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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, fe 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 which we cannot assign any limit ? 
In speaking of Mr. Darwin’s researches I carmnot 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 the 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 wouid be of still greater value if 
the directions of faults and fissures which result from his 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 has since been employing himself in tracing the conse- 
quences of another idea, truly ingenious and philosophical, and which 
a person in full possession of the resources of mathematics could 
alone deal with. Some of the effects which the sun and moon pro- 
duce upon the earth (as the precession and nutation,) include the 
attraction of those bodies upon the interior portion of the earth, and 
have hitherto been deduced from the theory by mathematicians, 
upon the supposition that the earth is solid. But what if the central 
portion of the earth were fluid? What ifit appeared, by calculation, 
that the fluid internal condition would make the amount of the pre- 
cession of the equinoxes, or of the nutation of the axis, different 
