Nem Brunswick in New Jersey^ U. S., June 19, 1835. 23 



5. In considering further the eiFects of such action, we 

 may expect to find that the increased activity of gyration 

 which is observed near the centre of a vortex, will be indi- 

 cated by a more violent and irregular action in and near the 

 path pursued by the axis of the whirlwind, than is found 

 under its more outward portions. 



This effect is often strikingly exhibited in the path of tor- 

 nadoes ; while, in the supposed ascent of a non-whirling co- 

 lumn, it would seem that no part of the surface would be so 

 much exempted from its action as that lying near its centre. 



6. As the effect of rotation must be to produce, on one 

 side of the advancing axis, a reversed motion which is con- 

 trary to the course of the tornado, it is evident that on this 

 side the prostrating power will be much lessened ; that the 

 cases of prostration, therefore, will be less numerous ; and 

 that some of these, at least, will be produced in a backward 

 direction, more or less opposite to the course of the tornado. 

 By this criterion, not only the whirling movement, but the 

 direction of the rotation also may be clearly ascertained. 



This effect is best observed by comparing the two opposite 

 margins of the track ; and is strongly exemplified in the case 

 before us. Here we find, that most of the trees prostrated 

 within five chains (110 yards) from the northern or left-hand 

 margin of the track, lie in directions which are more or less 

 backward from the course of the tornado. The prostrations 

 in this part of the track are also for the most part less general 

 than on the opposite side of the axis *, a greater portion of 

 the trees being left standing. 



It sometimes happens, owing perhaps to the inward or 

 involute motion having exceeded the progressive motion at a 

 particular point, that some inclination backward will be found 

 in the prostrations on the progressive side of the whirl, as 

 seen on the sketch, Nos. 77 to 80. But these unfrequent 

 cases by no means compare with the numerous backward 

 and sometimes outward prostrations, found on the reverse 

 side of the whirl, as illustrated by Nos. 1, 3, 4, 7, 9, 10, 12, 

 13, &c. on the left side of the track. 



Thus we find here a satisfactory indication that this tor- 

 nado was a whirlwind; and that the course of its rotation was 

 to the left in front. 



7. It is also apparent, that the prostrating power of a 

 whirlwind on the side of its reversed motion as just consi- 



• There was a vacant space in the belt of wood, immediately to the 

 right of the line cc or axis of the tornado, owing to which the effect men- 

 tioned does not appear so obvious in the figure. 



