No, you fellows don't understand. There are different ways of dowsing. I believe one theory was eletromagnetic fields can move the rods, if they're light enough, and therefore show a reaction. I believe there is testing to show that this happens with underground water. This is physical dowsing, elements outside of the dowser cause the rod to move. I don't understand much of this and don't rely on this. I use mental dowsing, which is something even less understood about the right side of the brain. Other topics up for debate, due to the lack of scientific study concerning these areas, are dreams, intuition, emotions. Like what is the conection between physical movements and music? No one really knows. Anyway, mental dowsing does not rely on any external elements to dowse. The rod is an extention of the hand/wrist. It is the dowser, subconciously, who causes the rod to move.
These are the differences between art and I or physical and mental dowsing.
I know people who only know how to dowse for water and disturbed soil. Also I believe wood and iron...but not quite sure on that. But anyway, these people (most people) only think they can dowse for water and disturbed soil...like recently dug graves or the like. I believe this has something to do with the electromagnetic fields.
The person that I learned to dowse from originally dowsed for four different elements. Water, disturbed soil, wood, and iron. At this time, when he dowsed he just dowsed for any of these four. I believe this was a physical style of dowsing that he was doing. He could differentiate them by what shapes they make. He could tell it was a viking ship by the elliptical shape, a water vein by its long slightly changing course, graves by their rectangular shape and iron again by its shape.
His friend, found that he could dowse for corn and then found that by focusing on the object while dowsing he could identify any object. Thus he made "sensor boards" which were, at this time, literal boards with holes drilled into them so that objects like corn, types of fish, human bone, could be placed in these holes. When dowsing he would carry these boards, if he found a grave and wanted to check to see if it was a human grave, he would slide the rod across the human bone hole and then dowse and he would only get a reaction to human bone.
I believe the rubbing of the rod on the object just re-enforces the focus on the object. One does not need to do this, I found that when first learning it does help to do this, but later all one has to do is focus on the object.
It was discovered later that these same boards could be made on paper by typing (for example) "corn" on the paper and then using a piece of corn or a picture of corn to empower it. Again, I believe this is just a re-enforcement of this focus. There is no magic to this, but it is agreeably that this form of dowsing is much more of a mental activity then the "physical dowsing".
Once it was found that, through this focus, one could dowse for really almost anything there are probably almost 50 sensor boards dealing with different areas from identifying specific types of trees to finding depth of a specimen. And now this style has evolved into a very complex system and is like no other type of dowsing. But they all share one common purpose, all styles of dowsing are a means for acquiring desired information.