Pendulum and dowsing
Using a swinging weight or a forked rod to find water, objects or answers.
Also: dowsing, water divining, divining rod, radiesthesia
A dowser walks with a forked stick or a pair of bent rods and watches for movement said to mark water, ore or buried objects. The practice is recorded in German mining regions by the 1500s and spread with miners. In the twentieth century a French variant, radiesthesia, brought in the pendulum, a small weight on a string held over a map or a list of answers. Many farmers and some water companies still use dowsers. Controlled tests, including large German trials in the 1980s, have not shown the ability to find water beyond chance. Scientists explain the movements by the ideomotor effect, small unconscious muscle actions, as with the Ouija board.