Page:The Gradual Acceptance of the Copernican Theory of the Universe.djvu/29

 Pürbach (1432-1462) died before he had fulfilled the promise of his youth, leaving his Epitome of Ptolemy's Almagest to be completed by his greater pupil. In his Theorica Planetarum (1460) Pürbach sought to explain the motions of the planets by placing each planet between the walls of two curved surfaces with just sufficient space in which the planet could move. As M. Delambre remarked: "These walls might aid the understanding, but one must suppose them transparent; and even if they guided the planet as was their purpose, they hindered the movement of the comets. Therefore they had to be abandoned, and in our own modern physics they are absolutely superfluous; they have even been rather harmful, since they interfered with the slight irregularities caused by the force of attraction in planetary movements which observations have disclosed." This scheme gives some indication of the elaborate devices scholars evolved in order to cope with the increasing number of seeming irregularities observed in "the heavens," and perhaps it makes clearer why Copernicus was so dissatisfied with the astronomical hypothesis of his day, and longed for some simpler, more harmonious explanation.

Regiomontanus (1436-1476) after Pürbach's death, continued his work, and his astronomical tables (pub. 1475) were in general use throughout Europe till superseded by the vastly more accurate Copernican Tables a century later. It has been said that his fame inspired Copernicus (born three years before the other's death in 1476) to become as great an astronomer. M. Delambre hails him as the wisest astronomer Europe had yet produced and certainly his renown was approached only by that of the great Cardinal.

21