in the doctrines of refraction, the principle which he sought. Having procured two spectacle-glasses, both of which were plane on one side, while one of them had its other side convex, and the other its second side concave, he placed one at each end of a leaden tube a few inches long; and having applied his eye to the concave glass, he saw objects pretty large, and pretty near him. This little instrument, which magnified only three times, and which he held between his fingers or laid in his hand, he carried to Venice, where it excited the most intense interest. Crowds of the principal citizens flocked to his house to see the magical toy; and after nearly a month had been spent in gratifying this epidemical curiosity, Galileo was led to understand from Leonardo Deodati, the Doge of Venice, that the Senate would be highly gratified by obtaining possession of so extraordinary an instrument. Galileo instantly complied with the wishes of his patrons, who acknowledged the present by a mandate, conferring upon him for life his professorship at Padua, and raising his salary from 520 to 1000 florins. The interest which the exhibition of the telescope excited at Venice did not soon subside; Sirturi describes it as amounting to frenzy. When he himself had succeeded in making one of these instruments, he ascended the Tower of S. Mark, where he might use it without molestation. He was recognised, however, by a crowd in the street; and such was the eagerness of their curiosity, that they took possession of the wondrous tube, and detained the impatient philosopher for several hours, till they had successively witnessed its effects. Desirous of obtaining the same gratification for their friends, they endeavoured to learn the name of the inn at which Sirturi lodged; but he, overhearing their enquiries, quitted Venice early next morning. The opticians speedily availed themselves of this wonderful invention. Galileo's tube, or the double eye-glass, or the cylinder, or the trunk, as it was called-for Demisiano had not yet given it the appellation of telescope-was manufactured in great numbers and in a very inferior manner. The instruments were purchased merely as philosophical toys, and were carried by travellers into every corner of Europe. The art of grinding and polishing lenses was at this time very imperfect. Galileo, and those whom he instructed, were alone capable of making tolerable instruments. In 1634, a good telescope could not be procured in Paris, Venice, or Amsterdam; and even in 1637, there was not one in Holland which could show Jupiter's disk well defined. After Galileo had completed his first instrument, which magnified only three times, he executed a larger and better one, with a power of about eight. At length,' as he himself re marks, 'sparing neither labour nor expense,' he constructed a telescope so excellent that it bore a magnifying power of more than thirty times. Thus was Galileo equipped for a survey of the heavens. The first celestial object to which he directed his telescope was the moon, which, to use his own words, appeared as near as if it had been distant only two semi-diameters of the earth. It displayed to him her mountain ranges and her glens, her continents and her highlands, now lying in darkness, now brilliant with sunshine, and undergoing all those variations of light and shadow which the surface of our own globe presents to the Alpine traveller or to the aëronaut. The four satellites of Jupiter illuminating their planet, and suffering eclipses in their shadow like our own moon; the spots on the sun's disk, proving his rotation round his axis in twenty-five days; the crescent phases of Venus; and the triple form, or the imperfectly developed ring of Saturn, were the other discoveries in the solar system which rewarded the diligence of Galileo. In the starry heavens, too, thousands of new worlds were discovered by his telescope; and the Pleiades alone, which, to the unassisted eye, exhibits only seven stars, displayed to Galileo no fewer than forty. It was then that, to his unutterable astonishment, Galileo saw, as a celebrated French astronomer (M. Biot) has expressed it, what no mortal before that monent had seen-the surface of the moon, like another earth, ridged by high mountains and furrowed by deep valleys; Venus, as well as it, presenting phases demonstrative of a spherical form; Jupiter surrounded by four satellites, which accompanied him in his orbit; the milky way; the nebulæ ; finally, the whole heavens sown over with an infinite multitude of stars, too small to be discerned by the naked eye.' Milton, who had seen Galileo, nearly half a century after the invention, refers to some of the wonders thus laid open by the telescope :— The moon, whose orb, Through optic glass the Tuscan artist views Or in Valdarno, to descry new lands, Rivers, or mountains, in her spotty globe. 'There are,' says Everett, the American orator, 'occasions in life in which a great mind lives years of rapt enjoyment in a moment. I can fancy the emotions of Galileo, when, first raising the newly-constructed telescope to the heavens, he saw fulfilled the grand prophecy of Copernicus, and beheld the planet Venus crescent like the moon. It was such another moment as that when the immortal printers of Mentz and Strasburg received the first copy of the Bible into their hands, the work of their divine art; like that when Columbus, through the grey dawn of October 12, 1492 (Copernicus, at the age of eighteen, was then a student at Cracow), beheld the shores of San Salvador; like that when the law of gravitation first revealed itself to the intellect of Newton; like that when Franklin saw, by the stiffening of the fibres of the hempen cord of his kite, that he held the lightning in his grasp; like that when Leverrier received back from Berlin the tidings that the predicted planet was found.' 'The starry Galileo,' with his woes, is enshrined among the martyrs of science.' His noblest discoveries were the derision of his contemporaries, and were even denounced as crimes which merited the vengeance of Heaven. He was the victim of cruel persecution, and spent some of his latest hours within the walls of a prison; and, though the Almighty granted him, as it were, a new sight, to discern unknown worlds in the obscurity, yet the eyes which were allowed to witness such wonders were themselves doomed to be closed in darkness, Sir David Brewster eloquently says:— 'The discovery of the moon's libration was the result of the last telescopic observations of Galileo. Although his right eye had for some years lost its power, yet his general vision was sufficiently perfect to enable him to carry on his usual researches. In 1636, however, this affection of his eye became more serious; and in 1637 his left eye was attacked by the same disease; the disease turned out to be in the cornea, and every attempt to restore its transparency was fruitless. In a few months, the white cloud covered the whole aperture of the pupil, and Galileo became totally blind. This sudden and unexpected calamity had almost overwhelmed Galileo and his friends. In writing to a correspondent, he exclaims, "Alas, your dear friend and servant has become totally and irreparably blind. Those heavens, this earth, this universe, which by wonderful observation I had enlarged a thousand times beyond the belief of past ages, are henceforth shrunk into the narrow space which I myself occupy. So it pleases God; it shall, therefore, please me also." Galileo's father, Father Castelli, deplores the calamity in the same tone of pathetic sublimity: "The noblest eye," says he, "which nature ever made, is darkened; an eye so privileged, and gifted with such rare powers, that it may truly be said to have seen more than the eyes of all that are gone, and to have opened the eyes of all that are to come."" MENSURATION, To find the convex surface of a sphere: (1) What is the convex surface of a sphere whose diameter is 20 in. ? (2) What is the area of the earth's surface, calculating its diameter at 7957.75 miles? (3) What is the diameter of a ball, the area of whose surface is one square foot? To find the solid content of a sphere: (4) What is the solid content of a sphere whose diameter is 10 in. ? (5) What is the weight of a solid globe of silver which is 6 in. in diameter, the specific gravity of silver being 10·3? (6) What would be the value of a golden sphere of 1 in. in diameter at £3 15s. per ounce, the specific gravity of gold being 19.5? SELECTIONS FROM THE POEMS OF SCOTT, BYRON, AND BURNS. DEATH OF DE ARGENTINE. (Sir Walter Scott.) [Born, 1771; died, 1832. Chief works: 'Lay of the Last Minstrel,' 'Marmion,' "The Lady of the Lake,'The Lord of the Isles,'' Rokeby,'' Bridal of Trier main,' the Waverley Novels,' &c. &c.] ALREADY Scattered o'er the plain, O give their hapless prince his due! They gained the summit of the hill, ‘In yonder field a gage I left,- Speed hence, my liege, for on your trace God send my sovereign joy and bliss, Again he faced the battle-field,— And of the bold pursuers, The gallant knight from saddle bore; And through his bloody tartans bored, And swung his broadsword round! Stirrup, steel-boot, and cuish gave way, Beneath that blow's tremendous sway, The blood gushed from the wound; And the grim lord of Colonsay Hath turned him on the ground, And laughed in death-pang, that his blade Now toiled the Bruce, the battle done, |