SEQUEL TO COPERNICUS. 269 



This letter is dated 1536, and implies that the work of Copernicus 

 was then written, and known to persons who studied astronomy. De- 

 lambre says that Achilles Gassarus of Lindau, in a letter dated 1540, 

 sends to his friend George Vogelin of Constance, the book De Revolu- 

 tionibus. But Mr. De Morgan 9 has pointed out that the printed work 

 which Gassarus sent to Vogelin was the Narratio by Rheticus of Feld- 

 kirch, a eulogium of Copernicus and his system prefixed to the second 

 edition of the De Revolutionibus, which appeared in 1566. In this 

 Narration, Rheticus speaks of the work of Copernicus as a Palingenesia, 

 or New Birth of astronomy. Rheticus, it appears, had gone to Coper- 

 nicus for the purpose of getting knowledge about triangles and trigo- 

 nometrical tables, and had had his attention called to the heliocentric 

 theory, of which he became an ardent admirer. He speaks of his 

 " Preceptor" with strong admiration, as we have seen. " He appears 

 to me," says he, " more to resemble Ptolemy than any other astrono- 

 mers." This, it must be recollected, was selecting the highest known 

 subject of comparison. 



CHAPTER III. 



Sequel to Copernicus. — The Reception and Development of the 



Copernican Theory. 



Sect. 1. — First Reception of the Copernican Theory. 



THE theories of Copernicus made their way among astronomers, in 

 the manner in which true astronomical theories always obtain the 

 assent of competent judges. They led to the construction of Tables 

 of the motion of the sun, moon, and planets, as the theories of Hippar- 

 chus and Ptolemv had done : and the verification of the doctrines was 

 to be looked for, from the agreement of these Tables with observation, 

 through a sufficient course of time. The work Be Revolutionists 

 contains such Tables. In 1551 Reinhold improved and republished 

 Tables founded on the principles of Copernicus. " We owe," he says 

 in his preface, "great obligations to Copernicus, both for his laborious 



9 Ast. Mod. i. p. 138. I owe this and many other corrections to the personal kind- 

 ness of Mr. De Morgan. 



