gh not immediately connected with the Copernican tion, was an important step taken on the dangerous and ly trodden path of knowledge of nature, uninfluenced by matism or petrified professorial wisdom. This inviollity of the vault of heaven was also conditioned by the evailing views of the universe. What wonder then that ost of the professors who had grown grey in the Aristotelian octrine (Cremonio for instance, Coressio, Lodovico delle Colombo, and Balthasar Capra) were incensed at these opinions of Galileo, so opposed to all their scientific prepossessions, and vehemently controverted them. The spark, however, which was to set fire to the abundant inflammable material, and to turn the scientific and religious world, in which doubt had before been glimmering, into a veritable volcano, the spark which kindled Galileo's genius. and made him for a long time the centre of that period of storm and stress, was the discovery of the telescope. We will not claim for Galileo, as many of his biographers have erroneously done, priority in the construction of the telescope. We rely far more on Galileo's own statements than on those of his eulogists, who aim at effect. Galileo relates with perfect simplicity at the beginning of the "Sidereus Nuncius," published at Venice in 1610, that he had heard about ten months ago that an instrument had been made by a Dutchman, by means of which distant objects were brought nearer and could be seen very plainly. The confirmation of the report by one of his former pupils, a French nobleman, Jean Badovere of Paris, had induced him to reflect upon the means by which such an effect could be produced. By the laws of refraction he soon attained his end. With two glasses fixed at the ends of a leaden tube, both having one side flat and the other side of the one being concave and of the other convex, his primitive telescope, which made objects appear three times nearer and nine times larger, was constructed. But now, having "spared neither expense nor labour," he had got so far as to construct an instrument which magnified an object C CHAPTER II. THE TELESCOPE AND ITS REVELATIONS. Term of Professorship at Padua renewed.—Astronomy.-A New Star.The Telescope.—Galileo not the Inventor.-Visit to Venice to exhibit it.-Telescopic Discoveries.-Jupiter's Moons.-Request of Henry IV. -“Sidereus Nuncius."-The Storm it raised.—Magini's attack on Galileo.-The Ring of Saturn.-An_Anagram.—Opposition of the Aristotelian School.-Letter to Kepler. THE first six years of Galileo's professorship at Padua had passed away, but the senate were eager to retain so bright a light for their University, and prolonged the appointment of the professor, whose renown was now great, for another six years, with a considerable increase of salary.1 As we have seen, he had for a long time renounced the prevailing views about the universe; but up to this time he had discussed only physical mathematical questions with the Peripatetic school, the subject of astronomy had not been mooted. But the sudden appearance of a new star in the constellation of Serpentarius, in October, 1604, which, after exhibiting various colours for a year and a half, as suddenly disappeared, induced him openly to attack one of the Aristotelian doctrines hitherto held most sacred, that of the unchangeableness of the heavens. Galileo demonstrated, in three lectures to a numerous audience, that this star was neither a mere meteor, nor yet a heavenly body which had before existed but had only now been observed, but a body which had recently appeared and had again vanished. The subject, 1 Op. xv. p. 390. His salary at first was 72 Florentine zecchini=£18, and rose by degrees to 400 zecchini=£100. (Op. viii. p. 18, note 3.) * Some fragments of these lectures are extant, and are included by Albèri in the Op. v. part ii. though not immediately connected with the Copernican question, was an important step taken on the dangerous and rarely trodden path of knowledge of nature, uninfluenced by dogmatism or petrified professorial wisdom. This inviolability of the vault of heaven was also conditioned by the prevailing views of the universe. What wonder then that most of the professors who had grown grey in the Aristotelian doctrine (Cremonio for instance, Coressio, Lodovico delle Colombo, and Balthasar Capra) were incensed at these opinions of Galileo, so opposed to all their scientific prepossessions, and vehemently controverted them. The spark, however, which was to set fire to the abundant inflammable material, and to turn the scientific and religious world, in which doubt had before been glimmering, into a veritable volcano, the spark which kindled Galileo's genius and made him for a long time the centre of that period of storm and stress, was the discovery of the telescope. We will not claim for Galileo, as many of his biographers have erroneously done, priority in the construction of the telescope. We rely far more on Galileo's own statements than on those of his eulogists, who aim at effect. Galileo relates with perfect simplicity at the beginning of the "Sidereus Nuncius," published at Venice in 1610, that he had heard about ten months ago that an instrument had been made by a Dutchman, by means of which distant objects were brought nearer and could be seen very plainly. The confirmation of the report by one of his former pupils, a French nobleman, Jean Badovere of Paris, had induced him to reflect upon the means by which such an effect could be produced. By the laws of refraction he soon attained his end. With two glasses fixed at the ends of a leaden tube, both having one side flat and the other side of the one being concave and of the other convex, his primitive telescope, which made objects appear three times nearer and nine times larger, was constructed. But now, having "spared neither expense nor labour," he had got so far as to construct an instrument which magnified an object C nearly a thousand times, and brought it more than thirty times nearer.1 Although, therefore, it is clear from this that the first idea of the telescope does not belong to Galileo, it is equally clear that he found out how to construct it from his own reflection and experiments. Undoubtedly also the merit of having made great improvements in it belongs to him, which is shown by the fact that at that time, and long afterwards, his telescopes were the most sought after, and that he received numerous orders for them from learned men, princes and governments in distant lands, Holland, the birthplace of the telescope, not excepted. But the idea which first gave to the instrument its scientific importance, the application of it to astronomical observations, belongs not to the original inventor but to the genius of Galileo. This alone would have made his name immortal.3 A few days after he had constructed his instrument, imperfect as it doubtless was, he hastened with it to Venice, having received an invitation, to exhibit it to the doge and senate, for he at once recognised its importance, if not to the full extent. We will now let Galileo speak for himself in a letter which he wrote from Venice to his brother-in-law, Benedetto Landucci : "You must know then that about two months ago a report was spread here that in Flanders a spy-glass had been presented to Prince Maurice, so ingeniously constructed that it made the most distant objects appear quite near, so that a man could be seen quite plainly at a distance of two miglia. This result seemed to me so extraordinary that it set me thinking; 1 Op. iii. (“Astronomicus Nuncius,” pp. 60, 61.) In his "Saggiatore also he relates the circumstance in precisely the same way, only adding that he devised the construction of the telescope in one night, and carried it out the next day. 2 Nelli, pp. 186, 187. 3 History has acknowledged the optician Hans Lipperhey, of Middelburg, to be the inventor of the telescope. Compare the historical sketch in Das neue Buch der Erfindungen," etc., vol. ii. pp. 217–220. (Leipzig, 1865.) The instrument receivedits name from Prince Cesi, who, on the advice of the learned Greek scholar Demiscianus, called it a "teleskopium." and as it appeared to me that it depended upon the theory of perspective, I reflected on the manner of constructing it, in which I was at length so entirely successful that I made a spy-glass which far surpasses the report of the Flanders one. As the news had reached Venice that I had made such an instrument, six days ago I was summoned before their highnesses the signoria, and exhibited it to them, to the astonishment of the whole senate. Many noblemen and senators, although of a great age, mounted the steps of the highest church towers at Venice, in order to see sails and shipping that were so far off that it was two hours before they were seen steering full sail into the harbour without my spy-glass, for the effect of my instrument is such that it makes an object fifty miglia off appear as large and near as if it were only five."1 Galileo further relates in the same letter that he had presented one of his instruments to the senate, in return for which his professorship at Padua had been conferred on him for life, with an increase of salary to one thousand florins. On his return to Padua he became eagerly engrossed in telescopic observation of the heavens. The astonishing and sublime discoveries which were disclosed to him must in any case have possessed the deepest interest for the philosopher who was continually seeking to solve nature's problems, and were all the more so, since they contributed materially to confirm the Copernican theory. His observations were first directed to the moon, and he discovered that its surface was mountainous, which showed at all events that the earth's satellite was something like the earth itself, and therefore by no means restored it to the aristocratic position in the universe from which it had been displaced by Copernicus. The milky way, as seen through the telescope, revealed an immense number of small stars. In Orion, instead of the seven heavenly bodies already known, five hundred new stars were seen; the number of the Pleiades, which had been fixed at seven, rose to thirty-six; the planets showed themselves as disks, while the fixed stars appeared as before, as mere bright specks in the firmament. But the indefatigable observer's far most important dis1 Op. vi. pp. 75-77. 2 See the decree of the senate, 25th Aug., 1609. (Op. xv. pp. 392, 393.) |