41G THE PHYSICAL GEOGKAPHY OF THE SEA. 



soons of the China Sea are not five-month monsoons (§ 681) ; 

 they do not prevail from the west of south for more than two or 

 .three months. Plate Y. exhibits the monsoons very clearly in a 

 part of this sea. In the square between 15° and 20° north, 110° 

 and 115° east, there appears to be a system of three monsoons ; 

 that is, one from northeast in October, November, December, and 

 January ; one from east in March and April, changing in May ; 

 and another from the southward in June, July, and August, chang- 

 ing in September. The great disturber of the atmospheric equi- 

 librium appears to be situated among the plains and steppes of 

 Asia; their influence extends to the China Seas, and about the 

 changes of the monsoons these awful gales, called typhoons and 

 white squalls, are experienced. 



783. In like manner, the Mauritius hurricanes, or the cyclones 

 The Mauritius hurri- ^f the Indian Occau, occur during the unsettled 

 ^''"^'■' state of the the atmospheric equilibrium which 

 takes place at that debatable period during the contest between 

 the trade- wind force and the monsoon force (§ 699), and which de- 

 batable period occurs at the changing of the monsoon, and before 

 either force has completely gained or lost the ascendency. At 

 this period of the year, the winds, breaking loose from their con- 

 trolling forces, seem to rage with a fury that would break up the 

 very fountains of the deep. 



784. So, too, with the West India hurricanes of the Atlantic. 

 The West India hurri- Thcsc wiuds arc most apt to occur during the 

 ^'^°^^- months of August and September. There is, 

 therefore, this remarkable difference between these gales and 

 those of the East Indies : the latter occur about the changing 

 of the monsoons, the former during their height. In August 

 and September, the southwest monsoons of Africa and the south- 

 east monsoons of the West Indies are at their height ; the agent 

 of one drawing the northeast trade-winds from the Atlantic into 

 the interior of New Mexico and Texas, the agent of the other 

 drawing them into the interior of Africa. These two forces, 

 pulling in opposite directions, assist now and then to disturb the 

 atmospheric equilibrium to such an extent that the most power- 

 ful revulsions in the air are required to restore it. " The hur- 

 ricane season in the North Atlantic Ocean," says Jansen, ''occurs 

 simultaneously with the African monsoons ; and in the same sea- 



