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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 'J'J 



ing telescope of Mt. Wilson Observatory. He not only could observe 

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



ntjth^*^ 



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 



