Time Measurement and Calendar Construction

12 lunations 1st January 30 days accurate adopted ancient Armenian astronomical autumnal equinox Babylon Babylonian beginning calculation calendar reform calendar system called celebration celestial century B.C. Chaldeans China Chinese Christian chronology civil clepsydra clock commencement constellations count day doin daylight divided dominical letters early earth Easter eclipse Egypt Egyptian calendar emperor Ezen feast festival fixed free days full moon gnomen Greek Gregorian calendar Hebrews heliacal rising Hindu India indicated intercalary month intercalation intervals Julian calendar Jupiter known League of Nations leap length lunar calendar lunar month market week Maya mean solar measurement method Metonic Cycle midnight modern Mohammedan month names Nakshatras natural divisions night observed orbit origin period Persian planets Pleiades proposed purposes quintal recorded religious Roman seasons seems seven-day week sexagenary cycle siderial signs solar calendar solar day Sothic cycle stars summer solstice Sunday sundial sunset tion tropical vernal equinox winter solstice Zodiac