250 — dh. Crol—Geological Climatology. 
objections which have been advanced in regard to this part of 
the inquiry. I shall also take the present opportunity of 
discussing more fully some points on which I have been some- 
times misunderstood, and which appear to have been treated 
rather too briefly on former occasions. 
In the American Journal of Science for April, 1876, Pro- 
fessor Newcomb has done me the honor to review at some 
length my work, ‘Climate and Time.’ And as his article is 
objections, however, as will be seen, are based upon a misap- 
prehension of my reasoning. 
Temperature of Space.—One of the most important factors 
in the theory of oN ae climate resulting from changes in 
the eccentricity of the earth’s orbit is obviously the tempera- 
ture of stellar space. Unless we have, at least, some rough 
idea of the proportion which the heat derived from the stars 
bears to that derived from the sun, we can not form any esti- 
mate of how much the temperature of our earth would be low- 
ered or raised by a given decrease or increase of the sun’s dis- 
tance. : 
The question of the temperature of space has been investi- 
gated in different ways by Pouillet and Herschel ; and the 
result arrived at was that space has a temperature of —239° F., 
or an absolute temperature of 222°. The mean absolute tem- 
perature of our earth is about 521°. Consequently, according 
to these results, the heat received from the stars is to that 
received from the sun as 222 to 299. All my determinations 
of the change of temperature due to changes in the sun’s dis- 
tance were computed on these data, although I believe, for 
reasons stated, that space must have a much lower tempera~ 
ture. Recent observations of Professor Langley made during 
the Mount Whitney Expedition confirm the correctness of my 
belief 
ef. 
Professor Newcomb, however, wholly ignores all that has 
been done on that subject, for he commences his review by the 
statement that “practically there is but one source from which 
the surface of the earth receives heat—the sun, since the 
i 
Surely Professor Newcomb must have forgotten all about 
the researches of Pouillet and Herschel into what has bee? 
