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 Kazeh was started with 152 porters; both men had to return as their military leaves were coming to and end although Jeal contends that they could have extended the trip by asking for an extension as their clear mission statement of the Royal Geographical Society (RGS) was to find the source of the Nile. The expedition had lost a great many people through desertions, disease and hostilities but in Kazeh, on the return journey, Mabruki had recruited local porters. Again Speke and Burton suffered from severe illnesses and had to be carried in a litter (machilla) by the porters some