ON THE DELUGE. 



681 



as it were, of the earth, which was so general as to have occa- 

 sioned a marked and unquahtied record, as of an event well 

 known to all. 



Many philosophers think that the world has a central region 

 of surpassing heat, and that the greater part of the interior of 

 the globe is in a state of incandescence, if not of fusion. That 

 small portion which they call the crust of the earth is supposed 

 to be the only cooled part ; and they differ merely as to the 

 degree of fluidity in the central region. I take it for granted that 

 they have duly estimated the moon's tendency to cause tides in 

 a fluid mass, within her influence : — if there were no crust, of 

 course she would cause such an effect, but a well hardened case, 

 we must suppose, can resist any such movement in the central 

 fluid mass. Upon the principle of the arch, it would be easier 

 to imagine resistance to pressure from without than from within; 

 but the case or crust of our globe must be so solid that it 

 neither yields nor vibrates to an internal expansive force. 



This theory, however, is unsupported by any satisfactory 

 evidence. Men of character and attainments have advocated 

 it, although resting on conjecture : but when we look back 

 along the roll of history, and discover so few philosophers 

 who have not greatly erred, although famed in their day, it 

 is natural to pause, and not acquiesce hastily in mere human 

 assertion unsubstantiated by proof. Boring the ground, or 

 examining the temperature of the bottom of a deep mine, 

 affords no estimate for that of the central regions: — Sir 

 John Herschel says,^* that " the deepest mine existing does 

 not penetrate half a mile below the surface ; a scratch or pin- 

 hole duly representing it on the surface of such a globe, (six- 

 teen inches in diameter), would be imperceptible without a 

 magnifier." As our globe is about eight thousand miles in 

 diameter, and external influence may be supposed to penetrate 

 some distance, we can draw but unsatisfactory conclusions from 

 experiments at depths not nearly so great even as that to which 



* Treatise on Astronomy; Cabinet Cyelopsedia, p. 22, Art. 30. 



