A radiesthsist is someone who is sensitive to certain substances and whose sensitivity is amplified by a pendulum. It appears that the radiesthsist has a peculiar type of psychic mediumship, attuned to material things rather than spirits. Usually a pendulum is small ball or pendant attached to a thin string. The string may be held between the fingers or attached to the end of a stick. The string is preferably nylon, so as to register any movements of the pendulum.
The string and bob are observed closely for any changes. It usually oscillates in a clockwise or anticlockwise movement. It is held over a map or the area in which the object is thought to be located. Or, in medical diagnosis, the pendulum is first placed over the healthy portion of a body, and then over an unhealthy area. Differences between the two movements is noted between the two areas. The pendulum may also be used in a sequence of "Yes" and "No" questions. It will rotate clockwise for yes, and counter clockwise for no.
Though dowsing and Radiesthesia have become virtually identical terms, dowsing has been used in discovering hidden water and metals, minerals and objects using rods or dowsing sticks, while radiesthesia has been used more often in discovering missing persons, in making medical diagnosis, and in proscribing treatments using a pendulum.