Why is nautical miles the preferred measurement for naivgation?
As Q writes, the nautical mile is one minute of latitude; not approximately but exactly! That is; the earth is not exactly a sphere and a minute of latitude, as measures as an angle in relation to a celestial body, varies, but the nautical mile, or 1852 meter is the average minute of latitude on earth. The Babylonians divided the circle in 360 degrees on the belief that a year was 360 days. The Phoenicians then measured the north star elevation above the horizon as a measure of latitude. If you are e.g. at latitude 45 north, the north star is then 45 degrees over the horizon. Both Babylonians and Phoenicians used the sixtieth as a fraction. The degree (and later, the minute) was then divided into 60 subdivision; the minutes and seconds. It is interesting that today, we still measure angles and time, using those ancient units. While the Greek estimated quite accurately the earth circumference and therefore, the minute of latitude; the Romans used a mile that was somewhat shorter, and so
