The Megalith Movers Prehistoric Engineering
Blog 23rd August 2014    Erecting a Stonehenge Trilithon    I first starting thinking about obelisks and how they may have been erected some years ago when I was organising a series of experiments for a National Geographic film about Stonehenge.    The only experiment that was considered a complete failure was an attempt at erecting a Stonehenge Trilithon by planting a replica Stonehenge upright into a hole. At this time I knew nothing about the profiles of the stone- holes for the Stonehenge uprights and had assumed the holes had been excavated by digging a hole with four vertical sides. After this rather spectacular failure, word was passed to me from the Archaeologist by way of the producer. Could I see a way of erecting an upright while making use of a hole with one side sloping at an angle of maybe 30 or 40 degrees? I looked at my 12 ton stone sitting on it’s support logs ready for the stone-rowing experiment, see NatGeo film clip (on the right-hand side of this page), and could almost immediately see how having a sloping side to the stone-hole could be used to great advantage.    How this moment effected my later thoughts about obelisk erection, I will leave you to speculate on for the time being. Look for similarities between the two theories.    But back to the main subject of this blog sub-plot. “Erecting a Stonehenge Trilithon” I saw that having a stone- hole with one sloping side might be advantageous and armed with this new knowledge I began to envisage a new theory.    I had already proved that stone-rowing was a viable method of moving heavy stones long distances with a limited workforce and had many other advantages over the old theory that the stones were moved by means of wooden rollers. I won’t go into this argument now but two of these advantages are applicable to the problem of erecting a Stonehenge upright. One, the ability to make precise changes in direction when approaching the stone- hole (the stone can be steered just like rowing a boat), and two, the final positioning can be controlled to within a fraction of an inch. Why this is necessary will be clear shortly.    Two or three years after formulating my new erection theory, I was given the chance to test it for real when I was invited to speak about stone-rowing at a megalithic conference being held in New York State, USA. I was also asked if I would give a demonstration at a workshop being held during the conference. I accepted this all expenses paid offer provided they would supply me with a suitable stone for a stone erection experiment along with the necessary voluntary labour.    Some months later I was met at a small airport in up-state New York by my host Rob Roy and his wife Jaci. Rob and Jacki proved to be excellent hosts, and I had a very enjoyable time during my 2 week stay. They drove me to their home in West Chazy stopping on the way for a meal at one of Rob’s favourite bars where I learned of his passion for real ale, I realised we had more in common than just a mutual interest in prehistoric engineering.    Next day Rob showed me round his place, he had built his own stone circle using natural stones each standing perhaps 3 to 5 foot high and had space left for one more stone. Rob had also erected two concrete replicas of the uprights for a Stonehenge Trilithon and had the proposed lintel stone ready to be put in place on top of the uprights. This would be the project he would use for the workshop he was conducting during the forthcoming conference. He led me over to show me the stone I would be using both for the stone-rowing demo and the erection experiment. It was a small natural stone of about 3 tons, more like a long boulder maybe 7 ft overall, rather than a Stonehenge upright. Trying hard to hide my disappointment I turned to Rob and said “It’s not a good shape for rowing so we are going to have to lever it up and build a cradle underneath. We can then row the cradle with the stone on top over to the stone hole”. In the end, both the rowing demonstration and the erection experiment went well and we had the stone upright making full use of the 30 degree sloping side of the stone hole. The cradle, or stone-boat as I called it, was to prove very useful during the erection experiment, as I had left it tied to the stone throughout the erection, and we were able to lever and pack a few inches at a time under the stone-boat, until the stone was upright.    When I returned to England after this experiment I was already sure this method would work equally as well on one of the 45 ton Stonehenge uprights. We would need more men and more levers of course, but the method itself had proved faultless. Getting enough levers into place on either side of the 45 ton stone in order to row it into position wouldn’t be a problem as the biggest upright is 32 ft long, 25 levers arranged along each side would provide more than enough lift. Although the top end is only about 7ft wide, as we are lifting only one end we will be lifting only half the weight. In fact as the balance point of the stone will now be sitting on the edge of the sloping side, we will be lifting almost nothing. Just one man with one lever should be enough to tip the balance, and as the balance continues to shift, the bottom end of the stone will drop fairly gently into place at the bottom of the stone-hole. With the stone now lying on the 30 degree slope, we will be effectively one third of the way through our 90 degree travel arc.    As the stone is progressively levered though the next 60 degrees, the centre of gravity moves progressively towards the bottom of the stone, and each lift becomes easier. On the downside is the fact that the shoring or packing becomes progressively harder, as we move higher from the ground level with each lift. More difficult that is, but not impossibly so.    So what are the main differences between erecting a Trilithon upright and erecting an obelisk? The first and most obvious difference is the shape of the obelisk, in comparison to the Trilithon uprights. The obelisk is very narrow at the top making it impossible to get enough levers arranged in the most efficient manner at the top end. We overcome this problem by using a lifting frame (barn door) under the obelisk. The second difference is the fact that with the obelisk erection we have to lever from zero degrees to 90 degrees. We overcome this problem by using two barn doors.    The first barn door equates to the 30 degree slope on the Trilithon stone-hole, the second barn door equates to the stone-boat at 70 degrees. Apart from these two differences the two experiments are essentially the same, and a repeat of the stone erection I successfully performed in America. Everything else is a matter of scale, the American experiment was about 3 tons, the obelisk experiment is about 10 tons, and the Trilithon experiment will be 45 tons. <<previous blog page next blog page >> To read & post comments click here return to top of this page

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