176 LIGHT SCIENCE FOR LEISURE HOURS. 



Generated, like the West-Indian hurricanes, at a dis- 

 tance of some ten or twelve degrees from the equator, 

 typhoons sweep in a curve similar to that followed 

 by the Atlantic storms around the East - Indian 

 Archipelago, and the shores of China to the Japanese 

 Islands. 



There occur land-storms, also, of a cyclonic charac- 

 ter in the valley of the Mississippi. " I have often ob- 

 served the paths of such storms," says Maury, " through 

 the forests of the Mississippi. There the track of 

 these tornadoes is called a ' wind-road,' because they 

 make an avenue through the wood straight along, and 

 as clear of trees as if the old denizens of the forest had 

 been cleared with an axe. I have seen trees three or 

 four feet in diameter torn up by the roots, and the top, 

 with its limbs, lying next the hole whence the root 

 came." Another writer, who was an eye-witness to 

 the progress of one of these American land-storms, 

 thus speaks of its destructive effects : " I saw, to my 

 great astonishment, that the noblest trees of the forest 

 were falling into pieces. A mass of branches, twigs, 

 foliage, and dust, moved through the air, whirled on- 

 ward like a cloud of feathers, and passing, disclosed 

 a wide space filled with broken trees, naked stumps, 

 and heaps of shapeless ruins, which marked the path 

 of the tempest." 



If it appeared, on a careful comparison of observa- 

 tions made in different places, that these winds swept 



