[tz] Fwd: DST changes in Hungary (full historical revision)
Michael H Deckers
michael.h.deckers at googlemail.com
Tue Jun 9 18:53:03 UTC 2020
On 2020-06-09 16:05, Paul Eggert wrote:
> ... I didn't see anything in the source about time-of-day for
> the transition, though. In cases like that we simply list the date. So for now I
> installed the attached proposed patch.
Yes, I know: in such cases the zic default is taken, so that the time
of day is supposed to jump from 00:00 to 23:43:40.
But this is certainly not the way of how railway times were adjusted.
Railway time was not produced by each station but was disseminated via
time signals sent from a single observatory. These time synchronization
signals were sent frequently (eg, every ten minutes or so) on a
line to all the stations in order to make sure that they all had the
time -- and the "same" time at least to the minute is essential for
So the jump in railway time would most likely be realized by the
of several time synchronization signals for a short while before the
(to alert the service personnel that clocks needed adjustment),
the synchronization signals for the time scale after the jump. In
the jump would be from (some signals before) 00:16:20 to the first
synchronization signal for the new scale, at 00:00 exactly.
In all the cases where I could check the exact time of day of a switch
to time zone time, this turned out to be the case -- except, of course,
for Dublin on 1916-10-01 where British law said that the time had to
from 03:00:00 to 02:25:21.1.
I guess I just wanted to say that the default jump produced by zic
is not necessarily a good guess of what really has happened (except
possibly for Britain).
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