Unfortunately the grad (gon or grade), which was the original decimal metric
angle unit, was never able to replace the Babylonian degrees, minutes, and
seconds. I believe this is because the British dominated world mapping in
the 18th and 19th centuries, and they used degrees. Today, gons are NOT
approved for use with SI--only degrees are allowed. It is extremely unlikely
that we will throw away our universal system of spherical geographic
coordinates (latitude and longitude), which is based on degrees and has been
used for two millenia. Even the metric UTM rectangular coordinates are based
on standard meridians measured in degrees. Therefore, minutes of latitude
("nautical miles") are likely to remain the most convenient distance unit
for long-range navigation on Earth.
The irony is that the meter was originally based on the size of the Earth,
with navigation obviously in mind: 1 grad = 100 km, 1 cgrad = 1 km. But this
advantage has never been realized because the grad was never widely adopted.
We can be very happy, however, that for large-scale, short range navigation,
the kilometer grid of the rectangular UTM coordinate system is far easier to
use than miles (statute or nautical), minutes, feet, yards, or any other
units. And UTM and GPS receivers are definitely encouraging ordinary
red-blooded Americans who travel in the boondocks (hunters and wilderness
enthusiasts and such) to think in meters and kilometers.
> -----Original Message-----
> From: Joseph B. Reid
> >
> The nautical mile is approximately one minute of latitude measured
> north-south. It is unlikely that the nautical mile will be
> abolished until
> new maps and charts are available gridded in gons (or, if you prefer,
> grads). Then the kilometre would replace the nautical mile for
> navigation.
>
> The nautical mile is much older than the metric system.
>
>
