GEOGRAPHY. I3 



which corresponds to the greatest observed mean temperature of about 82° F. 

 It will be seen that this is far from coinciding Avith the terrestrial equator. 

 The chart also expresses the equatorial limit of perpetual snow, and of the 

 falling of snow ; these show how for to the south perpetual snow lies in differ- 

 ent countries, and how far it falls during winter. The former line coincides 

 with the polar limits of mosses and berries. 



The chart likewise indicates the limits of different kinds of plants, among 

 which, in addition to the various cerealia, are to be found the sugar-cane 

 (Zucker), coffee (Kaffee), tea (Thee), cotton (Baumwolle), rice, &c. ; also, the 

 polar limits of trees, the equatorial and polar limits of the vine, and of the 

 European tropical cerealia. 



3. Africa {Plate 5). 



This still, for the most part, unknoAvn portion of the earth, extends from 

 37° 20' north latitude to 34° 50' south latitude ; its limits in longitude are 

 51° 22' east, and 1T° 32' west longitude, reckoned from Greenwich. Its 

 greatest length is 5000 statute miles ; its greatest breadth about 4800. It 

 contains about 8,902,000 square geographical, or nearly 12,000,000 statute 

 miles. It is bounded on the north by the Mediterranean Sea, on the west by 

 the Atlantic, on the south and east by the Indian Ocean ; to the north-east it 

 is connected to Asia by the Isthmus of Suez, and is separated from Europe 

 to the north-west by the Straits of Gibraltar. 



The portion of the Atlantic Ocean washing the south-western part of 

 Africa, is the South Atlantic, the northern part of which is termed the Gulf 

 of Guinea. Smaller portions of the Gulf of Guinea are the Bights of Benin 

 and Biafra. The small portion of the Indian Ocean which separates the 

 Island of Madagascar from the mainland of Africa, is called the Mozambique 

 Channel. Between the north-eastern coast of Africa and the western coast of 

 Arabia, the Indian Ocean runs up in a long, narrow gulf, the Arabian gulf, or 

 the Red Sea ; this is connected with the main ocean by the Straits of Bab-el- 

 Mandeb. The northern extremity of the Red Sea is called the Gulf of Suez. 

 In the northern part of Africa the Mediterranean forms the Gulfs of Sidra, 

 Cabes, and Tunis. 



Among the Currents of the African seas, as represented on our physical 

 chart of the Continent {pi. 5), the following are the most important : Two 

 currents from the Indian Ocean (one of them much the stronger of the two, 

 coming through the Mozambique Channel) unite not far from the southern 

 point of Africa, and there constitute a current from 360 to 400 miles broad 

 (the Cape current), which soon after takes a north-westerly direction, with a 

 mean velocity of about twelve miles per hour. From this branches off the 

 South Atlantic current, which passes along the western coast of South Africa, 

 and subsequently, when the coast takes a direction to the west, continues 

 westward along the equator. It now forms the main Equatorial current, 

 but between it and the coast there runs another current from north to 

 south, nearly in the opposite direction, and known as the Guinea current. 



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