254 , Phyfical and Poltthal Geography of North Africa. 



S. W. winds ; which corrcfponds in all its circumllances with the fame monfoon in 

 India *. 



To tlie north of this belt, with the exception of the Egyptian Nile, the waters conform 

 generally to the dirc^Slion of the high land ; paffing at no great diftance (comparatively) 

 from its bafe to the right and left ; as if the furface of the Sahara had a general dip to the- 

 fouthward \. Thefe rivers moreover receive all their fupplies from the fouth j no dreams 

 of any bulk being collcded in the Defert. 



In order to produce this efFcft, there muft neceflarily be a vaft hollow in the interior of 

 Africa, between the high land of Nubia on the eaft, and Manding on the weft ; and of 

 which the mountains and defert form the other two fides. Nor is this ftate of things un- 

 exampled in the other continents. In Afia, the hollow, to whofe waters the Cafpian and' 

 Aral ferve as recipients, is no- lefs extenfive than the one juft mentioned ; reckoning from 

 the fources of the Wolga to thofe of the Oxus ; (which latter has ever communicated with 

 the Cafpian, cither throughout the year or during a part of it :} the diiTcrence is, that lit 

 Afia a greater portion of the hollow is filled up with water than in Africa-. 



The third part is of courfe the Great Defert (or Sahara) and its members; confifting of 

 the lefler deferts of Bornou, Bilma, Barca, Sort, &c. This may be confidfered as an oceah 

 OF SAND J, prefenting a furface equal in extent to about one half of Europe^ and having its 

 gulfs and bays ; as alfo its iflands fertile in groves and paftures, and in many inftances con- 

 taining a great population fubjed to order and regular government. The great body or 

 weftern divifion of this ocean, comprifed between Fezzan and the Atlantic, is no lefs. 

 than 50 caravan journeys acrofs from north to fouth ; or from 750 to 800 G. miles ; and 

 double that extent in length : without doubt the largeft defert in the world. This divifion- 

 contains but a fcanty portion of iflands (or oafes), and thofe alfo of fmall extent : but the 

 eaftern divifion has many ; and fome of them very large. Fezzan, Gadamis, Taboo, 

 Ghanat, Agadez, Augela, Berdoa, are amongfl: the principal ones : hefides which there are 

 a vaft number of fmall ones. In effed this is the part of Africa alluded to by Strabo 11, 

 when he fays from Cneius Pifo, that Africa may be compared to a leopard's fkin. I conceive. 

 the reafon why the oafes are more common here than iii the weft, is, that the ftratum of 

 fand is fliallower from its furface to that of the earth which it covers. In other words, that 

 the water contained in that earth is nearer to, the furface ; as in moft of the oafes it fprings 

 up fpontaneoufly §. Can any part of the caufe be affigned to the prevalent eafterly winds, 

 which, by driving the finer particles of fand to leeward, may have heaped it up to a hio^her 

 level in the Sahara than elfewhere .' 



The 



• A ridge ftretches to the fouth through the middle of South Africa, and forms an impenetrable barrier 

 between the two coafts. M. Correa de Scrra informs me, that the Portuguefe in Congo and Angola have 

 never been able to penetrate to the coaft of the Indian Ocean. 



Mr. Bruce learned (vol. lii. p. 668.) that a high chain of mountains from b" runs fouthward through tke 

 middle of Africa. He fuppofes the gold of Sofala to be drp.wn from thcfe mountains, (p. 669.) 



+ Circumftances have fliewn, that it declines to the eaiiward alfo. 



+ " A wild expanfe of lifelefs fand and fky !" Thomson, 



H Page 130. 



I Water is found at the depth of afew feet in Feizaa (Africau Aflbc. Q^p. 96. O, p. 146.) The fame ia 



fai4 



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