Nautical mile 1 sea mile", followed by "For most practical purposes distance is measured from the latitude scale, assuming that one minute of latitude equals one nautical mile". One tenth of a nautical mile is a cable length. The derived unit of speed is the knot, defined as one nautical mile per hour. The metre was originally defined as of the meridian arc from the North pole to the equator passing through Dunkirk. The Earth’s circumference is therefore approximately 40,000 km. The equatorial circumference is slightly longer than the polar circumference – the measurement based on this (40,075.017 km x x =
The Nautical Almanac US, an official (and initially separate) series of [[ephemeris]] publications began with the issue for 1855 as "The [[American Ephemeris and Nautical Almanac]]"; but before that, the British "Nautical Almanac" was commonly used on American ships and in the United States – sometimes in the form of an independently printed American 'impression' instead. Almanac data is now also available online from the [[US Naval Observatory]]. [[Category:1767 establishments in Great Britain]] [[Category:British non-fiction books]] [[Category:United States Naval Observatory]] [[Category:Astronomical almanacs]] The Nautical Almanac The Nautical Almanac has been the familiar name for a series of official British almanacs published under various