Leon Foucault's 194th birthday has been marked a Google doodle. Foucault was a French physicist.

The interactive Google doodle showcases the Foucault Pendulum, a device which was invented by Foucault to demonstrate the effect of earth's rotation. The doodle features two toggles for time and the position on the earth. Different combinations make the pendulum knock down pins placed at at different positions.

The Foucault pendulum, invented in 1851, was one of the first simple experimental proofs of earth's rotation. The original pendulum was first showcased in the Meridian of the Paris Observatory, with a 28kg brass-coated lead bob and a 67-metre long wire being hung from the dome of the Pantheon. The pendulum completed a full circle every 32.7 hours, rotating clockwise at 11 degrees every hour.

Leon Foucault was born on September 18, 1819 to a publisher, in Paris. He started studying medicine but left due to his fear of blood.

In his initial years he investigated subjects like the intensity of the light of the sun, as compared with that of carbon in the arc lamp, and of lime in the flame of the oxyhydrogen blowpipe, interference of infrared radiation and on the chromatic polarisation of light, among others.

Leon Foucault's other discoveries include the "Foucault currents." In 1855 he discovered that the force required for the rotation of a copper disc becomes greater when it is made to rotate with its rim between the poles of a magnet, the disc at the same time becoming heated by the eddy current or "Foucault currents" induced in the metal.

Foucault also invented the polariser in 1857 and subsequently invented a method of testing the mirror of a reflecting telescope to determine its shape. Known as the "Foucault knife-edge test," it allowed the worker to tell if the mirror was perfectly spherical or had non-spherical deviation. 

Leon Foucault became a member of the Bureau des Longitudes and an officer of the Legion d'Honneur. He was also made a member of the Royal Society of London in 1864. Foucault's name is among the 72 names inscribed on the Eiffel Tower. An asteroid, 5668 Foucault, has also been named after him.

Foucault died on February 11, 1868 at the age of 48, after suffering from multiple sclerosis.

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