"DOCTRINE OF UNIFORMITY" REFUTED. 7 



more than enough to melt a mass of surface rock 

 equal in bulk to the whole eartJi. No hypothesis 

 as to chemical action, internal fluidity, effects of 

 pressure at great depth, or possible character of 

 substances in the interior of the earth, possessing 

 the smallest vestige of probability, can justify the 

 supposition that the earth's upper crust has re- 

 mained nearly as it is, while from the whole, or 

 from any part, of the earth, so great a quantity of 

 heat has been lost. 



APPENDIX. 



ESTIMATE OF PRESENT ANNUAL LOSS OF HEAT 

 FROM THE EARTH. 



LET A be the area of the earth's surface, D the 

 increase of depth in any locality for which the tem- 

 perature increases by i Cent., and k the conduc- 

 tivity per annum of the strata in the same locality. 

 The heat conducted out per annum per square foot 



k 

 of surface in that locality is =?. Hence, if we give 



k and D proper average values for the whole upper 

 crust of the earth, the quantity conducted out 



