THE SVN'S TRUE ATMOSPHERE. 97 



out the dark spaces corresponding to their special 

 absorptive powers. To use Mr. Lockyer's striking, 

 though perhaps not strictly poetical, description of 

 their action, these vapours c gobble up the light on its 

 way to the observer, so that it comes out with a 

 balance on the wrong side of the account.' Each 

 vapour produces its own special set of lines, occupying 

 precisely those parts of the spectrum which the vapour's 

 light would illuminate if the vapour shone alone. For 

 these vapours, notwithstanding their action in inter- 

 cepting or absorbing portions of the sunlight, are 

 themselves in reality glowing with a light so intense 

 that the human eye could not bear to rest upon it. If 

 we could examine the vapours we supposed just now 

 removed from the sun, we should obtain the very lines 

 of light which are wanting in the spectrum of the 

 sun. 



When Kirchhoff had recognised in this way the 

 presence of absorptive vapours around the real light- 

 globe of the sun, he judged that they form the solar 

 atmosphere. Because, although his mode of observa- 

 tion was not such as to assure him that these vapours 

 completely envelope the sun, yet the telescopic aspect 

 of the sun, and especially that darkening near the edge 

 to which I have just referred, seemed to leave room 



; for no other conclusion. But at this stage of the 

 inquiry Kirchhoff fell into a mistake. He judged that 

 the solar corona was the atmosphere which produced 



, the solar dark lines, as well as the darkening of the 

 sun's disc near the edge. The mistake is one which, 



H 



