Miles and Metrics

vega2052 · May 17, 2006

well,
though the old metre-prototype is stored in Paris, the origin of the
metre is also based on the Blue Planet.
It's 10 million metres,i.e. 10000 km, from the equator to the North Pole.
That results in 40000 km around the world (at the equator).
/Mike

SVFlyAway · May 17, 2006

1 nautical mile equals one minute of latitude -- equal to 1.85 kilometers
and 1.15 statute miles. (Technically it is defined as a minute of arc along
a great circle).

All nautical charts I know of use NM as the basis for distance (except the
charts for the Great Lakes in North America - those are done in statute
miles - they are also polyconic rather than Mercator projections).

The meter originally was intended to be one ten millionth of the distance
from a pole to the equator along a meridian. The French measured it about
1800 on an expedition along the meridian from Dunkerque to Barcelona,
through Paris. But it was slightly miss-measured, but just a fraction of a
millimeter because of the irregularity of the earths shape (so the earth's
circumference is about, but not exactly 40 million meters).

That is probably more than you wanted to know, but I teach this stuff and
find is very interesting.

_____

From: AlbinVega@yahoogroups.com [mailto:AlbinVega@yahoogroups.com] On Behalf
Of Victor Schreffler
Sent: Wednesday, May 17, 2006 9:32 AM
To: AlbinVega@yahoogroups.com
Subject: [AlbinVega] Miles and Metrics

Regarding Steve's observation about using miles for the foreseable
future...aren't miles, nautical of course, based on the size and shape
of the planet while the metre is based on the distance of Paris to
somewhere?

Victor
V1553

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stevebirch2002 · May 17, 2006

Hi Chris

Many thanks for the metre explanation, didn’t know that. Always thought
it was the length of a Frenchmans arm as just that bit longer than a
brit so they could pick our pockets!! Only joking.

Cheers

Steve Birch (Technical)

lastgaspid · May 17, 2006

Victor I think you are correct on the Metre.
Dave
V3233

wxt8981 · May 17, 2006

Hi Steve;
The meter was established in 1773 as the 1/10,000,000
distance from the pole to the equator.
Today the meter is the distance light travels in vacuum in
the time interval of 1/299 792 458 of a second.
The uncertainty is plus/minus 2.5 x 10 to the minus
eleventh power.
The nautical mile is based on the 360 degrees of the
equator.
The statut mile is 5280 feet (1,609 km).
Wilhelm, V-257

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Vega1447 · May 17, 2006

Steve,
sounds like you need a plate of Freedom Fries.....

John

Vega 1447 Breakaway

vega1860 · May 17, 2006

Knots and Nautical miles are good old navy terms. The nautical mile was based on the circumference of the earth at the equator. Since the earth is 360 degrees of longitude around, and degrees are broken into 60 so-called "minutes", that means there are 360 * 60 = 21,600 "minutes" of longitude around the earth. This was taken as the basis for the nautical mile; thus, by definition, 1 minute of longitude at the equator is equal to 1 nautical mile. So the earth is ideally, by definition, 21,600 nautical miles (and 21,600 "minutes" of longitude) in circumference at the equator. If anyone ever asks you how far is it around the earth, you can quickly do the math in your head (360 degrees * 60 minutes per degree) and answer "about 21,600 nautical miles!" FAQ: What is a knot? What is a nautical mile?

Chuck Rose

emmajen5 · May 17, 2006

The mix of measurements in the world of aviation can be
very interesting. Here in metric Canada flying
distance is measured in Nautical miles, although
distance within an airport control zone is expressed in
statute miles. Wind speed is in knots. Altitude is
measured in feet but temperature is expressed in
celsius.

Garry
"Raven", V.2427