compass in hand and notebook. I entirely admit, however, that a conclusion
drawn from striking a rough balance in one's mind is worth nothing compared
with the evidence drawn from one continuous line of section. I read
Studer's paper carefully, and drew the conclusion stated from it; but I may
very likely be in an error. I only state that I have frequently seen
cleavage-laminae dipping inwards on mountain sides; that I cannot give up,
but I daresay a general extension of the rule (as might justly be inferred
from the manner of my statement) would be quite erroneous. Von Buch's
statement is in his "Travels in Norway" (537/3. "Travels through Norway
and Lapland during the years 1806-8": London, 1813.); I have unfortunately
lost the reference, and it is a high crime, I confess, even to refer to an
opinion without a precise reference. If you never read these travels they
might be worth skimming, chiefly as an amusement; and if you like and will
send me a line by the general post of Monday or Tuesday, I will either send
it up with Hopkins on Wednesday, or bring it myself to the Geological
Society. I am very glad you are going to read Hopkins (537/4. "Researches
in Physical Geology," by W. Hopkins. "Phil. Trans. R. Soc." 1839, page
381; ibid, 1842, page 43, etc.); his views appear to me eminently worth
well comprehending; false views and language appear to me to be almost
universally held by geologists on the formation of fissures, dikes and
mountain chains. If you would have the patience, I should be glad if you
would read in my "Volcanic Islands" from page 65, or even pages 54 to 72--
viz., on the lamination of volcanic rocks; I may add that I sent the series
of specimens there described to Professor Forbes of Edinburgh, and he
thought they bore out my views.

There is a short extract from Prof. Rogers (537/5. "On Cleavage of Slate-
strata." "Edinburgh New Phil. Journ." Volume XLI., page 422, 1846.) in the
last "Edinburgh New Phil. Journal," well worth your attention, on the
cleavage of the Appalachian chain, and which seems far more uniform in the