The principal ground of this supposition is, the opinion of some of the best informed writers of antiquity on the geography of Africa, and a sort of general persuasion prevalent among the ancients to the same effect; circumstances, it must be acknowledged, of considerable weight in determining this question: since there is good reason to believe, that the knowledge of the ancients concerning the interior of Africa was much more extensive and accurate than that of the moderns. It is justly observed by Dr. Robertson, that the geographical discoveries of the ancients were made chiefly by land, those of the moderns by sea; the progress of conquest having led to the former, that of commerce to the latter. (Hist. Of America, vol. ii. p. 3l6, 8vo.) Besides which, there are several distinct and peculiar causes which have essentially contributed to our present ignorance respecting the interior of Africa; namely, the great prevalence of the slave trade, which has confined the attention of European adventurers exclusively to the coast; the small temptation which the continent of Africa held out, during the continuance of that trade, to internal commerce; and the almost impenetrable barrier raised up against Europeans in modern times, by the savage intolerance of the Moors. The ancient opinion, respecting the termination of the Niger which has just been alluded to, receives a certain degree of confirmation from the best and most authentic accounts concerning that part of Africa, in which the Niger is supposed to disappear. This is represented by various concurrent testimonies to be a great tract of alluvial country, having several permanent lakes, and being annually overflowed for three months during the rainy season. Against the hypothesis of an inland termination of the Niger, several objections have been urged, which are well deserving of attention. They are principally founded on a consideration of the vast magnitude which the Niger must have attained after a course of more than 1600 geographical miles, and the difficulty of conceiving so prodigious a stream to be discharged into lakes, and evaporated even by an African sun. To account for such a phenomenon, a great inland sea, bearing some resemblance to the Caspian or the Aral, appears to be necessary. But, besides that the existence of so vast a body of water without any outlet into the ocean, is in itself an improbable circumstance, and not to be lightly admitted; such a sea, if it really existed, could hardly have remained a secret to the ancients, and entirely unknown at the present day.