Have you ever had a go at water divining?
You wander around with a forked stick until it points to water. It’s good fun, but you have to watch for passing clouds or you might poke your eye out. Or at least you would if it worked. My mother gets quite cross at the suggestion that Great Auntie Molly couldn’t find water with a bit of hazel. She found water when nobody else could.
Water divining, dowsing or witching, is the (alleged) art of finding underground water. Traditionally, the diviner uses a forked stick, but in modern times a couple of bits of bent wire are also believed to work. Some use a pendulum. People also dowse for gold, oil, archaeological sites and Ley lines — I wonder sometimes how the dowsing rods know what to look for.
Susan Blackmore and Adam Hart-Davis, in their excellent book Test Your Psychic Powers (Thorsons, London 1995), write:
“Imagine a dowser walking through a field. Suddenly her hazel rod twitches and dances in her hands. She stops, and marks the spot. Later an underground stream is found beneath the turf.”
What’s wrong here? The phrase “underground stream” conjures up an image of a tunnel, through which water is flowing. The sort of stream in the movies where the hero and heroine are trapped in a cave and they have to swim through it to escape. “Look Tarzan, the water is moving. If the water can get out of here, so can we.”
The implication is that if you dug your well a little bit to the left or right, you’d miss the stream. In real life, underground streams flow through gravel, sand and clay and may be many kilometres wide.
I live in the middle of the Waikato river valley – lots of rainfall. There isn’t anywhere within a 10 km radius where the water table is more than 10 metres underground. Nine times out of ten, it is less than two metres (in winter, perhaps three metres in summer.) Note the term “water table” as opposed to “underground stream”. If you think about underground water in these terms, it makes the job of finding underground water seem less difficult. The question becomes not “Is there water here?” but “How far underground is it?”
Despite this, people will sagely point at a spot on the ground and say “Drill here” — as if that spot were somehow different from all others on the 10-acre block. I’d be more impressed if they could point to where water was not.
A few years ago we bought a block of land. One of the first jobs was to put in a water supply. The soil type was a “heavy clay”. It isn’t free draining and holds water. Even in summer, while the surface might be bone dry, there is water only a metre underground. But while there are millions of litres of water within arm’s reach, water flows through clay very slowly. After you’ve pumped all the water out of the well, you might have to wait for a day or two for the well to fill up again.
I needed a sand diviner to tell me “Drill here. There’s a large vein of sand at 5 metres.” I could then have pumped large volumes out of this quickly and cheaply. As the water is pumped out of the sand, more water flows in from all directions to replace it. (if the sand/clay interface has a large enough surface area.)
I didn’t need a diviner. I already knew there was lots of water everywhere but people kept telling me “Oh, you should talk to Fred*, he does water divining.” The fact that people kept telling me about diviners told me two things. First, lots of people believe in water diviners. Secondly, and more importantly, they have no understanding of the real problems of “finding water.” Of what use is a water diviner when there is always water underground?
There are some places where water is harder to find. You can tell a lot about the underground water by looking at what is above ground. The slope of the land, the soil type, the yearly rainfall, local plant life, nearby rivers and streams, all provide clues about where the underground water will be.
So is it the water that makes the stick move, or the dowser? Blackmore and Hart-Davis suggest a simple test.
Take a small bucket and fill it with water. Place it in the middle of the lawn and see if the dowser can get the divining rods to move when they are passed over the top of it. At this point the diviner may think that he has proven his ability, but the test isn’t over yet. Next, place a larger bucket over the first so the bucket underneath can’t be seen. Ask the diviner to do it again. Hopefully he will succeed again.
Finally, go behind the house and bring back 5 or 10 more large buckets. Randomly hide the bucket with the water in it under one of these larger buckets. Don’t let the diviner see which bucket it is under. Now ask the diviner to find the water. He should find it nearly every time. But he won’t. As yet I don’t think anybody has passed this final test.
Do several trials. If you hide 1 small bucket of water under one of 10 large buckets, the diviner has a 1 in 10 chance of finding it. If he gets it right 8 or 9 times out of 10, maybe he really can divine, or maybe you were unable to prevent him from cheating. Check the experimental conditions again. If he only gets 1, 2 or even 3 out of 10, then he can’t do it.
OK, so why do the sticks move? The simplest explanation seems to be that the diviner s hands are never really still. If you hold your hands in front of you, your nervous system is constantly sending signals to your hands to move up, down left and right. This constant stream of signals is necessary just to keep them in the same place.
Try it. Hold your hand in front of you and try to keep it still. Look closely and you’ll see your hand wobbling. A diviner’s hands also are constantly moving like this just to keep the divining rod reasonably still. The divining rod moves, not so much because the diviner makes it move, but because he fails to prevent it from moving when he expects it to. When he (or she) passes the rods over the bucket of water, he knows there is water there. He is expecting the rod to move, so he doesn’t prevent it from moving.
I don’t think many diviners are faking it. Water divining is like a magic show where the diviner is both the magician and the audience. Because they never test themselves under controlled conditions, they don’t realise they are fooling themselves.
Every good skeptic knows you shouldn’t reject any claims before it’s been properly investigated, but we’re past that point for water divining. I’ll be willing to eat a live hedgehog if somebody can do it under controlled conditions. But at the moment, the hedgehog looks safe.
