So that after 28 years we come back to Friday again; and so on every 28 years, until change of style in 1582, when the Gregorian rule of intercalation being adopted by suppressing the intercalations in three centurial years out of four interrupts this order at the close of these three centuries. For example--1700, 1800 and 1900, after which the cycle of 28 years will be continued until 2100, and so on. The cycle being interrupted by the Gregorian rule of intercalation, causes all events which occur between 28 and 12 years of the close of the centuries to fall on the same day of the week again in 40 years; and those events that fall within 12 years of the close of these centuries, to fall on the same day of the week again in 12 years; after which the cycle of 28 years will be continued during the century. See following table: 1804 February has five Wednesdays. 1808 " " " Mondays. 1812 " " " Saturdays. 1816 " " " Thursdays. 1820 " " " Tuesdays. 1824 " " " Sundays. 1828 " " " Fridays. 1832 " " " Wednesdays. 1836 " " " Mondays. 1840 " " " Saturdays. 1844 " " " Thursdays. 1848 " " " Tuesdays. 1852 " " " Sundays. 1856 " " " Fridays. 1860 " " " Wednesdays. 1864 " " " Mondays. 1868 " " " Saturdays. 1872 " " " Thursdays. 1876 " " " Tuesdays. 1880 " " " Sundays. 1884 " " " Fridays. 1888 " " " Wednesdays. 1892 " " " Mondays. 1896 " " " Saturdays. 1900 1904 " " " Mondays. 1908 " " " Saturdays. 1912 " " " Thursdays. 1916 " " " Tuesdays. 1920 " " " Sundays. 1924 " " " Fridays. 1928 " " " Wednesdays. It will be seen from this table that in 1804 February had five Wednesdays; and then again in 1832, 1860 and 1888; then suppressing the intercalation in the year 1900 suppresses the 29th of February; so opposite 1900 in the table is blank, and the 29th of February does not occur again till 1904, and the five Wednesdays do not occur again till 1928--that is, 40 years from 1888, when it last occurred. Again taking the five Mondays which occurred first in this century, in 1808, and then again in 1836, 1864 and in 1892, you will see, for reasons already given, that it will occur again in 12 years, that is, in 1904; and so on with all the days of the week, when it will be seen what is peculiar concerning the 29th of February.