120 THE PHYSICAL GEOGRAPHY OF THE SEA. 



of the parching drought, the crocodile and the boa become mo- 

 tionless and fall asleep, deeply buried in the dry mud 



" The distant palm-bush, apparently raised by the influence of 

 the contact of unequally heated and therefore unequally dense 

 strata of air, hovers above the ground, from which it is separated 

 by a narrow intervening margin. Half-concealed by the dense 

 clouds of dust, restless with the pain of thirst and hunger, the 

 horses and cattle roam around, the cattle lowing dismally, and 

 the horses stretching out their long necks and snuffing the wind, 

 if haply a moister current may betray the neighborhood of a not 

 wholly dried-up pool 



"At length, after the long drought, the welcome season of the 

 rain arrives ; and then how suddenly is the scene changed ! . . . . 



" Hardly has the surface of the earth received the refreshing 

 moisture, when the previously barren steppe begins to exhale 

 sweet odors, and to clothe itself with killingias, the many pani- 

 cles of the paspulum, and a variety of grasses. The herbaceous 

 mimosas, with renewed sensibility to the influence of light, unfold 

 their drooping, slumbering leaves to greet the rising sun ; and the 

 early song of birds and the opening blossoms of the water plants 

 join to salute the morning." 



283. The arid plains and deserts, as well as high mountain 

 ranges, have, it may well be supposed, an influence upon the 

 movements of the great aerial ocean, as shoals and other obstruc- 

 tions have upon the channels of circulation in the sea. The des- 

 erts of Asia, for instance, produce (§ 203) a disturbance upon the 

 grand system of atmospherical circulation, which, in summer and 

 autumn, is felt in Europe, in Liberia, and away out upon the In- 

 dian Ocean, as far to the south as the equinoctial line. There is 

 an indraught from all these regions toward these deserts. These 

 indraughts are known as monsoons at sea; on the land, as the 

 prevailing winds of the season. 



284. Imagine the area within which this indraught is felt, and 

 let us ask a question or two, hoping for answers. The air which 

 the indraught brings into the desert places, and which, being heat- 

 ed, rises up there, whither does it go ? It rises up in a column a 

 few miles higli and manv in circumference, we know, and we can 



