or Rocking Stones, for which Corn wall is famous.
Pliny tells us of a rock near Harpasa which might be moved with a finger. Ptolemy says the Gygonian rock might be stirred with a stalk of asphodel. Half a mile from St. David's is a Logan stone, mounted on divers other stones, which may be shaken with one finger.
At Golcar Hill (Yorkshire) is a rocking stone, which has lost its power from being hacked by workmen who wanted to find out the secret of its rocking mystery.
In Pembrokeshire is a rocking stone, rendered immovable by the soldiers of Cromwell, who held it to be an encouragement to superstition.
The stone called Menamber in Sithney (Corn wall) was also rendered immovable by the soldiers, under the same notion.
There are very many others.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894