Have to say i'm curious myself. Having seen dowsing with the rod and the wire, it looks dodgy. Seemed a bit Paul Daniels to me, so i looked at Tc Lethbridges work with the pendulum. I tried it myself with various penduli, made myself a chart for the various 'rates' and legnths of string, but ended up getting completely tangled up in briars with the bloody cord and gave up.