How France laid the basics of the world metric system
He is there, a simple rule presented on an ordinary table and yet it is our “national” etalon meter! Because, let’s learn, that kept at the Breteuil pavilion, sits since 1875 of the International Bureau of Weights and Measures, is the “international” stallion. In a way, we have before us the eldest “son” of the “real” meter, which has determined, since the French Revolution all our length measurements.
On May 20, 1875, 17 countries signed in Paris, a “meter convention”. That is to say, they adopted this decimal metric system. Since then, most countries of the globe have followed them because the global harmonization of measurement units is an essential fact to guarantee the reliability of scientific, industrial and commercial exchanges.
The original meter
“Each country which adopted the metric system has thus received a stallion like the one for the meter and for the kilogram,” explains the engineer Bartholomé Blanc, of the National Laboratory of Metrology and Essays (LNE) which introduced journalists, exceptionally, in this “white chamber” (sterile) where these historical pieces are preserved, in an iridié platinum, a hard alloy that does not alter. The meter meter has a X-shaped section in order to be less sensitive to deformations.
“Today, this metallic object is designated as the” meter of the archives “, specifies Jean-Pierre Wallerand, head of the dimensional team of the LNE. It is only there to recall that the meter was defined during the revolution as on the 10 millionth in the quarter of the terrestrial meridian ”. Because since the 1960s, the stallion has been defined by the wavelength of a laser: “With our” laser-stallions “we arrive at a specific length at 10-9 decimal instead of 10-7. The measures are therefore now dematerialized, made in “black boxes” that we discover in this laboratory.
Seek precision
It is at the LNA that the “stall holds” sent by manufacturers arrive to be checked. We realize that in our modern world, from miniature watchmaking to the construction of a dam of several kilometers, from the weighing of micrograms of drugs to the tons of a rocket, everything must be evaluated with very fine precision. This laboratory is therefore a calibration place: “But we only confirm the reference stallions, adds Jean-Pierre Wallerand. To manufacture meters of seamstress or school rules, manufacturers will go to seek stallion stallions, or even more derived from the reference, because they are not necessary to be at this specific point. “
The LNE is always a place of research, linked but also in competition with other international laboratories, to go always further in the infinitely small or in the gigantic. For example, a team is currently testing a device capable of measuring very long distances with an error of less than a millimeter per kilometer. Interest? Detecting field movements around a dam, for example, to anticipate possible damage.
