APR 12 1898 
PATURAY SCIENCE: 
A Monthly Review of Scientific Progress. 
No, 12,- Vor, lly) FEBRUARY, 189s: 

NOTES AND COMMENTS. 
Tue AGE OF THE EARTH. 
MONG the wider problems of Natural Science towards the solution 
of which contributions have been made during last month, the © 
most striking is that of the Age of the Earth. Mr. Clarence King, 
the well-known American geologist and explorer, contributes an 
elaborate article on the subject to the American Fournal of Science (ser. 
3, vol. xlv., pp. 1-20, pls.i., ii.), in which he claims to have advanced 
Lord Kelvin’s method of determining the earth’s age to a further 
order of importance. He discusses the experimental investigations 
of Dr. Carl Barus on the effect of heat and pressure on certain rocks, 
and particularly selects the case of diabase, which has a specific 
gravity approximately equal to the average specific gravity of the 
earth’s crust. In the light of the new facts, he then reconsiders the 
probable rate of cooling of the earth, rendering more precise the 
conclusions of Lord Kelvin, which were arrived at on more imperfect 
data so long ago as 1862. As the result of the detailed discussion, 
Mr. King concludes that the earth’s age probably does not exceed 
twenty-four millions of years—in fact, that the estimate of the 
physicists is approximately correct, while that of the geologists is 
‘“‘ vaguely vast’”’ and unreasonable. 
We have already referred on a former occasion (vol. i., p. 487) 
to Professor John Young’s observations on the possible sources of 
error in the geological and biological estimates of past time. We 
feel convinced there is no sure chronometer beyond the realms of 
physics and astronomy, and even in those spheres the mathematicians 
begin with so many assumptions that we are often inclined to look 
with scepticism on the results. It is, however, satisfactory to learn 
’ that those who approach the subject from the physical standpoint 
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