corrected DST data Switzerland 1941 and 1942, final report

Alois Treindl alois at
Wed Dec 17 15:36:09 UTC 2008


I have researched the DST usage in Switzerland during the 1940ies.

As I wrote in an earlier message, I suspected the current tzdata values 
to be wrong. This is now verified.

I have found copies of the original ruling by the Swiss Federal 
government, in 'Eidgenössische Gesetzessammlung 1941 and 1942' (Swiss 
federal law collection) and attach GIF copies of the two pages for 1941.

DST began on Monday 5 May 1941, 1:00 am by shifting the clocks to 2:00 am
DST ended on Monday 6 Oct 1941, 2:00 am by shifting the clocks to 1:00 am.

DST began on Monday, 4 May 1942 at 01:00 am
DST ended on Monday, 5 Oct 1942 at 02:00 am

There was no DST in 1940, I have checked the law collection carefully. 
It is also indicated by the fact that the 1942 entry in the law 
collection points back to 1941 as a reference, but no reference to any 
other years are made.

Newspaper articles I have read in the archives on 6 May 1941 reported 
about the introduction of DST (Sommerzeit in German) during the previous 
night as an absolute novelty, because this was the first time that such 
a thing had happened in Switzerland.

I have also checked 1916, because one book source (Gabriel,  Traite de 
l'heure dans le monde) claims that Switzerland had DST in 1916. This is 
false, no official document could be found. Probably Gabriel got misled 
by references to Germany, which introduced DST in 1916 for the first time.

The tzdata rules for Switzerland must be changed to:
Rule  Swiss   1941    1942    -       May     Mon>=1  1:00    1:00    S
Rule  Swiss   1941    1942    -       Oct     Mon>=1  2:00    0       -

The 1940 rules must be deleted.

One further detail for Switzerland, which is probably out of scope for 
most users of tzdata:
The zone file
Zone    Europe/Zurich   0:34:08 -       LMT     1848 Sep 12
                         0:29:44 -       BMT     1894 Jun #Bern Mean Time
                         1:00    Swiss   CE%sT   1981
                         1:00    EU      CE%sT
describes all of Switzerland correctly, with the exception of
the Cantone Geneve (Geneva, Genf). Between 1848 and 1894 Geneve did not 
follow Bern Mean Time but kept its own local mean time.
To represent this, an extra zone would be needed.

Two GIF files are attached.

best regards
|| Alois Treindl,  Astrodienst AG,  mailto:alois at
|| Zollikon/Zurich, Switzerland
|| Free astrological charts at
|| SWISS EPHEMERIS Free Edition at
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