DISCOVERIES IN THE CELESTIAL SPACES. 305 



earlier 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 Rhsetieus to Johann Schoner, profess- 

 or 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 aftei 

 its first promulgation led to the brilliant astronomical discov- 

 eries that characterize the commencement of the seventeenth 

 century ; for these discoveries were the result of the accident- 

 al invention of the telescope, and were the means of at once 

 perfecting and extending the doctrine of Copernicus. Con- 

 firmed and extended by the results of physical astronomy (by 

 the discovery of the satellite-system of Jupiter and the phases 

 of Venus), the fundamental views of Copernicus have indica- 

 ted to theoretical astronomy paths which could not fail to lead 

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

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

 the analytic calculus. While George Peuerbach and Regio- 

 montanus (Johann Muller, of Konigsberg, in Franconia) ex- 

 ercised a beneficial influence on Copernicus and his pupils 

 Rhseticus, Reinhold, and Mostlin, these, in their turn, influ- 

 enced in a like manner, although at longer intervals of time, 

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

 ideal links which connect the sixteenth and seventeenth cen- 

 turies ; and we can not delineate the extended astronomical 

 views of the latter of these epochs without taking into consid- 

 jration the incitements yielded to it by the former. 



An erroneous opinion unfortunately prevails, even in the 

 present day,* that Copernicus, from timidity and from appre- 

 hension of priestly persecution, advanced his views regarding 

 the planetary movement of the earth, and the position of the 

 sun in the center of the planetary system, as mere hypotheses, 

 which fulfilled the object of submitting the orbits of the heav- 

 enly bodies more conveniently to calculation, "but which need 



than 1507. Herr Voifjt doubts whether the aqueduct and hydraulic 

 works at Frauenburg, generally ascribed to Copernicus, were really ex- 

 ecuted in accordance with his designs. He finds that, so late as 1571, 

 a contract was concluded between the Chapter and the " skillful mas- 

 ter Valentine Lendel, manager of the water-works at Breslau," to bring 

 the water to Frauenburg, from the mill-ponds to the houses of the can- 

 ons. Nothing is said of any previous water-works, and those which ex- 

 ist at present can not have been commenced until twenty-eight yeara 

 after the death of Copernicus. 



* Delambre, Histoire De V Astronomie Moderne, t. i., p. 14C. 



