STEPPES AND DESERTS. 31 



shade the soil beneath from the direct influence of the sunbeams, 

 and exhaling, in the interior of the country, at a great distance from 

 the mountains and from the ocean, vast quantities of moisture, 

 partly imbibed and partly elaborated: all these circumstances 

 afford to the flat part of America a climate which by its humidity 

 and coolness contrasts wonderfully with that of Africa. It is to the 

 same causes that we are to attribute the luxuriant vegetation, the 

 magnificent forests, and that abundant leanness by which the New 

 Continent is peculiarly characterized. 



If, therefore, one side t>f our planet has a moister atmosphere than 

 the other, the consideration of the present condition of things is 

 amply sufficient to explain the problem presented by this inequality. 

 The physical inquirer needs not to clothe the explanation of these 

 phenomena in a mantle of geological myths. He needs not to as- 

 sume that on our planet the harmonious reconciliation of the de- 

 structive conflict of the elements took place at different epochs in 

 the eastern and the western hemispheres ; or that America emerged 

 later than the other parts of the globe from the chaotic watery 

 covering, ( 19 ) as an island of swamps and marshes tenanted by alli- 

 gators and serpents. 



There is, indeed, a striking similarity between South America 

 and the southern peninsula of the Old Continent in the form of the | 

 outline and in the direction of the coasts ; but the nature of the 

 soil, and the relative position of the neighboring masses of land, 

 produce in Africa that extraordinary aridity which over an immense 

 area checks the development of organic life. Four-fifths of South 

 America are situated on the southern side of the equator ; or in a 

 hemisphere which from the greater proportion of sea and from other 

 causes is cooler and moister than our northern half of the globe, (*) 

 to which the larger part of Africa belongs. The breadth of the 



South American Steppe, measured from east to west, is only a tKimy 

 of that of the African Desert. The Llanos receive the influence of* ^f 

 the tropical sea wind, while the African Deserts, being situated in 

 the same zone of latitude as Arabia and the south of Persia, are in 

 contact with strata of air which have blown over warm heat-radiat- : 

 ing continents. The venerable and only lately appreciated father' Fl 

 of history, Herodotus, in the true spirit of an enlarged view of na- 



