ANNOTATIONS AND ADDITIONS. 183 



P*) p. 17 . " Conical-shaped clouds." 



The singular phenomenon of these "sand spouts/' 

 something analogous to which may occasionally be seen on 

 a small scale in Europe where four roads meet, is par- 

 ticularly characteristic of the Peruvian Sand Desert between 

 Amotape and Coquimbo. Such a dense cloud of sand or 

 dust may prove dangerous to the traveller who does not 

 cautiously avoid its approach. It is also worthy of notice 

 that these partial conflicting currents of air only arise 

 when the air generally is perfectly calm. The aerial ocean 

 resembles the sea in this respect, for in the latter also the 

 small currents which are often heard to ripple audibly, 

 (filets de courant), are only perceptible in a dead calm 

 (calme plat). 



( 35 ) p. 18. " Increases the suffocating heat!' 



I have observed in the Llanos de Apure, at the Guada- 

 lupe cattle farm, the thermometer rise from 27 to 29 

 Reaumur (92.7 to 97.2 Mir.) whenever the hot wind 

 began to blow from the Desert, which at such times was 

 covered either with sand or with short withered turf. In 

 the middle of the sand-cloud the temperature was for some 

 minutes 35 E. (111 P.). The dry sand in the village of 

 San Fernando de Apure had a temperature of 42 R. 

 (126 Pahr.) 



( 36 ) p. 18. t: The illusive image of a cool rippling 



watery mirror" 

 The well-known phenomenon of the mirage is called in 



