[tz] uniform time in Switzerland in second half of 19th century

Alois Treindl alois at astro.ch
Wed Sep 11 11:35:41 UTC 2013

On 11.09.13 10:56, Paul Eggert wrote:
> Thanks for looking into that.  It confirms that Bern time was not
> exactly GMT+0:30, though we still don't know what it was;
> our current value (derived from one of the Shanks values) is probably
> wrong by a few seconds.  It also confirms my suspicion that the 1894
> transition was messy, but it suggests that our 1894 transition
> date of June 1 is correct for Zurich, as my guess is that Zurich was not
> one of the recalcitrant cantons (though it'd be nice to confirm this).

Shanks gives Bern time meridian as 7°26' which is (because he is never 
more precise than minutes of arc) as close as he can get to the 
coordinates of the old Bern observatory, which are also the base point 
of Swiss country topography (Fundamenalpunkt der Schweizer 

The Federal regulations say

Der Fundamentalpunkt im Meridianzentrum der alten Sternwarte von Bern 
hat die ellipsoidische Länge l = 7°26'22.50" und die ellipsoidische 
Breite j = 46°57'08.66".

I.e. the meridian for Bern mean time, which was based on this 
observatory, is 7°26'22.50"

Expressed in time, it is 0h29m45.5s

> It'd also be helpful to know what time of day the 1894 transition
> was; we're currently guessing 00:00.

I guess so as well. Lacking other information, it seems sensible to 
assume a change of time

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