TORNADOES PRODUCED BY ELECTRICITY. 109 



machine, shows that the air is put in motion by 

 electric currents. 



The uplifting of water by a passing tornado is 

 called a " water-spout." This effect is illustrated 

 by holding the finger over a vessel of water placed 

 on the excited conductor of an electric machine. 

 The water will rise in spray to meet the finger. 



The writer had once an opportunity of witness- 

 ing, in fearful proximity, the phenomena accompa- 

 nying the passage of a tornado. An account of 

 it was given in a letter to Dr. Robert Hare, and 

 was by him published in the " Transactions " of the 

 American Philosophical Society, in 1838. This 

 tornado passed over the south part of the city of 

 Providence, and across Narragansett Bay. The 

 central whirl proceeded from west to east through 

 a calm atmosphere, overturning trees and build- 

 ings in its path of about one hundred yards in 

 width. Roofs were uplifted, and the fragments 

 were scattered through the air like missiles. To 

 escape them the writer fled to an open field, while 

 the whirling materials moved on with terrific 

 force and an appalling roar of crashing sounds. 



In passing over the water the inverted cone of 

 dark mist swerved about like a huge trunk of an 

 elephant, while the surface of the water beneath it 

 was upheaved tumultuously. The adjacent waters 

 foamed like a boiling caldron. At times the dark 

 misty cone of spray was rendered brilliant with 

 gleams of lightning, followed by a momentary lull. 



