Scaphe

Antique hollow sphere sundial (scaphe). The horizontally mounted gnomon was lost.

Modern replica of a scaphe with a ball as a nodus

The scaphe ( ancient Greek σκάφη skáphē "bowl") is probably the oldest type of sundial . Its dial is in a half hollow sphere with a horizontal edge. When it was noticed that the part facing south (northern hemisphere) was not needed, it was often left out. This made it possible to read the scaphe from a distance. The shadow thrower is point-shaped ( nodus ), for which purpose the tip of a vertically or horizontally mounted gnomon was usually used.

The name Skaphe coined in the 3rd century BC. The astronomer Aristarchus of Samos , whose hollow sphere sundial the Roman Vitruvius around 30 BC. Describes in the ninth of his books about architecture. It is designed as a mirror image of the visible celestial sphere .

In addition to determining time , the scaphe was also used by ancient astronomers to measure the height of the sun - which is why it was also called heliotrope - and thus to determine latitude . A similar construction comes from the Babylonian Berossus , who called it Hemispherium .

Literature and Sources

• Karlheinz Schaldach: Roman sundials. An introduction to ancient gnomonics , 3rd edition, Harri Deutsch, Frankfurt am Main 2001, ISBN 978-3-8171-1649-2 .
• Skaphe , in: Art Lexicon by PW Hartmann .
• From the history of the sundials , chap. 1.3, Antiquity (PDF file; 84 kB)