396 GEOGRAPHICAL SYSTEMS, &C. 
exertions for the extension of discovery in this 
part of the world. In Major Rennell too, the ma- 
terials thus collected have happily found an illus- 
trator, who, in the precision of his data, and the 
accuracy with which he applies them, is scarcely 
equalled by the most illustrious of his predecessors* 
His maps of Africa, which form the basis of the 
present geography of that continent, are rendered 
doubly valuable by the copious and instructive man- 
ner in which he unfolds the principles upon which 
they are constructed. 
