No influence has been so potent in improving the art of the explorer, or in raising the standard of the work required of him, as the enormous interest that for thirty years past has centred in African exploration. The larger part of the best achievements of the explorers of the present generation in scientific investigation, and in an approach to scientific map-making, are found in tropical Africa. Many of the hundreds of the route surveys are not unworthy to be compared with those of Pogge and Wissmann, when they laid down on their map every cultural and topographic feature for two miles on both sides of their route, from Angola to the Upper Congo. The extreme care with which some of the best explorers have performed their tasks is illustrated by the remarkable achievement of the late Dr. Junker along the Mobangi River. After years of service, his scientific equipment had become practically worthless. He started on his four-hundred-mile journey down the river through the jungle, with absolutely no instrument except a compass to aid him in determining his positions. Endeavoring, by the most scrupulous care, to make up as far as possible for his lack of scientific outfit, he trudged through the grass, compass in hand, counting every step. Every fifteen minutes he jotted in his notebook the distance and the mean direction travelled. At night he used these accumulated data to lay down on his route map the journey of the day. For many weeks he kept up this trying routine till he reached his furthest west, and again till he had returned to his starting-point, whose latitude and longitude he had previously determined. When he returned to Europe, Dr. Hassenstein and he made a map from the data Junker had collected, and fixed the position of his furthest west. This position was found later by the astronomical observations of Lieutenant Le Marinel to be less than two miles out of the way.