dowsing

Ascertaining the presence of water or minerals beneath the ground with a forked twig or a pendulum. Unconscious muscular action by the dowser is thought to move the twig, usually held with one fork in each hand, possibly in response to a local change in the pattern of electrical forces. The ability has been known since at least the 16th century and, though not widely recognized by science, it has been used commercially and in archaeology.

When used for finding water, this method is also referred to as water divining. The usual practice is for a forked branch to be cut from a tree such as a hazel, willow, or peach. This is held out parallel to the ground by the diviner. As the substance being searched for is approached, the rod moves, the motion it makes varying from dowser to dowser. The degree of sensitivity also varies and the ability is not present in everyone.

Dowsing with a pendulum (sometimes called radiesthesia) is used in many fields, including the sexing of chickens before they hatch, alternative medical diagnosis, and the tracing of missing persons and objects.