74 On the Whirling Action of the 



The facts here considered are too important to be overlooked, 

 and seem fully to establish both the whirling action and the 

 course of rotation. 



9. If a rotative action be exhibited, the mean directions of all 

 the prostrations, on each of the two opposite sides, will differ 

 greatly in their respective inclinations to the line of progress, and 

 the mean direction of those on the reverse side will be found 

 more backward than on the opposite side, where the rotative 

 course coincides with the progressive action. 



In the case before us, the mean direction of all the prostrations 

 on the right side of the track is found to incline 52 degrees in- 

 ward from the line of progress. The course of the tornado is 

 here taken to be east ; although for the last half mile its course 

 had been a little north of east. On the left side, the mean direc- 

 tion is found to be S. 3° W., or 93 degrees inward and back- 

 ward ; a difference in the mean inclination from the course on 

 the two sides of 41 degrees.* 



If we now take the indications afforded by the two exterior 

 portions of the track, to the width of five chains on each side, 

 where the effects are more distinctive in their character, we find 

 on the right side a mean inward inclination of 46 degrees, the 

 mean direction being N. 44° E. ; while on the left side of the 

 track the mean inclination is not only inward but 48 degrees 

 backward, the mean direction on this side being S. 48° W. We 

 have thus a mean difference in the inclination of the fallen trees, 

 on the two exterior portions of the track, of no less than 92 degrees. 



These indications seem conclusive, also, in favor of the whirl- 

 ing action in the direction from right to left. 



10. Although of less importance, it should be mentioned that 

 the diminished action of the tornado which is commonly ob- 

 served on the hillsides and summits over which it passes, and the 

 greatly increased action in the bottoms of the valleys, and even 

 in deep ravines, afford a strong argument against ascribing the 

 effects to the ascent of a non-whirling rarefied column ; as the 

 latter, it would seem, must act with greater force on the hillsides 

 and summits than in the bottoms of valleys. The general cor- 

 rectness of the observation above stated cannot justly be ques- 

 tioned. 



'* The inclinations of the fallen trees from the course, on both sides the axis, are 

 reckoned inward and backward. 



