I discovered that I could dowse during an interesting session, run by Peak District Mines, at Magpie Mine, many years ago. What does not seem to have been touched upon in the recent interesting discussion on the subject is that there appears to be a rough guide as to what the bent coat hangers, twigs, &c are responding to. Or at least, so we were informed at the time. From memory, it was stated that if one puts a small item in one of one's hands which is of the same material as the suspect subject matter - for example a bit of galena, if you are traversing a suspected lead vein - then the rods will not respond. In other words "like material" cancels out the reaction. For water, a little bottle of this in one's hand will cancel out the reaction over a subterranean water source. I have tried this out by putting copper and "silver" coins in a match box and asking someone to put them on the ground, suitably spaced out - without my seeing which was which. And, sure enough, the rods do not respond when over the match box containing the copper coin, if one has such a coin in one's hand. Ditto the silver. Not 100% infallible but I found it curiously effective most of the time, much to the amazement of my work colleagues. Obviously this experiment needs to be done over a "sterile" piece of ground. Just how one goes about "detecting" voids is a moot point however. I would be interested to hear if anyone else who can dowse has tried this and what results they may have had. And no, this is NOT a send up! Dickie Bird.