DISCOVERIES IN THE CELESTIAL SPACES. 685 



an important part of his theory had been made known by 

 the publication of a letter of one of his most zealous pupils 

 and adherents, Joachim Rhaeticus to Johann Schoner, Pro- 

 fessor at Nuremberg It was not, however, the propagation 

 of the Copernican doctrines, the renewed opinion of the 

 existence of one central sun, and of the diurnal and annual 

 movement of the earth, which somewhat more than half 

 a century after its first promulgation led to the brilliant as- 

 tronomical discoveries that characterise the commencement 

 of the seventeenth century; for these discoveries were 

 the result of the accidental invention of the telescope, 

 and were the means of at once perfecting and extending 

 the doctrine of Copernicus. Confirmed and extended by 

 the results of physical astronomy (by the discoveiy of 

 the satellite- system of Jupiter and the phases of Venus) 

 the fundamental views of Copernicus have indicated to 

 theoretical astronomy paths which could not fail to lead to 

 sure results, and to the solution of problems which of neces- 

 sity demanded, and led to a greater degree of perfection in 

 the analytic calculus. While George Peurbach and Regio- 

 montanus (Johann Miiller, of Konigsberg in Franconia) exer- 

 cised a beneficial influence on Copernicus and his pupils 

 RhaBticus, Keinhold, and Mostlin, these in their turn in- 

 fluenced in a like manner, although at longer intervals of 

 time, the works of Kepler, Galileo, and Newton. These are 



was so far completed in 1530, that only a few corrections were 

 subsequently added. The publication was hastened by a letter from 

 Cardinal Schonberg, written from Rome in 1536. The cardinal wishes 

 to have the manuscript copied and sent to him by Theodor von Reden. 

 We learn from Copernicus himself, in his dedication to Pope Paul III., 

 that the performance of the work has lingered on into the guartum 

 novenniiim. If we remember how much time was required for print- 

 ing a work of 400 pages, and that the great man died in May, 1543, it 

 may be conjectured that the dedication was not written in the last- 

 named year; which, reckoning backwards thirty-six years, would not 

 give us a later, but an earlier year than 1507. flerr Voigt doubtg 

 whether the aqueduct and hydraulic works at Frauenburg, generally 

 ascribed to Copernicus, were really executed in accordance with hia 

 designs. He finds that, so late as 1571, a contract was concluded be- 

 tween the Chapter and the " skilful master Valentine Lendel, manager 

 of the water-works, at Breslau," to bring the water to Frauenburg, from 

 the mill-ponds to the houses of the canons. Nothing is said of any 

 previous waterworks, and those which exist at present cannot have beeu 

 commenced until twenty-eight years after the death of Copernicus. 



