Foucault’s other work

French physicist Jean-Bernard-Leon Foucault is best remembered for giving his name to the Foucault pendulum, which he prominently displayed in 1851, but he also made several discoveries in optics and mechanics.

Together with fellow French physicist Armand Fizeau, Foucault was able to take detailed photographs of the surface of the sun. He independently developed a method of measuring the speed of light that involved a lens, a stationary mirror and a rotating mirror, and he showed that light moved faster in air than in water, disproving theories of a constant velocity.

His other innovations in optics included a method to measure the curvature of telescope mirrors and a light polarizer known as the Glan-Foucault prism.
Foucault also named the gyroscope and demonstrated the existence of eddy currents, sometimes called Foucault currents, generated within conductors by magnetic fields. His name is one of 72 French scientists’ engraved on the Eiffel Tower.

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