Page:Collier's New Encyclopedia v. 01.djvu/404

ASTRONOMY 318 ASTRONOMY an accuracy far surpassing anything haps the greatest of these was the in- before done in that line. He left behind vention of logarithms by Lord Napier, him a mass of observations of the sun In 1603, John Bayer, of Augsburg, pub- and planets which he had made to lished his "Uranometria," or maps of demonstrate the truth of his system of the 48 constellations which had been the universe, but which afterward be- handed down from Hipparchus through came, in Kepler's hands, the means of Ptolemy in the "Almagest," and, on THE 40" REFRACTOR TELESCOPE AT YERKES OBSERVATORY its overthrow and the final and perma- nent establishment of the truth of the Copernican system. Kepler's brilliant discovery of the three laws of planetary motion made his name immortal. Galileo Galilei was the contemporary of Kepler, and, as his discoveries were of a more popular character, he obtained a more immediate fame and reputa- tion. In the interval between the great discoveries of Kepler and Galileo and those of Newton various astronomers made valuable additions to astronomical knowledge or invented new apparatus for observing the heavenly bodies. Per- these maps, he for the first time assigned to the individual stars the letters that are used to-day. The researches of Descartes gave a new help to mathe- matical analysis. Horrox observed the transit of Venus in 1639, the first ever seen by man. The most accurate determinations of the positions of the heavenly bodies made without the help of the telescope were those of Hevelius, a rich citizen of Danzig. The catalogue of stars which bears his name, and by whose numbers in the different constellations the indi- vidual stars are still called to-day with