TORNADOES. 167 



for this channel, e and, reaching it, turns and follows it 

 in its course, sometimes entirely across the Atlantic.' 

 f The southern points of America and Africa have won 

 for themselves,' says Maury, f the name of " the stormy 

 capes," but there is not a storm-find in the wide 

 ocean can out-top that which rages along the Atlantic 

 coasts of North America. The China seas and the 

 North Pacific may vie in the fury of their gales with 

 this part of the Atlantic, but Cape Horn and the Cape 

 of Good Hope cannot equal them, certainly in fre- 

 quency, nor do I believe, in fury.' We read of a 

 West Indian storm so violent, that ( it forced the Gulf 

 Stream back to its sources, and piled up the water to 

 a height of thirty feet in the Gulf of Mexico. The 

 ship " Ledbury Snow " attempted to ride out the 

 storm. When it abated, she found herself high up on 

 the dry land, and discovered that she had let go her 

 anchor among the tree-tops on Elliott's Key.' 



By a like reasoning we can account for the cyclonic 

 storms prevailing in the North Pacific Ocean. Nor 

 do the tornadoes which rage in parts of the United 

 States present any serious difficulty. The region 

 along which these storms travel is the valley of the 

 great Mississippi. This river at certain seasons is 

 considerably warmer than the surrounding lands. 

 From its surface, also, aqueous vapour is continually 

 being raised. When the surrounding air is colder, 

 this vapour is presently condensed, generating in the 

 change a vast amount of heat. We have thus a channel 

 of rarefied air over the Mississippi valley, and this 



