Speke, John Hanning (1827-1864), was a British explorer who explored much of eastern Africa. In 1858, Speke and Richard Francis Burton became the first Europeans to reach Lake Tanganyika. While Burton lay ill, Speke discovered Lake Victoria and speculated that it might be the source of the Nile. In 1864, on his last expedition, he confirmed his theory. Speke was born in the county of Somerset, England.