在现代社会生活中，几乎很少有人不知道长度单位“米”。但“米制”单位源于何处，它与测绘有何关系？却鲜为人知。

        原来早在1792年，法国国民议会决定建立新的长度单位要与地球椭球子午线弧长发生联系。为此，从1792～1797年进行了弧度测量，计算了1800年德兰勃尔椭球，取其子午圈长度的四千分之一作为长度单位，称为1米。1872年在巴黎召开的世界长度会议上决定，制造31支“米原型尺”，每支尺都编了号。除了N0.6号为国际原尺外,其它的都以国际原型尺为标准,精密检定,求出长度,分发各国保存,作为长度单位的标准。我国因未加入国际度量衡协会，没有获得米原型尺。这种实物“米”定义为“1米是N0.6‘米原型尺’在冰溶点温度时两刻划线间的距离。”其缺点是：难以复现，容易损坏；随时间有缓慢变化；精度不够高，仅1～2×10-6；少数国家有，满足不了大多数国家长度传递的要求。因此，实物米需用自然米来代替。

        1960年第11届国际计量大会通过了光波米的定义，第二次“米”定义为“氪-86原子的2P10 和5d5 能级之间跃迁辐射在真空中波长的 1650 763．73倍为 1米。” 氪-86谱线轮廓稍微有些不对称，光波米在实验室复现精度为 4 × 10-9。

        1983年第17届国际计量会议上通过了第三次光速米的定义，“1米是光在真空中 299 792 458分之一秒时间内所传播的距离。”

        用子午圈弧长来制定长度单位，在中国早已采用。清康熙四十三年（1702年），规定子午圈  l°弧长为200里，l里分1800尺，即1尺等于0.O1″子午圈弧长。

        1984年我国国务院颁布的《中华人民共和国法定计量单位》规定，从1990年以后，长度单位一律采用国际单位制的单位名称米，取消日常生活中长期沿用的市制计量单位市尺。
 

Life in modern society, few people almost do not know the length of units "meters." But the "metric" units where it had any relationship with the mapping? But little known.

         As early as the 1792 original, the French National Assembly decided to establish a new unit of length with the Earth ellipsoid radial contact length. To this end, in 1797 from 1792 ~ to the curvature measurement, calculated in 1800 ellipsoid Derlandbore, select the meridian 1/4000 length as the length of units, known as 1 meter. Held in Paris in 1872 the length of the world decided to create 31 "m-foot prototype," each ruler are numbered. In addition to the international N0.6 its original feet, the other is the international prototype of the foot as a standard, precision control, calculated the length of the distribution of States to preserve, as a standard unit of length. China's failure to join the international weights and measures association, not foot-meter prototype. This kind, "m" defined as "1 meter is N0.6 'm prototype scale' in the ice melting point temperature between the two characters from the line." The drawback is: it is difficult replicable, easy to damage; with slow time change; accuracy is not high enough, only 1 ~ 2 × 10-6; a few countries, most countries can not meet the requirements of the length of transmission. Therefore, the physical meter required to replace the natural rice.

         1960 11th International Metrology波米the General Assembly adopted the definition of light, the second "m" defined as "-86 krypton atoms 2P10 and 5d5 transitions between energy levels of radiation in a vacuum wavelength of 1650 to 763.73 times 1 meters. "Krypton -86 slightly asymmetric line profile, light in the laboratory complex is mile accuracy of 4 × 10-9.

         1983 17th International Conference on measurement of the third the speed of light through the definition of m "1 m is the light in a vacuum 299 792 458 time per second by the spread of distance."

         Meridian arc length used to develop the length of units, is already being used in China.四十三年Qing Emperor Kangxi (1702), in the l ° meridian arc length of 200 years, l-ri at 1800 feet, that is equal to 1 foot 0.O1 "meridian arc.

         1984 China's State Council issued the "People's Republic of China legal units of measurement" provides that after 1990, the length of units using the International System of Units will be the name of meters, the abolition of the daily life of the city and long-term use of measurement units.