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
Thai units of measurement "wa", "ngan" and "rai" are still used in measurements of land area. The "baht" is still used as a unit of measurement in gold trading. However, one "baht" of 96.5% gold bullion is defined as 15.16 grams rather than the generic standard of 15 grams. The "baht" has also become the name of the currency of Thailand, which was originally fixed to the corresponding mass of silver. Thai units of measurement Thailand adopted the metric system on 17 December 1923. However, old Thai units are still in common use, especially for measurements of land. Before metrication, the traditional system of