HtTRRICANES. 13& 



whole of its motion, in a tangential direction, and by their reverse 

 directions produce a uniform circular motion. If the south-east 

 S. E. Trades. 



Westerly Monsoons, 

 trade impinges upon one side at the rate of 30 miles per hour, 

 and the monsoon at the same velocity on the other, the amount, 

 converted into a rotary motion, would be equal to 60 miles at the 

 exterior. The stormy revolution appears to extend to a great 

 height, passing over the lofty mountains of the Isle of Bourbon 

 and the Mauritias without being destroyed, though these arrest the 

 trade winds. The same cause which produces the gyratory mo- 

 tion carries the storm forward. 



The awful phenomena developed during a hurricane, depend 

 upon the sudden reductions of the masses of air involved in it, 

 of different temperatures, to the same standard, producing the 

 most terrific exhibitions of thunder and lightning, attended with 

 rain, hail &c. The trade winds are cool, but the monsoons are 

 hot and humid. In most hurricanes, the fall of the mercurial 

 column is equal to 1 inch, or even 2 inches, and the velocity of 

 the wind just entering the focus as great as 150 miles an hour. 

 In the focus of a rotary storm the horizontal direction of the wind 

 suddenly ceases, and often, the storm appears, to one ignorant of 

 its nature, to have passsed off, when suddenly it commences again, 

 with the utmost fury, and at a point of the compass opposite to 

 where it left off. This fact is strikingly noticeable even in the 

 small hurricanes which in the autumn and spring, blow over our 

 western lakes, and we have several times witnessed a violent 

 hail and thunder storm, during which the wind raged with the 



