Geological Society. 50S 



Beaumont refer to the same examples ; and while M. tie Beaumont 

 conceives that the cones of the Andes must have been formed by an 

 abrupt elevation, caused by subterranean force, Mr. Darwin has 

 maintained the opinion, tliat these lofty summits have been gra- 

 dually thrust into the place which they occupy by a series of suc- 

 cessive injections of molten matter from below, each intruded por- 

 tion of fluid having time to harden into rock before it was burst 

 and again injected by the next molten mass. For how otherwise, 

 he asks, can we conceive the strata to be thrust into a vertical po- 

 sition by a liquid from below, without the very bowels of the earth 

 gushing out ? Without attempting to answer this question, we may 

 observe, that when we suppose, as Mr. Darwin supposes, a vast por- 

 tion of the earth's crust, the whole territory of Chili for example, 

 to rest on a lake of molten stone, there is considerable force in M. 

 de Beaumont's argument : — that when such a fluid is raised to the 

 top of a mountain ten or twenty thousand feet high, the pressure 

 upon the crust which is in contact with the fluid must be more than 

 a thousand atmospheres ; and who, he too asks, flatters himself that 

 he knows enough of the interior machinery of volcanos, to be cer- 

 tain that this vast pressure, acting upon a large surface, may not, by 

 some derangement of its safety-valve, the volcanic vent, produce 

 effects to M'hich we cannot assign any limit ? 



In speaking of Mr. Darwin's researches I cannot refrain from ex- 

 pressing for myself, and I am sure I may add for you, our disap- 

 pointment and regret that the publication of Mr. Darwin's journal 

 has not yet taken place. Knowing, as we do, that this journal con- 

 tains many valuable contributions to science, we cannot help lament^ 

 ing, that tiie customs of the Service by which the survey was con- 

 ducted have not yet allowed this portion of the account of its results 

 to be given to the world. 



Although not communicated to us, but to our Alma Mater the 

 Royal Society, I may notice Mr. Hopkins's endeavours to throw 

 light upon such subjects as this by the aid of mathematical reason- 

 ing. The researches of Mr. Hopkins respecting the effects which a 

 force from below would produce upon a portion of the earth's crust, 

 have already interested you, and would be of still greater value if 

 the directions of faults and fissures which result from liis theory did 

 not depend very much upon that which in most cases we cannot ex- 

 pect to know, the form of the area subjected to such strain. Mr. 

 Hopkins lias since been employing himself in tracing tlie conse- 

 quences of another idea, truly ingenious and philosophical, and which 

 a person in full possession of the resources of mathenuitios could 

 alone deal with. Some of the effects which the sun and moon pro- 

 duce upon the earth (as the precession and imtation,) include the 

 attraction of tliose bodies u])on the interior portion of the earth, and 

 liav(! hitherto been deduced from the theory by mathematicians, 

 upon th(( supposition that the earth is solid. But what if the central 

 portion of the earth were fluid ? What if it appeared, by calculation, 

 that the fluid internal condition would make the amount ol' the ))re- 

 cession of the e(piinoxes, or of the nutation of the axis, diflerent 



