Jean Bernard L矇on Foucault (September 18, 1819 - February 11, 1868) was a French physicist. After an education received chiefly at home, he studied medicine, which he abandoned in favor of physics due to a blood phobia. He is best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of the Earth's rotation by showing the rotation of the plane of oscillation of a long and heavy pendulum suspended from the roof of the Panth矇on, Paris. The experiment caused a sensation in both the learned and popular worlds, and "Foucault pendulums" were suspended in major cities across Europe and America and attracted crowds. He joined Fizeau in measuring the speed of light. This measurement was improved when he developed a method of reflecting light off mirrors. Foucault showed that light moves slower in water which was important evidence for the wave-theory of light. He also discovered eddy currents, and is credited with naming the gyroscope (although he did not invent it). He died of what was probably a rapidly developing case of multiple sclerosis in 1868 at the age of 48. His is one of the 72 names inscribed on the Eiffel Tower.