Geological Society, 61 



fifteen thousand feet above the level of the sea. Imagine, therefore, 

 what they must be at Hamburgh!! 



If mines derive their temperature from heat lodged in the centre of 

 the earth, the temperature ought to vary with their distance from the 

 centre, and therefore, since the earth is an oblate spheroid, the mines 

 of Scandinavia ought at the same depth from the surface to be propor- 

 tionally warmer than those of tropical countries j a result which has 

 never been, I believe, even suspected. 



The existence of Central Heat in the sense and to the extent as- 

 sumed in the Huttonian theory, is contrary to all our experience. If 

 Heat there be in the Centre of the globe, it must have the properties of 

 heat, and none other. I ask not how the Heat originally was lodged 

 in that situation, for the origin of all things is obscure j but I ask why, 

 in the countless succession of ages which the Huttonian requires, the 

 Heat has not passed away by conduction, and if it has passed away, by 

 what other heat it has been replaced? 



Dr. Chalmers in speaking of Sir Isaac Newton, observes, that it was 

 a " distinguishing and characteristic feature of his great mind, that it 

 " kept a tenacious hold of every position which had proof to substan- 

 " tiate it j but a more leading peculiarity was, that it put a most de- 

 " termined exclusion on every position destitute of such proof. The 

 " strength and soundness of Newton's philosophy was evinced as much 

 " by his decision on those doctrines of science which he rejected, as 

 " by his demonstration of those doctrines of science which he was 

 " the first to propose. He expatiated in a lofty region, where he met 

 *f with much to solicit his fancy, and tempt him to devious speculation. 

 " He might easily have found amusement in intellectual pictures, he 

 " might easily have palmed loose and confident plausibilities of his 

 " own on the world. But no, he kept by his demonstrations, his mea- 

 " surements, and his proofs." 



Gentlemen, let us, as far as is consistent with the nature of geolo- 

 gical investigation, show the strength and soundness of our philo- 

 sophy in the same manner. 



That Heat of considerable intensity prevails occasionally, in certain 

 places, at some depth, is all that we have as yet clearly established. 

 Whether that Heat is permanent, whether it is generally diffused, 

 whether it is central, are questions of mere speculation. 



Intimately connected with the hypothesis of Central Heat is that of 

 Refrigeration. 



It has been observed by one of our members, that " the Remains both 

 " of the animal and vegetable kingdom preserved in strata of different 

 " ages, indicate that there has been a great Diminution of Tempera- 

 " ture throughout the northern hemisphere, in the latitudes now oc- 

 u cupied by Europe, Asia and America ; the change has extended to 

 " the arctic circle as well as to the temperate zone; the heat and 

 " humidity of the air, and the uniformity of climate, appear to have 

 " been most remarkable when the oldest strata hitherto discovered 

 " were formed. The approximation of a climate similar to that now 

 " enjoyed in these latitudes, does not commence till the aera of the 

 " formations termed tertiary ; and while the different tertiary rocks 



