Dowsing is one of those difficult subjects that bring out the worst in people: the mystically inclined get carried away by spiritual energies while otherwise sober and rational scientists rant with rabid, even evangelical fervour against the mere mention of the idea. Ley lines fare little better, with historians also keen to offer dubious theories that keep the pot boiling. So when I choose to tell you about my own experience of dowsing a ley line and the events which surrounded it, I trust you will forgive me. But it needs to be said, if only to honour the man who developed the first truly rational and scientific theory as to how it all works.
Anthony Hopwood, Tony to his friends, was a highly intelligent and imaginative scientist who unfortunately suffered from dyslexia and dyspraxia - inabilities with spelling and numbers. Consequently he could never tackle higher mathematics, write a serious scientific paper or cope well with computers, and so he was forced to work, unqualified and unsupported, outside the mainstream. But he was as sharp as a razor, understood electricity and magnetism better than anyone I have ever met and could wield a soldering iron with the greatest ingenuity and effect. Sadly he died a few days ago on 26 June 2014, so this essay stands as my epitaph to a great man.
I first met him when he appeared in my parents' garden many years ago, dashing about enthusiastically with his dowsing rods and demonstrating how he could do it blindfold. There he found a ley line, cutting diagonally across the garden wherever a lack of trees and overhead pylons allowed him to dowse it through. I tried his dowsing rods, and it worked! I closed my eyes and it still worked. We stuck in a line of thin posts and took a compass bearing. Afterwards over tea, Tony explained how in conditions of poor visibility, such as in fog or at night, a dowser would naturally follow a ley to avoid getting lost. Old trackways would then equally naturally be found along them. There was also often a curious pattern of repetition near them, which led to a kind of grid of subsidiary lines emanating from the main one, some parallel and some across it. In fact, I had watched while Tony found our ley by working along these in the direction of increasing strength. These subsidiary lines should in turn lead to the creation of parallel local tracks. We should also expect to find archaeological features scattered along the track, again easy to find in the dark. I got out a large-scale map and we plotted the line through our garden. There they were! It ran from Little Malvern Priory on the Malvern Hills, parallel with many a straight stretch of our winding local lanes and right along one of them, through a good number of old farmsteads and across the river Severn - smack where the old ferry lay disused. Near the Eastern bank sat Towbury Hill, an old Iron Age earthwork fort, one side parallel to the river and a nearby brook and one inexplicably askew. That skew side lay along the line. Beyond there it faded off into the Vale of Evesham.
Of course! Imagine you are a shaman or similar, asked where to put the new mill or whatever. You work up your ritual, take hold of your hazel twigs or whatever and trot off along the river bank. When you reach the ley, bingo! the twig twists in your hands - where else could be more auspicious than a spot chosen by the Gods?
Except, Tony did not believe in such Gods and neither did I. There had to be a more mundane reason why the ancients were so frequently able to recognise ley lines. An idea mooted at the time was that the human nervous system could pick up stray magnetic signals from the air and somehow amplify them into visible movement, especially if they were tensed in an awkward position holding a twig or a couple of dowsing rods, or perhaps holding a pendulum. This was his starting point, although the technical case for magnetism as such was pretty shaky and he wanted to explore other electromagnetic fields.
He began working on experiments to nail down the signal, looking for electromagnetic energies in the air that might affect the human nervous system. He would come back to our garden from time to time with this or that lashed-up frequency generator to see if it affected the ley line. He was not above risking a few minutes' unlicensed upset to the Royal Signals Research Establishment as it then was, a few miles away over the open fields. I think Defford may have still been active then too, more or less in line of sight across the river. Thankfully, nobody ever came knocking at the door. When he did finally ferret out the answer it was both simple and subtle. First, the dowsing sense:
First he confirmed that magnetism didn't do it. Radio waves at any reasonable frequency didn't do it either. But then he turned to another field which permeates the outdoor air around us, a natural electrostatic field between the ground and the sky. The air acts as an insulator between above and below, and when it breaks down we call the spectacular result lightning. The field is enormous, around a thousand volts per metre. You can release a lot of energy when that short-circuits, perhaps you could release enough to affect a nerve fibre just by disturbing it. Could dowsing be an ability to detect disturbances, local variations, in this powerful field?
And so it proved. He put up a metal bar overhead. With the bar earthed he could dowse it in an under-the-trees kind of way. He made a high-voltage generator and attached it to the bar. With the generator at full whack the bar stood out against the background sky and he could dowse that too, with his rods swinging the opposite way. But when he turned the generator down a little so that the field strength under the bar exactly matched the field strength in the free air all around, an amazing thing happened: he could no longer dowse it. It had somehow become invisible to his dowsing sense, merging like a chameleon into the background field. This seemed to be the secret to dowsing, it all made sense and the test was repeatable.
But what about ley lines? They too were thought to be magnetic in nature. Earth currents flow through the ground, generated by lightning strikes and other forces. Any current flow creates a magnetic field around it. Where such a current meets a geological fault line its flow is disturbed and so too is its magnetic field. The current cannot change size but it can - and must - change course. Surely such a fault line would leave its stamp in the magnetic field above ground. But experiments attempting to correlate the properties of such magnetic fields with dowsing had repeatedly failed, allowing the sceptics to crow with delight and the mystics to hold their faith.
Tony however recalled his basic physics, that wherever there is a changing magnetic field there must also be a changing electric field. Where an Earth current changes, its magnetic field changes and the associated change in electric field would affect the ambient electrostatic field. Could we be sensing not the changing Earth current but the change in the electrostatic field near it? That would explain why things like running water, trees and power lines mess up the detection of ley lines - they all in their different ways affect the electrostatic field between ground and sky. A few more experiments with his test rig seemed to confirm his suspicions.
The only thing he did not tell me was whether he thought the subsidiary grid was down to additional cracking in the geology or some kind of resonance in our ability to dowse. But really, that is not important to the basic principle. To all intents and purposes, it was a wrap.
But Science with a capital S was not convinced. And quite rightly so, for like every result in science it needed independent verification. And here, sadly, Science did not acquit itself well - or at least not if the journalist who reported it was accurate. The experiment is described in the journal New Scientist, 22 October 1981. Its designers were illustrious enough: Denys Parsons, SCICOP, Prof. Bernard Watson and the television personality Prof. Heinz Wolff. The idea was that Tony would try repeatedly to dowse a high-voltage cable strung above his head without knowing if it was switched on or off. Wolff sat nearby, calling out each test in a long series. The biggest problem for Tony was that the experiment was to be conducted indoors, inside a large lecture hall. The hall would have had plenty of metal in the roof or ceiling, both structural and in the mains wiring strung through it for the lighting. It must have been just like his attempts to conduct experiments in my parents' apple orchard - hopeless. As a result of Tony's vociferous protests they condescended to move the experiment to an outside courtyard. Tony told me several times how the courtyard was itself far from clear of overhead wires, steel-reinforced walls alongside and other electrically disturbing objects. The vertical field would have been almost as badly messed up as indoors. Unsurprisingly, the last run proved as negative as the others.
Let me now explain why I regard the experiment as a sham and its conduct a farce. Despite going to some lengths to ensure that the experimental subject had no idea of what he was dowsing, they failed to confirm in the slightest what they were actually asking him to dowse. Recall that his theory assumed an ambient vertical field of around a thousand volts per metre and this was what his overhead electrode was disturbing. But here there was no establishment of the ambient vertical field strength, no clue how the overhead cable related to it, in other words, no idea of the disturbance they were actually creating. Now, Tony was acting as a human measuring instrument, intended to detect possibly quite small changes in the strength of a large and directed field. In any sensible experiment such instruments are carefully calibrated before the experiment against known inputs, then equally carefully checked again afterwards. One does not take an instrument formerly used within a certain operating range, throw at it an arbitrarily different environment and there rely on it to give accurate readings. Yet this was exactly what they did with Tony. He persuaded them at least to change the voltage on the off chance that this might improve matters, but it did not.
Then, New Scientist states that this was a double-blind experiment. This is a standard precaution for such experiments, however as described it was not in fact double-blind. Wolff is said to have read the test number aloud while himself setting the on/off switch accordingly. But this is not double-blind. For that, Wolff should not have known whether the device was to be switched on or off. He should have called out his anonymous number to, say, a hidden technician who operated the switch according to their own list which Wolff had not seen. In this way, Wolff would not have known when he read out each number what the field would be. This would have avoided any risk of his tone of voice or body language either aiding or confusing Tony. As it was, he reportedly knew in each case and consequently the trial was not conducted correctly.
Unless New Scientist was mistaken, those responsible showed serious lapses of rigour in both its design and its execution. As a piece of science the experiment appears to have been both badly conceived and ineptly executed. To add insult to injury Tony's fundamental objections were not listened to and acted on with any real understanding but were for the most part brushed aside. He was offered only a couple of token but inadequate gestures.
I am sorry, but I saw from relatively close up the careful and methodical work which led to Tony's results, I discussed with him the theories that he discarded along the way, I watched the electrostatic field theory grow through his accounts of solid experimental technique and highly innovative equipment design. He was forced to invent novel electrostatic detectors, which would go on to create a minor revolution in their own right, for example allowing 24/7 monitoring of the sky for meteor trails as they puncture the ionosphere, hitherto possible only visually on a clear night. This was a man of methodical science and engineering, of deep insight and carefully reasoned thinking. His personal library of rare and important scientific texts would put any Professor to shame and many a whole Faculty.
Now, I am not claiming that Tony was necessarily right about dowsing or ley lines. It may be that he deluded both himself and me with unconscious thoroughness, I will be the first to accept the truth of the matter when it is confirmed. But one thing is abundantly clear, and that is that the case against is at best unproven and needs to be re-examined. If nothing else, Tony's memory deserves it.Notes:
 Charfas, J.; "No better than chance", New Scientist 22 October 1981, p. 262. See also Hopwood's own account of his key experiments in "Dowsing, ley lines and the electromagnetic link", New Scientist 20/27 December 1979, pp. 948-9.
 I am no longer a practising electromagnetic test engineer and my personal friendship with Tony must also place a question mark over my objectivity. I therefore feel that it is not appropriate for me to present such a re-examination. But that doesn't stop me calling for it.
Updated 17 July 2015
So then on 23 July 2015 I wrote an email to New Scientist on the question of, "Was Hopwood doing good science?":
Dear Opinion Editor,
New Scientist has twice reported on the electrostatic theory of dowsing and ley lines proposed by Tony Hopwood. The first account was Hopwood's own. The second was of an experiment, involving among others SCICOP and Heinz Wolff, which purported to falsify his claims. Hopwood died recently and I was moved to revisit the story. In short order I was further moved to debunk the debunkers. If New Scientist's account is to be believed there were serious flaws in both the conception and execution of the independently-run experiment. It was, frankly, worthless.
Hopwood's theory remains unverified either way. As a sometime electromagnetic test engineer and before that a confidant of his during its development, I found it to be far the most rational of any that I encountered. Both in the name of Science and in the memory of Tony, I would make so bold as to ask New Scientist to once more bring the matter to public attention.
 Hopwood, A.; "Dowsing, ley lines and the electromagnetic link", New Scientist 20/27 December 1979, pp. 948-9
 Charfas, J.; "No better than chance", New Scientist 22 October 1981, p. 262
 Inchbald, G.; "Dowsing, ley lines and Tony Hopwood", http://www.steelpillow.com/blocki/philosophy/DowsingTony.html
Do ask them if they ever read it.
Updated 30 July 2015