The Foundation of the Metric System in France in the 1790s: The Importance of Etienne Lenoir’s Platinum Measuring Instruments

On 22nd July 1799 the definitive standards of the metric system, the platinum metre and the platinum kilogramme, were ceremonially deposited in the French National Archives (), and on 10th December 1799 a law was passed confirming their status as the only legal standards for measuring length and mass in France (). The accurate determination of these standards had occupied a number of outstanding French scientists for ten years, using elaborate equipment partly made from platinum by Etienne Lenoir, a skilled instrument maker. This work had been undertaken after more than a century of discussion. The events surrounding this momentous occasion which now affects all our everyday lives are described here.