GNU bug report logs - #16663
emacs/calc/date

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Message #11 received at 16663 <at> debbugs.gnu.org (full text, mbox):

From: Steve Allen <sla <at> ucolick.org>
To: 16663 <at> debbugs.gnu.org
Subject: bug#16663: emacs/calc/date
Date: Thu, 6 Feb 2014 19:00:10 -0800

On Wednesday, February 5, 2014 8:03:33 PM UTC-8, Jay Belanger wrote:
> These are during daylight savings time:
> > <8:00pm Sun Mar 18, 1610>,
> > <8:00pm Wed Mar 15, 1620>,
> > <8:00pm Sat Mar 13, 1630>,

> The hour differences are because of daylight savings time.

The notion of daylight saving time in the 17th century should be a
clue that some underlying concept here is very wrong in the calendar
model.

Also note that it was 4 March 1674 ( Julian calendar, Old Style
corresponding to 1675-03-14) that King Charles II appointed John
Flamsteed as the first Astronomer Royal, and the observatory wasn't
built until the next year, so before then GMT wasn't even a thing.

In this and many other cases of computed proleptic dates the only
reasonable interpretation of the time scale is Universal Time (UT, not
UTC).  There have never been leap seconds in Universal Time, for UT is
actually a count of calendar days that can be subdivided into seconds,
not a count of seconds that can be integrated into days.

--
Steve Allen                 <sla <at> ucolick.org>                WGS-84 (GPS)
UCO/Lick Observatory--ISB   Natural Sciences II, Room 165    Lat  +36.99855
1156 High Street            Voice: +1 831 459 3046           Lng -122.06015
Santa Cruz, CA 95064        http://www.ucolick.org/~sla/     Hgt +250 m

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