184 Scientific Intelligence—Geography. 
most correct idea of the results already gained by the expedi- 
tion, will be found by comparing the maps of the present work 
with those published by their immediate predecessors, namely, 
those illustrating the travels of Denham and Clapperton. First, a 
large portion of Northern Africa and the Sahara, never before 
visited by Europeans, has now for the first time been thoroughly 
explored. The discoveries in the country of the Tuaricks, compris- 
ing the kingdom of Air in particular, form a considerable addition 
to our geographical knowledge of Africa. But the great achiev- 
ments lie within Sudan, in the vast region between Guber and Ma- 
riadi inthe West, and Dar For in the East, and ranging from the 15th 
parallel as far South as 5° north of the equator. The important 
discoveries of Denham and Clapperton, it must be borne in mind, 
were as yet confined to a region of which a great portion was known 
and mapped with some amount of truth before them, according to 
the information possessed by the Roman, Egyptian, and Arab geo- 
graphers ; whereas the whole region beyond the points reached by 
Denham, Clapperton, and Lander, presented a great blank—some 
vague indications only; as, for example, the existence of a country 
called Adamaua. Except Mandara, no pagan country to the south 
of Lake Tsad had ever been reached by any European before Barth 
and Overweg, and the merit of pioneering into these totally unknown 
regions belongs to them, 
The actual extent of the routes accomplished by these travellers 
has been calculated from the present maps thus :— 
Geographical 
miles. 
hoot Oo ueenah 
(not represented in 
530{ the sections). 
Routes in Map of Northern Africa, 
Do. in Map of Central Africa. ‘ i 3050 
Do. in General Map, not contained in the 
enlarged maps, . ) > ‘ . 820 
5800 
This only comprises the journeys of Dr Barth up to August 
1852. The extent of the routes actually performed—viz., 5800 
geographical miles—will be better appreciated when compared with 
other recent travels ; as, for example, those of Galton in South 
Africa, the routes of whidh only amount to 1280 miles. The whole 
distance, in a direct line, from Tripoli to the Cape of Good Hope, 
is only 4080 miles. 
But the mere linear extent of the routes of their explorations 
would convey an inadequate idea of the importance of their labours. 
It is the value of their astronomical, hypsometrical, and geological 
observations—the extent of their historical, philological, and ethno- 
logical researches—which, the writer confidently believes, will form 
a new era in the geography of the whole of Northern and Central 
Africa. And if the navigableness of the river discovered by Dr 
nO a 
