Plate 02 of 11 · cca-1991-barbury-castle-tetrahedron
Barbury Castle tetrahedron
An equilateral triangle whose sides cross the hub's broad outer ring at six points, with spokes to a ringed centre and three deliberately different corner devices: a simple ring, a broken ratchet spiral, and a disc cut by six curved vanes. Widely read at the time as a two-dimensional projection of a tetrahedron.
Survey record
- Reported
- 1991-07-17
- Location
- Barbury Castle, Wroughton, Wiltshire · map
- Coordinates
- 51.488, -1.777 (±800 m)
- Crop
- wheat
- Span
- 80 m
- Symmetry
- 1-fold
- Elements
- 24 rendered from 24 declared
- Fidelity
- level 3 · confidence medium
- Digitized
- claude-fable-5, 2026-08-20
Construction
Hub circle + thin ring + broad outer ring that the triangle's sides cross at six points; triangle circumradius 27 m with sides and centre spokes as 1.1 m bands. Corners: simple ring (standing centre, spoke line running to its centre); six-step broken ratchet spiral with a small offset dot; flattened disc cut by six curved standing vanes, each an arc of the disc's own radius centred on its rim. Read at the time as a 2-D projection of a tetrahedron.
Sources