Directional Dowsing and Roman Roads by Jim Andrews

Back in 1975, I watched on television a man seated in the stern of a rowing dinghy, keeping his head down over a pair of angle-rods, and directing a boy to row him across a wide, tidal creek to a distant, red plastic mooring buoy.  The lad at the oars naturally had his back to this, and the man never once looked up, but kept saying ‘pull left’ as the boat crabbed across the strong current.  Without looking, they actually bounced off the red mooring – whereupon it struck me that ‘direction-finding by dowsing’ might have considerable potential!  It took me years to realise it just could be the answer to a very long-standing, archaeological question.

In 1990, my wife and I began searching for un-mapped Roman roads in the Lake District.  We’d read (in his obituary) how a Member of the British Society of Dowsers, Colonel Merrilees, had famously map-dowsed the position of an unsuspected, unexploded bomb under part of Buckingham Palace after the war, and that it was subsequently excavated.  Apparently, from his home in England, he also used maps and a pendulum to locate where water might be bored for – in Africa.  And again, it was and it was, if you follow me.

Although we’re assured that map-dowsing has no scientific explanation whatsoever, it must have – or it wouldn’t work.  But then, I’ve no idea how lots of devices I use actually work.  Just as long as they do, I’m happy.

So one day, blissfully using the Colonels’ method, I pendulum-dowsed along two edges of our local map, seeking co-ordinates for where some small trace of un-marked Roman roads in South-East Cumbria might still be even faintly visible.  Judy and I then drove to the spot indicated, looked over the field hedge – and were stunned to see two parallel linear depressions angling across the field from where we stood – the fosses either side of an unrecorded agger.  After that, a map-dowse and walk became an exciting routine, and our map gradually blossomed with portions of Roman roads and byways.

Inevitably, we soon became intrigued by that age-old puzzle:- how did the Romans actually align their roads, from the starting points, in the correct direction towards the appropriate objectives, despite intervening high ground and great distance – without accurate maps?

Major forts would have been established of course, several months before being linked with proper, made up roads.  But the highway the Romans built towards London from Chichester, for example, sets off from the latter fort on precisely the correct bearing – with the South Downs, thick forests and goodness knows what else, intervening.  Similarly, the Roman road to York, begun from their Manchester fortress, immediately takes off on a heading over the Pennines which, if projected on a modern Ordnance Survey map, only misses its counterpart in far distant York by a little over 2 miles.  There are umpteen other examples of such astonishing accuracy.

Roman surveying, often in enemy-held territory, was admirable to say the least, but I simply cannot be persuaded that their engineers initially laid out such lengthy routes by lining up people with poles, or by lighting hilltop fires ‘on the right bearing’, as has been suggested.  Did they just guess the ‘right bearing’?  Besides, in wet, windy old Brittanicum anyway, the drift of smoke through the trees that then covered most of the country, is likely to have been hard to spot, and well off-line by the time it emerged – even supposing you got your fire to light in the first place.  And in forests, pole-bearers can’t have had a lot of hope of being seen, either.

So to me, neither method seems practical, not over such huge distances.  For a start, how would one know in what direction to position the very first pole (or bonfire) in the chain?  How could a Roman stand in Chichester, for instance, and point straight at the Roman fort in London, 60 miles away?  Come to that, how would he accurately line up men, all the way from one place to the other, through wild, untamed and possibly still hostile country, in order to get the ‘right bearing’?  Yet somehow, Roman engineers habitually got such alignments precisely right, from the outset.

So how did they do that?  Remembering the gentleman using angle rods to direct a boat between two known points without looking, I began wondering if the Romans might have done something similar.

Their main surveying instrument, the groma, had pendulums dangling from its rotatable arms.  We also know that the ancient Egyptians could dowse, and the Romans got to know them pretty well, so I believe it’s quite reasonable to conjecture that Roman surveyors may well have been able to dowse, directionally, with their pendulums.

So, at our Windermere home I experimented, setting up a wooden table in an area free from magnetic interference, with a piece of A4 paper taped to it.

With a ruler placed on the paper, I held an angle-rod directly above that, seeking the direction from our house to the Ambleside Roman fort, which happens to be only 5 miles distant, but is well out of sight behind a hill.  As the rod steadied, I aligned the ruler beneath it, marked the paper, then used an accurate compass to find its magnetic bearing.  After correcting the result for the year’s local Magnetic Variation in the area, I drew the resulting True bearing on an Ordnance Survey map, starting from where our house is marked.

To my astonishment, that very first trial direction-line actually clipped a corner of the fort 5 miles away – just one degree out from its centre.  However, there’s apparently nothing remarkable about this because I’ve done it numerous times since, towards that and far more distant sites.  And yes, it helps to know the very approximate direction, especially if you’re using a pendulum – or to have visited the target at some time or other, so that you can see it in your mind – though neither is necessary.

I cannot see why, never mind how, the system works, and admit that my attempts to do the same thing with a pendulum are quite often over 10 degrees out – but then, mine is a tiny pendulum on a very short line, designed for map-dowsing rather than direction-finding.  A heavier weight and longer line would be much better for the latter – and the Romans had dozens like that. 

Your Roman surveyor, of course, wasn’t bothered about compasses and magnetic variation, because he didn’t know about them, and in all probability had no map either – however, if he used something like the method I’ve just described, he didn’t need them!

I suggest, therefore, that a professional Roman surveyor could have been able to achieve a precise direction for the start of his roadway, using a pendulum over a longish wax tablet fixed to a table.  He’d then only to get a guy with a ranging pole lined up with the scratch he’d made below his pendulum’s swing, and his road-building squaddies could get going at once – on exactly the right bearing.

The fact that as the route progressed, significant re-alignments often became necessary around bothersome bits of geography or to link up, by a deliberate fork in the route, with other roads, seems not to have been any kind of problem. In practised hands, a quick check with a pendulum would instantly re-establish the desired heading.

So there it is; if I, a total amateur, can dowse reasonably accurately for direction, highly professional Roman surveyors almost certainly could.

And so, of course, could you.  Why not try!