On Sat, 17 Nov 2007 16:48:38 GMT, "The Medway Handyman"
wrote:

They use ultrasonic scanners,

What I've seen is they use a pair of microphones that straddle the
leak by quite a few metres. They then apply a variable delay (positive
or negative) to the signal from one microphone and subtract the signal
fom mic 1 from mic 2 and tune for a null by varying the delay (and
amplitudes).

They can then work out where the leak is.

listening rods and
also apparently dowsing rods. She reckoned it did actually work.

I still have an open mind on dowsing.

DG