538 THE POPULAR SCIENCE MONTHLY. 



to the western part of the basin that the French contemplate inun- 

 dating, bearing in that part of its course the name of Oued Rihr, or river 

 Rihr. Into this same depression flows another subterranean stream, 

 the Oued Djeddi, which has its sources on the plateaux of Laghouat in 

 the west. The two streams in all probability united in past ages, and 

 possibly even connected with the Mediterranean. However that may 

 be, there seems little doubt that water in considerable quantities may 

 be found by boring in the dry beds of these two streams. M. Lar- 

 geau saw several wells in that of the Igharghar, only twenty-five feet 

 deep, giving very sweet water, of a temperature of 70° Fahr. 



With this in consideration, and the example of the marabout of 

 Tendouf still in mind, it would seem possible not only to fertilize large 

 areas of Algerian soil, but to bore our way as it were up the slopes of 

 the Ahaggar and gradually restore the rain-causing forests of M. Lar- 

 geau, which in their turn might attack the desert from the center, as 

 Professor Rohlf's mimosas do from the south. 



The lowest estimate of the cost of inundating the depressions in 

 the Algerian Sahara being $5,790,00^, we see that that sum otherwise 

 appropriated would j^ay for boring 7,400 wells averaging 154 feet in 

 depth, assuming the cost per foot to be the same as south of the Ziban 

 oases. Allowing the issue to be only one half that of the wells near 

 Biskra, the total flow would be 1,100,000 gallons per minute, which, 

 according to M. Ville, would suffice for the irrigation of about 24,- 

 600,000 palms. One tenth of this labor and expense would produce 

 great results. 



So far facts and discussion alike have been limited to the region 

 bordering upon Algeria and Tunis. This is because explorations have 

 naturally been carried on there somewhat to the exclusion of the Tri- 

 politan neighborhood, and not because similar causes and effects may 

 not be found farther east. There is every reason to believe that the des- 

 olate region bordering the south shore of the Mediterranean between 

 the tenth and twenty-fifth meridians is destined to experience an equal 

 improvement with the western Sahara. The writer of this article, who 

 was one of a party of officers of the United States Navy engaged in 

 surveying along that coast in 1878, had occasion to observe in several 

 places, notably at Zouaga near Tripoli, and along the shores of the 

 Gulf of Sidra (Syrtis Major), hottest of the hot and driest of the dry, 

 that water was to be had by digging but a short distance. He noticed, 

 also, not a few oases just on the sandy horizon, that bespoke the pres- 

 ence of the life-giving element. An examination of the map shows 

 many more. While this would not be very convincing proof to a 

 skeptical mind, in the absence of organized investigation, it may at 

 least be considered encouraging. The day is not far distant, however, 

 when certain knowledge will confirm or disprove hazardous opinions. 

 The various geographical societies of the world have ceased to let the 

 matter rest, and Professor Rohlfs is even now in charge of an expedi- 



