﻿Unmapiml Areas on EartKs Surface. 435 



blank lias been filled up with bewildering rapidity. 

 Great rivers and lakes and mountains have been laid 

 down in their main features, and the whole continent, 

 with a few unimportant exceptions, has been parcelled out 

 among the powers of Europe ; but much still remains 

 to be done ere we can form an adequate conception 

 of what is in some respects the most interesting and the 

 most intractable of the continents. Many curious 

 problems still remain to be solved. The pioneer work of 

 exploration has to a large extent been accomplished ; 

 lines have been run in all directions : the main features 

 have been blocked out ; but between these lines the 

 broad meshes remain to be filled in, and to do this 

 will require many years of careful exploration. How- 

 ever, there still remain one or two regions that afford 

 scope for the adventurous pioneer. 



To the south of Abyssinia and to the west and north- 

 west of Lake Eudolf, on to the Upper Nile, is a region of 

 considerable extent, which is still practically unknown. 

 Again, in the western Sahara there is an extensive area, 

 inhabited mainly by the intractable Tuaregs, into which 

 no one has been able to penetrate, and of which our 

 knowledge is extremely scanty. Even in the central 

 Sahara there are great areas which have not been 

 traversed, while in the Libyan desert much remains to be 

 done. These regions are of interest almost solely from 

 the geographical and geological standpoints ; but they 

 deserve careful investigation, not only that we may 

 ascertain their actual present condition, but in order, also, 

 that we may try to discover some clues to the past history 

 of this interestincr continent. Still, it must be said that 

 the great features of the continent have been so fully 

 mapped during the last half century that what is required 

 now is mainly the filling-in of the details. This is a 

 process that requires many hands and special qualifi- 

 cations. All over the continent there are res^ions which 



