For thousands of years the world had speculated about the origin of the River Nile, but it was not until Richard Burton and John Hanning Speke, two experienced explorers, led an expedition to Africa in 1857 that a real attempt was made to solve the problem. The entire journey was complicated from the start by the fact that neither of the two men could stand each other, and argued violently the whole time. They both became extremely ill, and the expedition achieved little more than the discovery of Lake Tanganyika. On the return journey, Speke reached Lake Victoria, which he thought might be the source of the Nile, although Burton strongly disagreed. In 1860 Speke set out on another expedition, this time with James Grant. They followed the previous route as far as Tabora, but from there headed towards the country west of Lake Victoria. Continuing around the lake, Speke finally reached the Ripon Falls (1860), at which point he was certain that he had found the source of the Nile, and indeed his theory was proved right.