Source of the Nile: falls draining Lake Victoria
Throughout the 18th and 19th centuries, like the mythical Northwest passage across the North American continent, explorers wondered and dreamed about the source of the Nile - which was unknown to western Europeans and therefore ready for discovery.
As early as the geographer Strabo, natural scientists speculated about its origin. In Strabo's case, he believed it to be the mountainous highlands of Ethiopia. He was correct in pointing out a major component of its water volume during the flood season (summer monsoons), but technically not the point of origin itself.
This remained unknown until the journeys of Sir Richard Burton and John Hanning Speke, two army officers of the East India company who wrote copiously of their experiences in the mid 19th century. Granted a subvention from the Royal Geographical Society, the men conducted numerous expeditions in East Africa, witnessing a vast lake in the Great Rift Valley which Speke named "Victoria."
While Burton was recuperating from illness and his wounds (he once had a javelin thrust through one cheek and out the other in a skirmish), Speke raced back to England by packet steamer and gave a talk at the Royal Society announcing that he had found the source of the Nile - Lake Victoria. His subsequent book and celebrity annoyed Burton, who actually was far more experienced as a linguist, soldier, and trailblazer than Speke. In fact, Burton was praised as the first Englishman to experience the pilgrimage to Mecca (haj), in the guise of a pious Indian merchant, enabling him to explain away his strange Arabic accent. He also was the first white man to see Harrar, a coffee and qa'at trading city in Ethiopia. The wholesale price of 27 lbs of fine Ethiopian coffee beans was 25 cents in the 1850's.
The latter 19th century saw different parts of East Africa claimed by England, France, the Netherlands, and two latecomers in the colonial landgrab - Italy and Germany, especially as Turkish influence in the region waned.