170 A CENTURY'S PROGRESS IN ASTRONOMY. 



of stellar spectra, but shortly afterwards turned 

 his attention to astronomical photography. The 

 actual founders of stellar spectroscopy were the 

 eminent Italian observer, Angelo Secchi, and the 

 illustrious Englishman, William Huggins. 



Angelo Secchi was born in 1818 at Reggio, in 

 the Emilia. Educated in the Collegio Romano, 

 he was ordained priest in 1847, but his love of 

 science, and particularly astronomy, dates from 

 the beginning of his career. In 1849 he suc- 

 ceeded Di Vico as director of the Observatory 

 of the Collegio Romano. This post he filled 

 with conspicuous ability for a period of twenty - 

 nine years, until his death on February 26, 1878. 

 To Secchi is due the credit of the first spectro- 

 scopic survey of the heavens. He reviewed the 

 spectra of 4000 stars, and classified them into 

 four distinct groups, which are recognised to 

 this day. The first type embraces over half 

 of 'those which Secchi examined. This type is 

 represented by Sirius, Vega, Altair, and other 

 bluish -white stars, and is characterised by the 

 intensity of the hydrogen lines. The second 

 type embraces the yellow stars, such as Capella, 

 Arcturus, Aldebaran, Pollux, and the Sun itself, 

 and is known as the Solar type. The spectra 

 of these stars closely resemble that of the Sun, 

 and are distinguished by innumerable lines. 



