144 Objections to Mr. RedfieWs Theory of Storms. 



20. In this mode of viewing the phenomena, no difference of 

 opinion exists between Espy and myself, however we may differ 

 respecting the cause of the diminution of atmospheric pressure 

 within the track of a tornado, which gives rise to the ascending 

 current. 



21.1 adduced several facts, upon the authority of the accurate 

 survey made by that gentleman and his associate, proving that the 

 effects were, in some cases, inconsistent with the existence of a 

 whirl; and I mentioned one which could not be explained without 

 attributing it to a gyratory force. Hence I was led to consider gy- 

 ration as a casual, not an essential feature in the meteors in ques- 

 tion. It appeared reasonable to suppose that the conflict of conflu- 

 ent streams of air, rushing towards an axis moving progressively, 

 might be productive of a whirling motion. The contortion of 

 six feet of the upper part of a brick chimney upon the lower por- 

 tion, so as to cause the corners of either portion to project beyond 

 the sides of the others, was deemed inexplicable, without ascri- 

 bing it to a gyratory force. Subsequently, howevjer, it occurred 

 to me that this fact was more likely to be the result of a local 

 than of a general whirl ; since, in the latter case, the chimney 

 could not have been twisted as described without being precisely 

 at the centre of the whirlwind. That such could have been its 

 position, appeared to me to be extremely improbable, and had it 

 been so situated, as the whirlwind was estimated to be moving 

 progressively, at the rate of seventeen miles per hour, it is to me 

 incomprehensible how the portion which was dislocated could 

 have escaped an overthrow. Evidently, although twisted upon 

 its base while concentric with the axis of gyration, it would in 

 one second of time have been twenty feet upon the windward 

 side of it, and consequently subject to the tangential force of the 

 whirlwind. I adduce this, as well as other facts, to prove, that 

 in tornadoes and hurricanes, there are local whirls, causing bod- 

 ies, which are of a nature to favor an electrical discharge, to be 

 particularly affected. 



22. A fact, irreconcilable with a general whirling motion, has 

 been recorded by Messrs. Espy and Bache. A frame building was 

 so situated as to be protected by another edifice in one direction 

 from the suction of the tornado, and yet, was exposed to its influ- 

 ence as it advanced, and as it moved away. Hence two of the 

 four posts, on which the frame rested, were so impelled by the 



