104 STEPPES AND DESERTS. 



il faut aux lions de 1'eau corn-ante ^t de la chair vive. Aussi des lions 

 ne paraissent dans le Zahara que la ou il y a des collines boisees et 

 de 1'eau. Nous ne craignons que la vipere (lefa) et d'innombrables 

 essaims de moustiques, ces derniers la ou il y a quelque huniidite." 



Whereas Dr. Oudney, in the. course of the long journey from 

 Tripoli to Lake Tschad, estimated the elevation of the southern 

 Sahara at 1637 English feet, to which German geographers have 

 even ventured to add an additional thousand feet, the Ingenieur 

 Fournel has, by careful barometric measurements based on cor- 

 responding observations, made it tolerably probable that a part of 

 the northern desert is below the level of the sea. "That portion 

 of the desert which is now called " le Zahara d' Algerie" advances 

 to the chains of hills of Metlili and el-G-aous, where the northern- 

 most of all the Oases that of el-Kantara ; fruitful in dates is 

 situated. This low basin, which touches the parallel of 34 lat., 

 receives the radiant heat of a stratum of chalk (full of the shells 

 of Inoceramus), inclined at an angle of 65 towards the south 

 (Fournel sur les Grisemens de Muriate de Soude en Algerie, p. 6 in 

 the Annales des Mines, 4me serie, t. ix. 1846, p. 546). " Arrives 

 & 'Biscara" (Biskra), says Fournel, "un horizon indefini comme 

 celui de la mer se deroulait devant nous." Between Biscara and 

 Sidi Ocba the ground is only 228 (243 Eng.) feet above the level of 

 the sea. The inclination increases considerably towards the south. 

 In another work (Asia Centrale, t. ii. p. 320), where I have brought 

 together everything relating to the depression of some portions of 

 continents below the level of the sea, I have already noticed that, 

 according to Le Pere, the " bitter lakes" on the Isthmus of Suez, 

 when they have a little water and, according to General Andreossy, 

 the Natron Lakes of Fayqum are also lower than the level of the 

 Mediterranean. 



Among other manuscript notices of M. Fournel, I possess a ver- 

 tical geological profile, which gives all the inflexions and inclinations 

 of the strata, representing a section of the surface the whole way from 

 Philippeville on the coast to the Desert of Sahara, at a spot not far 

 from the Oasis of Biscara. The direction of the line on which the 

 barometric measurements were taken is south 20 west ; but the ele- 

 vations determined are projected, as in my Mexican profiles, on a dif- 



