﻿SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VI II . t/, PL. I 



BOLOGRAPHIC ENERGY CURVES OF THE SOLAR SPECTRUM OF A 60° GLASS PRISM 

 Fig. i, Spectrum between wavelengths 0.66 fj. and 2.6 fi. ; (Upper curve, February 19, 1903, small water-vapor ab- 

 sorption ; Lower curve, September 14, 1903, great water-vapor absorption). Fig. 2, Detailed structure of band +,. 



