The _rocking stone_, or _logan_, is a stone of a prodigious size, so
nicely poised, that it rocks or shakes with the smallest force. Several
of the consecrated stones mentioned above, were rocking stones; and
there was a wonderful monument of this kind near Penzance in Cornwall,
which still retains the name of _main-amber_, or the sacred stones. With
these stones the ancients were not unacquainted. Pliny relates that at
Harpasa, a town of Asia, there was a rock of such a wonderful nature,
that, if touched with the finger, it would shake, but could not be moved
from its place with the whole force of the body. Ptolemy Hephistion
mentions a stone of this description near the ocean, which was agitated
when struck by the stalk of the plant asphodel, or day-lily, but could
not be removed by a great exertion of force. Another is cited by
Apollonius Rhodius, supposed to have been raised in the time of the
Argonauts, in the island Tenos, as the monument of the two-winged sons
of Boreas, slain by Hercules; and there are others in China, and in
other countries.
Many rocking stones are to be found in different parts of Great Britain;
some natural, and others artificial, or placed in their position by
human art. That the latter are monuments erected by the Druids, many
suppose can not be doubted; but tradition has not handed down the
precise purpose for which they were intended. In the parish of St.
Leven, Cornwall, there is a promontory called Castle Treryn. On the
western side of the middle group, near the top, lies a very large stone,
so evenly poised, that a hand may move it from one side to the other;
yet so fixed on its base, that no lever, or other mechanical force, can
remove it from its present situation. It is called the _logan-stone_,
and is at such a hight from the ground as to render it incredible that
it was raised to its present position by art. There are, however, other
rocking stones, so shaped and situated, that there can not be any doubt
of their having been erected by human strength. Of this kind the great
_quoit_, or _karn-le hau_, in the parish of Tywidnek, in Wales, is
considered. It is thirty-nine feet in circumference, and four feet thick
at a medium, and stands on a single pedestal. In the island of St.
Agnes, Scilly, is a remarkable stone of the same kind. The under rock is
ten and a half feet high, forty-seven feet round the middle, and touches
the ground with not more than half its base. The upper rock rests on one
point only, and is so nicely balanced, that two or three men with a pole
can move it. It is eight and a half feet high, and forty-seven in
circumference. On the top is a basin hollowed out, three feet and eleven
inches in diameter at a medium, but wider at the brim, and three feet in
depth. From the globular shape of the upper stone, it is highly probable
that it was rounded by human art, and perhaps even placed on its
pedestal by human strength. In Sithney parish, near Helston, in
Cornwall, stood the famous logan, or rocking stone, commonly called _Men
Amber_, that is, _Men an Bar_, or the top stone. It was eleven feet by
six, and four high, and so nicely poised on another stone, that a little
child could move it. It was much visited by travelers; but Shrubsall,
the governor of Pendennis castle, under Cromwell, caused it to be
undermined, by dint of much labor, to the great grief of the country.
There are some marks of the tool on it; and it seems probable, by its
triangular shape, that it was dedicated to Mercury.