fit mow*. 87 



equator, now becoming a part of the lower 

 trade wind. This causes a calm at that point 

 where it turns. The upper parts of this cur- 

 rent continue on, in a northerly and southerly 

 direction, on the surface until they meet with 

 the cold air of the north and south polar 

 regions, where there is a conflict of the ele- 

 ments as there always is when cold and warm 

 currents meet. 



The only point where the trade wind has 

 free play is in the South Indian Ocean, and 

 this is called the " heart of the trades." 



If the whole globe were covered with water 

 there would be a more constant condition of 

 temperature ; but owing to the great difference 

 between the land and water, both as to altitude 

 and the ability to absorb and radiate heat, we 

 have all of these varied and complicated con- 

 ditions of wind and weather. The trade 

 winds shift from north to south and vice versa 

 with the advancing and receding seasons, due 

 to the fact that the earth has a compound 

 motion. It not only revolves on its axis once 

 in twenty-four hours, but it rocks back and 

 forth once a year, which is gradually changing 

 the direction of its axis; and in addition to 

 these motions it is traveling around the sun as 

 well. 



