On 12/13/11 8:19 AM, Chuck Harris wrote:
But it wouldn't be a nice 10,000 km from pole to equator...
And surprise! It still isn't! It is more like 12,713.5 km.
Huh?
For WGS84 ellipsoid
Equatorial radius 6378km * 2 * pi = 40080.4 km
Polar Radius 6357km
(Clarke 1866 is 6377.5, 6356.6)
At about 49 degrees latitude (e.g. Paris), the radius of curvature is
about 6366km which corresponds to 9999.68 km from pole to equator. A
more precise calculation gives a meridional radius of 6367.4491 km for a
circumference 40007.86 km..
Delambre estimated 6377 for equatorial in 1810.
... unless you measure it to one significant figure.
Metric vs English is purely about a set of arbitrary constants.
Decimal pounds, decimal inches and decimal seconds is just as
arbitrary, and just as easy to use as the metric system.
And besides that's the whole Britannia rules the waves so they get the
prime
meridian and the French make good maps so they get the meter thing.
I think it was more that the French were so ghoulishly violent
with their revolution that the rest of Europe was afraid of them.
Yes, that might have had an effect...
-Chuck Harris
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