What Sunday Letter was Year of Creation? II

What was the Sunday Letter for the Year of Creation?

Part I · Part II · Part III · Part IV · Part V

We will be starting from the present year, and we will be counting backwards, so, here is how we go when counting backwards in time:

2017	a
2016	c, b
2015	d
2014	e
2013	f
2012	a, g
2011	b
2010	c
2009	d
2008	f, e
2007	g
2006	a
2005	b
2004	d, c
2003	e
2002	f
2001	g
2000	b, a
1999	c
1998	d
1997	e
1996	g, f
1995	a
1994	b
1993	c
1992	e, d
1991	f
1990	g
1989	a
1988	c, b

2016
1988
0100 (20-19, but move over)
0030 (11-8, but move over 1, remain 20)
0028 (16-8)

So, the periodicity is once every 28 years - and in the Julian calendar that is always so.

In the Gregorian calendar, there are times, three per four centuries, when leap years are 8 years apart, which of course changes things.

28
56 (2*28)
84 (adding both, 3*28)

1988 c, b
0084
1904 c, b

Here we will be getting our first centurial year back which was not divisible by 400:

1904	c, b
1903	d
1902	e
1901	f
1900	g !
1899	a
1898	b
1897	c
1896	e, d
1895	f
1894	g
1893	a
1892	c, b

1904
1892
0100 (19-18, but move over)
0010 (10-9)
0012 (4-2)

1892 c, b
0084
1808 c, b
0012
1800 (18-0, but move over one)
1790 (10-9)
1796 (8-2) c, b
0084
1712 c, b

We are in trouble, we cannot use c, b for 1700 by 1712-12, since 1700 was not in Gregorian a leap year.

1712	c, b
1711	d
1710	e
1709	f
1708	a, g
1707	b
1706	c
1705	d
1704	f, e
1703	g
1702	a
1701	b
1700	c !
1699	d
1698	e
1697	f
1696	a, g
1695	b
1694	c
1693	d
1692	f, e
1691	g
1690	a
1689	b
1688	d, c
1687	e
1686	f
1685	g
1684	b, a
1683	c
1682	d
1681	e
1680	g, f
1679	a
1678	b
1677	c
1676	e, d
1675	f
1674	g
1673	a
1672	c, b

And let's check wikipedia on the matter:

1672 (MDCLXXII) was a leap year starting on Friday (dominical letter CB [ - yes!]) of the Gregorian calendar and a leap year starting on Monday (dominical letter GF) of the Julian calendar.

Of course, week days were the same in countries with Gregorian and Julian calendars, what was different was the dates. In countries with Julian calendar, January 1 had been 10 days later, as in 16th C. since the year in which Gregorian calendar was introduced (1600 was a leap year and did not change the glitch between the calendars, 10 days after as before).

Does 10 days glitch match up with CB corresponding to GF?

1672, first Sunday of Gregorian year was January 3. So, January 3 (C) being ten days later in Julian style, it fell on January 13. An N+5, with January 3 being an N+2. 5-2=3.

C+3=CDEF

Seems to me, Julian year should have had Sunday letter or Dominical letters FE rather than GF, in 1672? Is that just me? If so, what did I do wrong?

Hans Georg Lundahl
ut supra
uel in bloggo
ut infra

PS, found the problem! If Gregorian January 3 was a Sunday, obviously Julian January 3 would be on Gregorian January 13, but 10 days is not a week, so that was not a Sunday. Here we get the table:

Jan 1672
Greg.		Jul.
A 1	F
B 2	Sa
C 3	Su
D 4	M
E 5	Tu
F 6	W
G 7	Th
A 8	F
B 9	Sa
C 10	Su
D 11	M	A 1
E 12	Tu	B 2
F 13	W	C 3
G 14	Th	D 4
A 15	F	E 5
B 16	Sa	F 6
C 17	Su	G 7

So, yes, it was GF after all./HGL

PPS Julian GF, that is./HGL