have been described as truncated cones
with the apex cut off,[7] and their general plan and elevation were
everywhere almost uniform. The ground floor was solid masonry, but
contained small chambers in its thickness of about 15 feet. Above the
ground floor the broch consisted of two concentric walls about three
feet apart, the whole rising to a height in the larger towers of 45
feet or more, with slabs of stone laid horizontally across the gap
between and within the two walls, at intervals of, say, five or six
feet up to the top, and thus forming a series of galleries inside
the concentric walls, in which large numbers of human beings could be
temporarily sheltered and supplies in great quantities could be stored
for a siege. These galleries were approached from within the broch by
a staircase which rose from the court and passed round between the two
concentric walls above the ground floor, till it reached their highest
point, and probably ended immediately above the only entrance, the
outside of which was thus peculiarly exposed to missiles from the end
of the staircase at the top of the broch. The only aperture in the
outer wall was the entrance from the outside, about 5 feet high by 3
feet wide, fitted with a stone door, and protected by guard-chambers
immediately within it, and it afforded the sole means of ingress to
and egress from the interior court, for man and beast and goods and
chattels alike. The circular court, which was formed inside, varied
from 20 to 36 feet in diameter, and was not roofed over; and the
galleries and stairs were lighted only by slits, all looking into the
court, in which, being without a roof, fires could be lit. In some few
there were wells, but water-supply, save when the broch was in a loch,
must have been a difficulty in most cases during a prolonged siege.

In these brochs the farmer lived, and his women-kind span and wove and
plied their querns or hand-mills, and, in raids, they shut themselves
up, and possibly some of their poorer neighbours took refuge in the
brochs, deserting their huts and crowding into the broch; but of this
practice there is no evidence, and the nearest hut-circles are often
far from the remains of any broch.

For defence the broch was as nearly as possible perfect against any
engines or weapons then available for attacking it; and we may note
that it existed in Scotland and mainly in the north and west of it,
and nowhere else in the world.[8] It was a roo