INTRODUCTION. XXi 
the other branches have a tendency to the north-west. 
Whether, therefore, they unite, or not, the probability cer- 
tainly is in favour of all the streams, from Guinea to Biafra, 
having their sources in the southern face of the Kong 
mountains. It can scarcely be supposed that the same 
mountains, whose northern sides give rise to the three 
large rivers, the Niger, the Senegal, and the Gambia, 
should have their southern faces destitute of streams. If 
however, we refer these numerous branches to some great 
stream crossing the continent, from the north-east, the 
Houssa merchants, in their journey to Lagos, must neces- 
sarily psas it; but by their own account, though nume- 
rous streams, and lakes, and marshes occur, they neither 
cross any high mountain, or very large river 
In this unsatisfactory state of doubt and conjecture, in 
which a most important geographical problem was involved, 
two expeditions were set on foot under the auspices of 
Government; the one to follow up the discovery of Park 
by descending the stream of the Niger, the other to ex- 
plore the Zaire upwards towards its source. Indepen- 
dently of any relation which the latter might be supposed 
to have to the former, the river itself, from all the descrip- 
tions which had been given of it, from its first discovery 
by Diego Cam down to the present time, was of sufficient 
magnitude to entitle it to be better known.  'T’o accom- 
plish this object more of difficulty was apprehended in the 
navigation, than of danger from the hostility of the 
nalives, or the unhealthiness of the climate, neither of 
which had opposed any obstacle to the progress of the 
Portuguese. It was well known both to them and the 
slave dealers of Liverpool, who used to frequent this river, 
