Metric measurement. Artwork demonstrating metric measurements. The measurements are (clockwise from top left): the litre; the kilogram; the metre; the stere (unit of volume); the Franc (decimalised currency); the are (unit of area). The metric system was first introduced in France during the 1790s. It was an attempt to simplify ancient, complicated units of measurement and currency. The metre was defined as one ten-millionth of the distance between the equator and the North Pole; a litre was a thousandth of a cubic metre and the kilogram is the weight of a litre of water. The metric system is now the means of scientific measurement. French illustration from 1799.