FW: Time zone: the next generation
Clive D.W. Feather
clive at demon.net
Fri Mar 4 13:56:50 UTC 2005
Olson, Arthur David (NIH/NCI) said:
> - Prior to the Julian conversion, different locales had different
> rules for when the number of the year changed. In and before
> 1752 in Great Britain, for instance, the number of the year changed
> on 25 March; 1-24 March belonged to the previous year! With
> the adoption of the Gregorian calendar, the change was
> universally 1 January.
It's not even that simple:
- England and Wales used the March 25th rule, but Scotland used January 1st.
- Some uses even in E&W followed the January 1st rule anyway (e.g. leap
- The change wasn't synchronised with the Gregorian change, but happened
a little earlier: 1751 began on Mar 24th but 1752 began on 1st January
(thus, while 1752 lost 11 days, 1751 lost 83).
> (For this reason, you'll sometimes see
> eighteenth-century dates as O.S. ("Old Style") or N.S. ("New Style")
> when the year would otherwise be ambiguous.
And the day, actually.
> - As you correctly observe, leap years were observed irregularly
> in Rome in Republican and early Imperial times. In fact, they were
> so irregularly observed that it was occasionally necessary to
> intercalate entire months.
You're confusing the pre-Julian calendar (which used intercalary months)
with the Julian one (which used leap days). It wasn't so much "irregular"
as "erroneous" - leap days were inserted every *three* years in the period
starting 46 BCE; when the mistake was spotted, several leaps had to be
omitted. I *believe* that 45, 45, ... 9 BCE were all leap years, then there
were 15 common years in a row, with 8 CE being the next leap year.
> - I use a message catalog (the same catalog in which I hold localised
> month names) to hold a locale's Julian conversion date, and then
> select the catalog according to LC_TIME. Tcl's ordinary
> message catalog functionality can be used to change the date.
There may be more than one conversion date: Sweden converted twice
(including a year which had a February 30th in it).
Clive D.W. Feather | Work: <clive at demon.net> | Tel: +44 20 8495 6138
Internet Expert | Home: <clive at davros.org> | Fax: +44 870 051 9937
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