§ 327. RED FOGS AND SEA BREEZES. I43 



soil, brings with it no refreshment, but rather a still more burning 

 glow. The pools which the yellow, fading branches of the fan- 

 palm had protected from evaporation, now gradually disappear. 

 As in the icy north the animals become torpid with cold, so here, 

 under the influence of the parching drought, the crocodile and the 

 boa become motionless 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 une- 

 qually 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 dis- 

 mally, and the horses stretching out their long necks and snufling 

 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 panicles 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." 



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

 Are the great des- langcs, havc, it mav wcll bc supposcd, an influence 



erts centres of circu- . ^ ^ ^ 



lotion? upon the movements of the great aerial ocean, as 



shoals and other obstructions have upon the channels of circula- 

 tion in the sea. The deserts of Asia, for instance, produce (§ 299) 

 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 Indian Ocean, as far to the south as the equi- 

 noctial 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. 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 heated, rises up there, 

 whither does it go ? It rises up in a column a few miles high and 



