56 CONTEMPORARY SCIENCE 



Bore Hole. In my address to Section G in 1904 I dis- 

 cussed the question of sinking a shaft to a depth of twelve 

 miles, which is about ten times the depth of any shaft in 

 existence. The estimated cost was 5,ooo,ooo/., and the 

 time required about eighty-five years. 



The method of cooling the air-locks to limit the baro- 

 metric pressure on the miners and other precautions were 

 described, and the project appeared feasible. One essen- 

 tial factor has, however, been queried by some persons: 

 Would the rock at the great depth crush in and destroy 

 the shaft ? Subsequent to my address, I wrote a letter to 

 Nature, suggesting that the question might be tested ex- 

 perimentally. Professor Frank D. Adams, of McGill Uni- 

 versity, Montreal, acting on the suggestion, has since car- 

 ried out exhaustive experiments, published in the Journal 

 of Geology for February, 1912, showing that in limestone 

 a depth of fifteen miles is probably practicable, and that 

 in granite a depth of thirty miles might be reached. 



Little is at present known of the earth's interior, except 

 by inference from a study of its surface, upturned strata, 

 shallow shafts, the velocity of transmission of seismic 

 disturbances, its rigidity and specific gravity, and it seems 

 reasonable to suggest that some attempt should be made 

 to sink a shaft as deep as may be found practicable and 

 at some locality selected by geologists as the most likely 

 to afford useful information. 



When we consider that the estimated cost of sinking a 

 shaft to a depth of twelve miles, at present-day prices, 

 is not much more than the cost of one day of the war to 

 Great Britain alone, the expense seems trivial as com- 

 pared with the possible knowledge that might be gained 

 by an investigation into this unexplored region of the 

 earth. It might, indeed, prove of inestimable value to 

 Science, and also throw additional light on the internal 

 constitution of the earth in relation to minerals of high 

 specific gravity. 



In Italy, at Lardarello, bore holes have been sunk, which 



