354 
ON THE ACTION OE FREE MOLECULES ON RADIANT HEAT. 
beyond the point to which it has been followed below; and being made on a scale 
different from that of the laboratory—on one indeed as grand as nature can furnish— 
and by means wholly independent of those usually applied to the research, must, I 
think, when published, put an end to every doubt as to the accuracy of the statements 
so long since made by you, as to the absorbent power of this agent over the greater 
part of the spectrum, and as to its predominant importance in modifying to us the 
solar energy. 
“ I am, with much regard, 
“ Very truly yours, 
“ S. P. Langley.” 
