ObjID21-1
‹ Ancient Sundials
Dialface ID 21
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Abstract
Gibbs: A tapering gnomon groove, 34 mm wide at the top, 14 mm wide at the bottom, and 32 mm deep pierces the top surface.
Measurements
Measurement record: pipeline ObjID 21, matched to this dialface by inventory number.
| Quality grade | A (completeness 100 %) |
|---|---|
| Dial surface | sphere (decisive) · fit residual mm: cone 6.02, cylinder 7.16, sphere 1.08 |
| Latitude φ | 40.32 ± 0.03° (consensus of witnesses) |
| Klima | nearest Hellespont (19.5 sigma) |
| Engraved lines | 11 hour lines, 3 day lines |
| Cone half-angle α | not shown: surface fit decisively sphere: cone-specific quantities do not apply |
| Measured | 2026-06-12 20:35 |
What the dial shows at this latitude
| Winter solstice | Equinox | Summer solstice | |
|---|---|---|---|
| Noon altitude of the Sun | 26.0° | 49.7° | 73.4° |
| Noon shadow (gnomon heights) | 2.05 | 0.85 | 0.30 |
| Length of the day | 9.1 h | 12.0 h | 14.9 h |
| Length of a seasonal hour | 45 min | 60 min | 75 min |
Computed for the measured latitude with the obliquity of the JPL ephemeris at 101 BC (year -100). The latitude is the one the dial was made for, not a find-spot coordinate.
References
- – Gibbs, Sharon L., Greek and Roman Sundials, New Haven and London, 1976, p. 136, p. 137, plate 4.
- – Severino, Nicola, De Monumentis Gnomonicis apud graecos et romanos. Le meridiane greco-romane. La storia, il catalogo, gli articoli, Roccasecca, 2003, p. 24.
3D Models
