While these brilliant discoveries were enlightening Germany, others of scarcely less importance were mak ing in Italy, by the industry of Galileo. The discovery of the telescope gave a vigorous impulse to the human mind, and enabled it to penetrate into the remotest re gions of space, far beyond the limits which Nature had assigned. Though Galileo had not the merit of invent ing this admirable instrument, he has the undisputed honour of having greatly improved it, and applied it to the heavens. His first observations which were made upon the moon, induced him to conclude, that OA lumi nary was an opaque body like our earth, variegated with hills and valleys. He perceived in every part of the hea vens numbers of stars which were beyond the reach of unassisted vision ; and he considered the light of the mil ky way as arising from the innumerable stars which were collected in that zone of the heavens. He discove red four satellites circulating round the planet Jupiter, and verified the prediction of Copernicus, that Venus would exhibit phases similar to those of the moon. The surface of the sun, when seen through the telescope, was covered with a number of dark spots ; and Galileo explained the phenomena which they exhibited, by sup posing them to adhere to the body of that luminary, and to be affected by a revolution about its axis. The dis tance of Saturn was too great for the imperfect instru ment which Galileo employed ; but lie saw plainly that this planet was not round like the rest, and he consider ed it as composed of three bodies. The appearance of the fixed stars like brilliant points, when magnified by the telescope, and the other discoveries which he made, were irrefragable proofs of the Copernican hypothesis, and Galileo did not scruple to disseminate and defend the doctrine of the earth's motion. The holy inquisi• tion, the pretended guardian of the Chistian faith, de nounced Galileo as the abbettor of irreligious opinions; and the Cardinal Bellarmin made him promise never to support the new system, either in his conversation or his writings. Galileo was not insensible to the enthusi asm which the discovery of truth never fails to inspire ; and he burned with impatience to throw off the fetters which had been imposed upon his mind. The horrors of a prison, and the vengeance of superstition entrench ed in power, were the sufferings which he had, to ba lance against the abhorrence of cherished error, against the impatience of a persecuted spirit, and the anticipa ted applause of future times. Preferring a middle course, Galileo resolved neither to shrink from his convictions, nor yet openly to avow them. In the third dialogue of his Systema Cosmicum, he introduces three speakers, Salvatius, Sagredus, and Simplicius, who discuss the subject of the earth's motion. One of these is a peri patetic philosopher, who defends the Ptolemaic system with all the ingenuity of which it is susceptible, while the other two, by a force of reasoning which could not be resisted, endeavoured to support the system of Co pernicus. Though Galileo did not decide between these opposite opinions, yet the success which his dialogues experienced, and the strength of argument with which he answered every objection to the earth's motion, again roused the hostility of the inquisition. Notwithstanding the interposition of the grand duke of Tuscany, he was summoned before this jealous tribunal, and condemned to solitary confinement. On the 22d June 1633, an assem bly of seven cardinals sat in judgment upon Galileo. They issued a decree against him, maintaining, that the motion of the earth was a proposition absurd, false in philosophy, heretical, and contrary to scripture ;* and they threatened him with the severest punishments if he continued to propagate this fatal error, or adhered with contumacy to such dangerous sentiments. Galileo saw that he had no alternative but an implicit submission to the mandates of the church, and he agreed to sign a formula, in which he abjured, execrated, and detested, the absurdity, error, and heresy, of the earth's motion. t What a mortifying picture of human infirmity on the one hand, and of atrocious presumption on the other ! A ve nerable old man, turned of seventy, with his head silver ed over by the study of Nature, disavowing, against rea son and conscience, the great truths which he had pub lished to the world, and which shone forth in every part of those heavens to which he appealed! An assembly of reverend cardinals, encircling the aged philosopher on his knees, fixing the laws and arrangements of nature, repressing the great truths which she unfolds, and con demning to perpetual imprisonment the venerable sage, who first disclosed to man the unexplored regions of boundless space The solicitations of the grand duke of Tuscany obtain ed the release of Galileo after a year's confinement, but he was compelled to remain within the territory of Flo rence, in the small village of Arcetri. In this state of captivity he to console himself by his for mer studies. He observed the phenomena of the moon's libration, and ascribed them to the position of the obser ver on the surface of the earth, and to the motion of the moon in an orbit inclined to the ecliptic. He continued
to observe, likewise, the motions of Jupiter's satellites ; and he proposed a method of finding the longitude, by observing the phenomena of these bodies in different meridians. The Dutch government heard of this propo sal, and sent Hortensius and Bleau to consult with Ga lilco. They carried with them a golden chain, as a to ken of Aspect for the talents of this great man; but im mediattTy upon their arrival at Arcetri, Galileo became suddenly blind. After continuing his studies for a lew years, and committing his opinions to writing, he was seized with a dangerous disorder, or which he died, in January 1642, in the seventy-eighth year of his age.
Contemporary with Galileo were a number of astrono mers, who contributed to the progress of the science. Baron Napier published his Tables of Logarithms in 1614. Bayer obtained great celebrity by his Uranome tria, in which the stars arc designated by the letters of the Greek alphabet. Landsbergius published astronomi cal tables in 1632. Horrox and Crabtree observed Ve nus, for the first time, on the sun's disc. Scheirer made numerous observations on the solar spots ; Gassendi ob served the transit of Mercury over the sun in 1631; Morin was the first who applied the telescope to the quadrant; Riccioli published his valuable work, entitled dllmagestum No-oum; Azout invented the micrometer with a moveable wire ; Mouton determined the diame ter of the sun and moon, by means of the telescope and simple pendulum ; and Seth Ward maintained, that the motion of a planet was uniform about the focus of its el liptical orbit in which the sun was not placed.
The indefatigable labours of Hevelius will be long re membered in the history of astronomy. His observatory; founded at Dantzic in 1641, was furnished with excel lent instruments, some of which were divided into eve ry five seconds. The numerous observations which he made on the spots and libration of the moon are publish ed in his Selenographia, illustrated with good engravings of the lunar disc. His observations on the spots of the sun, and on the nature of comets, were numerous and deli cate, and his catalogue of the fixed stars, containing the longitude and latitude of 1888, was remarkable for its ac curacy. The observatory of Hevelius, with all the books and instruments which it contained, was consumed by fire on the 26th September 1679; but descriptions and drawings of his instruments were fortunately preserved in his Machina Celestis. About this time the use of tele scopic sights in quadrants was strenuously recommended by the ingenious Dr Hooke. Hevelivs employed plain sights in all his instruments ; and a dispute upon this subject commenced between the two astronomers. This difference of opinion induced Dr I 'alley, in 1679, to pay a visit to Hevelius, with whom he remained for some time, charmed with the construction of his instruments, and the accuracy of his observations. Had Hevelius adopted the suggestion of Dr Hooke, his observations would have been distinguished by a precision which practical astronomers had not hitherto attained.
The improvement of the telescope continued to lay open new sources of discovery. The celebrated Huy gens, by means of two excellent telescopes, of 12 and 24 feet focal length, discovered, that the singular appear ance which Saturn had exhibited to Galileo and Ileve lius, was occasioned by a large ring which surrounded the planet ; that the plane of the ring was inclined 30° to the ecliptic; and that the various appearances which the ring exhibited, arose from the different position of the earth with regard to this plane. He discovered also the fourth satellite of Saturn ; and as this discovery made the number of secondary planets equal to the primary ones, Huygens imagined that there were no more sa te,lites to discover, and was probably prevented by this foolish prejudice, from exploring with sufficient care the regions in which they were to be Found. We are indebted also to Huygens for the application of pendu lums to clocks, an invention of great use in practical astronomy. His beautiful theorems on centrifugal for ces, and his discoveries respecting involutes, paved the way for the theory of curvilineal motion, which was af terwards established by Newton. The reputation of Huygens obtained him an invitation from Louis XIV. and he was one of the first members of the French aca demy. But Huygens was a Protestant, and was com pelled to retire to the Hague, his native place, in con sequence of that harsh edict which deprived France of her most valuable citizens.
About this time the establishment of learned soci2 tics in London and Paris concentrated in these favoured capitals all the genius of Europe. The enthusiasm which they inspired, the encouragements which they held out, the rivalry which they produced, were the causes of that rapid advancement which all the sciences experienced.