[tz] switches at 1883-11-18 at the same instant

Michael H Deckers michael.h.deckers at googlemail.com
Tue Mar 20 22:11:18 UTC 2018

   On 2018-03-19 22:51, Paul Eggert wrote abput my proposal to
   change the switches on 1883-11-18 in the US to a single instant:

> But we have a reliable eyewitness account that New York had two noons 
> that day. See the quotation from William F. Allen in the 
> "northamerica" file, taken from Bartky's 1989 paper 
> <http://dx.doi.org/10.2307/3105430>. So the New York switch cannot 
> have been at 18:00 GMT that day, as that would have meant two 
> instances of 13:00, not two instances of 12:00. Bartky writes that it 
> was called the "day of two noons" because eastern parts of the new 
> zones observed noon twice, which wouldn't have happened if everyone 
> switched at 18:00 GMT.
> Allen also wrote that New York got its time signal from the Naval 
> Observatory, not from the Allegheny Observatory. Back then, different 
> observatories were competing for the time-setting business. Perhaps 
> the SpaceWatchtower sources included Allegheny partisans? (It's hard 
> to tell from its source list.)
> It's possible that parts of the US switched at around 12:00 local time 
> while other parts switched at 18:00 GMT; but if that's the case, I'd 
> like sources for which parts switched which way.
    Yes, I do not know a primary source supporting my propsal,
    so you are right to ignore it.

    On the other hand, one cannot trust [Bartky 1989] in this
    technical matter: he implies on [page 49] that the railway time
    scales switching on 1883-11-18 started the new scale with
    1883-11-18 + 12 h while he reproduces a primary source on [p 50]
    that shows that the new scale in Louisville, KY started with
    1883-11-18 + 10 h, so that no "double noon" could occur.

    Michael Deckers.

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