170 8. P. Langley—Selective Absorption of Solar Energy. 
sensible heat from the grating spectrum without gathering all 
that lay in the two halves of it together, and could consequently 
only infer the result of complete measures. But it followed 
that if it ever became possible to measure amounts of heat so 
inute, these conclusions could be verified on separate rays of 
the most favorable circumstances reach one-tenth that in the 
which should be at the same time equally accurate—whiec 
er” and not a mere 
evidence the subject admits of, that every ray, whether lying 
in the “ch e of 
