on the surface of that luminary, by which he ascertained that that mighty orb performed a revolution round its axis. He brought to view multitudes of stars imperceptible to the naked eye, and ascertained that those nebulous appearances in the heavens which constitute the Milky Way, consist of a vast collection of minute stars, too closely compacted together to produce an impression on our unassisted vision. The results of Galileo’s observations were given to the world in a small work, entitled ‘_Nuncius Sidereus_,’ or, ‘News from the starry regions,’ which produced an extraordinary sensation among the learned. These discoveries soon spread throughout Europe, and were incessantly talked of, and were the cause of much speculation and debate among the circles of philosophers. Many doubted; many positively refused to believe so novel and unlooked-for announcements, because they ran counter to the philosophy of Aristotle, and all the preconceived notions which then prevailed in the learned world. It is curious, and may be instructive, to consider to what a length of absurdity, ignorance and prejudice carried many of those who made pretensions to learning and science. Some tried to reason against the facts alleged to be discovered, others contented themselves, and endeavoured to satisfy others, with the simple _assertion_ that such things were not, and could not possibly be; and the manner in which they supported themselves in their incredulity was truly ridiculous. ‘O my dear Kepler,’ says Galileo in a letter to that astronomer, ‘how I wish we could have one hearty laugh together. Here at Padua is the principal professor of philosophy, whom I have repeatedly and urgently requested to look at the moon and planets through my glass, which _he pertinaciously refuses to do_, lest his opinions should be overturned. Why are you not here? what shouts of laughter we should have at this glorious folly! and to hear the professor of philosophy at Pisa labouring with the Grand Duke with logical arguments, as if with magical incantations, to charm the new planets out of the sky.’ Another opponent of Galileo, one Christmann, says in a book he published, ‘We are not to think that Jupiter has four satellites given him by nature, in order, by revolving round him, to immortalize the Medici who first had notice of the observation. These are the _dreams of idle men_, who love ludicrous ideas better than our laborious and industrious correction of the heavens. Nature abhors so horrible a chaos; and to the truly wise, such vanity is detestable.’ One Martin Horky, a would-be philosopher, declared to Kepler, ‘I will never concede his four new planets to that Italian from Padua, _though I should die for it_;’ and he followed up this declaration, by publishing a book against Galileo, in which he examines four principal questions respecting the alleged planets; 1. Whether they exist? 2. What they are? 3. What they are like? 4.