Mr. Thomas Ewbank is preparing for the press a work on Brazil, being observations made during a twelve months' residence in that country. From a personal acquaintance with this gentleman, his reputation as a man of observation, and his well known capacity as a writer, we think a valuable book may be expected. AFRICA. The zeal which was manifested a few years since for the discovery and exploration of the interior of Africa, and which seemed to have terminated with the Landers, and the unsuccessful voyage of the steamers up the Niger, has again shown itself, and we now find as much curiosity awakened, and as much zeal manifested for geographical discovery in this vast continent, and the solution of questions for ages in doubt, as has been exhibited at any former period. The Travels of M. d'Abaddie, Dr. Beke, Isenberg, and others make known to us the immense extent and windings of the Bahr-el-Abiad and the Bahr-el-Azrek, or the white and blue Nile, but they have not yet been traced to their rise, and the solution of the question of the true source of the Nile, remains still unsettled. We have received from Mr. Jomard, member of the French Institute, a work entitled "Observations sur le voyage au Darfour" from an account given by the Sheikh Mohammed-el-Tounsy, accompanied by a vocabulary of the language of the people, and remarks on the white Nile by Mr. Jomard. This is a valuable contribution to our knowledge of a portion of the interior of Africa, only known to us by the visit of Mr. Browne in 1794, and forms a link in the chain between Lake Tchad and a region of country quite unexplored, and of which we have no knowledge whatever. We have some information of interest, relating to Senegal, communicated to the Royal Geographical Society of London,[24] being a narrative of Mr. Thomson, linguist to the Church Missionary Society at Sierra Leone, from that place to Timbo, the capital of Futah Jallo. His place is about four hundred miles northeast of Sierra Leone. "The principal object of the mission, was to open a road for a regular line of traffic through that country, between the colony and the negro states on the Joliba or Niger." Mr. Thomson's narrative is full of interest and shows the great hardships to be encountered in effecting a communication with the interior. No man could be better prepared for such an enterprize, both by knowledge of the languages of the country, and the manners of the people; zeal, perseverance, and courage, also were prominent traits in his character; yet his enterprize failed and death cut him off, when on the point of starting for the eastward.