14 
stituted a convenient homogeneity. This 
is recognized in a more recent number of 
Science (May 26) in the article by Dr. See, 
in which he offers a correction which in- 
volves an extension of the previously as- 
signed output (18 million times the present 
annual radiation) to about 32 million times 
the annual radiation. But even in mak- 
ing this correction he neglects to consider 
the distribution of this heat in time, and 
leaves upon the reader the impression that 
the life-history of the earth was limited to 
82 million years. Assuming the correct- 
ness of his computations, the past thermal 
discharge of the sun is merely limited to 32 
million times the present annual expendi- 
ture. For aught that appears to the con- 
trary, the actual output of this heat may 
have been spread over any assignable num- 
ber of years. It is obvious upon consider- 
ation that a certain distribution of this past 
heat would favor longevity of life upon the 
earth, provided it could exist with a more 
limited heat supply than the sun is now 
yielding. On the other hand, it is equally 
evident that if the supply be distributed in 
certain other ways, either in the nature of 
excessive prolongation or of excessive con- 
centration, the life era will be shortened. 
Doubtless the admonitory physicists have 
assumed that it was sufficient for the gross 
purposes of restraining geologists within 
due limits to determine the total amount of 
heat without assiduously considering the 
actual facts relative to its distribution, but 
some of us are unwilling to accept this 
loose method of dealing with the problem, 
since there are resources of application of 
which our physical friends have perhaps 
not taken cognizance. For example: 
1. If at a certain stage in the evolution of 
the sun it occupied essentially all the space 
within the earth’s orbit, and was giving 
forth one-half as much heat per year as 
now, it would possibly have sufficed for the 
needs of life upon the earth essentially as 
SCLENCE, 
[N. S. Von. X. No. 236. 
well as at present, without the assumption 
of any change in the constitution of the 
earth or of its atmosphere. For, on this 
supposition, approximately one-half of the 
space into which the earth radiated its heat 
would be blanketed by the sun and the heat 
thrown forth from the earth would be 
measurably caught and returned, and hence 
the loss of heat by radiation from the sur- 
face of the earth would have been reduced. 
2. If, af the same time, we suppose that 
the material now concentrated in the outer 
planets was dispersed in a broad nebulous 
or meteoric belt mantling the heavens on 
the opposite side, another means would be 
provided by which some portion of the 
heat radiated away would be caught and 
returned to the earth, and a further small 
reduction in the original receipt of heat 
from the sun may be made consistently 
with the existence of life. This outer belt 
would be very tenuous and its effects cor- 
respondingly meagre, but it is a factor to 
be considered in a complete set of assump- 
tions. 
3. If, in addition to this, we make the 
consistent assumption that many other 
bodies of the heavens which are now con- 
centrated into suns or into dark bodies 
were then in a more dispersed nebulous or 
meteoroidal condition, the general space of 
the stellar universe would be partially man- 
tled, and there would be less free scope 
for the escape of the heat, solar and terres- 
trial alike, which is now freely lost through 
the open regions of space. It may be con- 
ceived that there was a common blanketing 
of the heavens by the dispersal of its now 
concentrated matter. This conception is 
the logical companion of the supposed dis- 
persal of the solar matter. If the volume 
of matter in the stellar universe could be 
supposed to be sufficient, it might be so 
distributed hypothetically as to mantle the 
whole heavens and largely prevent the es- 
cape of central] heat outwards, just as the 
