WINDS. 



393 



The Southeast Trade Winds are interrupted by the Northwest Mon- 

 soon, and their limits encroached upon by the southwest winds ; both 

 denser winds. All these winds seek the areas which are most rarefied 

 by the temperature of the ocean and the sun's heat, in order to restore 

 the equilibrium of temperature. 



In all countries there are local winds, but they are chiefly those 

 which approximate to the general direction. For instance, in Eng- 

 land, and perhaps throughout all Europe, the westerly winds are most 

 common in the summer months. In the winter months, they have 

 those from the north, northeast, and east; which prove, so far as Europe 

 is concerned, that the great aerial currents flow from the colder to the 

 warmer regions. 



We now perceive that there can be no accumulation at the Equator, 

 nor deficiency at the Poles ; and consequently, that we need not recur 

 to any hypothesis to supply the one or carry off the other, to maintain 

 the equilibrium throughout the earth's surface, or secure the circula- 

 tion and supply the great currents. Under the Equatorial limits the 

 temperature is high ; — under the areas on the outer border of the 

 Trade Winds, the thermometer stands at temperate heat throughout 

 the year; while within the Polar Circle, during the long nights, calms 

 prevail : then the temperature is always low and generally equable. 

 When the atmosphere is highly heated, the weight of its column is 

 decreased ; — hence the barometer stands low. Along the area of 

 calms, between the Trades and Variables, it stands higher throughout 

 the year, owing to the mean temperature being lower; but at the 

 Poles there is less height of atmosphere ; — consequently its standing is 

 lower. 



The supply for these great Equatorial currents comes from the 

 north and south Variables and Polar regions, through the Monsoons, and 

 alternately with greater or less force during the presence of the sun 

 in either hemisphere. These currents of air do not flow towards the 

 regions of the calm areas, or from them. The calm areas maintain 

 nearly an equable temperature throughout the year. They confine 

 the Equatorial currents to their bounds, and their limits only extend 

 along the Trade Winds; they do not cross the Monsoons. These 

 move freely to the north and south between them and the continents, 

 and flow almost continuously. Short calms take place, but they are 

 altogether transitory in their character, and confined to small spaces, 

 where the temperature acquires a temporary equilibrium. But the 



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