THE LIGHT OF THE STARS. 1*73 



In 1874 the German Government established 

 at Potsdam the Astrophysical Observatory, for 

 the spectroscopic study of the Sun and stars. 

 A position on the staff was given to Hermann 

 Carl Vogel, whose researches in astronomical 

 spectroscopy rank with those of Secchi and 

 Huggins. Born in Leipzig in 1842, he was from 

 1865 to 1869 employed in the Leipzig Observa- 

 tory. Called to Bothkamp as director in 1870, 

 he resigned his post in 1874 to accept a position 

 on the staff at Potsdam Observatory. In 1882 

 he became director of that Institution, which 

 position he still retains. 



In 1874 Vogel revised Secchi's classification of 

 stellar spectra, and in 1895 he further improved 

 on it. His classification improves rather than 

 supersedes the previous work of Secchi ; never- 

 theless, he approached the question from a 

 different standpoint. Vogel concluded in 1874 

 that a rational scheme of stellar classification 

 "can only be arrived at by proceeding from the 

 standpoint that the phrase of development of the 

 particular body is, in general, mirrored in its 

 spectrum." Vogel divides Secchi's first type into 

 three classes. In the first type, designated la, 

 represented by Sirius and Vega, the metallic 

 lines are " very faint and fine," and the hydrogen 

 lines conspicuous. In 16 no hydrogen lines are 



