Page:Popular Science Monthly Volume 64.djvu/343

Rh accurate tables to replace those constructed for Alphonso the Wise, which no longer served to predict eclipses or to account for the configurations of the planets. Errors of a couple of hours in the predicted time of a lunar eclipse were noted, and Mars was two degrees away from its calculated place.

In the work of observation and calculation he gained an invaluable coadjutor in Johann Müller, of Königsberg, a village of Franconia, one of his pupils. Müller called himself, after the fashion of the time, Johannes de Monteregio, but is known to us as Regiomontanus. Together they studied the works of Ptolemy, and together they observed the planets with the best instruments they could construct, though their apparatus was much inferior to that of the Arabs. Like all men of their time they were believers in judicial astrology, and their tables were arranged to meet the wants of this pseudo-science. At the same time astronomy benefited by their investigations, which began to be based on actual observation of the sky.

The Papal Nuncio in Vienna was then Cardinal Bessarion, once Bishop of Nicaea in the Greek, now high in power in the Latin Church and a friend of learning. Purbach's enthusiasm for the works of Ptolemy was shared by the cardinal, and they planned a new edition of his writings. For such an edition it was necessary to collect Greek manuscripts. After the death of Purbach (1461) Regiomontanus went to Italy in the cardinal's suite for this purpose (1462). Here he remained some seven years, collecting manuscripts, mastering the Greek language, studying the sciences, and writing his treatise on trigonometry. His text of Ptolemy was printed at Basel in 1538 and was used by Copernicus.

In 1471 he was settled in Nuremberg near the printing presses that had been installed a few years earlier. Here he had the fortune to meet a wealthy amateur, Bernhard Walther (1430–1504), who built an observatory for their joint use, and aided him in his publication of various writings, his own and Purbach's. The Ephemerides of Regiomontanus made him famous. They were the nautical almanacs of those days, and were used by Columbus and Vasco da Gama in their voyages of discovery. He is also the inventor of the method of lunar distances for determining the longitude at sea. He was invited to Rome by the Pope in 1475 to reform the calendar and there died in 1476.

There is a legend that Regiomontanus was assassinated by the sons of George of Trebizond, the first translator of the Almagest of Ptolemy from the Greek, because of strictures passed upon it. The legend