From ccbd7d2eff2449cef48aefcd41dd87034940007b Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Fri, 12 Jun 2020 14:35:33 -0700 Subject: [PATCH 13/47] Go back to midnight transitions for France etc. * NEWS: Simplify. * africa (Africa/Algiers, Africa/Tunis): * europe (Europe/Monaco): Propagate changes from Paris. * europe (Europe/Paris): Assume 1911 transition was at 00:00. * theory.html (Accuracy of the tz database): Adjust accordingly. --- NEWS | 11 ++++------- africa | 6 +++--- europe | 63 ++++++++++++++++++++++++++++++++++++++++--------------------- theory.html | 9 +++++---- 4 files changed, 54 insertions(+), 35 deletions(-) diff --git a/NEWS b/NEWS index ec73943..3bcddd0 100644 --- a/NEWS +++ b/NEWS @@ -16,13 +16,10 @@ Unreleased, experimental changes (Thanks to Géza Nyáry.) Also, the 1890 transition to standard time was on 11-01, not 10-01 (thanks to Michael Deckers). - The 1911-03-11 French transition from +00:09:21 to +00 is now - modeled as occurring at 00:09:21, not at 00:01. Clocks reportedly - stopped at 00:00 for 9 minutes, 21 seconds but this cannot be - represented in tzdb, so tzdb instead represents the also-common - practice of keeping an old clock running until the new clock - started up. Similarly for the 1891-03-16 transition. - (Thanks to Michael Deckers.) + The 1891 French transition was on March 16, not March 15. The + 1911-03-11 French transition was at midnight, not a minute later. + Monaco's transitions were on 1892-06-01 and 1911-03-29, not + 1891-03-15 and 1911-03-11. (Thanks to Michael Deckers.) Changes to code diff --git a/africa b/africa index d5ddbce..567ad90 100644 --- a/africa +++ b/africa @@ -89,8 +89,8 @@ Rule Algeria 1980 only - Apr 25 0:00 1:00 S Rule Algeria 1980 only - Oct 31 2:00 0 - # See Europe/Paris for PMT-related transitions. # Zone NAME STDOFF RULES FORMAT [UNTIL] -Zone Africa/Algiers 0:12:12 - LMT 1891 Mar 16 0:02:51 - 0:09:21 - PMT 1911 Mar 11 0:09:21 # Paris MT +Zone Africa/Algiers 0:12:12 - LMT 1891 Mar 16 + 0:09:21 - PMT 1911 Mar 11 # Paris Mean Time 0:00 Algeria WE%sT 1940 Feb 25 2:00 1:00 Algeria CE%sT 1946 Oct 7 0:00 - WET 1956 Jan 29 @@ -1466,7 +1466,7 @@ Rule Tunisia 2006 2008 - Oct lastSun 2:00s 0 - # See Europe/Paris for PMT-related transitions. # Zone NAME STDOFF RULES FORMAT [UNTIL] Zone Africa/Tunis 0:40:44 - LMT 1881 May 12 - 0:09:21 - PMT 1911 Mar 11 0:09:21 # Paris MT + 0:09:21 - PMT 1911 Mar 11 # Paris Mean Time 1:00 Tunisia CE%sT # Uganda diff --git a/europe b/europe index 6e3fe33..e8ec780 100644 --- a/europe +++ b/europe @@ -1342,21 +1342,24 @@ Link Europe/Helsinki Europe/Mariehamn # he announced "Heure nouvelle". See the "Le Petit Journal 1911-03-11". # https://gallica.bnf.fr/ark:/12148/bpt6k6192911/f1.item.zoom # -# From Paul Eggert (2020-06-11): +# From Michael Deckers (2020-06-12): +# That "all French clocks stopped" for 00:09:21 is a misreading of French +# newspapers; this sort of adjustment applies only to certain +# remote-controlled clocks ("pendules pneumatiques", of which there existed +# perhaps a dozen in Paris, and which simply could not be set back remotely), +# but not to all the clocks in all French towns and villages. For instance, +# the following story in the "Courrier de Saône-et-Loire" 1911-03-11, page 2: +# only works if legal time was stepped back (was not monotone): ... +# [One can observe that children who had been born at midnight less 5 +# minutes and who had died at midnight of the old time, would turn out to +# be dead before being born, time having been set back and having +# suppressed 9 minutes and 25 seconds of their existence, that is, more +# than they could spend.] +# +# From Paul Eggert (2020-06-12): # French time in railway stations was legally five minutes behind civil time, -# which explains why "old time" ran to 00:04:21 instead of to 00:09:21. -# The Brooklyn Daily Eagle Almanac (1912), page 494, says: -# -# ALL CLOCKS STOPPED IN FRANCE. -# On March 10, 1911, all clocks in the Republic of France were stopped -# for 9 minutes and 21 seconds. This was in obedience to a measure -# adopted by the French Senate, which went into effect at midnight.... -# Owing to this change in time a question arose in the French press as -# to whether or not a child that was born and died within the elapsed -# time could be said to have legally lived. -# -# There are similar stories in the Washington Herald and Washington Times -# (1911-03-11). The law's text (which Michael Deckers noted is at +# which explains why railway "old time" ran to 00:04:21 instead of to 00:09:21. +# The law's text (which Michael Deckers noted is at # ) says only that # at 1911-03-11 00:00 legal time was that of Paris mean time delayed by # nine minutes and twenty-one seconds, and does not say how the @@ -1364,9 +1367,13 @@ Link Europe/Helsinki Europe/Mariehamn # # tzdb has no way to represent stopped clocks. As the railway practice # was to keep a watch running on "old time" to decide when to restart -# the other clocks, model this as a transition for "old time" at 00:09:21. -# Do something similar for the 1891-03-16 transition, which has a similar -# problem in Algiers and Monaco. +# the other clocks, this could be modeled as a transition for "old time" at +# 00:09:21. However, since the law was ambiguous and clocks outside railway +# stations were probably done haphazardly with the popular impression being +# that the transition was done at 00:00 "old time", simply leave the time +# blank; this causes zic to default to 00:00 "old time" which is good enough. +# Do something similar for the 1891-03-16 transition. There are similar +# problems in Algiers, Monaco and Tunis. # # Shank & Pottenger seem to use '24:00' ambiguously; resolve it with Whitman. @@ -1434,7 +1441,7 @@ Rule France 1976 only - Sep 26 1:00 0 - # on PMT-0:09:21 until 1978-08-09, when the time base finally switched to UTC. # Zone NAME STDOFF RULES FORMAT [UNTIL] Zone Europe/Paris 0:09:21 - LMT 1891 Mar 16 - 0:09:21 - PMT 1911 Mar 11 0:09:21 # Paris MT + 0:09:21 - PMT 1911 Mar 11 # Paris Mean Time # Shanks & Pottenger give 1940 Jun 14 0:00; go with Excoffier and Le Corre. 0:00 France WE%sT 1940 Jun 14 23:00 # Le Corre says Paris stuck with occupied-France time after the liberation; @@ -2075,10 +2082,24 @@ Zone Europe/Chisinau 1:55:20 - LMT 1880 2:00 Moldova EE%sT # Monaco -# See Europe/Paris for PMT-related transitions. +# +# From Michael Deckers (2020-06-12): +# In the "Journal de Monaco" of 1892-05-24, online at +# https://journaldemonaco.gouv.mc/var/jdm/storage/original/application/b1c67c12c5af11b41ea888fb048e4fe8.pdf +# we read: ... +# [In virtue of a Sovereign Ordinance of the May 13 of the current [year], +# legal time in the Principality will be set to, from the date of June 1, +# 1892 onwards, to the meridian of Paris, as in France.] +# In the "Journal de Monaco" of 1911-03-28, online at +# https://journaldemonaco.gouv.mc/var/jdm/storage/original/application/de74ffb7db53d4f599059fe8f0ed482a.pdf +# we read an ordinance of 1911-03-16: ... +# [Legal time in the Pricipality will be set, from the date of promulgation +# of the present ordinance, to legal time in France. Consequently, legal +# time will be retarded by 9 minutes and 21 seconds.] +# # Zone NAME STDOFF RULES FORMAT [UNTIL] -Zone Europe/Monaco 0:29:32 - LMT 1891 Mar 16 0:20:11 - 0:09:21 - PMT 1911 Mar 11 0:09:21 # Paris MT +Zone Europe/Monaco 0:29:32 - LMT 1892 Jun 1 + 0:09:21 - PMT 1911 Mar 29 # Paris Mean Time 0:00 France WE%sT 1945 Sep 16 3:00 1:00 France CE%sT 1977 1:00 EU CE%sT diff --git a/theory.html b/theory.html index de105f2..1a5b568 100644 --- a/theory.html +++ b/theory.html @@ -692,10 +692,11 @@ href="https://www.dissentmagazine.org/blog/booked-a-global-history-of-time-vanes
  • The tz database cannot represent stopped clocks. - However, on 1911-03-11 at 00:00, French clocks were changed by - stopping them for 9 minutes, 21 seconds. This is approximated - in tz as a transition from 00:09:21 back - to 00:00:00 that day. + However, on 1911-03-11 at 00:00, some public-facing French clocks + were changed by stopping them for a few minutes to effect a transition. + The tz database models this via a + backward transition; the relevant French legislation does not + specify exactly how the transition was to occur.
  • Sometimes historical timekeeping was specified more precisely -- 1.8.3.1