46 CLOUDS. [chap. in. 



in the shade. Dr. Heberden's observations on the UEste, 

 Oct. 20, 1750, are as follows: — 



Hours 10, 12, 4. Thermometer within doors, 73, 70, 77. 

 Do. exposed to the air, 81, 82, 77. 



In the UEste of 1850, on the 28th of February, Mason's 

 hygrometer showed 18 degrees of dryness. It is invariably 

 accompanied by a haze, though less dense than that which 

 is said to characterize the Harmattan*. The cause of this 

 haze is not known, though it may probably be due to the 

 minute particles of red sand, which, when this wind blows 

 strong, may be seen plentifully deposited. Many curious 

 birds are blown over from the African coast by the UEste, 

 of which the oi'dinary direction is, by the compass, E.S.E. 

 It generally lasts about three, six, or nine days. After the 

 wind ceases rain almost invariably follows. 



CLOUDS. 



The clouds are so regular in their movements that it seems 

 as if these might be reduced to rule. Early in the morning, 

 the tops of the hills are generally clear; later in the day, 

 light clouds make their appearance, which presently unite, 

 generally to separate again, and break into those varied shapes 

 and masses which enhance so greatly the beauty of the 

 scenery. At nightfall the bank of clouds usually forms again, 



* The nature of the Harmattan, of the Simoom, and of the Sirocco, is 

 sufficiently well known ; Josephus Acosta, lib. iii., cap. 9, mentions a wind 

 which he experienced in India in these words : — " The iron gates were 

 so rusted and consumed by a peculiar wind, that pressing the metal be- 

 tween your fingers, it would be dissolved and crumbled, as if it had been 

 hay or parched straw." 



