Dialface ID 241
Abstract
Gibbs: The equinox is a horizontal straight line as it should be for all latitudes between equator and pole. As plane sections of sunlight cones, the day curves should be parts of hyperbolas for latitudes above the torrid zone. The curve closest to the projection of the gnomon point on the vertical face is that traced by the shadow of the gnomon point on winter solstice. The day curve at winter solstice is limited by a horizontal line passing through the projection of the gnomon point. In spring and summer, the shadow of a gnomon point will fall on a south-facing vertical dial for only part of the day. An additional north-facing vertical dial with its own gnomon point is required for marking some of the seasonal hours between the spring and autumn equinox. It seems likely that the designer of the south (and north) face of the Tower of Winds determind the pattern of hour lines and day curves by constructing seasonal hour points on the dial face and joining them. The Ptolemaic coordinates relevant to the construction of prime vertical sundials are the vertical and horarius arcs. (p. 43) If the vertical dials on the eight sides of Andronicus' Tower of Winds in Athens were engraved at the time the tower was built, they belong to the first century B.C. (p.78 f) Some time during the first century B.C. Andronicus Cyrrhestes designed and built an octagonal tower on which eight planar sundials are visible today (see Vitruvius, De architectura I, 6.4). The dials face the principal points of the compass. (p. 342) Schaldach: Achteckiges Gebäude. Unter einem flachen Pyramidendach befinden sich durch ihre Namen gekennzeichnet - die Reliefs der Windgötter, männliche geflügelte Wesen, die sich dem Betrachter im Halbprofil zuwenden. Darunter ist auf jeder Wand über ihre gesamte Breite das Liniennetz einer Vertikaluhr aufgetragen. Der Bau ist, mit einer Höhe von13,5 m und einer Wandbreite von 3,3 m auf jeder Seite, über einer dreistufigen Krepis äußerst präzise nach den Himmelsrichtungen orientiert. An der NO- und NW-Seite sind die beiden Eingänge mit kurzen rechteckigen Portikus. Von den drei kleinen Fenstern auf der N-, W- und S-Seite ist keines original. Kernstück der Inneneinrichtung war eine Wasseruhr, von der nur mehr das innere Becken und die Zu- und Ablaufrinnen erkennbar sind.
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
- – Delambre, Jean-Baptiste Joseph, Histoire de l ‘Astronomie Ancienne, Paris, 1817, p. 487 ff and plates 11 and 12 (drawings).
- – Schaldach, Karlheinz, Die antiken Sonnenuhren Griechenlands. Festland und Peloponnes, Frankfurt am Main, 2006, CD, 01
- – Gibbs, Sharon L., Greek and Roman Sundials, New Haven and London, 1976, p. 43, 78, 342 ff.
- – Noble, Joseph V., de Solla Price, Derek J., The Water-Clock in the Tower of the Winds, 1968, p. 345 ff, plates 111-118 with photographs.
- – Robinson, Henry S., The Tower of the Winds and the Roman Market-Place, 1943, p. 291 ff.
- – Stuart, James, Revett, Nicholas, The Antiquities of Athens, London, 1762, p. 13 ff (drawings with measurements).
- – Alberi Auber, Paolo, Gli orologi solari della Torre dei Venti a Atene e a Tinos del greco Andronico Cirreste, 2006
- – Winter, Eva, Zeitzeichen. Zur Entwicklung und Verwendung antiker Zeitmesser, Berlin and Boston, 2013, 295-297.
- – Kienast, Hermann J., Der Turm der Winde in Athen, Berlin, 2014