Earth's circumference mile in the seventeenth century and the metre in the eighteenth. Earth's polar circumference is almost exactly 40,000 km because the metre was originally calibrated on this measurement (1/10-millionth of the distance between the poles and the equator), which is almost exactly 21,600 nautical miles (being defined as one minute of a degree – i.e. 360 multiplied by 60). It has been described as "the single most important measurement" of the Earth, assuming the Earth to be a sphere (the Earth is an technically an ellipsoid, albeit with just 0.3% flattening). Earth's circumference lines are the foundation of the coordinate
Icelandic units of measurement Icelandic units of measurement A number of units of measurement were used in Iceland to measure length, mass, area, capacity, etc. Since 1907, metric system has been compulsory in Iceland. A number of units were used and these units were analogues to Danish. A number of units were used in Iceland to measure length. One fet was equal to 0.31385 m and one sjómíla was equal to 1855 m, as they were defined by their metric equivalents. Some other units are given below: 1 lína = 1/144 fet 1 þumlungur = 1/12 fet 1 alin = 2 fet 1 faðmur