David Livingstone was one of the greatest British explorers of the Victorian era, who spent years in Africa, initially as a missionary, and only later as an explorer. He conducted the first detailed investigation of the Zambezi River, which he hoped would serve as a trade route to open up the interior of the continent. Later, he made another expedition to try to find the headwaters of the Nile. At the time of his meeting with Stanley, on the shores of Lake Tanganyika, he had been out of contact with Europe for six years on the latter expedition.
Henry Morton Stanley was a Welshman who had worked as a journalist in the United States, and considered himself American enough to fight in the Civil War (on the Conferedate side). His mission to find Livingstone was a self-conceived stunt done more for fame and fortune than any more humane reason.
After their meeting, the two went their separate ways, although each of them remained in Africa. Livingstone died less than two years later (he had contracted malaria in the course of his explorations); Stanley wrote a book about their meeting, and his fame was such that he was one of the cheif agents of King Leopold of Belgium in the claiming of the Congo for his nation. Stanley was racist even by the standards of his day (Richard Burton, another explorer and no saint, wrote that Stanley “shot negroes as if they were monkeys”). Many regard him as the model for Kurtz in Conrad’s “Heart of Darkness“.
Oh, and chances are that he made up saying “Dr. Livingstone, I presume”, too.
Dr. Livingstone, I Presume — Moody Blues