2:59pm Thursday 18th February 2010
At Stonehenge on the cloudless midsummer morning of 1720, two men observed the shimmering orange disc of the sun rise above the distant horizon. One was the antiquarian William Stukeley, regarded by many as the father of modern archaeology, his companion was the renowned astronomer Edmund Halley.
The previous year Stukeley had noticed that the entrance to Stonehenge approximated to the direction of midsummer sunrise but, he wrote, it did not ‘correspond to the quantity precisely enough’.
Stukeley, a doctor by profession, was a man of remarkable insight, and recognised an opportunity to undertake what was the first attempt at the scientific dating of a site of antiquity.
Thinking that Stonehenge had originally been set out by aid of a magnetic compass, and knowing that magnetic north shifted over time, he thought that if it were possible to establish the apparent discrepancy, then the date of the construction of the monument could be determined.
This event marked the beginning of a preoccupation with the summer solstice and prehistoric astronomical alignments, both real and imaginary, which has endured for almost 300 years.
Forty years after Stukeley and Halley’s observations were made, the architect of Georgian Bath, John Wood, produced the first detailed measured survey of the stones. Wood left us the most important record of Stonehenge ever made.
His survey was annotated with hundreds of measurements, which he resolved on the ground to a half, sometimes even a quarter, of an inch.
Wood’s survey has immense archaeological value, for he recorded the stones more than 50 years before the collapse of the western Trilithon (which fell in 1797 and was not restored until 1958). Using his original dimensions it has been possible to re-draw his work on a computer and compare it with the modern plan.
On the night of December 31, 1900, a raging winter storm brought down a stone and lintel of the outer circle. The event was reported in the Times and raised concern for several other stones which were beginning to lean precariously, some only supported by wooden props.
The first of the stones to be restored was the western upright of the Great Trilithon, its partner and lintel having fallen in antiquity. This massive stone lay with its top pitched to the north-east and was in real danger of toppling.
The man appointed to restore the stone was Professor William Gowland, then associate of the Royal School of Mines and Fellow of the Society of Antiquaries.
Tasked with the job of straightening the 45 ton stone, and having secured it with timber cribs, props and ropes he carefully excavated part of the original socket into which the stone had been introduced (finding the hole to be a remarkable 2.5m (8ft) deep).
His excavation and careful recording provides the first clue as to how the stones were raised, and of the intentions of the builders.
On the south-west side the face of the stone sat against a vertical wall of natural chalk, on the opposite side there was evidence of a ramp down which the stone had been introduced by the builders some 4,500 years ago.
If we look more closely at the nature of the more substantial stones, the sarsens as they are known, the uprights are seen to have one relatively smooth face and one rough or largely unworked face.
In raising the uprights the best surface was the one that conformed to the geometry of the structure so that, for example, it is the inner smoother face of the outer ring of sarsens that forms a near perfect circle.
This accuracy is maintained throughout the structure, for it was the centre of each upright which was fixed by the prehistoric surveyors, regardless of the width of the individual stones.
We see how the central Trilithon array was raised in the photograph which shows the Great Trilithon upright with its better face outwards towards the southwest, the others face inwards as do the stones of the sarsen Circle.
Clearly, the Trilithons had to be in place before the Circle, and the Great Trilithon (introduced as we know from the northeast), was almost certainly the first to be erected, with its better face towards the midwinter sunset.
Anyone approaching Stonehenge entered the site through a causeway on the north east; in doing so they faced south west, in the direction of the midwinter sunset.
Writing in 1912 the archaeologist John Abercromby commented that ‘from the analogy of Greek temples, cathedrals and mosques it is evident that the central part of worship lies in the opposite direction of the entrance to which the worshippers when in prayer invariably turn their backs.’ We know that each stone had its foundation accurately cut, so that each centered on a predetermined position, and that variations in the length of the stones were accommodated by varying the depth of the cut so that the tops could be levelled to accept the lintels.
The builders clearly worked not only to a carefully premeditated ‘architects plan’, but also had much, if not all the stonework prepared beforehand. Essentially Stonehenge was created on a prehistoric drawing-board and largely prefabricated.
How can we be sure?
There are many clues, one is to be found in the careful design of the lintels, not only do they have extremely clever interlocking joints, but they display a gentle curvature — details which would have been impossible to create unless they were dressed and trial-fitted on the ground.
Knowing where each join and tenon socket lay in relation to the uprights allowed the builders to ensure a perfect fit when the heavy (c.5 ton) lintels were lifted some 4m (13ft) above the ground.
Any modern builder would know that the effort of fitting each of the 30 lintels would be one that would be wished to be undertaken only once.
One further detail gives yet more information as to how this was done; the lintel that now spans two stones on the northwest side (Stones 21 and 22) has not two but three sockets on its underside. This shows that in the course of construction the top of Stone 21 cracked, leaving a much smaller bearing surface than had been anticipated, as there was no longer enough stone to create a tenon to match the pre-cut socket, so a new socket had to be cut.
Stonehenge hides many such details. The evidence for an architectural design is to be found within the internal integrity and archaeology of the monument, not in what people claim to see in the sky above.
At Stonehenge we have a superbly executed plan based on mirrored symmetry, an empirical geometry easily translated and scaled by the prehistoric surveyors using ropes and pegs. Its form was then set astride the axis of the longest days of the year forming part of en elegant geometric array.
So what of all the theories about Stonehenge being not only an observatory, but a place of healing, or more recently a ‘royal burial ground’?
We may adopt whatever practical or cosmological model we choose, so long as we also acknowledge that it is impossible to know what the prehistoric builders of Stonehenge believed in.
The material remains, the hard archaeological evidence, implicit within the structure goes some way in illustrating what they knew — what is often called embedded knowledge. Thereafter we choose to believe what we wish.
Some will hold an unshakeable belief that Stonehenge was a complex astronomical observatory, choosing to construct alignments to particular stars and events to suit a particular theory to ‘prove’ that the theatre of the celestial dome was the preoccupation of the builders.
Likewise, elaborate imaginary prehistoric events are invented and re-invented; in truth there is not a single ‘modern’ theory that is not at least 100 years-old, including the idea that it faced midwinter. or that Stonehenge was a burial site.
The theory that it was a burial site is in fact the oldest of all documented explanations and was first presented by the medieval chronicler Geoffrey of Monmouth more than 800 years ago. The evidence, in the form of Neolithic cremations inserted into earlier cuts and the surrounding ditch relate to a 500-year period of use of the site prior to the construction of the iconic stone monument.
Stonehenge has become a victim of fashion. The notion that it functioned as an observatory or even a ‘computer’ found increasing favour in the 20th century, with contemporary technological models fitting the period in which they emerged.
Today in the popular imagination, in what for many are less secure times, it is becoming once again totemic and less tangible, infused with ancestral association, healing, magic and ritual.
Such theories come and go, but one thing is certain, there is still much more to learn about the monument which has recently and eloquently been described as ‘a haunting, graceful tribute to prehistoric genius.’ Adapted from Solving Stonehenge by Anthony Johnson, published by Thames & Hudson, 2008 ISBN 978-0-500-05155-9
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