No leap years on Mondays between 1872 and 1912?

Recycle calendars · Or Don't Recycle Them, After All · No leap years on Mondays between 1872 and 1912?

No. After 1872, the next one in line would have been 1900, but in the Gregorian calendar, 1900, unlike 2000, was not a leap year.

Here is how it works out in some detail, and leap years have two letters for the Sundays. 1900 is marked as G!, starting on a Monday, and remaining G for the rest of the year, due to omission of leap day.

1872 GF	1879 E	1886 C	1893 A	1900 G!	1907 F
1873 E	1880 DC	1887 B	1894 G	1901 F	1908 ED
1874 D	1881 B	1888 AG	1895 F	1902 E	1909 C
1875 C	1882 A	1889 F	1896 ED	1903 D	1910 B
1876 BA	1883 G	1890 E	1897 C	1904 CB	1911 A
1877 G	1884 FE	1891 D	1898 B	1905 A	1912 GF
1878 F	1885 D	1892 CB	1899 A	1906 G

I think I have on the occasion also shown why it is practical to use Dominical letters.

The one for Sunday takes one step back each January 1st, as it is an A coming after December 31st, also A, but weekdays go on.

It also takes one step back on the leap day, whether you count it as "ante diem bis sextum Kalendas Martias" coming after "ante diem sextum Kalendas Martias" or as February 29th coming after February 28th. The named Roman day names in leap years are February 24th and 25th, of which the latter is the day of St. Matthias, outside leap years, there is only "ante diem sextum Kalendas Martias" on February 24th.

So, "ante diem quintum" would on normal years be February 25th, on leap years February 26th, either way it is the day after St. Matthias.

Hans Georg Lundahl
ut supra (vel infra in bloggo)