THE WEATHER. 221 



nity afforded by the extreme dryness of the grass and 

 young trees, to set fire to them, especially near their 

 roads, not only to keep the roads open to travellers, but 

 to destroy the shelter which long grass, and thickets of 

 young trees would afford to skulking parties of their ene- 

 mies. A fire thus lighted flies with such rapidity as to 

 endanger those who travel. A common method of es- 

 cape is, on discovering a fire to windward, to set the 

 grass on fire to leeward and then follow your own fire. 

 There are other extraordinary effects produced by the 

 extreme dryness of the harmattan. The covers of books 

 even closely shut up in a trunk, and lying among clothes, 

 are bent as if they had been exposed to the fire. House- 

 hold furniture is also much damaged ; the pannels of 

 doors and of wainscot split and any veneered work flies to 

 pieces. The joints of a well laid floor of seasoned wood 

 open sufficiently to lay one's finger in them ; but become 

 as close as before on the ceasing of the harmattan . The 

 seams also in the sides and decks of ships are much in- 

 jured, and the ships become very leaky, though the 

 planks are two or three inches in thickness. Iron bound 

 casks require the hoops to be frequently driven tighter ; 

 and a cask of rum or brandy with wooden hoops, can 

 scarcely be preserved ; for unless a person attend to keep 

 it moistened, the hoops fly off. 



' The parching effects of this wind are likewise evi- 

 dent on the external parts of the body. The eyes, nos- 

 trils, lips and palate, are rendered dry and uneasy, and 

 drink is often required, not so much to quench thirst, as 

 to remove a painful aridity in the fauces. The lips and 

 nose become sore, and even chapped; and though the 

 air be cool, yet there is a troublesome sensation of prick- 

 ling heat on the skin.' 



(e) Force of Winds. 



This instrument by which the force and velocity of 

 winds is measured is called a wind gage, or anemometer. 

 It is constructed as follows. A B C E is a bended tube, 

 large at A, which side is to be turned towards the wind. 

 The part F B C E is filled with water or some other 

 liquid less likely to freeze, and the whole apparatus is 



VOL. i. NO. ix. 20 



