The plateau of South Africa rises at Lattakoo, in the country of the Bechuanas, north of the Orange River, to the height of 6000 feet. To the east, near the Snow Mountains, where the river has its source, it ascends to an altitude of over 10,000 feet. To the north, discovery had made great progress since 1849. There, on a broad plateau, Oswell and Livingstone brought to the knowledge of the world the existence of Lake Ngami, whose surface is 2825 feet above the level of the sea. The plateau which includes this lake at its place of deepest depression cannot be less than 3000 feet high, and at some localities yet higher. Still more to the north, at latitude 14° south, on the water-shed between the Zaire or Congo on the west and the Zambeze in the east, the plateau reaches an elevation of 5000 feet, according to Livingstone. Yet farther to the west, it rises still higher and takes undisputed rank among plateaus of the first class. There, at 18° south latitude, Galtne, on his journey of discovery in 1850, ascended the table-land of Ovompâ, a region of great natural productivity. On the way thither, going from south to north, at 21° south latitude, and therefore in the parallel of Lake Ngami, but about 500 miles westward, he ascended north of the Swakop River, the table-land of Demara, which he found to be 6000 feet high. From that plateau mountains, Koniati and Ometako, for instance, rise to a height of 8800 feet. From the Swakop River to Lake Ngami there is a continuous plateau. The high table-land of southern central Africa does not then extend, as was once supposed, as far north as 9° north latitude, nor even to the later limit of 4½° north latitude; but at about 4° 10′ the distinction between lowland and highland seems to be sharply drawn, as the cataracts which terminate the navigation of the White Nile indicate. Here Father Knoblecher turned back in 1849, but he ascended the first of the mountains which there began to rise; his eye reached onward to mountains very near or on the equator. He says that those high mountains stand upon an elevated table-land. Thus, here at the source of the White Nile we have a plateau seemingly of the first rank. From such a plateau it is probable that the snow-capped mountains, seen by Rebmann and Krapf in the neighborhood of the equator, rose, which they thought, approaching from the eastern coast, held the source of the Nile. At the northwest of Africa, too, at 10° north latitude, the territory which feeds the springs of the Senegal and the Niger is supposed to be a plateau of great elevation and of great extent. But at present our lack of knowledge prevents our attaining certainty regarding it. No thorough system of measurement has been yet applied there.