John Hanning Speke questions about the height and extent of the lake could not be answered easily. Speke's eyes were still bothering him and he only saw a small part of the southern end of the lake and his view was blocked by islands in the lake so he could not judge the size of the lake well. However, Speke did estimate the elevation of Lake Victoria at 4000 feet by observing the temperature at which water boiled at that level. (This lake's being substantially higher than Lake Tanganyika did make it a more likely candidate for the source of the Nile.) From
John Hanning Speke the wider world and were the first to record and map this section of Africa, the efforts and labors of Sidi Mubarak Bombay and Mabruki were instrumental in discovering the lake. Bombay was captured as a child near Lake Nyasa by slave traders and was sold to Indian merchants on the coast of Africa who took him to Sindh. Thus he spoke Hindustani and after his master's death he sailed back to Zanzibar where Speke and Burton met and hired him. Both spoke Hindustani, which greatly facilitated the travel in the interior as Bombay spoke several native languages beside Swahili.