In a note from a MS. of Mr. Rowlands, the author of Mona Antiqua, this stone is said, having long lost its virtue, to have been stolen within his memory. There was once a tradition also concerning it, that when a wish was made before it, if the wish was to come to pass, the person who expressed the wish could lift it up with ease; but, if not, then it became so heavy, that his utmost strength could not raise it. In the latter case, it required but little art to produce the effect unknown to the simple inquirer.
from ‘The Cambrian Popular Antiquities’ by Peter Roberts, 1815.
archive.org/stream/cambrianpopular00robegoog#page/n230
I’m not sure that makes sense. I admit I don’t know if it’s still there.