In the same year, 1609, Galileo heard the report, that a spectacle-maker of Middleburg, in Holland, had made an instrument by which distant objects appeared nearer. He tasked his ingenuity to discover the construction, and soon succeeded in manufacturing a telescope. His telescope, however, seems to have been made on a different construction from that of the Dutch optician. It consisted of a convex and concave glass, distant from each other by the difference of their focal lengths, like a modern opera-glass; while there is reason to believe that the other was made up of two convex lenses, distant by the sum of their focal lengths, the common construction of the astronomical telescope. Galileo’s attention naturally was first turned to the moon. He discovered that her surface, instead of being smooth and perfectly spherical, was rough with mountains, and apparently varied, like the earth, by land and water. He next applied to Jupiter, and was struck by the appearance of three small stars, almost in a straight line, and close to him. At first he did not suspect the nature of these bodies; but careful observation soon convinced him that these three, together with a fourth, which was at first invisible, were in reality four moons revolving round their primary planet. These he named the Medicean stars. They have long ceased to be known by that name; but so highly prized was the distinction thus conferred upon the ducal house of Florence, that Galileo received an intimation, that he would “do a thing just and proper in itself, and at the same time render himself and his family rich and powerful for ever,” if he “named the next star which he should discover after the name of the great star of France, as well as the most brilliant of all the earth,” Henry IV. These discoveries were made known in 1610, in a work entitled “Nuncius Sidereus,” the Newsman of the Stars: in which Galileo farther announced that he had seen many stars invisible to the naked eye, and ascertained that the nebulæ scattered through the heavens consist of assemblages of innumerable small stars. The ignorant and unprejudiced were struck with admiration; indeed, curiosity had been raised so high before the publication of this book, as materially to interfere with the convenience of those who possessed telescopes. Galileo was employed a month in exhibiting his own to the principal persons in Venice; and one unfortunate astronomer was surrounded by a crowd who kept him in durance for several hours, while they passed his glass from one to another. He left Venice the next morning, to pursue his inquiries in some less inquisitive place. But the great bulk of the philosophers of the day were far from joining in the general feeling. They raised an outcry against the impudent fictions of Galileo, and one, a professor of Padua, refused repeatedly to look through the telescope, lest he should be compelled to admit that which he had predetermined to deny. In the midst of this prejudice and envy, Kepler formed a brilliant exception. He received those great discoveries with wonder and delight, though they overturned some cherished theories, and manifested an honest and zealous indignation against the traducers of Galileo’s fame.