Charles Babbage presents his plan for the Difference Engine to the Royal Astronomical Society, a mechanical calculator that foreshadowed modern computing.

Ulysses S. Grant, future Union general and 18th U.S. President, is born in Point Pleasant, Ohio, the son of a tanner.

Prince Pedro drew his sword on the banks of the Ipiranga River and declared Brazil's independence from Portugal, shouting "Independence or death!"

Bernardo O'Higgins, Chile's first head of state, resigned under political pressure, ending his six-year rule as Supreme Director.

Louis Pasteur, whose work on germ theory and vaccination would transform medicine and public health, was born in Dole, France.