Leon Foucault, French physicist, c 1850s.
© National Media Museum / Science & Society Picture Library
Daguerreotype. In 1852 Jean Bernard Leon Foucault (1819-1868) gave the first public demonstration of the rotation of the earth on its axis, by hanging a giant pendulum from the dome of the Pantheon in Paris. The pendulum appeared to change direction over the course of the day, but in fact it swung in the same direction, proving that the Earth was turning below the pendulum.