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Units in everyday use by country as of 2019 The history of the metric system began during the Age of Enlightenment with measures of length and weight derived from nature, along with their decimal multiples and fractions. The system became the standard of France and Europe within half a century. Other measures with unity ratios [Note 1] were added, and the system went on to be adopted across ...
The kilometre (SI symbol: km; / ˈ k ɪ l ə m iː t ər / or / k ɪ ˈ l ɒ m ə t ər /), spelt kilometer in American and Philippine English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo-being the SI prefix for 1000).
Today, all base units are defined by physical constants; not by example as physical objects as they were in the past. Other metric system variants include the centimetre–gram–second system of units, the metre–tonne–second system of units, and the gravitational metric system. Each has unaffiliated metric units. Some of these systems are ...
Today only the stone continues in customary use for measuring personal body weight. The present stone is 14 pounds (~6.35 kg), but an earlier unit appears to have been 16 pounds (~7.25 kg). The other units were multiples of 2, 8, and 160 times the stone, or 28, 112, and 2240 pounds (~12.7 kg, 50.8 kg, 1016 kg), respectively.
In formal situations (such as official road signs) only kilometres are given. The Swedish mile was standardised as 36,000 Swedish feet or 10.6884 kilometres (6.6415 miles) in 1649; before that it varied by province from about 6 to 14.485 km. [43] Before metrication, the Norwegian mile was 11.298 kilometres (7.020 miles).
Littlehales noted in 1909: "The lunar-distance tables were omitted from the Connaissance des Temps for the year 1905, after having retained their place in the French official ephemeris for 131 years; and from the British Nautical Almanac for 1907, after having been presented annually since the year 1767, when Maskelyne's tables were published."
An early definition of the metre was one ten-millionth of the Earth quadrant, the distance from the North Pole to the Equator, measured along a meridian through Paris.. The history of the metre starts with the Scientific Revolution that is considered to have begun with Nicolaus Copernicus's publication of De revolutionibus orbium coelestium in 1543.
The odometer was also independently invented in ancient China, [3] possibly by the prolific inventor and early scientist Zhang Heng (78 AD – 139 AD) of the Han dynasty. By the 3rd century (during the Three Kingdoms Period), the Chinese had termed the device as the 'jì lĭ gŭ chē' (記里鼓車), or ' li -recording drum carriage' (Note: the ...