Major Rennell, in his Geographical Illustrations of Park's travels, has done ample justice to the knowledge and judgment, so eminently displayed by D'Anville in the investigation of several important points relative to the geography of North Africa, which have been elucidated by this writer from very imperfect materials with extraordinary sagacity and success. In the 26th volume of the Memoirs of the Academy of Inscriptions, there are two very important Dissertations by this distinguished Geographer; the first, On the sources of the Nile; and the second, Concerning the rivers of the interior of Africa, with reference to the opinions of the ancient and modern writers who have treated on that subject. The latter is the most immediately connected with the particular questions alluded to in the text; and it is remarkable that the principal opinions, or rather conjectures, of D'Anville (of which the opinion relating to the course of the Niger is the most important), although deduced from very uncertain and discordant sources of information, have been confirmed in a great degree by the discoveries of modern travellers, especially by those of Park. It appears that D'Anville was well acquainted with the existence of Tombuctoo, and had even ascertained the situation of that city, as well as the general course of the Niger with a considerable degree of precision. He had also formed a plan for sending a person, properly qualified, on an expedition from the French settlement of St. Joseph on the river Senegal, to Tombuctoo; but owing to some circumstance which he does not explain, the scheme did not take effect. As the Dissertation here alluded to may not be in the hands of every reader, the passage relating to this subject may be worth transcribing.--After mentioning Ghana as the principal Mahometan city of Nigritia, spoken of by Edrisi, he says that many of the Fatimites, who escaped from the power of the Califs, took refuge in the interior of Africa, where they formed various states. He then proceeds as follows: