Since the later years of the eighteenth century geographical knowledge has been extended in the manner of a great railway system. The main lines of exploration will provide the subject of this and following chapters; with the ramification of branch lines we can hardly concern ourselves here. Taking one consideration with another, Africa may be termed the most important area of geographical conquest during this latest period of our history. The opening of the interior of that continent was long delayed for geographical reasons which have often been insisted upon. The difficulty of inland communication, the fact that the rivers do not offer uninterrupted highways, the barrier of the tropical forests, the unhealthiness of many parts both of the coast lands and of the interior, which modern science is only now fighting--such are the disabilities against which exploration had to contend, to which must be added the lack of commercial instinct in many of the native peoples, and their unhappy experiences of the early slave-trading, and the labour-recruiting which has in some instances provided its modern counterpart.
During the larger part of the eighteenth century hardly any progress was made with the exploration of Africa. The west coast was still a resort of traders for slaves and gold, but very little attempt was made even to acquire further territory. In the middle of the century, however, the Turkish dislike of intruders was somewhat allayed, owing partly to the growth of the coffee trade, and it became more easy for travellers to enter Egypt. In 1770 James Bruce started on the task, which he had been anxious to undertake for many years, of searching for the Nile sources. He was courteously received by the ruler of Abyssinia, and after finding and mapping the source of the Blue Nile, he traced it to its junction with the White Nile at Khartum. On his return he was disgusted when it was proved to him by D’Anville (whose map, based on a critical judgment of data, was considerably more correct than Bruce’s) that he had been anticipated by the Portuguese Jesuits. He delayed the publication of his results for seventeen years, and when they appeared, though they constitute a remarkable description of Abyssinia and its inhabitants, they were universally disbelieved.