xcvi GENERAL SUMMARY OF SCIENTIFIC AND 



mentioned is about two hundred and forty miles in length, 

 and so formed as to resemble the bottom of a gigantic 

 valley. As a whole, it is not uninterruptedly verdant, being 

 of the usual monotonous yellow, but having about the 

 springs black and green spots (or islands, as it were), form- 

 ing the arable portions. The ten inhabited positions of the 

 oasis are said to embrace 5700 inhabitants. In the village of 

 Kargeh itself the houses are built over the streets, as on 

 piles, and supported by rough beams, through which the 

 people grope in a stooping posture. Their language is sim- 

 ilar to that of the modern Egyptians, but the people are dif- 

 ferent, being apparently the remains of one of the numerous 

 Libyan races of the Berber nations. Many remains of tem- 

 ples, castles, etc., testify to a former prosperity as compared 

 with the present condition, and among these edifices are a 

 number belonging to the period of the Roman occupation. 



Water is obtained from wells. of great antiquity, although 

 it is probable that new ones might be had by Artesian boring, 

 to the great advantage of the country. The springs are all 

 thermal, registering much above the mean annual tempera- 

 ture of the year. The theory that the Nile originally flowed 

 through this oasis is considered by Dr. Schweinfurth as un- 

 founded, no fish being met with any where, and the botany 

 of the country being totally opposed to such a conclusion. 

 The principal production is the date-palm. The camel can 

 not be kept here, owing to the damp summer miasma and 

 the numerous irritating insects ; but donkeys, cows, buffaloes, 

 and sheep are easily reared. The explored portion of the 

 oasis yielded two hundred and twenty-five species of plants. 



Insuperable physical obstacles, in the way of shifting sands 

 and the absence of water, met the travelers. Sixty camels 

 were lost in this attempt. 



Dr. Zittel, who accompanied Rohlfs as geologist, in his 

 researches, is quite satisfied that the Sahara, as already sug- 

 gested, is the dried-up basin of a former shallow sea. The very 

 fine quartz sand found here is not produced from any forma- 

 tion in or near it, and must have been carried to it by some 

 foreign agency. The real surface of the desert is a bare, dry, 

 chalk plateau, resembling that of the Suabian Alps. Above 

 it rise peaks, which are, however, on the same level, and 

 show that they are the remains of an ancient surface, the 



