to his description it is much inferior in fertility to the cultivated parts of Europe and Asia, and suffering extremely from severe drought; yet he makes mention of a few spots, such as Cinyps, and the high tract Cyrene, which, undergoing the process of irrigation, may stand comparison with the richest portions of the globe.  Generally, however, in quitting the northern coast, which he terms significantly the forehead of Africa, the country became more and more arid.  Hills of salt arose, out of which the natives constructed their houses, without any fear of their melting beneath a shower in a region where rain was unknown.  The land became almost a desert, and was filled with such multitudes of wild beasts, as to be considered their proper inheritance, and scarcely disputed with them by the human race.  Farther to the south, the soil no longer afforded food even to these wild tenants; there was not a trunk of a tree, nor a drop of water—­total silence and desolation reigned.

This may be considered as the first picture on record of the northern part of Africa; a country, which, even after the lapse of two thousand years, presents to the eye of science, as regards its interior recesses, a blank in geography, a physical and not less a moral problem; a dark and bewildering mystery.  The spirit of enterprise has carried our mariners to the arctic seas, braving the most appalling dangers in the solution of a great geographical problem; by the same power, civilization has been carried into the primeval forests of the American continent, and cities have arisen in the very heart of the Andes.  The interior of Africa, however, notwithstanding its navigable rivers, has been hitherto almost a sealed chapter in the history of the globe.  The deserts, which extend from Egypt to the Atlantic, and which cover a great surface of the interior, have proved a barrier to the march of conquest, or civilization; and whatever science has gained, has been wrested by the utmost efforts of human perseverance and the continual sacrifice of human life.

It must, however, be allowed that there are obstacles existing to the knowledge and the civilization of central Africa, which cannot be overcome by the confederated power of human genius.  Extending 5000 miles in length, and nearly the same extent in breadth, it presents an area, according to Malte Brun, of 13,430,000 square miles, unbroken by any estuary, or inland sea, and intersected by a few long or easily navigable rivers; all its known chains of mountains are of moderate height, rising in terraces, down which the waters find their way in cataracts, not through deep ravines and fertile valleys.  Owing to this configuration, its high table lands are without streams, a phenomenon unknown in any other part of the world; while, in the lower countries, the rivers, when swelled with the rains, spread into floods and periodical lakes, or lose themselves in marshes.  According to this view of the probable structure of the unknown interior,