The Metre (or Meter)
In 1793, during Napoleon's time, the French government adopted a new system of standards called the metric system, based on what they called the metre. Relying on the assumed constancy of the earth's size as a basis for the permanency of their standards, this unit was reckoned to be one ten-millionth part of the distance from North Pole to Equator measured on a straight line running along the surface of the earth through Paris. Other linear units of the system were then set up in decimal ratios with the metre. Of particular interest in the present context is the millimetre - one thousandth part of a metre.
When first introduced the new system was not popular. Indeed, Napoleon finally was forced to abandon it. But, in 1837, France returned to the metre, this time for good, hoping to make it universal throughout the world. Today almost all countries use a modernized metric system called SI.