420 



THE PHYSICAL GEOGRAPHY OF THE SEA. 



788. According to Dove's "Law of Kotation," whicli is said to 

 Dov6'3 law. hold good iQ the northern hemisphere, and is sup- 

 posed to obtain in the southern also, the wind being N.W. and 

 veering, it ought to veer by W. to S.W., and so on, against the 

 hands of a watch*. This " law" is explained thus : Suppose a ship 



V 



be in S. lat. off Cape Horn as at «, with a low barometer to the 

 north of her, as at C, where the air ascends as fast as it comes 

 pouring in from all sides. The ship, let it be supposed, is just on 

 the verge of, but exterior to the vortex, or that place where the 

 wind commences to revolve. The first rush of the air at a will 

 be directly for the centre, C ; consequently, a ship so placed 

 would report the storm as commencing with the wind at south. 

 For the sake of illustration, we will suppose this place of low ba- 

 rometer to be stationary, and the air, as it rushes in, to ascend at 

 the disc, C. Thus the area of inrushing air will gradually en- 

 large itself by broad spreading, like a circle on the water, until 

 it be compassed by a circle with a radius, CS^ of indefinite length. 

 The air then, on the meridian, SON, but to the south of a, will 

 not blow along this meridian and pass over the ship ; in conse- 

 quence of the diurnal rotation of the earth, it will take a direc- 

 tion, S a', to the westward ; and the arrow d a, representing a 

 S.S.E. wind, will now show the direction of the wind at a. Thus 

 the ship will report that the wind commenced at south, and grad- 

 ually hauled to S.S.E. , i. e., against the hands of a watch ; and so 

 the arrows b' a' will represent the direction of the wind at each 



