ontinually cooling? what has given them their
local position? why near or less near the surface? what should have
arranged them in directions stretching in some cases nearly from Pole to
Pole?

Surely this creation of imaginary lakes, merely because it happens to
fit the vacant chink that seems needed to wedge up a falling theory, is
an instance of that abuse of hypothesis against which Newton so
vehemently declaims--"_Hypotheses non fingo._"

Hypothesis, to be a philosophic scaffolding to knowledge, must, as
Whewell has said, "be close to the facts, and not merely connected with
them by arbitrary and untried facts." Yet this appears accepted by Lyell
(10th edition, Vol. II., p. 227, and elsewhere); by Phillips
("Vesuvius," pp. 331, 332); by Scrope, if, as I hope, I mistake him not
("Volcanoes," pp. 265, 307-8); though none of these excellent
authorities seem either quite clear or quite satisfied with the notion;
and in the very passage referred to, Lyell _may_ have possibly a much
more philosophic notion in view, where he says: "It is only necessary,
in order to explain the action of Volcanoes, to _discover some cause
which is capable of bringing about such a concentration of heat as may
melt one after the other certain portions of the solid crust_, so as to
form seas, lakes or oceans of subterraneous lava." (Vol. II, pp. 226,
227). If by this is meant, that all that is needed to complete a true
theory of volcanic action is to discover _an adequate cosmical cause for
the heat_--that is to say, a prime mover to which all its phenomena may
be traced back, which shall be at once reconcilable with the conditions
of our planet as a cooling mass in space and with facts of Vulcanology
as they are now seen upon it--then I entirely agree with it.

It has been my own object to endeavour to discover and develope that
adequate cause in a Paper "On Volcanic Energy, an Attempt to develope
its True Nature and Cosmical Relations," read (in abstract) before the
Royal Society of London ("Proceedings, Royal Society," Vol. XX., May,
1872), and now (October, 1872) under consideration of Council with a
view to publication.

I propose concluding this review of the progress of Vulcanology (in
which I have had to limit myself to reviewing merely the chief stages of
advance towards knowledge of the nature and origin of volcanic heat
itself, and have had to pass without notice the vast and important mass
of facts and reasonings collected by