§ 57. Year, common and leap. For the purpose of computing and
reckoning the days of the year in the same regular course in the future,
every year, the number of which in the Christian era is a multiple of
four, is a bissextile or leap year consisting of three hundred and
sixty-six days, unless such number of the year is a multiple of one
hundred and the first two figures thereof treated as a separate number
is not a multiple of four, and every year which is not a leap year is a
common year consisting of three hundred and sixty-five days.