Mungo Park
Mungo Park was a Scottish explorer of West Africa. After an exploration of the upper Niger River around 1796, he wrote a popular and influential travel book titled Travels in the Interior Districts of Africa in which he theorized the Niger and Congo merged to become the same river. He was killed during a second expedition, having successfully traveled about two-thirds of the way down the Niger. With Park's death, the idea of a Niger-Congo merger remained an open question although it became the leading theory among geographers. The mystery of the Niger's course, which had been speculated about since the Ancient Greeks and was second only to the mystery of the Nile's source, was not solved for another 25 years, in 1830, when it was discovered the Niger and Congo were in fact separate rivers.