Chemist Antoine-Laurent Lavoisier called the journey “the most important mission that any man has ever been charged with.” After several years of work, they delivered their calculations (recent satellite surveys have affirmed their values were off, but not by very much). In 1792 astronomers Jean-Baptiste Delambre and Pierre Méchain began their measurements of the meridian. Borda’s invention of the repeating circle, a surveying instrument more accurate than a conventional quadrant, made this option more desirable. The distance would be calibrated by measuring the meridian arc that runs from Dunkirk, on France’s northern coast, via Paris, to Barcelona on Spain’s Mediterranean coast. The challenge to define the meter’s length, was taken up by a group of distinguished scientists: Jean-Charles de Borda, Joseph-Louis Lagrange, Gaspard Monge, Pierre-Simon Laplace, and Condorcet.Īfter some discussion, the group adapted an idea proposed by Wilkins a century before-one meter would equal one ten-millionth of the distance from the North Pole to the Equator. It remained in use as the definitive metric standard until replaced in 1878. In 1799 France’s premier instrument maker, Étienne Lenoir, made the definitive meter in platinum, replacing a provisional standard made from copper. Two are still in place today, but only one in its original location: 36 rue de Vaugirard, in front of the Palace of Luxembourg.
After 1796, engraved marble meter bars were installed in public places around Paris. In order to accustom the public to the new meter, the French government distributed leaflets, posters, and conversion tables. Each one could be divided and multiplied using a decimal scale. The savants eventually agreed that the various units of length, mass, and volume of the new system would all relate to each other.
The republican government promised the people of France “one law, one weight, and one measure,” a goal that would take 10 years to be approved and even longer to be accepted. The National Assembly agreed and asked the Academy of Sciences, led by Condorcet, to form a commission to select a new basic unit of measurement. The diplomat Charles-Maurice de Talleyrand-Périgord then proposed that an unchanging standard should provide the basic unit of measurement, which he hoped would be adopted by other nations and harmonize international trade. But for the savants, this approach seemed an arbitrary, unscientific baseline. “Vendémiaire” was the autumnal month of vintage, when grapes were harvested for wine.Īn early proposal was to impose the Parisian measures on the rest of the nation. The old months were replaced by ones with names to describe the natural phenomenon from that time of year: A period between avril (April) and mai (May) became “Floréal” for blooming flowers. In October 1793 they replaced the Gregorian calendar with their republican calendar (which would stay in use until late 1805). It was little wonder that this chaotic system was prone to fraud and stifled domestic and foreign trade.įrench revolutionaries not only reformed their government they also remade their calendars. An aune, used to measure cloth, was based on the width of local looms. There was little or no standardization: In Paris, a pinte was the equivalent of 0.93 liters in Saint-Denis, it was 1.46. Some measures were extremely basic: In early 18th-century Bordeaux, a unit of land was defined by how far a man’s voice carried.
The savants faced reforming a patchwork of up to 800 different units of measurement, from the toise to the lieue and the quart to the pinte. Over the centuries since Rome’s fall, it had broken down into myriad local systems across France. It also ended the right of the nobility to control the weights and measures used in their fiefdoms.Īs elsewhere in Europe, the old weights and measures originated in a system used by the Romans. The early stages of the revolution famously abolished the last vestiges of feudalism in France. ( A century earlier, France was also the dueling capital of Europe.) Order from chaosĪt the time of the French Revolution in 1789, Paris was the global capital of science, whose leading lights, the savants (wise ones), made lasting contributions to physics, chemistry, and biology.