switches at 1883-11-18 at the same instant
On 2018-03-19 09:18, Glenn A. Walsh wrote in a post to a different mailing list:
Centennial: Official Enactment of U.S. Time Zones & Daylight Saving Time A century ago today (March 19), U.S.President Woodrow Wilson signed into law the Standard Time Act of1918, which officially established time zones in the United States aswell as Daylight Saving Time. Although time zones had beenunofficially observed for a few decades. MORE INFO - CLICK ON IMAGE OR LINK --- LIKE THIS POST? - PLEASE SHARE! Link >>> http://spacewatchtower.blogspot.com/2018/03/centennial-official-enactment-of...
The link describes (among many other things) how the Allegheny Observatory synchronized the switch of US railway times to grid time zones. As one would expect, the switch was done at a single instant, when UT was 1883-11-18 + 18 h. This differs from the current description in tzdb which uses different instants for different target time zones -- not a likely choice for simplifying a nationwide railway schedule. Thus I propose: - Zone America/Los_Angeles -7:52:58 - LMT 1883 Nov 18 12:07:02 + Zone America/Los_Angeles -7:52:58 - LMT 1883 Nov 18 10:07:02 - Zone America/Boise -7:44:49 - LMT 1883 Nov 18 12:15:11 + Zone America/Boise -7:44:49 - LMT 1883 Nov 18 10:15:11 - Zone America/Phoenix -7:28:18 - LMT 1883 Nov 18 11:31:42 + Zone America/Phoenix -7:28:18 - LMT 1883 Nov 18 10:31:42 - Zone America/Denver -6:59:56 - LMT 1883 Nov 18 12:00:04 + Zone America/Denver -6:59:56 - LMT 1883 Nov 18 11:00:04 - Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 12:12:53 + Zone America/North_Dakota/Beulah -6:47:07 - LMT 1883 Nov 18 11:12:53 - Zone America/North_Dakota/New_Salem -6:45:39 - LMT 1883 Nov 18 12:14:21 + Zone America/North_Dakota/New_Salem -6:45:39 - LMT 1883 Nov 18 11:14:21 - Zone America/North_Dakota/Center -6:45:12 - LMT 1883 Nov 18 12:14:48 + Zone America/North_Dakota/Center -6:45:12 - LMT 1883 Nov 18 11:14:48 - Zone America/New_York -4:56:02 - LMT 1883 Nov 18 12:03:58 + Zone America/New_York -4:56:02 - LMT 1883 Nov 18 13:03:58 Michael Deckers.
On 03/19/2018 03:09 PM, Michael H Deckers via tz wrote:
the switch was done at a single instant, when UT was 1883-11-18 + 18 h. This differs from the current description in tzdb which uses different instants for different target time zones -- not a likely choice for simplifying a nationwide railway schedule.
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.
On 2018-03-19 16:51, Paul Eggert wrote:
On 03/19/2018 03:09 PM, Michael H Deckers via tz wrote:
the switch was done at a single instant, when UT was 1883-11-18 + 18 h. This differs from the current description in tzdb which uses different instants for different target time zones -- not a likely choice for simplifying a nationwide railway schedule.
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.
Civil time zone acceptance and standardization often lagged railway time zone standardization by years. A recent post documented Paris railway station clocks showing railway time inside and civil time outside 5 minutes apart IIRC. Clock towers in a number of locations are documented having two minute hands to show both local and standard times, until using standard time became a commonly accepted practice in that locale. The time zone db documents common civil practice not industry practices; for example, North American natural gas flows according to industry practice in a year starting Nov 1 and day starting 09.00 CT: time zones in North America would be greatly simplified if every industry followed this model and used CT. ;^> -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
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.
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.
participants (3)
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Brian Inglis -
Michael H Deckers -
Paul Eggert