It is probable that, besides settling on the coast, the Portuguese from time to time made explorations into the interior.  At any rate, in some maps of the sixteenth and seventeenth century there is shown a remarkable knowledge of the course of the Nile.  We get it terminated in three large lakes, which can be scarcely other than the Victoria and Albert Nyanza, and Tanganyika.  The Mountains of the Moon also figure prominently, and it was only almost the other day that Mr. Stanley re-discovered them.  It is difficult, however, to determine how far these entries on the Portuguese maps were due to actual knowledge or report, or to the traditions of a still earlier knowledge of these lakes and mountains; for in the maps accompanying the early editions of Ptolemy we likewise obtain the same information, which is repeated by the Arabic geographers, obviously from Ptolemy, and not from actual observation.  When the two great French cartographers Delisle and D’Anville determined not to insert anything on their maps for which they had not some evidence, these lakes and mountains disappeared, and thus it has come about that maps of the seventeenth century often appear to display more knowledge of the interior of Africa than those of the beginning of the nineteenth, at least with regard to the sources of the Nile.

[Illustration:  DAPPER’S MAP OF AFRICA, 1676.]

African exploration of the interior begins with the search for the sources of the Nile, and has been mainly concluded by the determination of the course of the three other great rivers, the Niger, the Zambesi, and the Congo.  It is remarkable that all four rivers have had their course determined by persons of British nationality.  The names of Bruce and Grant will always be associated with the Nile, that of Mungo Park with the Niger, Dr. Livingstone with the Zambesi, and Mr. Stanley with the Congo.  It is not inappropriate that, except in the case of the Congo, England should control the course of the rivers which her sons first made accessible to civilisation.

We have seen that there was an ancient tradition reported by Herodotus, that the Nile trended off to the west and became there the river Niger; while still earlier there was an impression that part of it at any rate wandered eastward, and some way joined on to the same source as the Tigris and Euphrates—­at least that seems to be the suggestion in the biblical account of Paradise.  Whatever the reason, the greatest uncertainty existed as to the actual course of the river, and to discover the source of the Nile was for many centuries the standing expression for performing the impossible.  In 1768, James Bruce, a Scottish gentleman of position, set out with the determination of solving this mystery—­a determination which he had made in early youth, and carried out with characteristic pertinacity.  He had acquired a certain amount of knowledge of Arabic and acquaintance with African customs as Consul at Algiers.  He