From:
http://www.straightdope.com/classics/a1_168.html
Does dowsing for water really work?
25-Sep-1981
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Dear Cecil:
Cecil, my world view has been severely altered, and I need your help. While on a recent trip to the wilds of Arizona, I had the opportunity to witness--and indeed, participate in--a demonstration of "wishing," which is the location of underground water through a divining rod, or "wish stick." I had always thought this practice was an old wives' tale, but the natives use it routinely to determine where to dig their wells.
If a stick of wood is used, it bends toward the ground; if a coat-hanger wire or thin brass rods are used, one is held in each hand, and they cross over each other when water is found. The only explanation the local experts could provide is that moving water creates a magnetic field, but this doesn't account for its effect on wood. I swear on a stack of Straight Dopes that I speak not with forked tongue. Illuminate me, Cecil. --Cooper B., Chicago
Cecil replies:
Good Lord, dowsing? Next you're going to tell me you got a great deal on a time-share condo. This is about the oldest dodge in the books.
You don't describe what your "participation" consisted of, but let me guess: you watched some old geek with a divining rod (typically a forked stick held in a peculiar grip with both hands, but sometimes just an ordinary single stick) wander around the desert for a while with a look of concentration on his face.
By and by the stick began to quiver, and suddenly plunged sharply downward, whereupon he exclaimed something to the effect of, "Dig here, you'll find water." Then he said, "You try it, sonny, it'll work for you, too." And gosharoonie, he gave you the stick and showed you how to hold it and lo and behold, when you got to the spot where the stick had plunged down for the old coot, it did the same thing for you--just like some mysto force had grabbed onto it.
Naturally, since water in Arizona is typically found 175 to 200 feet below the surface, you didn't actually dig a well to test the accuracy of the rod, but assumed that since it worked for you, it must be legit.
Congratulations, sucker. You've fallen victim to the classic Skeptical Young Guppy Becomes True Believer syndrome, described in great detail in a study of dowsing (as wishing is sometimes called) published by two University of Chicago researchers in 1959. "Wishing," incidentally, is a corruption of "witching," as in "water witching," the most common American expression for dowsing, AKA rhabdomancy and divination.
Although divining has been around in various forms for millennia, the well-known forked stick method appears to have been devised in the mining districts of Germany (you can supposedly find minerals with a dowsing rod, too) in the late 15th or early 16th century. It was first formally described in an essay in 1556, and since then has been spread around the world by European colonists. In the past 400 years, more than a thousand essays, books, and pamphlets have been published on the subject.
Needless to say, dowsing is entirely a fraud, although often an unconscious one. Innumerable experiments, beginning in 1641--that's right, 1641--have demonstrated that:
(a) The presence of water has no discernible effect on a rod held above it, whether the rod is made of wood, metal, or anything else.
(b) The success rate for diviners is about the same as that for people who use the hit-and-miss method when looking for water.
(c) Geologists trained to recognize telltale surface clues (certain kinds of rocks and plants, various topographical features) will invariably far outdo dowsers in predicting where water will be found, and at what depth.
Nevertheless, belief in dowsing has persisted, partly because most people secretly want to believe in magic, partly because water is fairly easy to find in most parts of the inhabitable world, and partly because the plunging-stick phenomenon seems so convincing to untutored observers.
It's worth noting that in many parts of the eastern U.S. it is virtually impossible to dig a hole and not find water. Granted it's tougher in the west, but I lived in Tucson for a spell and they had gotten well-digging down to such a science that the success rate approached 100 percent. Even over complex hydrological formations, the success rate by the hit-and-miss method is often as high as 75 percent.
The plunging-stick phenomenon is caused by a well-documented psychological effect known as "ideomotor action," first described in the 1800s and clinically demonstrated in the 1930s. What happens is that conscious thought gives rise to involuntary, usually imperceptible muscle movements.
If I strapped you to a table in a lab and loaded you up with sensors and told you to just think about raising your arm--but not to actually do so--the sensors would probably detect some slight upward motion in that arm, which you'd be completely unconscious of. Ouija boards and several other seance-type tricks make use of this principle.
In forked-stick dowsing, the two ends of the stick are held in a rather uncomfortable grip in such a way that the stick is under considerable tension--coiled up like a spring, as it were. Any of four minor muscle movements will result in the stick taking a sudden lurch downward (you can try this in the backyard sometime).
An experienced dowser, who has often picked up a fair bit of practical geological knowledge, particularly if he has worked in the same geographical area for many years, often develops a good instinct for judging where water might be just by looking at the terrain. When he walks around doing his number with the stick his mind unconsciously transmits this knowledge to his arm muscles, with predictable results.
You, the young sap, don't know anything about geology, but you do know where the stick pointed the first time, and unconsciously you want to duplicate that feat. If either you or the dowser is blindfolded, though, you won't even get close to the spot twice.
Besides forked sticks you can use barbed wire, a fork and spoon, coat hangers, welding rods, even a bunch of keys hanging by a chain from a Bible. If you want more information on this ridiculous art, most libraries have lots of books on the subject--right next to the section on tarot cards.
--CECIL ADAMS
