The units of measurement "meter" and "kilometer" are both from France. The unit of length "meter" in the international system of units originated in France. 1790 In May, a special committee composed of French scientists suggested that one fortieth of the total length of the earth meridian passing through Paris should be used as the unit of length-meter, and 179 1 year was approved by the French Parliament. 1790 In May, a special committee composed of French scientists set the equatorial circumference 1/40000 as 1 km. 1 km =10000m.
Counting unit:
People have no counting unit when expressing numbers, so it is particularly troublesome to express counting by counting chips. For the convenience of counting, decimal system was gradually discovered, and many numbers can be easily combined with tens from 0 to 9 to produce counting units.
Source of unit:
A long time ago, people used the human body as the standard to determine the unit of measurement for length. More than 3,000 years ago, the forearms of people were called "wrist rulers".
In the 6th century BC, a person stretched his arms to both sides, and the distance between the two middle fingertips was set as 1 foot. In the era of Julius Caesar in ancient Rome, it was stipulated that the 1000 step for Roman soldiers to March was 1 mile.
At the end of the 8th century AD, Charlemagne of the Roman Empire set his foot length as 1 foot.
In the 9th century AD, Henry I, a Saxon dynasty, stipulated that the arm should be stretched forward horizontally, and the distance from the tip of the nose to the fingertips was 1 yard. In the 10 century, King Edgar of England set the length between his thumb joints as 1 inch.
According to legend, Dayu in ancient China used his body length as the length standard to measure the water control project. Li Shimin, Emperor Taizong of Tang Dynasty, stipulated his double steps, that is, one step for his left foot and one step for his right foot, which was called one step. It was stipulated that one step was five feet, and three hundred steps were one mile. Later, it was stipulated that the length of the middle finger of human hand was 1 inch.
/kloc-in the 0/8th century, people began to feel that there were many disadvantages in using the human body as the length standard, and they were eager to find a fixed length measurement unit, and finally thought of the earth.
Emperor Kangxi of the Qing Dynasty in China stipulated that the meridian of 1 degree was 200 Li, and each Li was 1800 ft.
1789, the famous mathematicians da Lambert and hai obtained that 1 meter is equal to 0.5 12074 tuva (an ancient French ruler) through field measurement.
1875, diplomatic representatives from 17 countries signed the metric convention in Paris, France, and officially confirmed the metric ruler as the international common ruler.
1960, at the 1 1 International Metrology Conference, it was decided to abolish the prototype of the international meter scale used since 1889, and take 1650763.73 times of the wavelength of the orange spectrum generated by atomic discharge of isotope nitrogen -86 as/kloc. The accuracy of this light gauge is very high, and the error is only one in two billion.