92 LIGHT SCIENCE FOR LEISURE HOURS. 



constitution. Only we must remember that it is hy- 

 drogen glowing from intensity of heat simply, and not 

 burning hydrogen, that constitutes these prominences. 

 Now, it had long been recognized that the colored 

 prominences spring from an envelope of a similar na- 

 ture surrounding the whole surface of the sun. Father 

 Secchi, of the Collegio Romano, in a lecture given to 

 the pupils of the Ecole Ste. Gene vie ve, had thus in 

 1867 described this envelope (whose existence he was 

 the first to recognize) : " The observation of eclipses 

 furnishes indisputable evidence that the sun is really 

 surrounded by a layer of red matter, of which we com- 

 monly see no more than the most elevated points." 

 One of the first and most interesting results of the 

 eclipse-observations was Mr. Lockyer's confirmation of 

 the justice of this opinion. He and Jannsen had inde- 

 pendently shown that the existence of prominences can 

 be recognized when the sun is not eclipsed ; and the 

 same method supplied clear evidence of the existence 

 of this red envelope, to which Mr. Lockyer gave the 

 name of the chromosphere. Remembering who first 

 indicated its existence as " indisputable," we may con- 

 veniently call it Secchi's chromosphere. (See note at 

 the end of this paper.) 



Both the chromosphere and the prominences consist 

 of glowing vapor. But there is a difference in their 

 constitution. In the prominences there are usually but 

 very few constituent vapors. Hydrogen is there, and 



