Basics of Coordinate Metrology
Unit 1:  Units - History of the Definition of Length

Digression
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around 7000 BC Definition of a foot from about 7000 BC 
1 foot corresponds to the length of a foot from the big toe to the heel.
Definition of a foot (about 7000 BC)
around 4000 BC In Egypt and Chaldea, the basic measure for measuring length is the royal yardstick.
around 3000 BC In Chaldea the units for determining length, volume, mass and time are related to one another. The basis of the measurement was a cube with an edge length of 1 foot. The edge length corresponded to a unit of length. The water to fill the cube gave the unit for mass and volume. The time for the water to drain from the cube (water clock) gave a unit of time.
2100 BC On the statue of Gudea, the Prince of Sumer, the unit of length of 1 foot is subdivided into 16 finger's breadths.
Old Egyptian scale
(about 3000 BC)
2000 BC On a copper bar (the "Yardstick of Nippur") with a length of 1103.5 mm, a few linear measures have been marked: a yardstick, tile, foot, hand and finger's breadth. The 1103.5 mm are divided into 4 feet = 16 hands = 64 finger's breadth.
2000 BC

 

 The Greek adopt the schoinos (unit of length: ~ 6.3 km) from the Egyptians who had adopted it from the Persians.
around 25 BC

 

 A book on architecture describes a device for measuring distances which worked like a simple mileage indicator.
807 AC A uniform measurement and weight system is introduced in the empire of Charlemagne.
1101 The yard is established in Henry's II England as the length of his arm from the shoulder to the tip of his middle finger.
Yard - Definition under Henry II
1215 A uniform measurement and weight system is established in England, which, however, did not get accepted.
1324 The inch is established in England as the length of three barley grains taken from the center of an ear.
1494 King Henry VII tries to push through a measurement and weight system binding for entire England.
1588 In England legally binding standard measures and weights are produced. Their copies are distributed among the calibration officers.
Determination of the "yardstick" around 1595
1 yardstick = placing the left foot of the first 16 persons coming out of church on a particular Sunday next to each other
1627 In Ulm Johannes Kepler wants an oak tank to be produced which defines the measures valid in the city.
1722 In the Electorate of the Saxony, milestones are erected which indicate distances.
1791 According to the proposal by Pierre-Simon Laplace, the "metre" is defined as the ten-millionth part of the earth's meridian quadrant.
1 meter = forty-millionth part of the meridian of the earth on the Paris meridian
1795 The French National Convent decides that the "metre" is the forty-millionth part of the meridian of the earth going through the Observatory of Paris.
1799 The prototype of the meter is produced in the form of a platinum rod.
1824 In England the yard is defined as 0.9143834 m.
Prototype of the meter in the form of a platinum rod
1829 Henry Madslay constructs the micrometer screw which can be used to measure to the nearest 1/1000 of an inch.
1830 In Saxony the local length measure "Lachter" is defined as 2 m.
1831 Carl Friedrich Gauß suggests the absolute System of Units including the units millimeter, meter, milligram and second.
1840 "metre" and "kilogramme" are established as legally binding units of measure for length and weight.
Prototyp "M" of the German standard meter
1860 The upper house of the German Parliament suggests the creation of a uniform measurement system.
1868 The "Decree on weights and measures" of the North German Federation makes the metric system compulsory for wide parts of Germany.
1871 The "Decree on weights and measures" of the North German Federation gains acceptance in the whole of Germany due to laws issued by the German Empire.
1875 An international office for measurements and weights (BPIM) is established.

Bureau International des Poids et Mesures
1889 The prototypes for the meter and kilogram are established by the BIPM.
1918 The USSR introduces the metric system.
1960 The 11th General Conference for Measurements and Weights ratifies the "International System of Units (SI)". It establishes six base units: meter, kilogram, second, Ampere, Kelvin and candela. The length of the meter is redefined (krypton - wavelength definition).
1983 The meter is defined more precisely than previously as "the length traveled by light in a vacuum during (1/299,792,458)th" of a second.
1980-1985 The conversion to SI units takes place in many areas of economy and research.
1985 China decides to introduce the SI units by the year 1990.