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About 432 BCE Menton, an Athenian astronomer, developed a calendar utilizing the
19 year lunar cycle consisting of 12 years with 12 lunar months each and 7 leap
years with 13 lunar months each. The 19 year cycle is known as the Metonic
cycle.
The Greek calendar, introduced by Meton in
about 432 BCE is based on the discovery made by the Babylonians in the 8th
century BCE that 228 (12 times 19) sun months are almost equal to 235 moon
months so that he had to form cycles of 19 moon years, 12 of which have 12
and 7 of which have 13 months each, in order to adjust the solar calendar to
the lunar calendar (12 times 19 plus 7 = 235). The only practical principle
for the distribution of the 7 leap years among the 12 others is by the
following sequence:
3 periods of 3 years, 
total 9 years 
1 period of 2 years, 
total 2 years 
2 periods of 3 years, 
total 6 years 
1 period of 2 years, 
total 2 years 
7 periods 
total 19 years 
A certain year in each period, for
instance, the last, is a leap year (Frank
1956:4445.)
Page last
edited:
01/25/06 06:25 PM 
