tains an elevation of over four thousand feet. The journeys of Barth and Vogel discovered that, at a short distance south of Tripoli, a series of terraces lead gradually to the vast plains of the desert, where there are only moderate undulations with occasional ravines and isolated masses of rock to Soodan. The southern part of the route was over plains slightly inclined southward. The greatest height observed in that region was six hundred metres.
M. Dupouchel, Ingénieur en chef des Fonts et Chaussées, went in 1877 to examine the ground west of the Ahaggad, and study the practicability of opening a railway between Algeria and the valley of the Niger of Soodan. The results of his examinations have appeared in book form, accompanied with maps and drawings. The route that he recommends commences at Algiers, and passes by Afreville, Boghari, Laghouat, and the oases of Touat, finally striking the Niger at Bamba, a short distance east of Timbuctoo. An eastern branch would descend that river to longitude 2° east, and would run from there toward the Tchad Lake. A western branch would ascend the Niger as far as Kouma, and then run to Saint-Louis. The total length of the line from Algiers to the Niger, deducting the part already constructed to Afreville, would be about 1,700 miles, of which the total cost is estimated at 400,000,000 francs (about $77,000,000). This is $15,000 less per mile than the average of all the railroads built in the United States during the year 1874, and $60,000 less per mile than the cost of the Central Pacific. President Grévy has recently been written to, and urged to appoint a commission to examine a proposal to construct that railroad.
It will readily be seen what an important element in the construction of a railway will be the power to supply water from underground as the work progresses. But there are enthusiasts who maintain that the object now to be accomplished is not simply the establishing of communication across the desert, nor the submerging of one very small portion for the benefit of another small portion, but no more nor less than the reclaiming—the fertilization—of the whole Sahara. This, indeed, sounds rash, and yet no less an authority than Gerhard Rohlfs, who has explored greater areas of Sahara than any other European, and whose journey from Tripoli to Rhadames and Fezzan won him a gold medal from the Royal Geographical Society of London, sustains the idea by saying that Nature would soon begin to assist man in the herculean undertaking. According to this traveler, three distinct zones separate the center of the desert from the neighboring lands of the Tchad Lake in the south; in the third or northernmost of these are immense forests of mimosas, where the ground is characterized by the absence of the smallest stone, and which, according to the aborigines, extend from Egypt to Timbuctoo, covering the Kordofan, the Darfoor, the Kamen, and the country of the Touaregs. Professor Rohlfs advances the theory that these forests are encroaching on the desert, and that in
