Ancient Greek Units of Measurement - Time

Time

Athenians measured the day by sundials and unit fractions. Periods during night or day were measured by a water clock (clepsydra) that dripped at a steady rate and other methods. Whereas the day in the Gregorian calendar commences after midnight, the Greek day began after sunset. Athenians named each year after the Archon Eponymos for that year, and in Hellenistic times years were reckoned in quadrennial epochs according to the Olympiad.

In archaic and early classical Greece, months followed the cycle of the Moon which made them to not fit exactly into the solar year. Thus, if not corrected, the same month would migrate slowly in different seasons of the year. The Athenian year was divided into 12 months, with one additional month (poseideon deuteros, 30 days) being inserted between the sixth and seventh months every second year. Even with this intercalary month, the Athenian or Attic calendar was still fairly inaccurate and days had occasionally to be added by the Archon Basileus. The start of the year was at the summer solstice (previously it had been at the winter solstice) and months were named after Athenian religious festivals, 27 mentioned in the Hibah Papyrus, circ 275 BCE.