ILLUSTRATIONS (16). THE SAHARA. 89 



be regarded as the Great Atlas of Ptolemy; but where is the 

 limit of the Little Atlas ? Are we still to maintain the divi- 

 sion into two Atlas chains (which the conservative tendency 

 of geographers has retained for 1700 years) in the territory 

 of Algiers, and even between Tunis and Tlemse ? Are we to 

 seek a Greater and a Lesser Atlas between the coast and the 

 parallel chains of the interior? All travellers familiar with 

 geognostic views, who have visited Algeria since it has been 

 in the possession of the French, contest the meaning con- 

 veyed by the generally adopted nomenclature. Among the 

 parallel chains, that of Jurjura is generally supposed to be 

 the highest of those which have been measured; but the 

 well-informed Fournel (who was long Ingenieur en chef 

 des Mines de. V Algerie) affirms that the mountain range of 

 Aures, near Batnah, which even at the end of March was found 

 covered with snow, has a greater elevation. Fournel con- 

 tests the existence of a Little and a Great Atlas, as I do that 

 of a Little and a Great Altai*. There is but one Atlas, for- 

 merly called Dyris by the Mauritanians, " a name that must 

 be applied to the foldings (rides, suites de cretes), which 

 form the division between the waters flowing to the Mediter- 

 ranean and towards the lowland of the Sahara." The lofty 

 Atlas chain of Morocco inclines from north-east to south-west, 

 and not, like the Eastern Mauritanian portion of the Atlas, 

 from east to west. It rises into summits which, according to 

 Renou, attain an elevation of 11,400 feet, exceeding, there- 

 fore, the height of Etnaf. A singularly formed highland, of 

 an almost square shape (Sahab el-Marga), is situated in 33° 

 north lat., and is bounded to the south by high elevations. 

 From thence the Atlas declines in height in a westerly direc- 

 tion towards the sea, about a degree south of Mogador. This 

 south-western portion bears the name of Idrar-N-Deren. 



The northern boundaries of the extended low region of the 

 Sahara in Mauritania, as well as its southern limits towards 

 the fertile Sudan, have hitherto been but imperfectly inves- 

 tigated. If we take the parallels of 16^° and 321° north 

 lat. as the outer limits, we obtain for the Desert, includ- 

 ing its oases, an area of more than 1,896,000 square miles; 



* Humboldt, Asie centrale, t. i. pp. 247, 252. 



+ Exploration scientijique de V Algerie, de 1840 a 1842, publiee -par 

 ordre clu Gouvemement ; Sciences hist, et geogr., t. viii., 1846, pp. 

 364, 373. 



