Pendulum plane of oscillation of a pendulum, like a gyroscope, tends to stay constant regardless of the motion of the pivot, and that this could be used to demonstrate the rotation of the Earth. He suspended a pendulum free to swing in two dimensions (later named the Foucault pendulum) from the dome of the Panthéon in Paris. The length of the cord was . Once the pendulum was set in motion, the plane of swing was observed to precess or rotate 360° clockwise in about 32 hours. This was the first demonstration of the Earth's rotation that didn't depend on celestial
Which? shops selling hearing aids and an investigation into electronics shop staffs' knowledge of the products that they sell. Other publications include "Which? Travel", "Which? Car", "Which? Money", "Which? Computing" and "Which? Gardening". The Consumer's Association has experienced sharply increased income in recent years as its trading subsidiaries have expanded their activities. Which? regularly briefs and lobbies MPs, Peers, AMs, MLAs, MSPs and MEPs on national, European and international consumer issues. For example, Which? successfully lobbied to put an end to the '65-day rule' that allowed energy companies to wait 65 days before informing their customers of a price change. Following