The Back Dial and Back Plate Inscriptions

The rear face of the Mechanism consisted of a rectangular “Back Plate“ dominated by two large spiral dials. The upper five-turn Metonic Dial represented a 235-lunar-month calendrical cycle while the lower four-turn Saros Dial represented a 223-lunar-month eclipse prediction cycle. A subsidiary quadrant “Games“ dial was situated inside the Metonic Dial, and a subsidiary three-sector Exeligmos Dial inside the Saros Dial. Preserved text inscribed around the dials (from the lower right quarter of the plate), probably representing about a quarter of the original inscription, provided further information associated with the predictions of eclipses. This paper describes the reconstruction from the Mechanism’s fragments of the surviving parts of the text on the plate and its dials, giving transcriptions and translations. The Metonic Dial inscriptions imply a calendrical scheme similar to that described by Geminos. It was intended to be a version of the calendar of Corinth as it was practiced either at Corinth its...