Jean Benard Leon Focault was a Frech physicist who was the first person to take a picture of the Sun in 1845. He determined the speed of light using rapidly rotating mirrors and also proved that light travels faster in air than in water.
Focault's most spectacular demonstration was in 1851 when he demonstrated the rotation of the Earth. He suspended a pendulum, known now as a Focault Pendulum, on a long wire from the dome of the Pantheon in Paris. The movement of the pedulum duplicated the rotation on the Earth on its axis. His other achievements include a gyroscope that served as the basis for the modern gyrocompass, proving the existence of the eddy currents generated by magnetic fields, and devising a method to measure the curvature of telescopic mirrors.