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 =
240 mm Trench Mortar in mid-1918. The mortar was first introduced in 1915 as the "Mortier de 240 mm CT" ("court de tranchee"). It was a short barreled version which fired a 192 lb (87 kg) bomb for 1,125 yards (1,030 m), using a propellant charge of 1 lb 9 oz (710 g). Its first major use was in the Champagne offensive of September 25, 1915. This was followed later by the "Mortier de 240 mm LT" ("long de tranchée") which was a long barreled version with improved firing arrangement and breech-loaded charge which fired a bomb , using a propellant charge of .