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Subject: Re: half-hour time zones
From: Brian Whatcott (inet@XXX.XXX)
Date: Sat Nov 03 2001 - 06:34:05 EST
At 06:44 PM 11/2/01 -0800, you wrote:
>Anyone know why some places have time offsets not an integral number
>of hours from Greenwich? Like Newfoundland.
///
>paulhirose@XXX.XXX (Paul Hirose)
Once upon a time, people used a natural means of setting a time reference,
by inspection of the Sun's meridian crossing (though they might prefer to
postpone their lunch break to a few hours later, at the hottest time of day,
once called 'noon').
Then the railroad engine was developed in a compact country where holding a
common time standard was no inconvenience. It soon spread to Russia and
USA where the Sun takes several hours to transit. For railroad schedulers,
this was a nightmare - and wasn't much fun for continental travellers.
Greenwich competed successfully with Paris Mean Time as a time standard for
marine navigators, and so some means of indexing time zones from Greenwich
was hit on as a means of bringing order to the railroad schedule.
The trick was to draw lines on the map which avoided large conurbations,
as far
as possible. Having neighbors in a town operating at one hour offsets would
not
be a pleasant sight. And so an Eastern, Central, Mountain, and Pacific time
zone
was decided, which worked well in general - though in particular, there
were difficulties.
To mention just two: near Chicago, where there were several towns near a
boundary,
another east of Eastern time zone where there was not enough territory for the
'center of gravity' for the territory to be one hour earlier. They chose
a half hour
decrement to keep the local noon (modern sense) near the clock noon.
[I have slightly dramatized this story, hopefully without blurring the
messy truth
excessively]
Brian W
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