bling it
by throwing on water. By means of stone mauls the fragments were broken
up and removed. When the vein was sufficiently exposed on all sides, a
point was selected where the copper was thinner or narrower than the
average of the vein. Here they commenced cutting off a mass, and by
patient and long-continued hammering severed the two portions of the
vein. In all the ancient mines which I have visited there is abundant
evidence that fire was extensively used in the removal of rock; for not
only do the rocks give proof of having been heated, but charcoal and
ashes are invariably found at the bottom of all the rock excavations.

In general, the mining was done by surface openings along the line of
the outcrop of the vein; but occasionally adits are driven into the
rock, similar to the one first discovered at the Minnesota Mine before
alluded to.

The surface mines are usually nearly filled with leaves and vegetable
mould that have accumulated during the centuries that have elapsed since
their abandonment, and till within a few years a heavy growth of timber
covered the land; hence the numerous slight depressions that occurred
along the line of the vein excited no suspicion that they were
artificial excavations. By the closest observers they were regarded as
natural depressions, caused either by the disintegration of the
underlying rock or the peculiar manner in which the overlying drift was
deposited. In many of these depressions, which have proved to be
abandoned mines, trees of enormous size are found growing, some of which
are ascertained, by counting their concentric rings, to be four hundred
years old. At the Hilton Mine, directly over the leather bag before
alluded to, there was a hemlock-tree about three feet in diameter. I
noticed the stump of a tree nearly four feet in diameter in a gap near
the Rockland Mine, where a hill had been actually cut asunder by these
ancient miners, and a deep valley formed by the removal of the rock.
Until very recently this valley was not recognized as an ancient mine;
for, being ten rods in width, and cutting nearly at right angles across
the strata of the rock that formed the hill, it was considered too
extensive to have been made by human hands, and was supposed to be the
result of natural causes. But about two years since, during a very dry
time, a destructive fire swept through the woods, and so completely
burned up all the vegetable matter accumulated there as to expose t