TRANSACTIONS OF THE SECTIONS. 227 



on shale. When the experiments in hand have been repeated and largely added to, 

 it is hoped that this accession or loss of couducting-power in connexion with 

 the ordinary agents of geological force may be (perhaps only approximately) 

 expressed numerically. One might even suppose that the disturbance of heat- 

 transmitting equilibrium has something to do with the distribution of volcanic and 

 thermal phenomena. Without, however, treading further on such dangerously 

 speculative ground, we may hope, by dint of careful experiment of the kind now 

 brought before the Section, to throw some light on the curious discrepancy which 

 is constantly being noted in observations of underground temperature taken at 

 different places, the j-afe of transmission of heat (for which we hope to make in 

 time lists and tables) being manifestly intimately connected with that subject. 



G. A. Leboub. 



