Dialface ID 234
Abstract
Catamo: The usual parameters give a latitude of 45° (Tivoli is at 42°) and a perpendicular height for the gnomon of 36 mm. The directions and the distances measured from the projection of the gnomon point on the plane at the extremities of the hour lines on the three day curves (see figure) show discrepancies, albeit not large ones, from those obtained by calculation. As a whole, it seems to be a sundial of average accuracy. When it was first discovered, traces of lead and iron were found in the hole for the gnomon, which was some way from the correct position, suggesting that the rod was bent or curved so that its tip would be in the right position. At some time - it is impossible to know exactly when, but certainly after the discovery - a strongly curved iron gnomon was fixed in it with lead, but this is out of square.
Measurements
This object has not been measured by the 3D pipeline. Its entry in the catalogue rests on the published description only; no surface fit, latitude or line detection exists for it.
References
- – Catamo, Mario, Lanciano, N., Locher, K., Lombadero, M., Valdes, M., Fifteen Further Greco-Roman Sundials from the Mediteranean Area and Sudan, 2000, p. 216.
- – Mommsen, Theodor, Corpus Inscriptionum Latinarum, Berlin, 1863, XIV, 3660.
- – Gibbs, Sharon L., Greek and Roman Sundials, New Haven and London, 1976, p. 334.
- – Rossi, S., Settele, G., Sopra vari monumenti e particularmente di un antico orologio solare, trovati in Tivoli in occasione degli sterramenti fatti per la deviazione dell 'Aniene, 1838, p. 97 ff (drawing).
- – Winter, Eva, Zeitzeichen. Zur Entwicklung und Verwendung antiker Zeitmesser, Berlin and Boston, 2013, 579.