[tz] 1911 France change from Paris to GMT

Paul Eggert eggert at cs.ucla.edu
Wed Jun 17 17:44:01 UTC 2020

On 6/17/20 12:37 AM, Steve Allen wrote:

> Tour Eiffel may have broadcast one last set of midnight pulses on
> old Paris Mean Time at the June 30/July 1 boundary, or they may have
> omitted those pulses and waited until new 10:45 the next morning.

The French regulations quoted in
<https://mm.icann.org/pipermail/tz/2020-June/029101.html> say that the old-style
signals should be broadcast “Jusqu’a la nuit du 30 juin 1911 exclusivement” and
that the new-style signals should be broadcast “A partir de la nuit du 30 juin
an 1er juillet inclusivement”.

The “exclusivement” and “inclusivement” suggest that the new-style signals
should have won at the boundary, i.e., that the Eiffel Tower's last old-style
signal was at 1911-06-30 11:04:00 Paris Mean Time and the first new-style signal
was at 1911-06-30 23:45:00 GMT which temporally preceded what would have been
the next old-style signal (1911-07-01 00:00:00 Paris Mean Time = 1911-06-30
23:50:39 GMT).

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