Henry Morton Stanley the source of the Nile. Between 1875 and 1876 Stanley succeeded in the first part of his objective, establishing that Lake Victoria had only a single outlet – the one located by John Hanning Speke on 21 July 1862. If this was not the Nile's source, then the massive northward flowing river called by Livingstone, the Lualaba, and mapped by him in its upper reaches, might flow on north to connect with the Nile via Lake Albert and thus be the primary source. It was therefore essential that Stanley should trace the course of the Lualaba downstream (northward) from Nyangwe,
John Hanning Speke tried to remove it with a knife. Unable to rent the larger vessel from the Arab, Speke returned. The pair were unable to explore Lake Tanganyika properly and they initially misunderstood that a river flowed out of it from the north side. A few weeks later Sidi Mubarak Bombay confirmed via locals that the river flowed into the lake; however, since neither man actually saw this river, this remained a source of speculation. They had also heard of a second lake to the north-east, and in May 1858, they decided to explore it on the way back to the coast.