338 BREAKING OF CLOUDS. 



becoming obscured by dense black vapour, ac- 

 companied with thunder and lightning, violent 

 winds, and copious precipitations of rain. Dur- 

 ing such storms, more vapour is condensed into 

 rain in twenty or thirty minutes, than usually 

 falls during a whole day, or even a week, when 

 there is no lightning. All the phenomena par- 

 take of the violence which characterizes the 

 electric fluid when greatly accumulated. 



Lord Bacon observes in his Natural History of 

 Winds, that " tornados are caused by the sud- 

 den breaking of clouds ," by which he meant those 

 rapid precipitations of rain that accompany 

 lightning and thunder. He also observes, that 

 " when it lightens in a clear sky, winds and rain 

 are at hand from the quarter where it lightens : 

 but if it lightens in different quarters, there will 

 follow cruel and horrid tempests." He might 

 have added, that they have already begun in 

 the places where the lightning is seen. 



Hail Storms. 



On the subject of hail storms, which are inti- 

 mately related to whirlwinds, water-spouts, &c. 

 much learning and ingenuity have been ex- 

 pended since the days of Franklin, without any 

 satisfactory explanation of their cause. 



The celebrated Volta, supposed that they were 



