[LEAPSECS] Straw men

Clive D.W. Feather clive at davros.org
Tue Jan 10 03:12:53 EST 2012

Ian Batten said:

>> A more accurate statement is: ?Civil time is mean solar time?, because this is really just a definition of terms (p.7)


> I know you really, fervently believe that to be not only true currently but inevitably and essentially true, but it just isn't.

Indeed, and Rob needs to realize this. Until he does, he just comes over as
a fanatic.

> For a start off, as the examples of Penzance, Vigo and Brest show (and I'm sure there are other examples of places 4 and more degrees east of the timezone they are administratively placed in where the offset is in the opposite direction),

Doing a quick search, in the westwards direction the limit in the UK is
about 8 degrees west (the westmost large town appears to be Enniskillen, at
7d37'). Portugal reaches over 17 degrees west, and Iceland just manages
24 degrees.

Eastwards is harder, because there appears to be a tendency for people to
move their time east. Poland just manages 9 degrees east (i.e. 24E when in
zone 1), and it appears that Norway manages 10d54'.

Going further afield, India uses the time of 87d30' east, but stretches
from 68d16'E to 97d05'E, so errors of 19 degrees west and 10 degrees east.
China uses the time of 120E, but stretches from 73d38' to 134d33', so a
massive 46d22' west to 14d33' each. Incidentally, China has land borders
*at both ends* where crossing them involves a 3 hour change in local time.
Is this a record?

In the US, PST stretches about 4 west to 6 east, MST about 11d30' west to
about 4d30' east, CST about 16d30' west to just over 5 east, and EST about
14 west to just over 8 east. Including Canada stretches EST to almost 18
east, MST from over 31 west to over 17 east, and PST to over 20 west.

In other words, in parts of Canada:

> civil time is at best a very loose approximation of mean solar time

by over 2 hours.

(All the above ignores DST.)

> By driving for four hours, you can alter the relationship between civil time and mean solar time by twenty minutes.

And, as I point out above, there are places where you can walk a few metres
and it changes by 3 hours.

Clive D.W. Feather | If you lie to the compiler,
Email: clive at davros.org | it will get its revenge.
Web: http://www.davros.org | - Henry Spencer
Mobile: +44 7973 377646

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