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and deserved reputation, that this event has happened again and 

 again. Before vpe admit the Submersion of a continent, we must ad- 

 mit either that at a period immediately preceding that catastrophe, 

 there existed under the land a cavity large enough to contain the con- 

 tinent about to be submerged, or that during the process the subja- 

 cent beds shrunk in consequence of a reduction of the temperature, 

 and to such an extent that the contraction in a vertical line equalled 

 the distance from the level of the highest tops of the continent to 

 that of the surrounding ocean. In like manner, before we can admit 

 the Elevation of a continent, we must admit either that, at a period 

 immediately preceding that catastrophe, there happened an inroad of 

 sustaining matter equal in thickness and in extent to the Continent 

 about to be uplifted, or that during the process the subjacent beds 

 expanded in consequence of an increase of temperature, and to such 

 an extent that the expansion in a vertical line equalled the distance 

 from the level of the highest tops of the continent to that of the sur- 

 rounding ocean. These therefore are the events which we are taught 

 to credit, as having taken place again and again, notwithstanding the 

 tendency which caloric has to diffuse itself, and the apparently un- 

 altered dimensions of the fissures and local caverns by which the 

 strata are so often separated or intersected. 



I will not expend more of your time in arguing against such doc- 

 trines. All men are more or less lovers of the marvellous, but few, I 

 think, will upon reflection approve such marvels as these. 



Solids, fluids and aeriform substances exist, we know, in the interior 

 of the earth, and expand by heat, which exists there likewise. All of 

 these, therefore, are fit Agents of Elevation, subject to certain conditions. 



Dr. Daubeny attributes the liquefaction of lava, the throwing up of 

 ashes, and all other phenomena of disturbance attendant on volcanic 

 eruptions, to the Action of Water upon the Metallic Bases. This cause 

 is not oi)posed to experience, and appears well proportioned to the 

 effect, which is sudden, violent, occasional, temporary, accompanied 

 by heat and by flame. To me, at least, it seems far more satisfactory 

 than the explanation of those who ascribe the effect to the Elastic 

 Power of Subterranean Fires, repressed in one place and relieved in 

 another, or to the Undulations of a Heated Nucleus. 



A heated Central Nucleus is a mere invention of fancy, traceable, I 

 believe, to no other source than the hope of obtaining a good argument 

 from the multiplication of bad ones. To the Huttonian and every 

 other geological sectary who relies on this postulate, I say, be cau- 

 tious; " incedis per ignes dolosos." 



The only observation I recollect to have met with in favour of cen- 

 tral heat is, that the deepest mines are the warmest — be it so ! Might 

 not a geologist by parity of reasoning argue thus? — In travelling 

 from Rome to Chamonix, the country becomes continually more and 

 more mountainous ; some of the peaks of Chamonix are from ten to 

 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 



