Léon Foucault pendulum suspended from the roof of the Panthéon, Paris. The experiment caused a sensation in both the learned and popular worlds, and ""Foucault pendulums"" were suspended in major cities across Europe and America and attracted crowds. In the following year he used (and named) the gyroscope as a conceptually simpler experimental proof. In 1855, he received the Copley Medal of the Royal Society for his 'very remarkable experimental researches'. Earlier in the same year he was made "physicien" (physicist) at the imperial observatory at Paris. In September 1855 he discovered that the force required for the rotation of a copper
Foucault pendulum vector diagrams the longitudinal (north-south) direction the surface velocity vectors on either side of the swing are balanced in the same direction and the center-point of the pendulum swing is moving along with the direction of rotation (see Figure 2A). For the equatorial pendulum with a swing in the latitudinal direction (along the equator) the surface velocity vectors on either side of the swing are not balanced in the same direction but are acting within the same "x"-"y" plane as the pendulum swing (see Figure 2B). These vectors are all of the same magnitude, that of the equatorial velocity. On one side