CH. ix. COPERNICAN THEORY OF THE UNIVERSE. 63 



for our use and enjoyment. This system had been held 

 and taught in all the schools for nearly fourteen hundred 

 years, when, in the beginning of the sixteenth century, a 

 man arose who set it aside, and proposed a better explana- 

 tion of the movements which we see in the heavens. 



In 1473, a few y ears before Columbus sailed for America, 

 Nicolas Copernicus, the son of a small country surgeon, 

 was born at Thorn, in Poland. From his earliest boyhood 

 he had always a great love for science, and after taking a 

 doctor's degree at Cracow, he went as Professor of Mathe- 

 matics to Rome. About the year 1500 he returned to his 

 own country and was made a canon of Frauenberg, in 

 Prussia. Here he set himself to study the heavens from 

 the window of his garret, and often all night long from the 

 steeple of the cathedral. At the same time he read care- 

 fully the explanations which Ptolemy and other astronomers 

 had given of the movements of the sun and planets. But 

 none of their theories satisfied him, for he could not make 

 them agree with what he himself observed, and, moreover, 

 they required so many unlikely suppositions that it seemed 

 almost impossible they could be true. For example, 

 according to the Ptolemaic system, the movements of 

 Venus and Mercury could only be explained by supposing 

 a rigid bar, or something equivalent to it, to be connected 

 at one end with the earth, and at the other with the sun, 

 and these planets to revolve round some point on the same 

 bar. The movements of Mars, however, being much more 

 irregular, could not be explained by one bar, but required 

 that this bar should have a joint at some point beyond the 

 sun, so as to form a second bar revolving round the first, 

 and even a third joint and a third bar were necessary to 

 account for the whole of his irregularities. In order to get 

 rid of this cumbersome and intricate machinery, which was 



