% 



u 



■ 



■'00 



^th 



e 



^<i 



^en 



s 



-and 

 "'the 



^ and 



r ii _ 



' ^ 



^^'ll 



mand 

 iprin- 



y;^r„. 



1 



-I will 

 bitliij 



.quale 

 deve- 

 intk 



dt 



v.ioTiet 



re 



fX 



rill to 





i 



ttl)^ 



[ 



r 



i 



Ch. XXXIII.] EECAPITULATION OF CHAPS. XXXII. AND XXXIII. 241 



a mucli greater^ and even the general solidity of tlie entire 



. ^ ^^ ^^ ^H ^ ^H .^k. .^^ 



melted matter 



move 



with the solid portion. 



5. The heat in mines and Artesian wells increases as we 

 descend, but not in a nniform ratio, in different regions. If 

 the heat were continued downwards at the same rate, it would 

 imply such an elevation of temperature in the central nucleus 

 as must instantly fuse the crust. 



6. The hypothesis of a central fluid and of a thin solid 

 shell resting or floating upon it, is inconsistent with the 

 absence of internal tides, such as would make the lava ebb 

 and flow in volcanic craters during eruptions. 



7. The hypothesis of a change in the axis of rotation of a 



made 



from 



to lower, or from lower to higher, latitudes, is untenable, 



displaced and carried in one 



matter 



direction would be extremely slight, and the spheroidal figure 



I. of motion in 

 astronomical 



for inferring the original fluidity of the planet, such pristine 

 fluidity need not aff'ect the question of volcanic heat, for the 

 volcanic action of successive periods belongs to a state of the 



m 



difi'erent parts of the solid crust one after the other. 



9. The quantity of lava, fluid at any one time in the earth's 



im 



mountain 



may 



be quite insignificant in relation to the size of an external 



diameter 



10. The supposed greater energy of the volcanic forces in 



means 



observations on the quantity of lava produced in those several 

 periods. 



11. The old notion that the crystalline rocks, whether 

 stratified or unstratified, such as granite and gneiss, were 

 produced in the lower parts of the earth's crust at the expense 



VOL. II. 



E 



