Before its sighting in 1846, which eighth planet's existence was deduced from its gravitational pull on another planet?

Before independence in 1966, Botswana was a British protectorate known by what name? What does "LP", the term for a vinyl album, stand for? Which sitcom starring Lucille Ball and Desi Arnaz began on CBS in 1951 and became a rerun favorite for decades? Long before it named office machines, which job title described people like Johannes Gutenberg? Before its completion in 1917, the Quebec Bridge collapsed twice during construction. Which river does it cross? Before Joe Montana played for the Kansas City Chiefs, which team did he lead to four Super Bowl titles? Before John Speke named it in 1858, which African lake was known to Arab traders as Ukerewe? Before joining the Brooklyn Dodgers in 1947, which athlete lettered in four sports at UCLA?