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
Seer (unit) Seer (unit) A Seer (also sihr) is a traditional unit of mass and volume used in large parts of Asia prior to the middle of the 20th century. It remains in use only in a few countries such as Afghanistan and Iran, although in the latter it indicates a smaller unit of weight than the one used in India. In India, the seer (Government seer) was defined by the Standards of Weights and Measures Act (No. 89 of 1956, amended in 1960 and 1964) as being exactly equal to 1.25 kg (1.792 lb). However, there were many local variants of