THE STARS. 153 



In 1805, Harding, Schroter's assistant at 

 Lilienthal, resigned his position for a more 

 promising one at Gottingen. Gibers procured 

 for Bessel the offer of the vacant post, which the 

 latter accepted. At Lilienthal Bessel received 

 his training as a practical astronomer. He re- 

 mained in Schroter's observatory until 1809. 

 Although only twenty -five years of age, he 

 had become so well known in Germany that in 

 that year he was appointed Professor of As- 

 tronomy in the University of Konigsberg, and 

 was chosen to superintend the erection of the 

 new observatory there. Within a few years 

 a clerk in a commercial office had worked his 

 way from obscurity to fame. 



In 1813 the Konigsberg Observatory was 

 completed, and here Bessel worked for thirty- 

 three years, until his death, on March 17, 1846. 

 It was only about ten years before his death that 

 he commenced his search for the stellar parallax, 

 with the aid of Fraunhofer's magnificent helio- 

 meter. He determined to make a series of meas- 

 ures on a small double star of the fifth mag- 

 nitude in the constellation Cygnus, named 61 

 Cygni, the large proper motion of which led him 

 to suspect its proximity to the Solar System. 

 From August 1837 to September 1838 he made 

 observations on 61 Cygni, and he found that 



