e in question
cannot be shown. How neatly you draw your diagrams; I wish you would
turn your attention to real sections of the earth's crust, and then
speculate to your heart's content on them; I can have no doubt that
speculative men, with a curb on, make far the best observers. I
sincerely wish I could have made any remarks of more interest to you,
and more directly bearing on your paper; but the subject strikes me as
too difficult and complicated. With every good wish that you may go
on with your geological studies, speculations, and especially
observations...

LETTER 488. TO C. LYELL. Down, March 24th [1853].

I have often puzzled over Dana's case, in itself and in relation to the
trains of S. American volcanoes of different heights in action at the
same time (page 605, Volume V. "Geological Transactions." (488/1. "On
the Connection of certain Volcanic Phenomena in South America, and on
the Formation of Mountain Chains and Volcanoes, as the Effect of the
same Power by which Continents are Elevated" ("Trans. Geol. Soc."
Volume V., page 601, 1840). On page 605 Darwin records instances of the
simultaneous activity after an earthquake of several volcanoes in
the Cordillera.)) I can throw no light on the subject. I presume you
remember that Hopkins (488/2. See "Report on the Geological Theories
of Elevation and Earthquakes," by W. Hopkins, "Brit. Assoc. Rep." 1847,
page 34.) in some one (I forget which) of his papers discusses such
cases, and urgently wishes the height of the fluid lava was known in
adjoining volcanoes when in contemporaneous action; he argues vehemently
against (as far as I remember) volcanoes in action of different heights
being connected with one common source of liquefied rock. If lava was as
fluid as water, the case would indeed be hopeless; and I fancy we should
be led to look at the deep-seated rock as solid though intensely hot,
and becoming fluid as soon as a crack lessened the tension of the
super-incumbent strata. But don't you think that viscid lava might be
very slow in communicating its pressure equally in all directions? I
remember thinking strongly that Dana's case within the one crater of
Kilauea proved too much; it really seems monstrous to suppose that the
lava within the same crater is not connected at no very great depth.

When one reflects on (and still better sees) the enormous masses of lava
apparently shot miles high up, like cannon-balls, the force seems out of
all proporti