_The Nightmare._--I recently observed a large stone, having a natural
hole through it, suspended inside a Suffolk farmer's cow-house. Upon
inquiry of a labourer, I was informed this was intended as a preventive
of nightmare in the cattle. My informant (who evidently placed great
faith in its efficacy) added that a similar stone suspended in a
bed-room, or a knife or steel laid under the foot of the bed, was of
equal service to the sleeper, and that he had himself frequently made
use of this charm.
Is this practice common, and in what does it originate?