The Geometry of Stanton Drew.
A study by R. O. Wilcox.
23rd June 1979.
The megalithic monuments at Stanton Drew consist of three stone circles, the cove outside the circles, and at least one outlier Hautville’s Quoit. It has been noted by Grinsell (Ref.1) that the stone circles are so positioned that:
1) A line drawn south-westwards through the centres of the North-east circle and the Great circle will pass through the Cove. Let this be called the Cove line.
2) A line drawn through the centres of the South-west circle and the Great circle will continue to Hautville’s Quoit. Let this be called the Hautville’s Quoit line.
There thus appears to be a sort of cross-symmetry about the layout in spite of the differences in size and position of the circles.
An edge alignment exists with the three circles. A straight line can be drawn through their south eastern edges. (Ref. 2) This edge alignment gives clues to a further understanding of the layout of the complex. Let this be line a.
Draw a line from the eastern edge of the South-west circle to the western edge of the Great circle. Let this be line b. This line points true North. Draw a line from the southern edge of the North-east circle to the northern edge of the Great circle. Let this be line c. This line points due West. (See figure 1).
With the line running along the south-eastern edges of all the circles, a right-angled triangle is formed. This has precise angles of 90 degrees, 60 degrees and 30 degrees. This triangle would appear to be the fundamental alignment triangle of the complex. It has sides pointing due North/South and due East/West. Note the apex of both the 30 degrees and 60 degrees angles are located at stones in the South–west and North-east circles respectively.
Further edge alignments can be found:-
1) Draw a line from the northern edge of the Great circle to the northern edge of the North-east circle. Let this be line d. Extend lines a and d to intersect at point X. The angle of these lines is exactly 45 degrees. (See figure 2).
Now it can be seen that the Cove line, if extended from the Great circle through the North-east circle, will also pass through point X. It bisects the angle of line a to line d, (angle YXZ) as a direct result of the line going through the centre of the Great circle.
The Great circle is a true circle. The other two circles are strictly elliptical. (Ref. 3).
2) In a similar manner draw a line from the western edge of the South-west circle to the western edge of the Great circle. Let this be line e. Extend lines a and e to intersect at point Y. The angle of intersection is 20 degrees.
Now it can be seen that the Hautville’s Quoit line, if extended from the South-West circle will pass through point Y. It bisects the angle of line a to line e. (angle XYZ).
Lines d and e can be extended north westwards from the Great circle to intersect at point Z. A triangle is then formed (XYZ) aligned on the hypotenuse of the right angled triangle. The right angled triangle encloses the Great circle, but just excludes the other two circles.
The larger triangle encloses all three circles. Its angles appear to be 45 degrees, 20 degrees and 115 degrees.
The ratio of angles for the North-east circle is 60 degrees to 45 degrees. i.e. 4:3. The ratio of angles for the South-west circle is 30 degrees to 20 degrees. i.e. 3:2.
The ratio of angles for the Great circle is 90 degrees to 115 degrees. i.e. 18:23.
The ratio of major axis length for the South-west and North-east circles is 4:3. As these circles are in proportion (and in line) this ratio also applies to the minor axes. (Ref. 4)
This study illustrates that the Megalithic builders of Stanton Drew were aware of the significance of geographical direction, sufficient to incorporate this knowledge into the design of the ‘circles’ with a high degree of accuracy.’ It is an interesting feature that this is not directly apparent but appears ‘hidden’ in the plan of the complex in a special way. This seems to have something in common with the reported characteristics of the Celtic druids in keeping specialised knowledge restricted to within a band – we still say, circle, – of initiates. This special way, in fact the key to unravelling the mystery of the plan of monuments, appears to be that of edge alignment of circles ( or prehistoric enclosures such as camps rings, and hillforts/enclosures ). Watkins, in ‘The Old Straight Track’, gives the key in that edge alignment is more the rule ; centre-to-centre alignment more the exception. For Stanton Drew , edge-to-edge, or tangent-ial alignment gives the cardinal north -south and east-west directions. The third angle, completing the triangle, is 30/60 degrees – splitting the right angle symmetrically into 1/3 and 2/3. In circular measure the builders of the complex were familiar with the properties of the right-angle ; a feature noted by Professor Thom in his analysis of the internal angles associated with the structure of many stone circles in the British Isles.
The alignments shown in the second figure, the outer tangents triangle, give further clues to the extent of the geometrical knowledge of the builders. In this the outer tangents to the ‘circles’ make angles of (a) 45 degrees – a 1/2 right-angle – bisected by the alignment through the circle centres to the cove – to 1/4 right angle. (b) 20 degrees -2/9 right angle – bisected to 10 degrees (l/9 right angle) by the alignment through the circle centres to Hautville’s Quoit, (c) 115 degrees – the remaining angle of the triangle. This information suggests that the builders of Stanton Drew may have had a similar form of circular/angular measure to that which we use today, i.e., one in which units, or multiples of units, are expressed as sub-divisions of a right-angle which is, in turn, a quarter of a complete circle.
It is a pity that the stones at Stanton Drew are in so ruined a condition. It makes an accurate valuation of the mathematical and scientific achievements of the megalith builders impossible. Perhaps it is enough to glimpse what was . but the thoughtless, needless damage goes on. There is much to learn about the monuments, for instance the vestiges of a bank and ditch surrounding the complex, the stone avenues, the other outliers, and the relationship of the complex with other ancient sites in the area like the Long Barrows and Maes Knoll camp.
1. Grinsell L.V. Stanton Drew Stone Circles. Dept. of Environment leaflet 1971.
2. Castle C. Devereux P. Megaliths in the Senegambia. The Ley Hunter Issue No. 85. 1979.
3. Thom A. Megalithic Sites in Britain . Oxford 1967.
4. Russett V. The Old Stones of Mendip Pt. 3 Picwinnard, Issue No. 3 1978. The Geometry OF Stanton Drew