198 J. E. Keeler—Absorption of Radiant Heat. 
of an absorption band in the ultra red of a continuous spectrum, 
3. That the absorption is very considerable, and hence cannot 
correspond to a narrow line, but rather to a broad and heavy 
a 
that some other agent than this gas (which may not be water 
vapor, or possibly even of a gaseous nature), contributes 
ia 
i 
a 
essentially to the total absorptive power of the atmosphere, so, 4 
that a method of analysis based upon this power, in which the 
effect of the second agent is neglected, cannot lead to correct — ; 
results. 
Berlin, April, 1884. 
* This Journal, xxv, March, 1883. 
OTE.—Since the above was written I have seen in Professor Langley’s article 
ol. XXXVI, 
N 
on the determination of obscure wave-lengths (American Journal, ¥ 
pable that 
March, 1884), that observations made at his observatory make it pro 
the largest of the gaps referred to are of telluric origin. 
