How to look up historical time zones by date and location
Rustom Mody
rustompmody at gmail.com
Mon Aug 18 11:41:00 EDT 2014
On Monday, August 18, 2014 7:21:53 PM UTC+5:30, Joel Goldstick wrote:
> On Mon, Aug 18, 2014 at 9:12 AM, luofeiyu wrote:
> > I found that it is a concept LMT local mean time can express my meaning.
> Local Mean Time is time based on the actually astronomical position of
> the sun. It is defined as 12 noon when the sun is at its high point,
> directly south in the sky. This is the time you get when you read a
> sundial!
> So each town or village set their clocks differently. That all
> changed with the railroad industry. Once trains began traveling, time
> zones were invented so that everyone knew exactly what time it was in
> order to keep trains from meeting on the same tracks and colliding.
> Trains need time schedules. Time zones make this possible.
Add to that the fact that any two places even say a kilometer apart,
will have different LMT.
Naturally if one chooses a least count, say 1 sec, then that distance will
be larger.
40075 km equatorial circumference
86400 secs in a day (60×60×24)
40075/86400 = 2.1
ie LMT changes by 1 sec for every 2.1 km E-W along the equator
And even here the distance would shrink going towards the poles.
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