4137 / Mass (Kilogram): Watt-scale at the BIPM in SЏvres bei Paris: EUROPA, FRANKREICH, PARIS, SEVRES (PARIS, FRANCE), 29.08.2007: Watt balance experiment at the International Bureau of Weights and Measures/BIPM in Sevres near Paris, France, an attempt to redefine the SI base unit of mass, the kilogram, by tying it to a fundamental constant, the Planck constant. The balance compares the gravitational force on a mass - here represented by 5 copper weights - with the magnetic force on a coil in a magnetic field. Levers, hinges, counterweights, an electrostatic motor, sensors & a laser interferometer are needed to carry out the experiment. The final setup will be placed inside a vacuum chamber. At right: physicists Hao Fang, Alain Picard. - Marc Steinmetz / VISUM - Keywords: France, Paris, Sevres, Bureau, International, des, Poids, et, Mesures, BIPM, science, physics, metrology, base, unit, international, system, of, units, SI, measure, metrical, standard, accurate, accuracy, people