[tz] [PATCH 3/3] * europe (Europe/Vaduz): Now a link to Europe/Zurich.

Paul Eggert eggert at cs.ucla.edu
Tue Sep 10 04:51:48 UTC 2013

Russ Allbery wrote:

> The question is whether Liechtenstein would have done something
> other than all of Switzerland during that time period (with the
> exception, noted in comments but not in rules due to being out of
> scope historically for the database, of Cantone Geneve, which kept
> LMT rather than Berne Mean Time from 1848 to 1894).

Careful -- it sounds like you're starting to get addicted too....

Your note gave me an excuse to do a bit more research.  A problem
with that analysis is that it relies on the tz data, which says
that all of Switzerland (except Geneva) switched at the same time,
which I'm pretty sure is not true.  Shanks records it that way,
but this is most likely due to a dubious decision to guess the
date of the 1848 Swiss constitution as the introduction of almost
country-wide standard time, which historically makes little sense
-- it's like guessing July 4, 1776 as the date of construction of
the White House.

My bit of research found that Shanks's guess is almost surely
wrong (no surprise there), and I have the following further patch
to push.  One of these days I'll try to track down Messerli's
thesis, as he talks about Zurich quite a bit, according to the
Hathi Trust index (which is online even though Messerli's thesis
is not).

I hope this helps to explain why any distinction between Zurich
and Vaduz is not supported by reliable sources, as far as we know.

More generally, almost all of the tz database's transitions from
LMT to standard time lack reliable sources, and are most likely
wrong even in the city they purport to represent and are almost
certainly wrong for the region.  In that sense, the
LMT-to-standard-time transitions are no more reliable or useful
than the LMT offsets themselves are, and by themselves should not
justify the existence of distinct Zones in the database.

>From 147ea0873b6c18c3cd68895d951d0df22bd316c6 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert at cs.ucla.edu>
Date: Mon, 9 Sep 2013 21:49:20 -0700
Subject: [PATCH] * europe (Europe/Zurich): Move 1848 transition to 1855.

 europe | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/europe b/europe
index 434a2f1..79376b8 100644
--- a/europe
+++ b/europe
@@ -2661,11 +2661,20 @@ Zone Europe/Stockholm	1:12:12 -	LMT	1879 Jan  1
 # follow Bern Mean Time but kept its own local mean time.
 # To represent this, an extra zone would be needed.
+# From Paul Eggert (2013-09-09):
+# We can find no reliable source for Shanks's claim that all of Switzerland
+# except Geneva switched to Bern Mean Time at 00:00 on 1848-09-12.  On the
+# contrary, a more-reliable source talks about "the gradual introduction of a
+# national time (from the 1850s)" (Google translation) with a switch to CET in
+# 1894; see Speich's review of Messerli's thesis, Traverse 1997/3, 131-3
+# <http://www.tg.ethz.ch/dokumente/pdf_files/rez_messerli.pdf>.  For now, model
+# this messy process as a transition in 1855.  The "0:29:44" is also suspect.
 Rule	Swiss	1941	1942	-	May	Mon>=1	1:00	1:00	S
 Rule	Swiss	1941	1942	-	Oct	Mon>=1	2:00	0	-
-Zone	Europe/Zurich	0:34:08 -	LMT	1848 Sep 12
+Zone	Europe/Zurich	0:34:08 -	LMT	1855 # See above comment.
 			0:29:44	-	BMT	1894 Jun # Bern Mean Time
 			1:00	Swiss	CE%sT	1981
 			1:00	EU	CE%sT

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