SECTION SEVENTH. 



OF THE TORNADO OR WATER-SPOUT. 



Lemma. 



175. SUPPOSE a receiver, only a few hundred yards in 

 diameter, but so lofty that its top would reach to where the 

 barometer would stand at 10 inches, and that it contained 



air about 25|, for example, hotter than the air on the out- 

 side, this latter being at a mean, 32. The column of air 

 then in the inside of the receiver would be expanded of 



