There is a tradition respecting the large top of a cromlech, in Cornwall, that was removed to a brook at a distance, and converted into a bridge; it is said that this stone possessed the power of speech, and answered questions put to it, until on a certain time, it cracked in an effort to speak, and has been silent ever since. This vague tradition must have originated in the oracular use made of the cromlech from whence the stone was taken.
Vague indeed. Unless someone can enlighten us..
From p279 of The Graphic and Historical Illustrator
Edward Wedlake Brayley (1834) – which can be perused on Google Books.