364 Mr. Redfield's Reply to Dr. Hare, 



it should be observed, that the sketch of prostrations in the 

 orchard, which is included in fig. 3, is evidently on a more 

 reduced scale than that given in the plan of the building; 

 otherwise the buildings must be of size sufficient nearly to 

 have covered the orchard. This change of scale may cause 

 some confusion unless particularly noticed. 



That the velocity and consequent force of the whirling 

 movement of the tornado is maintained by the direct pressure 

 of the surrounding atmosphere, rather than by the "suction" 

 which has been alleged by Dr. Hare, I can readily conceive ; 

 but that the " transient forces of a whirlwind" of this charac- 

 ter are generally found to be " tangential " to its axis, which 

 he seems to consider a necessary condition, I do not admit. 



Dr. Hare appears to concede, that my survey of this tor- 

 nado shows effects which accord with whirlwind action ; but 

 he seems desirous of limiting this admission to the prostration 

 of " certain trees," and alleges that this survey " does not de- 

 monstrate gyration to be an essential feature of tornadoes ;" 

 and that " it is sufficiently accounted for by considering it as 

 a fortuitous consequence of the conflux of currents rushing 

 into a space partially exhausted." (26.) 



Now I cannot but think, that readers who have no theory 

 to support, will view the results of my survey in a very dif- 

 ferent light. Dr. Hare omits to mention, that the survey 

 comprised the entire breadth of the visible track, at perhaps 

 its broadest place; that it was intended to include every tree 

 prostrated within its limits ; that it essentially agrees with the 

 main features of the more partial surveys of Professor Bache ; 

 that I have shown by clear inductions from all the pro- 

 strations in the survey that the whirling motion was one ge- 

 neral effect, comprising the entire width of the track ; that the 

 tornado must have arrived at this ground in nearly its most 

 perfect action, having just left the surface of the Raritan river; 

 that the axis of prostration was not found in the centre of the 

 track, but nearest its left margin ; that the main rotation was 

 wholly to the left, or in one constant direction ; and that 

 the leading features of the prostration found in this survey, 

 have also been observed as constantly occurring in the tracks 

 of many other tornadoes *. 



I may add, that in a careful exploration of the track of this 

 tornado for several miles, I found nothing to contravene the 

 results of my published survey ; the general features of the 

 prostration being greatly analogous to those which I have 

 given. 



* See this Journal, January 1841, p. 1 7-29, and map. Journ. Frank. 

 Instit. vol. ii. third series, p. 40-49. 



