Carroll: Further evidence for dowsing has been presented by the Deutsche Gesellschaft f E Technische Zusammenarbeit (GTZ) [the German Society for Technical Co-operation] sponsored by the German government. They claim, for example, that in some of their water dowsing efforts they had success rates above 80% "results which, according to responsible experts, could not be reached by means of classical methods, except with disproportionate input." Of particular interest is a report by University of Munich physicist Hans-Dieter Betz, "Water Dowsing in Arid Regions: Report on a Ten-Year German Government Project," published in the Journal of Scientific Exploration in 1995. (This is the same Betz who, with J.L. König, authored a book in 1989 on German government tests proving the ability of dowsers to detect E-rays.) The report covers a ten-year period and over 2000 drillings in Sri Lanka, Zaire, Kenya, Namibia, Yemen and other countries. Especially impressive was an overall success rate of 96 percent achieved in 691 drillings in Sri Lanka. "Based on geological experience in that area, a success rate of 30-50 percent would be expected from conventional techniques alone," according to Betz. "What is both puzzling yet enormously useful is that in hundreds of cases the dowsers were able to predict the depth of the water source and the yield of the well to within 10 or 20 percent. We carefully considered the statistics of these correlations, and they far exceeded lucky guesses."
Betz ruled out chance and the use of landscape and geological features by dowsers as explanations for their success. He also ruled out "some unknown biological sensitivity to water." Betz thinks that there may be "subtle electromagnetic gradients" resulting from fissures and water flows which create changes in the electrical properties of rock and soil. Dowsers, he thinks, somehow sense these gradients in a hypersensitive state. "I'm a scientist," says Betz,"and those are my best plausible scientific hypotheses at this point....we have established that dowsing works, but have no idea how or why."
There are some puzzling elements to Betz's conclusions, however. Most of his claims concern a single dowser named Schröter. Who observed this dowser or what conditions he worked under remain unknown. Betz is a physicist and what knowledge he has of hydrogeology is unknown. Furthermore, Betz's speculation that dowsers are hypersensitive to subtle electromagnetic gradients does not seem to be based upon scientific data. In any case, the hypothesis was not tested and I am not sure how one would go about testing such a claim. At the very least, one would expect that geological instruments would be able to detect such "electromagnetic gradients."
When others have done controlled tests of dowsers, the dowsers do no better than chance and no better than non-dowsers (Vogt and Hyman; Hyman; Enright 1995, 1996; Randi 1995). Some of Betz's data are certainly not scientific, e.g., the subjective evaluations Schröter regarding his own dowsing activities. Much of the data is little more than a report that dowsing was used by Schröter and he was successful in locating water. Betz assumes that chance or scientific hydrogeological procedures would not have produced the same or better results. It may be true that in one area they had a 96% success rate using dowsing techniques and that "no prospecting area with comparable sub-soil conditions is known where such outstanding results have ever been attained." However, this means nothing for establishing that dowsing had anything to do with the success. Analogous sub-soil condition seems to be an insufficient similarity to justify concluding that dowsing, rather than chance or use of landscape or geological features, must account for the success rate.
Betz seems to have realized that without some sort of testing, reasonable people would not accept that it had been established that dowsing is a real phenomenon based upon the above types of data. He then presents what he calls "tests" to establish that dowsing is real. The first test involves Schröter again. A Norwegian drilling team dug two wells and each failed to hit water. The dowser came in and allegedly not only hit water but predicted the depth and flow. Apparently, we have the dowser's own word on this. In any case, this is not a test of dowsing, however impressive it might seem.
In the second test, Betz asserts that dowsers can tell how deep water is because "the relevant biological sensations during dowsing are sufficiently different to allow for the required process of distinction and elimination." He has no evidence for this claim. In any case, in this "test" Schröter again is asked to pick a place to dig a well and again he is successful. This time his well is near a well already dug and known to be a good site. Betz claims that there were some geological formations that would have made the dowser's predictions difficult, but again this was not a scientific test of dowsing.
The third test was a kind of contest between the dowser and a team of hydrogeologists. The scientific team, about whom we are told nothing significant, studied an area and picked 14 places to drill. The dowser then went over the same area after the scientific team had made their choices, and he picked 7 sites to drill. (Why they did not both pick the same number of sites is not explained.) A site yielding 100 liters per minute was considered good. The hydrogeologists hit three good sources; the dowser hit six. Clearly, the dowser won the contest. This test does not prove anything about dowsing, however. Nevertheless, I think Herr Schröter should knock on James Randi's door and be allowed to prove his paranormal powers under controlled conditions. If he is as good as he and Betz say he is, he should walk away a very rich man.
Betz has written a very long report, which is little more than a testimonial to the paranormal dowsing powers of Herr Schröter and a reiteration of the claims made for the Barn study. He would have done better to have set up a controlled, double-blind experiment with the dowser, one which does not allow the dowser himself to determine the conditions of the experiment and one which did not have as many uncontrollable variables as those rampant in the ten-year project.
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