ABSTRACT
Hardly a hundred years have elapsed since the primary outlines of African physiography were finally made clear. In 1862 the riddle of the Nile was solved when Speke showed that the continent’s longest river rose in Lake Victoria; in 1877 the course of the Congo to its estuary was first established. The climate of much of Africa also served as a deterrent to settlement and exploration. In the north the great Sahara desert, stretching from one side of the continent to the other, is broken only by the valley of the Nile, which is itself blocked for boats by the cataracts and by the vast swamp region of the Sudd above the cataracts. In the years 1430 to 1500 Portuguese seamen not only examined the whole Atlantic coast of Africa but also sailed round the southern Cape into the Indian Ocean for the first time for 2,000 years since the Phoenicians.
