224 winds 



this motion of the air continues to act, tlie air of 

 higher latitudes must share more and more in the 

 effects. The air coming as it does to the place of 

 observation from distances continually greater, 

 that is, farther and farther north, must have a 

 movement in the direction round the earth, that is 

 continually slower and slower, and must therefore 

 gradually take a more and more westward or 

 easterly direction. If therefore the cause of the 

 original north wind remains at work, the wind- 

 vane must gradually pass from a north direction 

 through north-east to east. 



A wind which at its commencement at the 

 place of observation appeared as a due south wind, 

 draws the air, if it lasts, from latitudes nearer and 

 nearer to the equator, and must therefore gradually 

 pass through south-west into west. 



If the north wind has passed by degrees into an 

 east, or the south wind into a west, it must very 

 soon, in consequence of the resistance of the ground, 

 lose that motion which the ground has not in 

 common with it, and must take the rate of motion 

 round the earth which the ground has at the lati- 

 tude, at which it is at the time, that is to say, a 

 calm ensues. 



If, however, the cause which first set up the 

 current continues, the same set of effects as oc- 

 curred at first must be repeated ; that is, the east 

 wind must, after the lull, become a north wind, 



