[tz] 1911 France change from Paris to GMT

Steve Allen sla at ucolick.org
Wed Jun 17 07:37:29 UTC 2020

On Sat 2020-06-13T19:39:42-0700 Paul Eggert hath writ:
> Although I haven't found sources for what practices were in place at the Eiffel
> Tower on March 10/11, 1911, I did find the following abstract on page 265 of
> Science Abstracts. Section B - Electrical Engineering. Vol. XIV. 1911. It
> suggests that an automatic relay was feasible at the Eiffel Tower in March 1911,
> as Norddeich was already doing that in 1910. And this source confirms that the
> Eiffel Tower was routinely broadcasting time signals near midnight by 1910.

Bulletin Horaire has an answer
vol 3 no 46 is a history of timekeeping
page 257 says

The time signals, inaugurated on May 23, 1910, were given only at
night, at 0h0m t. m. civil of Paris.  From the following November
21, they were also given in daytime, at 11h.0m. The law of March 9,
1911 having adopted, for the legal time in France, that of the
Greenwich meridian, the hours of emission were brought forward to
10h45m and 23h45m, from July 1, 1911

So 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.

Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
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Santa Cruz, CA 95064           https://www.ucolick.org/~sla/  Hgt +250 m

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