34 Transactions Tennessee Academy of Science. 



central vacuum, preventing the ready inrush of air from the out- 

 side. But as the friction against the ground would check the 

 velocity at that point and the irregularities of the surface of the 

 earth would from time to time make gaps under this "zvall;' blasts 

 cf air of great force would, in a somewhat irregular manner, rush 

 into the central vortex with destructive violence. This explains 

 the "flaws" already alluded to so that trees standing quite near to- 

 gether were sometimes very unec[ually damaged. Now, as this 

 vortex comes suddenly over the deep sinkhole the lower edge of 

 the "wall" of revolving air suddenly leaves the surface of the 

 ground, on account of the rapid sloping of the ground downward 

 into the sink; this allows surrounding air to rush from all sides, 

 with tremendous violence into the vacuum, "diving under the 

 wall," so to speak ; and as these blasts are much more swift than 

 the progressive motion of the funnel, trees are even overthrown 

 backward. 



9. It was noted that when the funnel passed suddenly over 

 the edge of a steep bluff where the ground dropped suddenly 

 downward, instead of skipping over as might have been expected, 

 the destruction was worse than usual, even down to the bottom 

 of the slope. This phenomenon may be explained on the same 

 principle as in the case of the sink-hole. 



10. It seems strange that there are not more lives lost in these 

 terrible storms. ]\Iany times isolated houses are completely de- 

 stroyed, and yet the occupants, though scattered about and much 

 shaken up, escape serious injury. Contrast the destruction of a 

 town by a tornado and by an earthquake. The loss of life is vastly 

 greater in the earthquake ; in this the house is shaken down upon 

 the occupants like a "dead-fall" on a rat. But the tornado gen- 

 erally lifts the roof, bursts out the walls, scatters the materials of 

 the house, often without damage to its inhabitants. The probable 

 ex|)lanation of this is as follows: Suppose the house is tightly 

 shut u]), as is usually the case during the storm. Now when the 

 vortex suddenly envelops the house, the air inside being much 

 denser than that constituting the ]:)artial vacuum of the vortex, 

 suddeiiK' c-.\])an(ls, lifting the roof and bursting out the walls. Cal- 

 cidations based on the probable difference of ])ressure inside and 

 outside the house show force anii)l)' alile to produce such re- 

 sults. 



