Foucault pendulum sharing the rotation of the earth about its own axis, the suspension point of the pendulum traces out a circular path during one sidereal day. At the latitude of Paris, 48 degrees 51 minutes north, a full precession cycle takes just under 32 hours, so after one sidereal day, when the Earth is back in the same orientation as one sidereal day before, the oscillation plane has turned by just over 270 degrees. If the plane of swing was north-south at the outset, it is east-west one sidereal day later. This also implies that there has been exchange of momentum;
Griffith Observatory the Foucault pendulum, which was designed to demonstrate the rotation of the Earth. The exhibits also included a 12-inch (305mm) Zeiss refracting telescope in the east dome, a triple-beam coelostat (solar telescope) in the west dome, and a thirty-eight foot relief model of the moon's north polar region. Col. Griffith requested that the observatory include a display on evolution which was accomplished with the Cosmochron exhibit which included a narration from Caltech Professor Chester Stock and an accompanying slide show. The evolution exhibit existed from 1937 to the mid-1960s. Also included in the original design was a planetarium under the