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 an appendix in his own book on his travels to Harrar. It seemed unlikely that the two would join again and Burton believed that he would not lead an expedition to the interior of Africa, his fervent hope, after this failed journey. In 1856, Speke and Burton went to East Africa to find the Great Lakes, which were rumored to exist in the center of the continent. It was hoped that the expedition would locate the source of the Nile. The journey, which started from Zanzibar Island in June 1857, was extremely strenuous and both men fell ill from a