162 



THE GEOLOGIST. 



bank's pole, the other extremity of which was held by infirm and 

 trembling hands. His body might be put in proper attitude and 

 position, and duly manoeuvred to acquire exactness of balance ; but 

 if the shaky hands gave way, the fall might be sudden and severe. 

 The supposed fire-origin of granite was one of the original causes 

 of the invention of the internal-heat theory ; but modern researches 

 have distinctly shown that certainly one at least of the petrological 

 elements of that rock — namely, quartz — as seen now as a consti- 

 tuent of that very granite, never could have been subjected to the 

 influence of dry heat. Another difficulty arises in respect to the 

 internal molten state of our earth : if the core of our globe be in 

 that condition, it would follow there must be internal tides, unless 

 the solid crust of the earth were of immense thickness, and of a 

 rigidity, at least, four times that of steel; for not less than that 

 would suffice to resist the internal tidal tendency, taking the thick- 

 ness of this crust as estimated by Mr. Hopkins. It is evident beyond 

 question that a liquid mass, whether fluid at ordinary temperatures, 

 such as the waters of the ocean, or rendered fluid by internal heat, 

 must be equally subject to the laws of attraction ; and consequently 

 the moon would have an influence upon the internal molten core, as 

 she has upon the external oceans. 



Now, Professor Frankland — repudiating all the explanatory theories 

 which have been hitherto given to account for superficial differences 

 of temperature, from Lyell's different distribution of land and sea 

 doctrine, to that of the higher elevation of all mountainous tracts 

 during the Glacial age suggested by Professor Kamtz — based his 

 new hypothesis on what he regarded as the incontrovertible fact of 

 the internal molten fluidity of our earth. The descriptions of the 

 fiords and the ice-scored land of Norway, which Dr. Frankland has 

 lately visited, were exceedingly interesting and instructive ; but 

 when the Professor came to deliver his new hypothesis, we at once 

 felt ourselves launched on the waves of an unnavigated sea, and saw 

 many reasons why the bark of the adventurous savant should be 

 deemed too frail for geologists to venture in. To say that the hypo- 

 thesis was ingenious is only to give it its just meed of praise ; to say 

 it was substantial is quite another thing. It was this : — We are all 

 familiar with the ordinary still. There is the boiler where the vapour 

 is raised, the spiral tube in which it is condensed, and the receiver 

 into which the condensed fluid falls. Compare the earth, its atmo- 

 sphere, and its mountains to the still. Prom the ocean the vapour 



