I spend an inordinate amount of my spare cycles thinking about latitude and longitude. Today I went looking for some ballpark figure to use that would let me approximate measurement in degrees, minutes and seconds of latitude in miles. I was intrigued to find that:
The nautical mile was historically defined as a minute of arc along a great circle of the Earth.
An extremely helpful forum post tells more of the story.
Special bonus revelation: speed measured in knots is really just speed measured in nautical miles per hour.
Stay tuned for picas, points and agate lines.