Longitude

[David Casseres]

>So the reason for using nautical miles in air and sea travel is that by
>these two modes of transportation you're more closely traveling along a
>perfect sphere, whereas on land you have to deal with and traverse a more
>irregular terrain?

Not so much that, I think, as the fact that at sea you are likely (even 
today) to be navigating in terms of latitude and longitude rather than in 
terms of objects on the surface of the Earth, i.e. landmarks, signs, 
roads, etc.  When your "terrain" is featureless you have to look to 
Heaven -- this also applied to the Arab travelers who invented celestial 
navigation to get them across the great deserts.  And the heavens are 
measured in degrees and minutes of arc, and so having distance units that 
are defined against those degrees and minutes just makes the arithmetic 
easier.

>Another question:  is the nautical mile part of the metric system?  Do
>pilots from countries other than the US reckon their distances in
>kilometers or nautical miles?  Is the kilometer, for some reason, equally 
>accurate over both land and sea?

Pilots in the U.S. use statute miles, nowadays, and the rest mostly use 
kilometers.  Given electronic navigation, the use of landmarks, and 
calculators, these units are just as good as nautical miles and of course 
they are familiar.  The nautical mile is more and more an orphan, but I 
predict that sailors will continue to use it for a long time since they 
are the most conservative of craftsmen, even when they have GPS receivers 
in their hands.

I don't know a thing about the British nautical mile that someone 
mentioned.  Could we have a bit more about it and why it is different 
from the one Americans use?

>I realize that this has nothing to do with Pynchon...but who knows, it
>might be useful for M&D.

I doubt there is anything that really has *nothing* to do with Pynchon!


Cheers,
David