In article ,
karel wrote:

wrote in message
roups.com...

wrote:

...

And we were talking about
CAD software instead of how many kangaroo hops there are in a nautical
mile :-)


One nautical mile is the arc length of one arc-minute at the equator.
or along any other great circle

*NOT*EXACTLY*.

The Earth is not a perfect sphere. it is, technically, an 'oblate spheroid'.

The 'equatorial circumference' of the Earth is *NOT* the same as the
'polar circumference'. The two figures differ by _26_ miles.

Want to explain one great circle can be 26 arc-minutes shorter than another
great circle? *e*v*i*l* grin

A Nautical mile was origially defined in terms of the _equatorial_
circumference of the Earth.


Useful for navigation, do you suppose?
yes, quite
especially as meridians are great circles