Time Zone Changes in 1993

an AP article (1993-08-22):

"The nearly 3,000 Americans living on this remote Pacific atoll have a good
excuse for not remembering Saturday night: there wasn't one.  Residents were
going to bed Friday night and waking up Sunday morning because at midnight
-- 8 A.M. Eastern daylight time on Saturday -- Kwajalein was jumping from
one side of the international date line to the other."
"In Marshall Islands, Friday is followed by Sunday", NY Times. 1993-08-22.
https://www.nytimes.com/1993/08/22/world/in-marshall-islands-friday-is-followed-by-sunday.html

Paul Eggert (1993-11-18):

Howse writes that Britain was the first country to use standard time.
The railways cared most about the inconsistencies of local mean time,
and it was they who forced a uniform time on the country.
The original idea was credited to Dr. William Hyde Wollaston (1766-1828)
and was popularized by Abraham Follett Osler (1808-1903).
The first railway to adopt London time was the Great Western Railway
in November 1840; other railways followed suit, and by 1847 most
(though not all) railways used London time.  On 1847-09-22 the
Railway Clearing House, an industry standards body, recommended that GMT be
adopted at all stations as soon as the General Post Office permitted it.
The transition occurred on 12-01 for the L&NW, the Caledonian,
and presumably other railways; the January 1848 Bradshaw's lists many
railways as using GMT.  By 1855 the vast majority of public
clocks in Britain were set to GMT (though some, like the great clock
on Tom Tower at Christ Church, Oxford, were fitted with two minute hands,
one for local time and one for GMT).  The last major holdout was the legal
system, which stubbornly stuck to local time for many years, leading
to oddities like polls opening at 08:13 and closing at 16:13.
The legal system finally switched to GMT when the Statutes (Definition
of Time) Act took effect; it received the Royal Assent on 1880-08-02.

In the tables below, we condense this complicated story into a single
transition date for London, namely 1847-12-01.  We don't know as much
about Dublin, so we use 1880-08-02, the legal transition time.

Attached to: GB-Eire (europe)

Paul Eggert (1993-11-18):

The mayor of Rio recently attempted to change the time zone rules
just in his city, in order to leave more summer time for the tourist trade.
The rule change lasted only part of the day;
the federal government refused to follow the city's rules, and business
was in a chaos, so the mayor backed down that afternoon.

Attached to: Brazil (southamerica)

Paul Eggert (1993-11-18):

Uruguay wins the prize for the strangest peacetime manipulation of the rules.

From Tim Parenti (2018-02-20), per Jeremie Bonjour (2018-01-31) and Michael
Deckers (2018-02-20):
... At least they kept good records...

http://www.armada.mil.uy/ContenidosPDFs/sohma/web/almanaque/almanaque_2018.pdf#page=36
Page 36 of Almanaque 2018, published by the Oceanography, Hydrography, and
Meteorology Service of the Uruguayan Navy, seems to give many transitions
with greater clarity than we've had before.  It directly references many laws
and decrees which are, in turn, referenced below.  They can be viewed in the
public archives of the Diario Oficial (in Spanish) at
http://www.impo.com.uy/diariooficial/

Ley No. 3920 of 1908-06-10 placed the determination of legal time under the
auspices of the National Institute for the Prediction of Time.  It is unclear
exactly what offset was used during this period, though Ley No. 7200 of
1920-04-23 used the Observatory of the National Meteorological Institute in
Montevideo (34° 54' 33" S, 56° 12' 45" W) as its reference meridian,
retarding legal time by 15 minutes 9 seconds from 1920-04-30 24:00,
resulting in UT-04.  Assume the corresponding LMT of UT-03:44:51 (given on
page 725 of the Proceedings of the Second Pan-American Scientific Congress,
1915-1916) was in use, and merely became official from 1908-06-10.
https://www.impo.com.uy/diariooficial/1908/06/18/12
https://www.impo.com.uy/diariooficial/1920/04/27/9

Ley No. 7594 of 1923-06-28 specified legal time as Observatory time advanced
by 44 minutes 51 seconds (UT-03) "from 30 September to 31 March", and by 14
minutes 51 seconds (UT-03:30) "the rest of the year"; a message from the
National Council of Administration the same day, published directly below the
law in the Diario Oficial, specified the first transition to be 1923-09-30
24:00.  This effectively established standard time at UT-03:30 with 30
minutes DST.  Assume transitions at 24:00 on the specified days until Ley No.
7919 of 1926-03-05 ended this arrangement, repealing all "laws and other
provisions which oppose" it, resulting in year-round UT-03:30; a Resolución
of 1926-03-11 puts the final transition at 1926-03-31 24:00, the same as it
would have been under the previous law.
https://www.impo.com.uy/diariooficial/1923/07/02/2
https://www.impo.com.uy/diariooficial/1926/03/10/2
https://www.impo.com.uy/diariooficial/1926/03/18/2

Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S

Attached to: Uruguay (southamerica)

Adam David (1993-11-06):

The name of the timezone in Iceland for system / mail / news purposes is GMT.

(1993-12-05):
This material is paraphrased from the 1988 edition of the University of
Iceland Almanak.

From January 1st, 1908 the whole of Iceland was standardised at 1 hour
behind GMT. Previously, local mean solar time was used in different parts
of Iceland, the almanak had been based on Reykjavík mean solar time which
was 1 hour and 28 minutes behind GMT.

"first day of winter" referred to [below] 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.

(1993-12-10):
I have a reference from the Oxford Icelandic-English dictionary for the
beginning of winter, which ties it to the ecclesiastical calendar (and thus
to the julian/gregorian calendar) over the period in question.
the winter begins on the Saturday next before St. Luke's day
(old style), or on St. Luke's day, if a Saturday.
St. Luke's day ought to be traceable from ecclesiastical sources. "old style"
might be a reference to the Julian calendar as opposed to Gregorian, or it
might mean something else (???).

Attached to: Iceland (backzone)