John Hanning Speke of the way. Once Speke and Burton were back on the coast they went by ship to Zanzibar and then traveled to Aden. When back at the coast Burton had written a letter to Norton Shaw of the Royal Geographical Society (which had partially sponsored the journey) in which Burton enclosed a map of Lake Victoria made by Speke and wrote "there are grave reasons for believing it (the map) to be the source of the principal feeder of the White Nile." Once in Aden, Burton was not granted a medical certificate to travel and thus Speke left on HMS
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.