320 THE CHEMISTRY OF CREATION. 



upper current descends to take the place of the 

 lower, at about the 30th degree of latitude, it 

 is actually felt as a violent westerly gale. At 

 the poles, and within the polar circles, there 

 is a constant steady polar gale toward the 

 equator on every side. The effect of the earth's 

 motion in altering the direction of these cur- 

 rents, is exhibited in the accompanying cut. 



N 





The upper current was long suspected to 

 exist, before its existence was positively known. 

 A curious accident at length decided it. In 1822 

 an immense volcano burst open in the island of 

 St. Vincent, and vomited to an enormous alti- 

 tude showers of stone and ashes. Strange to 

 say, although the trade wind blows so strongly 

 in the opposite direction, that a circuit of- one 



