2 DISCUSSIONS IN CLIMATOLOGY. 



proved by Mr. Hopkins, Sir William Thomson, and 

 others that this theory was utterly untenable. Sir 

 W. Thomson, for example, showed that the general 

 character of the climate of our globe could not have 

 been sensibly affected by internal heat at any time 

 beyond 10,000 years after the commencement of the 

 solidification of the surface. 



About twenty years ago an ingenious modification of 

 the theory of internal heat was propounded by Pro- 

 fessor Frankland * He assumed that the changes of 

 climate experienced by our earth during past epochs is 

 to be referred to a difference in the influence of internal 

 heat on the sea and on land. He concluded that the 

 cooling of the floor of the ocean would proceed less 

 rapidly than it would have done had it been freely 

 exposed to the air, and that hence it would continue 

 at a comparatively high temperature long after the 

 surface of the dry land had reached its present mean 

 temperature. And, as heat is transmitted from the 

 bottom to the surface of the ocean, not by conduction, 

 but by convection, i.e., by the warm stratum of water 

 in contact with the bottom rising to the surface, the 

 temperature of the ocean would consequently be 

 higher than the mean temperature of the earth's sur- 

 face. He concluded that this state of things satisfactorily 

 accounts for the Glacial Epoch. The higher temperature 

 of the ocean would give rise to augmented atmospheric 

 precipitation, and this would produce such an accumu- 

 lation of snow during winter as would defy the heat of 

 summer to melt. 



This theory never seemed to gain acceptance amongst 

 geologists, for it is well known that the sea of the 

 Glacial Epoch was intensely cold — not warm. 



* " Philosophical Magazine," May, 1864. 



