TYCHO BRAKE 



1546-1601 



Copernicus himself left behind him the wish that the posi- 

 tion of the planets calculated by his methods should in the 

 future be compared with their actual positions, for the 

 purpose of testing the correctness of his statement regarding 

 the paths of the heavenly bodies. The calculation was per- 

 formed by Erasmus Reinhold (151 1-1553) in the Prutenischen 

 Tafeln ('Prussian -Tables'), which represented a great 

 improvement as compared with the astronomical tables 

 hitherto in use, and became of importance also for the 

 calendar. Copernicus' work was thus proved to be correct; 

 but the agreement with actual observation was not perfect. 

 Thus Mars, for example, was occasionally found as much 

 as two degrees (four diameters of the full moon) distant 

 from its calculated position. Discrepancies of this kind might 

 depend upon the original data, which in Copernicus' case 

 were in part derived from Hipparchus, and the admirers of 

 the great advance made by Copernicus were inclined to 

 assume this to be the case; but it was also possible that the 

 actual path of the planets might still exhibit peculiarities 

 which were unknown to Copernicus. 



At this point, therefore, an unprejudiced and accurate 

 observer might again find the means of making further 

 progress, and in this capacity Tycho Brahe showed the 

 way to magnificent new discoveries. He refused to accept 

 Copernicus' system without question; he was simply 

 anxious to determine as accurately as possible the true path 

 of the planets among the fixed stars; to which end, the posi- 

 tions of the latter had also to be determined with greater 

 exactness than Hipparchus had done, and Tycho proposed 

 to make these determinations to a degree of accuracy 

 hitherto unattained. This aim he followed tirelessly during 

 almost thirty years of work. His measurements of stellar 



Cs 17 



