In order that the following narrative may be clearly understood, it is necessary to call to mind some things which took place previous to the Zambesi Expedition being sent out. Most geographers are aware that, before the discovery of Lake Ngami and the well-watered country in which the Makololo dwell, the idea prevailed that a large part of the interior of Africa consisted of sandy deserts, into which rivers ran and were lost. During my journey in 1852-6, from sea to sea, across the south intertropical part of the continent, it was found to be a well-watered country, with large tracts of fine fertile soil covered with forest, and beautiful grassy valleys, occupied by a considerable population; and one of the most wonderful waterfalls in the world was brought to light. The peculiar form of the continent was then ascertained to be an elevated plateau, somewhat depressed in the centre, and with fissures in the sides by which the rivers escaped to the sea; and this great fact in physical geography can never be referred to without calling to mind the remarkable hypothesis by which the distinguished President of the Royal Geographical Society (Sir Roderick I. Murchison) clearly indicated this peculiarity, before it was verified by actual observation of the altitudes of the country and by the courses of the rivers. New light was thrown on other portions of the continent by the famous travels of Dr. Barth, by the researches of the Church of England missionaries Krapf, Erkhardt, and Rebman, by the persevering efforts of Dr. Baikie, the last martyr to the climate and English enterprise, by the journey of Francis Galton, and by the most interesting discoveries of Lakes Tanganyika and Victoria Nyanza by Captain Burton, and by Captain Speke, whose untimely end we all so deeply deplore. Then followed the researches of Van der Decken, Thornton, and others; and last of all the grand discovery of the main source of the Nile, which every Englishman must feel an honest pride in knowing was accomplished by our gallant countrymen, Speke and Grant. The fabulous torrid zone, of parched and burning sand, was now proved to be a well-watered region resembling North America in its fresh-water lakes, and India in its hot humid lowlands, jungles, ghauts, and cool highland plains.