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date: 19 June 2018

clocks

The usual instrument for telling time in antiquity was the sundial. This employed the shadow of a pointer (γνώμων‎) cast on a plane, spherical, or conical surface marked with lines indicating the seasonal hours (one seasonal hour was of the length of daylight at a given place: hours of constant length were used only by astronomers). Often, there were lines indicating the solstices and equinoxes. Although crude sundials may have been introduced into Greece in the 6th cent. bce (Hdt. 2. 109 says that the Greeks imported the γνώμων‎ and twelve-part division of the day from the Babylonians), we find them more commonly used from the 3rd cent., when the mathematical theory necessary for correctly drawing the hour-lines had been developed. The earliest preserved Greek sundial found to date, from Oropos, dates from the 4th cent.

At night the ancients used the water-clock (κλεψύδρα‎), which measured time by the flow of water from a vessel. A simple form was in use in Athenian courts of the 5th cent. bce. Ctesibius (3rd cent.) invented a device to ensure a uniform flow and more accurate time-telling. He also added many refinements, including a dial with a moving pointer, and ‘side-effects’ (moving figurines). This was the ancestor of the elaborate display clocks of Byzantine and Islamic times. A variation is the ‘anaphoric clock’ described by Vitruvius (9. 8), which indicated the varying seasonal hours by a rotating disc, driven by water-power, on which the constellations were engraved in stereographic projection; a fragment of such an instrument is preserved.

Sundials of various types have been found across the Mediterranean, both in private settings, e.g. as garden decorations, and in public spaces (e.g. marketplaces and baths), often as dedications by benefactors. They are occasionally signed by their makers.

See solarium augusti; time-reckoning.

Bibliography

S. Gibbs, Greek and Roman Sundials (1976) (includes lists of preserved sundials).Find this resource:

K. Schaldach, Römische Sonnenuhren: eine Einführung in die antike Gnomonik (1998).Find this resource:

R. Hannah, Time in Antiquity (2009).Find this resource:

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