Seventeen nations signed the Metre Convention in Paris, establishing an international system for standardizing weights and measures.

Seventeen nations signed the Metre Convention in Paris, creating an international framework for standardizing weights and measures around the metric system.

Colonel Meriwether Lewis Clark Jr.'s vision for an American answer to England's Epsom Derby took shape in the founding charter of Churchill Downs.

Wilhelm Wundt received approval to establish a laboratory for experimental psychology at the University of Leipzig, a milestone in founding psychology as a science.