148 WONDERS OF ORGANIC LIFE. 



experienced mariner. The lowering sky sheds a 

 dim, almost straw-coloured light on the desolate 

 plain. The horizon draws suddenly nearer ; 

 the steppe seems to contract, and with it the 

 heart of the wanderer. The hot dusty par- 

 ticles which fill the air increase its suffocating 

 heat, and the east wind blowing over the long 

 heated 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 gra- 

 dually 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. 

 Everywhere the death -threatening drought pre- 

 vails ; and yet, by the play of the refracted rays 

 of light producing the phenomenon of the 

 mirage, the thirsty traveller is pursued by the 

 illusive image of a cool, rippling, watery 

 mirror. The distant palm bush, apparently 

 raised by the influence of its contact with un- 

 equally 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 dark 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 neigh- 

 bourhood of a not wholly dried-up pool. More 



