Down to 1858 all that Europe knew of the Nile basin was this: The course of the Blue Nile had been mapped to some extent from its source in Lake Tsana; and the travels of Rüppell (1830–1831) (the great German naturalist), of another German, Joseph Russegger, of the D’Abbadies (the great French surveyors), of Sir William Cornwallis Harris (who was sent on a mission to Shoa), Théophile Le Febvre, Mansfield Parkyns (1840–1845), H. Dufton, and C. T. Beke had cleared up a good many blank spaces in the geography of Abyssinia and of the various affluents of the Nile flowing from the snow-mountains of that African Afghanistan in the direction of the Atbara, the Blue Nile, and the Sobat. The Sobat had been explored for a hundred miles or so, as far as steamers could penetrate. The White Nile had been surveyed from Khartum to the junction of the Bahr-al-Ghazal. South of that point, under the name of Mountain Nile, it and some of its branches, such as the Giraffe River, had also been explored, and the River of the Mountains, as the Upper White Nile is called by the Arabs, had been ascended to a little distance south of Gondokoro. The Bahr-al-Ghazal, the great western feeder of the Nile, and several of its more important affluents, such as the Jur, had been made known, and the existence of the Nyam-nyam cannibal country ascertained. But the ultimate sources of the Nile stream were still undiscovered. This problem was now to be attacked from two very different directions. In 1829 the Church Missionary Society had resolved to attempt the evangelisation of Abyssinia, and sent missionaries to the northern part of that country. Amongst these missionaries, in 1840, was a Würtemberg student named Ludwig Krapf, sent to prospect in northern Abyssinia. But the Abyssinians eventually resented this missionary enterprise, and Krapf and some others were expelled from the country in 1842. [Illustration: REV. DR. L. LUDWIG KRAPF.]