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for they were executed in punishment for
their neglect. If this account be true, it
means that in the twenty-second century
B.C. some rule for calculating eclipses was
in use. Here, again, patient observation
would easily lead to the detection of the
eighteen-year cycle known to the Chaldeans
as the Saros . It consists of 235 lunations,
and in that time the pole of the moon’s or-
58