PLATE II. 



Fig. 1. — Full-sizod roproductioii of a pliotoRraph of tho II find K lines in tho 

 solar spectrum, made with the curved first slit. The two curved slits regularly 

 employed with the s]tectrohelio}ira])h to eliminate distortion of the solar image 

 have a radius of 522 nun., equal to that of the curved lines here shown. 



Fig. 2. — H and K lines on the solar disk and in the chromosphere (radial 

 slit). 



Fig. 2a. — Shows II3 and K^ (very faintly) in a prominence. 



147 



