1866.] Position of the Axis of the EarfJi's Crust. 



49 



of earthquakes and the enormous amount of upheaval and subsidence as 

 evidenced by the thickness of the sedimentary strata, seem inconsistent 

 either with the general solidity of the globe or any very great thickness of 

 its crust. 



The supposition that the gradual oscillations of the surface of the earth, 

 of which we have evidence all over the world as having taken place ever 

 since the formation of the earliest known strata up to the present time, are 

 due to the alternate inflation by gas and the subsequent depletion of certain 

 vast bladdery cavities in the crust of the earth, can hardly be generally 

 accepted. 



Those who wish to see the arguments for and against the theory of there 

 being a fluid nucleus within the earth's crust, will find them well and fairly 

 stated in Naumann's 'Lehrbuch der Geognosie'*. My object is, not to 

 discuss that question, but to point out what, assuming the theory to be 

 true, would be some of the effects resulting from such a condition of things, 

 more especially as affecting climatai changes. The agreement or disagree- 

 ment between these hypothetical results and observed facts may ultimately 

 assist in testing the truth of the assumption. 



The simplest form in which we can conceive of the relations to each 

 other of a solid crust and a fluid nucleus in rotation together is that of a 

 sphere. 



Let A C B D be a hollow sphere composed of solid materials and of 

 perfectly uniform thickness and density, and let it be filled with the fluid 

 matter E, over which the solid shell can freely move, and let the whole be 

 in uniform rotation about an axis F G, the line C D representing the equator. 



It is evident that in sucli a case, the hollow sphere being in perfect equi- 

 librium, its axis and that of its fluid contents would perpetually coincide. 



2nd edit., 1858, vol. i. p. 36. 



