Foucault pendulum
On the 3rd of February 1851, he repeated the experiment, with a 12m pendulum at the Paris observatory. On 26th of March he presented the experiment to the public: At the Panthéon, he used a 67m long pendulum, with a weight of 28kg. At the bottom of the pendulum, there was a tip that left a trace in a sandbox. This was an easy way to show the earth's rotation to common people. The metal ball of this pendulum still exists: Until 1946, it was stored at the Conservatoire national des arts et métiers, then it was returned to the Panthéon.