WIND AND STORMS. 



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patcd by the barometer, which falls very quickly for " wind." The quarter 

 whence the breeze may be expected is often indicated by the streamers of 

 clouds, or " mare's tails," across the sky ; though we must admit the opposite 

 direction to that anticipated by casual observers may often prove the right 



one. 



Hurricanes and tornadoes are really whirlwinds in motion. The rotatory 

 movement of the air is from right to left in the northern hemisphere, and 

 from left to right in the southern that is, in the opposite and same directions 

 respectively as the hands of a watch move. The whirlwinds are caused by 

 two currents of air meeting at a certain angle, just as a whirlpool is the 

 result of opposing currents of water. 



Fig. 716. Effects of storm at Halligen in 1834. 



The use of the wind in nature cannot be over-estimated. It is frequently 

 destructive and terrible in its effects, but these comparatively trifling damages 

 are as nothing when weighed against the advantages conferred upon mankind 

 by the wind and the currents of the atmosphere. The north cold is tempered 

 by the warm south wind. The pollen and the seeds of plants are borne 

 on the wings of the wind, and the clouds are carried over the land to " drop 

 fatness" upon our fields. The want of free circulation of air is very injurious. 

 Witness the terrible affliction of goitre, so prevalent in the closely shut-in 

 valleys such as the Rhone Valley, where cretinism or congenital idiotcy is 

 distressingly prevalent. 



