He is a French physicist that invented a pendulum that showed how the Earth rotates. He was born in 1819 on September 17th so that would make him 194!
What Did He Study???
He initially studied Medicine but then switched to Physics. The primary focus of his research was LJM Daguerre's photographic processes. he was also an assistant to the bacteriologist Alfred Donne with his work on microscopic anatomy.
What Is A Pendulum???
A pendulum is something hanging from a fixed point which, when pulled back and released, is free to swing down by force of gravity and then out and up because of its inertia.
How does it work???
Note that while the Pendulum seems to change its path during the day -- actually it is the floor beneath it that changes, being twisted around by the daily rotation of earth.
Why Was He So Important???
He proved that the Earth does revolve and found a way to show it to people. He also invented a bunch of other things like the Gyroscope.