ObjID439-1
‹ Ancient Sundials
Dialface ID 478
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Abstract
Two rather inexactly made miniature spherical dials in stone can be mentioned. One, in the Archaeological Museum of Rhodes, the other, in Syracuse is almost complete.
Measurements
Measurement record: pipeline ObjID 439, matched to this dialface by inventory number.
| Quality grade | A (completeness 99 %) |
|---|---|
| Dial surface | cylinder (preferred, not decisive) · fit residual mm: cone 0.40, cylinder 0.40, sphere 1.74 |
| Latitude φ | 2.81 ± 0.62° (single witness: path-III-front-back) |
| Engraved lines | 10 hour lines, 3 day lines |
| Cone half-angle α | not shown: the derived cone does not agree with the measured points (residual 6.0 mm; verified cones give under 1 mm); under review |
| Measured | 2026-06-12 20:47 |
What the dial shows at this latitude
| Winter solstice | Equinox | Summer solstice | |
|---|---|---|---|
| Noon altitude of the Sun | 63.5° | 87.2° | 69.1° |
| Noon shadow (gnomon heights) | 0.50 | 0.05 | 0.38 |
| Length of the day | 11.8 h | 12.0 h | 12.2 h |
| Length of a seasonal hour | 59 min | 60 min | 61 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
- – Bellina, Giovanni, Il tempo e l' identità. Dal sentimento del tempo al tempo del sentimento, Ragusa, 2002
- – Evans, James, Marée, Marcel, A Miniature Ivory Sundial with Equinox Indicator from Ptolemaic Tanis, Egypt, 2008, p. 14.
3D Models
