NATURAL SCIENCE: 



A Monthly Review of Scientific ProQ-ress. 



No. 12. Vol 11 FEBRUARY 1893. 



NOTES AND COMMENTS. 



The Age of the Earth. 



A MONG the wider problems of Natural Science towards the solution 

 -ii 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 Journal of Science (ser. 

 3, vol. xlv., pp. I-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 che 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 milhons 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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