Dowsing

Woodcut of a dowser holding a forked branch from La Physique Occulte (1693)

Dowsing is the practice of detecting the location of substances or entities — e.g. underground water sources, mineral veins, oil and natural gas, human beings, concealed locations, etc. — using the unconscious or psychic senses of the individual performing the dowsing operation (the dowser), whether operating with or without an apparatus such as a rod or pendulum. The French method of radiésthesie was originated as an ostensibly more scientific approach to the phenomena dealt with by dowsing, though the terms are commonly used interchangeably today.

Reading

• Lorrain, Pierre Le (1693) (in French), La Physique Occulte, ou Traité de la Baguette Divinatoire et de Son Utilité pour la Découverte des Sources d'Eau, des Miniéres, des Tresors Cachez, des Voleurs & Des Meurtriers Fugitifs: avec des Principes qui Expliquent les Phénoménes les Plus Obscurs de la Nature, Paris: J. Anisson, https://archive.org/details/laphysiqueoccult00vall  — [English: "Occult Physics, or Treatise on the Divinatory Wand and Its Usefulness in Discovering Water Sources, Mines, Hidden Treasures, Fugitive Thieves & Murderers: with Principles Which Explain the Most Obscure Phenomena of Nature."]
• Latimer, Charles (1876), The Divining Rod: Virgula Divina-baculus Divinatorius (Water-Witching), Cleveland, O.: Fairbanks, Benedict & Co., https://hdl.handle.net/2027/coo1.ark:/13960/t10p1nb2n 
• Ellis, Arthur Jackson (1917), The Divining Rod: a History of Water Witching, with a Bibliography, Washington: U. S. Govt. Print. Off., https://catalog.hathitrust.org/Record/006808702 
• Maby, J. Cecil; Franklin, T. Bedford (1939), The Physics of the Divining Rod: Being an Account of an Experimental Investigation of Water and Mineral Divining, London: G. Bell and Sons Ltd. 
• Tromp, Solco W. (1949), Psychical Physics: a Scientific Analysis of Dowsing, Radiesthesia and Kindred Diving Phenomena, New York: Elsevier Pub. Co. 
• Rudd, John; Maby, J. Cecil (1970), Resonating Reflex: A Critical Investigation of the Physical and Physiological Bases of Dowsing, Exploring the Potentialities of Angle Rods, with Detailed Instructions for Some Novel Practical Applications, Wrexham, Denbighshire, Wales: Privately Published