By the mid 19th century France had defined a nautical mile via the original 1791 definition of the metre, one ten-millionth of a quarter meridian.
Thus, Hues explicitly used nautical miles while Gunter did not. Since the Earth is not a perfect sphere but is an oblate spheroid with slightly flattened poles, a minute of latitude is not constant, but about 1861 metres at the poles and 1843 metres at the Equator.
The United States chose five significant digits for its nautical mile, 6080.2 feet, whereas the United Kingdom chose four significant digits for its Admiralty mile, 6080 feet. In 1929, the international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as exactly 1852 metres.
Britain adopted it in 1970, but legal references to the obsolete unit are now converted to 1853 metres. == Similar definitions == The metre was originally defined as of the length of the meridian arc from the North pole to the equator, thus one kilometre of distance corresponds to one centigrad of latitude.
The equatorial circumference is slightly longer than the polar circumference – the measurement based on this ( = 1855.3 metres) is known as the geographical mile. == See also == Conversion of units Orders of magnitude (length) == Notes == == References == Mile Units of length
Thus, Hues explicitly used nautical miles while Gunter did not. Since the Earth is not a perfect sphere but is an oblate spheroid with slightly flattened poles, a minute of latitude is not constant, but about 1861 metres at the poles and 1843 metres at the Equator.
France made it legal for the French Navy in 1906, and many metric countries voted to sanction it for international use at the 1929 International Hydrographic Conference. Both the United States and the United Kingdom used an average arcminute, specifically, a minute of arc of a great circle of a sphere having the same surface area as the Clarke 1866 ellipsoid.
The authalic (equal area) radius of the Clarke 1866 ellipsoid is .
France made it legal for the French Navy in 1906, and many metric countries voted to sanction it for international use at the 1929 International Hydrographic Conference. Both the United States and the United Kingdom used an average arcminute, specifically, a minute of arc of a great circle of a sphere having the same surface area as the Clarke 1866 ellipsoid.
France made it legal for the French Navy in 1906, and many metric countries voted to sanction it for international use at the 1929 International Hydrographic Conference. Both the United States and the United Kingdom used an average arcminute, specifically, a minute of arc of a great circle of a sphere having the same surface area as the Clarke 1866 ellipsoid.
The United States chose five significant digits for its nautical mile, 6080.2 feet, whereas the United Kingdom chose four significant digits for its Admiralty mile, 6080 feet. In 1929, the international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as exactly 1852 metres.
The United States did not adopt the international nautical mile until 1954.
Britain adopted it in 1970, but legal references to the obsolete unit are now converted to 1853 metres. == Similar definitions == The metre was originally defined as of the length of the meridian arc from the North pole to the equator, thus one kilometre of distance corresponds to one centigrad of latitude.
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