a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of the Earth's rotation. He also made an early measurement of the speed of light, discovered eddy currents, and is credited with naming the gyroscope (although he did not invent it). In 1850, he did an experiment using the Fizeau–Foucault apparatus to measure the speed of light; it came to be known as the Foucault–Fizeau experiment, and was viewed as "driving the last nail in the coffin" of Newton's corpuscular theory of light when it showed that light travels more slowly through water than through air.
