The countries described, though isolated both by position and policy, are sufficiently remarkable not to deserve utter neglect. They form part of the great system of states—black in population, but Mohammedan in religion—which stretches like a belt across Central Africa, with unexplored expanses of Paganism to the south, and to the north a desert, dotted with oases, and marked with caravan tracks leading to the Mediterranean. The valley of the Nile, which seems destined by Nature to be the highroad to this region, is rendered comparatively useless for that purpose by the restrictive regulations of Darfur. That cautious little kingdom stops the way. It is so fearful of aggression from Egypt—not entirely without cause—that it will not allow the easiest routes to be used, and compels all caravans to reach its frontiers exhausted by a two months’ march across the desert from Siout. The expedition sent by her Majesty’s government, under the late Mr. Richardson—which already counts two martyrs—will have vastly enlarged our knowledge of the largest, most populous, and most important Central African kingdoms. Drs. Barth and Vogel are still making gallant geographical forays towards the south—creating, as it were, ground under their feet—for unexplored countries must be considered as scientifically non-existing; whilst Mr. Petermann records their triumphs; as they are won, with a pride which must soften opposition and disarm criticism. His Atlas, however it may be modified by subsequent exploration, is so far the best and completest portraiture of Central Africa that we possess. It is not probable, however, that the German travellers will be able or willing to penetrate eastward across the kingdoms described in this Volume, although Mr. Richardson had contemplated such a journey, and had communicated, through government, with the English Consul-General in Egypt, that the way might, to a certain extent, be prepared. I believe it is still the practice, if not the rule, in Darfur, to prevent all strangers who penetrate into the interior of the kingdom from going away again. However, strong representations from Egypt might have obviated this difficulty. At present we cannot expect the experiment to be tried, as Dr. Barth seems to be directing his attention to a still more difficult expedition; and it is extremely probable that for many years to come the information contained in the present Volume will not be superseded.