ARTESIAN WELLS AND THE GREAT SAHARA. 537 



time the Sahara will disappear under a vegetation of which the mimo- 

 sas are the forerunner. "Thus," he adds, "while certain timorous 

 spirits fear that the earth may some day be overpeopled, Nature is si- 

 lently transforming the soil where man will in the future be abl? to 

 pitch his tent. The Sahara will be covered with green trees, new 

 lakes will be formed, and the rivers whose dry beds now fill the trav- 

 eler with horror will be running streams of limpid water as abundant 

 as that of the great streams of Europe." 



Such a return to what seems pretty certain to have been the state 

 of things ages ago would be most extraordinary without the help of 

 man. The vast tract comprised between the sixteenth and thirtieth 

 parallels of latitude, and extending from the Atlantic to the valley of 

 the Nile, once fertile, became the arid waste of to-day mainly through 

 neglect. A M. Largeau in 1874 visited the valley of the Igharghar, 

 with the intention of branching off to Rhadames to study the com- 

 merce of that oasis and test the practicability of diverting to Algeria 

 the caravans that come there by the central route from Soodan. He 

 questioned the chambas on the causes of the drying of the great 

 Saharan streams, and found that all agreed in saying that these dead 

 rivers once ran full through a country more fertile than the Tell (the 

 region north of the Atlas Mountain's crest), but could only explain it by 

 legends more interesting than satisfactory. 



M. Largeau gives the following explanation of the change : " It is 

 known that pastoral people have always been great destroyers of for- 

 ests, for they need large spaces of clear ground to feed the flocks that 

 form their wealth and to promote security against the wild beasts that 

 lurk in forests. Even noAV the Algerian Arabs are seen firing the 

 woods to enlai-ge the narrow limits imposed upon them by colonization. 

 So, although the great Saharan streams have not been explored to their 

 sources, yet it is known that they commence on the bare plateaux that 

 are but the skeletons of heights once wooded and fertile. All accounts 

 of the inhabitants of these regions agree on that point. Consequent 

 upon the destruction of the forests the periodical rains were replaced 

 by rare and short though violent storms, the waters from w^hich, instead 

 of soaking in as in past ages, slip by on the rocky masses, carrying 

 away the rich surface mold, and bring about the drying of the springs, 

 and, as a direct consequence, of the rivers." 



An admission of this theory leads the way easily and hopefiilly to 

 the prophecy of Professor Rohlfs, and raises the question whether it 

 would not be better on all accounts to let the salt waters of the Medi- 

 terranean circulate in their own proper bed and pursue the more eco- 

 nomical work of conquering the desert by assistance from under- 

 ground. Nearly all the fluvial network of the Algerian Sahara con- 

 verges toward the Igharghar. Formed by the confluence of several 

 small streams on the slopes of the Ahaggar, it flows northward, and 

 soon sinks through the light sands and pursues its underground course 



