portiou 

 was in the line joining the earth and star: this explanation is 

 sufficient for those which appear aud disappear with regularity ; in 

 other cases this transitory phenomenon may merely indicate an 

 epoch of change in the cosmogony of the peculiar system of the star. 



Astronomy did not however engross all the attention of Galilei. 

 He read and admired Gilbert's work, ' On the Nature of Bodies,' 

 and adopted his views on the subject of terrestrial gravity, and con- 

 structed magnets after his example ; about the same time he attacked 

 with some bitterness one Capra, who ascribed to himself the invention 

 of a species of compass which Galilei had made ; and he wrote also 

 on practical methods for the measurement of heights and distances. 

 Shortly afterwards he states in a letter, that " he intended hereafter 

 to write three books on the system of the universe; three books 

 on local motion ; three books of mechanics ; also on sound, speech, 

 light, the tides, continuous quantity, animal motion, and castrameta- 

 tion ; many of which, it is supposed, were destroyed by his relatives 

 after his death, at the instance of the family confessor. 



The year 1609 was signalised by the construction of the Galiloean 

 telescope, which consisted of a plano-convex object-glass, aud a plano- 

 concave eye-glass, and thus he laid the foundation of the brilliant 

 discoveries iu the solar system, which have rendered that science 

 the most perfect of which the objects are the most remote. It is 

 true that Jansen, a Dutch optician, and some others previous to him, 

 had constructed microscopes, and perhaps imperfect telescopes, but 

 they cannot claim the invention of the astronomical telescope, their 

 articles having been more intended for toys and puerile amusement 

 than any valuable practical purpose ; and aa they had no notion of 

 applying them to the heavenly bodies, it is obvious that their random 

 constructions would be totally Inapplicable to such a purpose. How- 

 ever the long-mooted questiou of the invention of this noble instru- 

 ment of science may be decided, its application by Galilei to 

 astronomy, for the first time, is indisputable. His first telescope 

 was presented to the Doge of Venice, by whom the professorship at 

 Padua was confirmed to hiui for life, with the greatest salary which 

 had ever been there given to the mathematical professor, namely 

 about 1000 florins. 



Galilei, impatient to obtain ocular evidence of what he called the 

 " structure of the universe," soon provided himself with a second 

 instrument, and on directing it towards the moon, this luminary 

 became immediately stripped of the character of geometrical per- 

 fection, absurdly attributed to all the celestial bodies by the school- 

 men, according to whom they were all perfectly round, self-luminous, 

 and uncorrupted by any terrestrial tarnish. 



The more obscure parts of the lunar surface, which they imagined 

 had arisen from some earthly taint consequent on the proximity of 

 the moon, being now rendered distinctly visible, taught Galilei that 

 the surface of the moon was irregular and uneven, having mountains 

 and valleys of much greater extent, in proportiou, than those on our 

 globe ; the faint light on the darkened portion of the moon's surface 

 he recognised to be the reflection of the Bun's rays from the earth ; 

 the luminous isolated points near her inner border, and the jagged 



