GEOGRAPHY. 15 



to twenty-five feet, and fertilizes the adjoining country by its over- 

 flow. 



II. Rivers emptying into the Atlantic. These are the Senegal, the Gam- 

 bia, the Rio Grande, the Niger (emptying by numerous arms into the Bight of 

 Renin, and there constituting an immense Delta), the Congo or Zaire, the Cu- 

 enza or Coango, and Orange River or the Gariep. 



III. Into the Indian Ocean there empty only inconsiderable rivers, the only 

 ones deserving mention being the Lorenzo-Marquez, the Zambeze, and the 

 Quilmance. 



Africa possesses but few inland Lakes. The largest, as far as known, is 

 Lake Tschad, situated in the interior, at an elevation of about 1400 feet, 

 and into which flow various rivers, as Yeou, Shary, &c. In the north-east 

 of Africa we find Lake Zana in Abyssinia, through which the Nile flows ; 

 south-east of this is the Zawaja ; also Lake Moeris (Berket el Kerun) and 

 the Natron lakes in Egypt ; and the Moravi or Zembre lake in the south- 

 east. The elevated Lake Koufia is situated to the north-west of the 

 latter. 



Islands. 1. To the east of xAfrica : Socotra, in the south of Arabia ; the 

 Seychelles or Mahe Islands, south of the equator, with the Almirante Islands, 

 together forming the Ethiopian Archipelago ; Madagascar, the largest of all 

 the islands of Africa, containing about 160.000 square miles, and separated 

 from the mainland by the Channel of Mozambique ; the islands of Comoro 

 and Primeira, in the Channel of Mozambique ; and the Mascarene Islands to 

 the east of Madagascar, among which are included the Mauritius (Isle ot 

 France) and Bourbon. Upon the latter is a mountain of more than 10,000 

 feet in height. 



2. In the west of Africa, a. North of the equator : the Azores or 

 Terceiras (among them St Michael, Terceira, Flores, Pico, &c.), Madeira, 

 the Canary Islands, Ferro, Palma, Teneriff*e, with its peak of 12,172 feet in 

 height ; the Cape de Verde Islands, the largest of which is St. Jago, with the 

 volcano of Fuego, 9154 feet high ; the Guinea Islands, of which Fernando 

 Po, Prince's Island, and St. Thomas lie north, and Anabon south of the 

 equator, b. South of the equators Ascension, St. Helena, and Tristan 

 d'Acunha. 



The Isothertnals of Africa are shown on the chart. The equator of heat, 

 or the isothermal of 82° F., passes through the middle of Africa, and the 

 equatorial limit of snow through the northern part of Africa, Algiers, Tunis, 

 and Morocco. The southern limit of the vine passes a little further south, 

 through Egypt, (fee. ; through South Africa passes the south polar limit of the 

 banana, and of the tropical grains ; also the equatorial limit of the European 

 tropical grains ;; still furth-er south is the polar limit of the palm. 



4. America {Plates 6 and 7). 



The continent of America is divided into two portions, called North and 

 South, by a narrow strip of land, the Isthmus of Panama. North America 



15 



