KNOTS AND MILES The U. S. Statute Mile is 5,280 feet in length. On the Continent most of the old miles, which varied in length from about 3,300 feet to over 36,000 feet, have been replaced, officially at least, by the kilometer, which equals 0.6214 statute mile or 3,280.8 feet. The Nautical, Geographic, or Sea Mile at any place is considered, for purposes of navi- gation, to be equal to the length of one minute of longitude at that place. The U. S. Nautical Mile is 6,080.20 feet in length and equal to one-sixtieth of a degree of a great circle of a sphere whose surface is equal in area to the area of the surface of the earth (Clarke's spheroid of 1866). The Knot is a measure of speed; a speed of one knot being a speed of one nautical mile an hour. A Nautical Mile — 1.1516 statute miles; a Fathom — 6 feet; a Cable — 100 fathoms or 600 feet or approximately 0.1 nautical mile. To convert statute miles into nautical miles, multiply statute miles by 0.8684; to convert nautical miles into statute miles, multiply nautical miles by 1.1516, or roughly 1-1/7. United States Air Forces and the Navy use the knot as the standard aeronautical unit of speed and the nautical mile as the correspond- ing unit of distance.