gems, engraved gems, agate, chalcedony, quartz, cameos, itaglios, turquoise, sard, onyx, coral, amethyst, glyptic

King describes and interprets an unusual ancient Roman intaglio engraved with a representation of a clepsydra, or water-clock, which he associates with the timing of races in the Circus Maximus. He examines the engraved device in relation to classical literary and archaeological evidence, discussing its construction, operation, and possible function in regulating or recording the duration of contests. Particular attention is given to the iconography of the gem and to comparable representations and descriptions of ancient time-measuring instruments. The paper illustrates the value of engraved gems as documentary evidence for aspects of Roman technology and public entertainments that are otherwise imperfectly represented in surviving monuments.