To Make a Divining Rod
How It Works.
Find a Y-shaped twig (Hazel is the traditional wood), or piece of whalebone, or similar. The only important criterion being it must be springy. The length of the Y's leg does not matter; it can be nonexistent.
The Proper Grip.
Hold the hands in front of the body, palms upward, thumbs pointing outward. Place the dowsing rod on the palms with the leg of the Y furthest from you. The ends of the Y's arms tuck under the thumbs.
Now fold the fingers backward gripping the rod tightly. Move the hands apart bending the arms of the Y further apart than they would naturally go: putting a strain into the rod.
It will now be found that, when subterranean water is below, the rod will twist violently out of the grip - as if seized by an external force. (Many dowsers have heavily callused hands.) This effect is guaranteed; if the rod is springy and held properly. You do not need to be an adept.
How This Remarkable Thing Is Brought About.
The phenomenon is a tactile illusion - this does not necessarily imply that divining is empty.
The rod is held in an unstable position. Any slight fluctuation in the forces acting upon it will cause it to adopt a position of lower potential energy - twist violently in the grip. The strain put into the rod by bending the arms of the Y apart is relieved as it shifts to its new orientation. Normally something this mundane would be obvious, but, in this case, it is not - you have to try it to see.
At least one divining book claims the sensation of a violent external force proves the reality of dowsing. But it might be unwise to judge too harshly. The instability of the rod means it is acting as an amplifier for small forces. A small change in the force exerted by a muscle, for instance, something normally unappreciated, calls forth the violent shift of the rod to its more stable, lower energy position.
Some tiny effect upon the nervous system, subsequently effecting the muscles, produced, perhaps, by an underground watercourse, might be being sensed by the divining rod.