therofore, that our firmament is but one of a series: one of the smaller chambers in the great mansion of the universe. All the stars and constellations that shine in the midnight sky, constitute a stellar scheme which is but a unit of a countless number. As seen from the faint objects we discern in the side of Hercules and the sword-handle of Perseus, our whole sphere would be compressed into a small streak of light, and appear in space like a snow flake in our atmosphere! "Distrusting the power of the Refracting Telescope," says Professor Mitchell, "Lord Rosse determined to give his energies to the construction of a Reflecting Telescope, that would enable him to make grander discoveries than had hitherto been made. He wanted an instrument that would burst through the barriers that had hitherto bounded human vision; that would show him what lay in the vast deep beyond. I need not detail to you the construction of this mighty instrument. Instead of limiting it to four feet in diameter, as Herschel did, he has given his speculum six feet, with a focal distance of sixty feet. The power of this instrument is almost incredible. Such is its capacity that if a star of the first magnitude were removed to such a distance that its light would be sixty thousand years in traveling to the earth, this telescope would reveal it; were it removed so far that its light would be three millions of years in reaching us, this telescope would show it to the human eye. With such an instrument, then it is not wonderful that great discoveries should be made. It has but been pointed to the heavens; we have only entered upon the beginning of its career, but it has already accomplished mighty things. There are scattered throughout the heavens objects nebulous in their appearance which would not yield up their character to the instruments heretofore employed; but this instrument resolves them completely. Among the different objects that have been subjected to its acter. scrutiny, is the wonderful nebula in the constellation Orion. I have had an opportunity of examining it. It is one of the most curious objects in the whole heavens. It is not round, and it throws off furious lights. This object has been subjected to the examination of every instrument from the time of Herschel, but it grew more and more mysterious, more difficult to understand, more strange and diverse in its charWhen Lord Ross's great telescope was directed to its examination, it for a long time resisted its power. He found it necessary to wait night after night and month after month, until finally a favoring combination of circumstances gave to him a pure atmosphere. He directed his telescope to the object, and lo! its station revealed itself, the stars of which it is composed burst upon the sight for the first time, and the problem was solved forever. Here is one of the mightiest triumphs of this instrument, but it has gone on from point to point revealing combinations of stars wonderful beyond what the imagination could conceive. "— New York Tribune. MEMOIR OF GALILEO. "When in dungeon damply lying, Yet, 'It moves! it moves" he cried." GALILEO GALILEI, the eldest son of Vincentio Galilei, was born at Pisa in Italy, on the 15th of February, 1564. Like most experimental philosophers, Galileo, in his carliest years, gave indications of that bent of mind, and intellectual superiority, which has made him rank so high among the philosophers of antiquity. Although his father was by no means wealthy, Galileo received a tolerable education. He was desirous of following the profession of a painter; but in obedience to his father's desire, he entered as a scholar of arts at the university of Pisa, on the 5th of November, 1581, and applied himself to the study of medicine. Music was a favorite study of Galileo's. In studying the principles of this science, he found it necessary to learn something of geometry, and commenced with Euclid's Elements. The demonstrations of the mathematician, and the new and wondrous truths which this science unfolds, took such hold of the ardent mind of Galileo, that after many fruitless attempts to confine him to the study of medicine, his father gave up the attempt, and allowed him to follow his own inclinations. From Euclid he ascended to the higher mathematicians; and, while studying Archimedes' treatise on hy drostatics, he wrote an essay on the hydrostatical balance, explaining its construction, and the mode by which the philosopher of Syracuse detected the fraud committed by the jewellers making Hiero's crown. This work introduced Galileo to Guido Ubaldi, an eminent mathematician, who engaged him to investigate the subject of the centre of gravity in solid bodies; and the treatise which he produced upon this subject was the foundation of his future celebrity Through his connexion with Ubaldi, Galileo was appointed lecturer on mathematics at Pisa in 1589, with a yearly salary of sixty crowns, which he increased by devoting some time to private teaching. At the early age of eighteen, Galileo doubted the philosophy of Aristotle; and on his establishment at Pisa, commenced to overthrow the doctrines of this philosopher. His first inquiries were into the mechanical doctrines of Aristotle, which he soon discovered to be untenable. The errors which he found existing, he exposed to his pupils, and a rancorous controversy commenced between the followers of Aristotle on the one side, and Galileo and his pupils on the other. Argument, and even experiment, failed in convincing Galileo's opponents. The doctrine of Aristotle, that the heavier of two falling bodies would fall quicker, was proved by the experiment of dropping bodies of different weights from the leaning tower at Pisa; but although these bodies struck the ground nearly at the same instant, the followers of Aristotle remained unconvinced, or at least unconverted. Conscious of his superiority, and the truth of his doctrines, Galileo turned not only the powers of argument, but the shafts of ridicule and sarcasm against his opponents; thus raising up a personal enmity, which afterwards developed itself in bitter persecution. Other circumstances increased the rancor of his enemies, and at last made his position so uncomfortable, that he gave up his situation at Pisa, and accepted the professorship of mathematics at the university of Padua, with an income of 180 florins. The death of his father having burdened Galileo with the family, he had to apply himself here as at Pisa, to private teaching. Notwithstanding his public and private duties, however, he still found leisure to make several discoveries and inventions, which were circulated in manuscript amongst his friends. Some of these abused the confidence reposed in them, and published several of Galileo's inventions as their own. The doctrines of Copernicus, regarding the stability of the sun and the revolution of the planets, were the subject of disputation among the learned in the time of Galileo. He early became a convert to the new doctrines, and believed in them even at the time he was teaching the opposite or Ptolemaic system, which regarded the earth as stationary, and the sun a revolving body. Shortly after he went to Padua, he published a treatise on the sphere, in which the system of Ptolemy was supported by the very arguments which he afterward ridiculed. It is rather considered, however, that it was some time after the publication of this treatise that Galileo changed his opinions. About this time he commenced a correspondence with Kepler, the German astronomer, which continued till his death. In 1593, he contracted a chronic disorder, from inadvertently sleeping at an open window, which afflicted him at intervals during the rest of his life. At this time, Galileo's reputation as a philosopher was widely extended all over Europe, and many of the nobility became his pupils. His first engagement as professor at Padua was for six years. On the expiry of this term, he was re-engaged for other six years, at an advanced salary of 320 florins. The first important discovery of Galileo was, that the vibrations of a pendulum are performed in equal times, whatever be the size of the arc described, within certain limits. In 1604, a new star was discovered by astronomers in the constellation of Ophiucus, and formed the subject of much speculation. By |