THEORY OF HURRICANES, ETC. 331 



flashes of lightning, which they called fire, 

 while the tornado was described by the Romans 

 as vortex igne factus, and was identical with 

 the prester, from 7rp?0w, inftammo, meaning a 

 fiery whirlwind. It is evident on the slightest 

 reflection, that violent winds which spring up 

 suddenly, and often immediately after a calm,* 

 cannot possibly be owing directly to the rarefy- 

 ing influence of solar heat, like regular winds, 

 the velocity of which rarely exceeds twenty or 

 thirty miles per hour ; while the tornado moves 

 at the rate of from one hundred to one hundred 

 and twenty miles per hour. It is during the 

 rainy season, that the tropical regions are visited 

 by those dreadful hurricanes, or fiery tempests 

 which tear up trees by their roots, destroying 

 every thing in their resistless course and when 

 rain is precipitated in floods with a rapidity pro- 

 portional to the amount of lightning. Those of 

 the East Indian seas occur during the shifting of 

 the monsoons, and are obviously owing to the 

 condensation of vapour, caused by the meeting 

 of extensive masses of air from opposite quar- 

 ters of different temperatures. The equinoctial 

 storms that sweep over the West Indies, the 



* We often see against some storm 



A silence in the heavens, the rack stand still, 

 The bold winds speechless, and the orb below 

 As hush as death : anon the dreadful thunder 

 Doth rend the region. Hamlet. 



