Today, we ask what water witches really are. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

A recent New Yorker article by Carolyn Kraus spun a complex web around water witching or dowsing. It's a subject we should face sooner or later. People have been finding water with forked sticks ever since Moses brought forth water by smiting a rock with a rod. Herodotus wrote about dowsing in the 5th century BC. Chinese texts tell of water witching 4000 years ago. Agricola's famous 15th-century mining text describes it. For millenia people have believed in something with no rational basis. Why?

Dowsing takes many forms. Some dowsers openly claim paranormal powers. The best of them say they neither know nor care how it works, but they're sure they can find water. The worst wrap their divining rods in bogus science.

Marine Corps engineers at Camp Le Jeune brought a dowser in and studied his technique during the Viet Nam war. They wanted to find enemy tunnels and hidden arms. The fellow told them that anyone could master dowsing except "athiests, morons, disbelievers, or the mentally disturbed." Engineers reporting back to the Pentagon picked up that theme. The method, they allowed, could fall into communist hands; but that would be no problem, because communists were all athiests.

Since dowsing enjoys some success, scientists flutter around it. A Freudian psychiatrist tells us that dowsers seek to penetrate Mother Earth with the dowsing rod. A physicist looks at certain glands that seem to have no purpose. Maybe they respond when underground cavities bend the earth's magnetic field. Maybe they cause a small muscular tic in the dowser's upraised arm.

A geologist points out that some people simply learn the subtle relations between earth's surface and aquifers below it. A good dowser, they claim, does what a good geologist does. Maybe the witching wand just helps him concentrate.

Dowsing may be pure bunk, or it may someday reduce to human understanding. But it reflects a powerful craving to find realities outside our understanding. That's where it's kin to invention. Pure invention precedes understanding, and it stands apart from deduction or reason. It's a water witch of the human mind. Invention means finding things without knowing quite how we found them.

Dowsing, UFO's, and the other paranormal whoop-de-do are ways some people try to find the delicious suprise we all crave. That surprise is available to us, but it comes from within. Invention finds water in the desert by creating the thing we did not expect to find.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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