24th of February, consisting of twenty-two and twenty-three days
alternately, so that four years contained 1465 days, and the mean length of
the year was consequently 3661/4 days. The additional month was called
_Mercedinus_ or _Mercedonius_, from _merces_, wages, probably because the
wages of workmen and domestics were usually paid at this season of the
year. According to the above arrangement, the year was too long by one day,
which rendered another correction necessary. As the error amounted to
twenty-four days in as many years, it was ordered that every third period
of eight years, instead of containing four intercalary months, amounting in
all to ninety days, should contain only three of those months, consisting
of twenty-two days each. The mean length of the year was thus reduced to
3651/4 days; but it is not certain at what time the octennial periods,
borrowed from the Greeks, were introduced into the Roman calendar, or
whether they were at any time strictly followed. It does not even appear
that the length of the intercalary month was regulated by any certain
principle, for a discretionary power was left with the pontiffs, to whom
the care of the calendar was committed, to intercalate more or fewer days
according as the year was found to differ more or less from the celestial
motions. This power was quickly abused to serve political objects, and the
calendar consequently thrown into confusion. By giving a greater or less
number of days to the intercalary month, the pontiffs were enabled to
prolong the term of a magistracy or hasten the annual elections; and so
little care had been taken to regulate the year, that, at the time of
Julius Caesar, the civil equinox differed from the astronomical by three
months, so that the winter months were carried back into autumn and the
autumnal into summer.

In order to put an end to the disorders arising from the negligence or
ignorance of the pontiffs, Caesar abolished the use of the lunar year and
the intercalary month, and regulated the civil year entirely by the sun.
With the advice and assistance of Sosigenes, he fixed the mean length of
the year at 3651/4 days, and decreed that every fourth year should have 366
days, the [v.04 p.0990] other years having each 365. In order to restore
the vernal equinox to the 25th of March, the place it occupied in the time
of Numa, he ordered two extraordinary months to be inserted between
November and December in the current year, the fi