No subject

GMT. Previously, local mean solar time was used in different parts of Iceland,
the almanak had been based on Reykjavik mean solar time which was 1 hour and
28 minutes behind GMT.

Summertime when it was applied was always by putting the clock an hour forward
during the summer months, which made the clock time equal to GMT. The following
list shows when this summertime was in force. The time of the clock change is
specified in GMT.

year	from			to
----	----			--

1908-1916 no summertime

1917	20.Feb. 0:00		21.Oct. 1:00
1918	20.Feb. 0:00		16.Nov. 1:00

1919-1938 no summertime

1939	30.Apr. 0:00		29.Nov. 2:00
1940	25.Feb. 3:00		 3.Nov. 2:00
1941	 2.Mar. 2:00		 2.Nov. 2:00
1942	 8.Mar. 2:00		25.Oct. 2:00

1943-1946 rule (first Sunday in March until first Sunday in winter)

1943	 7.Mar.	2:00		24.Oct. 2:00
1944	 5.Mar.	2:00		22.Oct. 2:00
1945	 4.Mar.	2:00		28.Oct. 2:00
1946	 3.Mar.	2:00		27.Oct. 2:00

1947-1967 rule (first Sunday in April until first Sunday in winter)

1947	 6.Apr.	2:00		26.Oct. 2:00
1948	 4.Apr.	2:00		24.Oct. 2:00
1949	 3.Apr.	2:00	******* 30.Oct. 2:00 (delayed by 1 week)
1950	 2.Apr.	2:00		22.Oct. 2:00
1951	 1.Apr.	2:00		28.Oct. 2:00
1952	 6.Apr.	2:00		26.Oct. 2:00
1953	 5.Apr.	2:00		25.Oct. 2:00
1954	 4.Apr.	2:00		24.Oct. 2:00
1955	 3.Apr.	2:00		23.Oct. 2:00
1956	 1.Apr.	2:00		28.Oct. 2:00
1957	 7.Apr.	2:00		27.Oct. 2:00
1958	 6.Apr.	2:00		26.Oct. 2:00
1959	 5.Apr.	2:00		25.Oct. 2:00
1960	 3.Apr.	2:00		23.Oct. 2:00
1961	 2.Apr.	2:00		22.Oct. 2:00
1962	 1.Apr.	2:00		28.Oct. 2:00
1963	 7.Apr.	2:00		27.Oct. 2:00
1964	 5.Apr.	2:00		25.Oct. 2:00
1965	 4.Apr.	2:00		24.Oct. 2:00
1966	 3.Apr.	2:00		23.Oct. 2:00
1967	 2.Apr.	2:00		29.Oct. 2:00

1968	 7.Apr. 2:00	(actually GMT after this)

"first day of winter" referred to above, means the first day of the 26 weeks
of winter, according to the old icelandic calendar that dates back to the time
the norsemen first settled Iceland. The first day of winter is always Saturday,
but is not dependent on the Julian or Gregorian calendars. This is the reason
for the discrepancy with October 1961.
I can find out more exactly how to determine when it falls, if necessary. It
is a pity I don't have that information handy, otherwise I could include it
here.

There are more serious discrepancies before 1941 which are not obviously
explainable. What to do... (?)

--
Adam David  <adam at veda.is>