Glossary K

Kalends.

Kallippic Cycle. A refinement of the Metonic Cycle made by Kallipos (c. 370 – c. 300 BCE), using the simplified formula of 1 year = 365 + ¹/₄ days, equating of 76 year (4 Metonic Cycles) to 940 lunations, when the same phases of the Moon would occur on the same day of the year. In modern terms, using the Tropical Year of 365.242188 days, the Kallippic Cycle of 940 lunations, which is 27758.753660 (= 29.530589 × 940) days, is equivalent to 76.000951 (= 6939.688415 / 365.242188) Tropical Years, which is 8 hours, 20 minutes too long.
     In later times, the first Kallippic cycle was deemed to have started on the summer solstice of 330 BCE which occurred at 02:50 on 28th June. It seems that the Kallippic cycle was taken up quite quickly by astronomers and was used by Timocharis of Alexandria in 283 BCE and later by Hipparchos and Ptolemy. The Antikythera Mechanism has a dial for the Kallippic Cycle and thus it appears to have been widely used in Hellenistic and Roman times.

Klepsydra.