Plate 11 of 11 · cca-2008-barbury-castle-pi
Barbury Castle 'Pi' formation
A thin ratchet path spiralling out through four full turns, encoding the first ten digits of pi: each digit swept as an arc of digit × 36 degrees before stepping outward at a decagon ray. A small circle marks the decimal point, three diminishing outlined circles read '…', and a wide dike ring frames the 46 m design.
Survey record
- Reported
- 2008-06-01
- Location
- Barbury Castle, Wroughton, Wiltshire · map
- Coordinates
- 51.4885, -1.7746 (±300 m)
- Crop
- barley
- Span
- 46 m
- Symmetry
- 1-fold
- Elements
- 31 rendered from 31 declared
- Fidelity
- level 3 · confidence high
- Digitized
- claude-fable-5, 2026-08-19
Construction
Thin ratchet path (band width 0.026 R ≈ 0.65 m), not solid wedges: ten spiral tracks at inner radii 0.174 + 0.0671 k R (uniform pitch) with radial connectors at each digit boundary; boundaries all fall on rays of the underlying decagon. Digit k of pi sweeps digit x 36 deg clockwise from 90 deg (total 1440 deg = 4 turns, ending back on the 12 o'clock ray). A small circle on the track-1 lane at -33 deg marks the decimal point. The outer dike is a wide flattened ring (0.824-0.9266 R) whose inner edge extends to 0.758 R over the arc where the tenth digit does not run — the radial end cuts of that extension read as two 'slots'. Three diminishing outlined circles continue the path lane as an ellipsis, the largest punching into the dike.
Sources
- Zef Damen (geometry reference) (reconstruction)
- Crop Circle Connector (copyrighted imagery — link only) (photo)
- en.wikipedia.org (report)