The quest for new caves is often a frustrating one, large areas of the country have substantial thickness' of limestone but no known cave system, although there are frequently tantalising signs of sub surface voids in the form of lines of shakeholes and other karst features.

In previous articles in Pelobates I have looked at some of the more exotic geophysical methods of finding caves, however I have not written about an a method that increasing numbers of people seem to believe is valid i.e. wandering around the surface with some form of rod waiting for a magical twitch to indicate the presence of a cave.

If you are beginning to suspect that their will be some element of cynicism about this method you would be right -as a scientist I know that there is - and there has to be - a scientific basis for any method for the systematic identification of anomalies (a void in rock is an anomaly).

The "art" of divining however is not based on any known mechanism whereby an underground anomaly whether a void ,water, or a metal ore can interact with the processes that go on in the human brain to produce a twitch. Indeed if they did it is probable that humans or any other species would not exist as it would have been reduced to a twitching mass aeons ago. There is also no evolutionary reason why such a faculty should exist as it is only within the last 10,000 years that humans have possessed the technology or the desire to dig significant sized holes in the ground.

Advocates of divining when pressed for a mechanism as to how it works often cite some speculative mechanism whereby the brain identifies some form of magnetic field. However in all the last 100 years of medical study no one has ever seriously suggested that any such mechanism exists, indeed modern scanning processes use powerful magnetic forces to map molecular processes yet the patient notices nothing.

Some animals such as birds are however known to have magnetic particles in their brain which probably help with long flight navigation, however no such ability has been identified in man and it is not suggested that we have an inherent ability to face north.

Magnetic processes cannot be invoked to identify caves as limestone is almost non magnetic.

Magnetotelluric current have also been suggested as a mechanism. Such currents are exceedingly small and flow as a result of potential differences induced in the crust by the earth's magnetic field, however these are too small and inconsistent to be used as a geophysical prospecting method and there has never been any demonstration of an effect on the human brain.

Does divining work? Obviously its proponents say it does, however that does not mean that it does. If I say my car is capable of flying the Atlantic no one will believe me until they have seen it do it (probably several times), so why is it that so many people are sympathetic to divining without requiring the same standard of proof.

Over the course of the last 50 years there have been many tests of diviners "powers" some more scientific than others. However the results of the more scientific tests have been summarised and in no case has it been demonstrated that diviners have a better than random chance of finding anything !

Divining is in fact based on medieval mumbojumbo, several medieval texts specify which type of tree the twigs should come from to find a specific metal or that they must be sprinkled with holy water or that prayers/spells must be said over them.

Credibility must also be severely questioned when you can find diviners who claim to be able to find water by swinging a pendulum over a map of Australia while sitting in Sevenoaks or to be able to identify cave while descending the heads of the valleys road at 40 MPH in a Land Rover!

However the famous German Miner Agricola in the 13th Century summed up the whole divining business when he wrote "A good prospector trusts not in spells and twigs but studies carefully the lie of the land ,the colour of the soil, and the vegetation" i.e. he uses his experience and power of observation. It is suggested that Cavers do the same.