At Science Museum in San Sebastián (Spain), also known as "KutxaEspacio de la Ciencia", we can see this Foucault Pendulum.
Jean Bernard Leon Foucault (1819-1868) was a French physicist mainly known to design a pendulum to demonstrate the rotation of the planet Earth.
This device is a long spherical pendulum that can oscillate freely in any vertical plane and during long time. Due to the Earth rotation, the vertical plane on which oscillates is changing. Thus, usually they are placed in the ground, in the form of circumference, indicators to be seeing as it is varying this plane of oscillation.
