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 the beginning, the relationship of Speke and Burton was one of opposites; Burton considered Speke inferior linguistically and a less experienced traveller in remote regions (which was partially true), but Burton himself appears to have been jealous and far less able to relate to the safari caravan to keep the expedition motivated and moving (a vital factor as they were completely dependent on their safari crew). While Speke enjoyed hunting and thus provided the caravan with meat, Burton was not much interested in such pursuits. Burton was appointed the head of the expedition and considered Speke the second in command, although the pair seemed to have shared the hardships and labours of the journey pretty much evenly. Once it became clear that Speke might have found the source of the Nile the relationship deteriorated further. Why Burton did not journey back to Lake Victoria with Speke to make a better reconnaissance of the Lake after Speke returned to base camp in Kazeh is unclear. Burton was incapacitated and had to be carried by bearers but this had been true for a great deal of the trip. While Speke and Burton were instrumental in bringing the source of the Nile to the wider world and were the first to record and map this section of Africa, the efforts and labours of Sidi Mubarak Bombay and Mabruki were instrumental in the discovery of 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.