POPPER, JULIUS (1857–1893), Romanian explorer. Popper's father was the principal of the first Jewish school in Bucharest. After studying engineering in Paris, he went on a world trip during which he heard about gold deposits on Tierra del Fuego. His exploration of the island proved the stories to be true, and he accordingly designed a machine for extracting the gold. Establishing himself as ruler over the island, Popper gave it a code of laws and defended it against other adventurers.