Agricola to ChevreulWhat the Rod Does
The dowsing rod is the oldest amplifier of the human hand, and the one whose physics is least understood by the people who sell it.
Agricola drew miners with forked hazel in De re metallica in 1556 and disapproved of them, which tells you the practice was already old. Water, ore, lost things, the dead: the rod has been asked about all of them. In 1833 Chevreul explained the pendulum and by extension the rod, and the explanation has not needed revision since: a tremor of the hand, produced by expectation and below the threshold of awareness, delivered into a mechanism designed to make it enormous.
The L-rod is that mechanism perfected. A right-angled rod sits in a sleeve; the sleeve is held level; the long arm is free to swing. The arm is in unstable equilibrium, balanced on nothing, so the smallest tilt of the wrist sends it swinging with a violence out of all proportion to the cause. Two rods crossing over a spot is a spectacle, and it is manufactured by the grip. None of that makes the instrument worthless. It makes it an honest amplifier of whatever the dowser's hand already knows, or believes, and there are people who have found water with it for forty years and would not be argued out of it by me.

What I MakeOn a Pin, Not in a Tube
Made to the physics
Because the rod is an amplifier, the engineering that matters is the freedom of the swing. The sleeve must let the rod turn without friction, which means a bearing and not a tube: mine run on a brass sleeve over a polished steel pin, with a hardwood handle turned around it, so that the rod swings from the pin and the hand holds only wood. The rods are solid brass, a quarter-inch, drawn and not cast, because cast brass is never straight and a rod that is not straight has a bias built in. The arms are matched to a hair so that a pair swings alike.
The Y-rod, the forked stick, I make in the traditional way in hazel or in a springy hardwood, and in a modern form in two brass rods joined at the tip, which holds its tension when hazel would dry and go dead. The tension is the point: the rod is held in a bent spring and the hands are the release.
The tools
- L-rods, pairQuarter-inch drawn brass, arms matched. Handles in ebony, rosewood or walnut, turned around a brass sleeve on a steel pin.
- Y-rodHazel, cut in winter and seasoned; or two brass rods joined, with a brass ferrule.
- BobberA single sprung rod with a weighted tip, for the dowser who works one-handed. Brass and hardwood.
- Supplied withA leather roll, the written method, the certificate.