lly an error, and
has no foundation in the facts of the case.

Mr. Pengelly has endeavored to maintain the value of the deposit of
stalagmite as a means of establishing dates, in his "Notes of Recent
Notices of the Geology of Devonshire," Part I., 1874; but, I confess,
with little success. He urges, in opposition to the Ingleborough Cave,
that at Cheddar, where, according to him, no appreciable deposit
whatever is taking place on the existing stalagmite. But this, of
course, is evidence not applicable to the case in hand, as in the
Cheddar case no stalagmite crust whatever would be produced. There
are, no doubt, crevices and caves in which old stalagmite is even
being removed or diminished in thickness. He farther asserts that in
Kent's Cave teeth of the cave bear and other extinct animals are found
covered by not more than an inch and a half of stalagmite, and
consequently that if this were deposited at the rate of a quarter of
an inch per annum--the supposed rate on the "Jockey Cap" at
Ingleborough--these animals must have lived in Devonshire only six
years ago, which is, of course, absurd. But he fails to perceive that
this mode of occurrence is quite intelligible on the supposition of a
rapid decrease in the amount of deposition in the later part of the
stalagmite period. He farther refers to the fact that the thicker
masses of stalagmite, which correspond to the places of more active
drip of water, are in the same position in both crusts of stalagmite.
This shows that the sources of water containing bicarbonate of lime
have been the same from the first; but it proves nothing as to the
rate of deposit.

Mr. Pengelly's own estimate of the rate of deposit gives, however, a
length of time which is sufficient to show that there must be error
somewhere in his calculations. He states the aggregate thickness of
the two crusts at twelve feet, and then, assuming a rate of deposit of
0.05 inch in 250 years, or one inch in 5000 years, he arrives at the
conclusion that the whole deposit required 720,000 years for its
formation. He is "willing to suppose" the mechanical deposits to have
accumulated more rapidly; but allowing one fourth of the time for
them, we have nearly a million of years claimed for the residence of
man in Devonshire, which, independently of other considerations, would
push back the Palaeozoic trilobites and corals of that county into the
primitive reign of fire, and which in point of fact amounts to a
_re