ObjID151-1
‹ Ancient Sundials
Dialface ID 149
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Abstract
North and south-facing conical surfaces have been carved into this marble rhombohedron with oblique angles of 128°.
Measurements
Measurement record: pipeline ObjID 151, matched to this dialface by inventory number.
| Quality grade | B (completeness 98 %) |
|---|---|
| Dial surface | cone (preferred, not decisive) · fit residual mm: cone 28.37, cylinder 37.77, sphere 38.82 |
| Latitude φ | 38.02 ± 0.05° (consensus of witnesses) |
| Klima | Athens |
| Engraved lines | 11 hour lines, 10 day lines |
| Cone half-angle α | not shown: the derived cone does not agree with the measured points (residual 46.6 mm; verified cones give under 1 mm); under review |
| Measured | 2026-06-12 20:24 |
What the dial shows at this latitude
| Winter solstice | Equinox | Summer solstice | |
|---|---|---|---|
| Noon altitude of the Sun | 28.3° | 52.0° | 75.7° |
| Noon shadow (gnomon heights) | 1.86 | 0.78 | 0.26 |
| Length of the day | 9.3 h | 12.0 h | 14.7 h |
| Length of a seasonal hour | 47 min | 60 min | 73 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
- – Diels, Herrmann, Antike Technik, Leipzig and Berlin, 1920, p. 176 ff, figures 55, 56, 57 (drawings).
- – Scott Gatty, Margaret, The Book of Sun-dials, London, 1900, p. 37 f (drawing).
- – Gibbs, Sharon L., Greek and Roman Sundials, New Haven and London, 1976, p. 268f.
- – Rayet, G., Les Cadrans Solaires Coniques, 1875, p. 61 ff, plate 1 (drawings).
- – Donderer, M., Signaturen auf Sonnenuhren. Konstrukteure oder Steinmetze?, 1998, p. 174.
- – Winter, Eva, Zeitzeichen. Zur Entwicklung und Verwendung antiker Zeitmesser, Berlin and Boston, 2013, p. 370.
3D Models
