32 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. JJ 



ing telescope of ]\It. Wilson Observatory. He not only could observe 

 the heat of the brighter stars, but, separating this into a long spectrum. 



Wdye - len(jth yd 



Fig. 39. — Normal energy-spectrum curves and corresponding black-body curves. 

 Various scales of ordinates ; two scales of abscissae. 



he obtained fairly accurate measurements of the heat of the different 

 colors, and even far into the infra-red. In this way curves were drawn 



