New Brunswick Tornado. 73 



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

 the track, he 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 pros- 

 trations 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 tornado 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 whirl- 

 wind on the side of its reverse motion as just considered, will be 

 hmited to a shorter distance than on the opposite or progressive 

 side of its axis. 



This is seen in the more limited extent of the prostrations on 

 the north or left margin of the track, as compared with the ex- 

 tent of those which incline inward on the right side of the appa- 

 rent axis. There were many trees standing beyond the northern 

 border of the track, but none had fallen. 



8. It follows, in like manner, that on that side of a whirlwind 

 in which the rotary motion coincides with the progressive move- 

 ment, the prostrating power will not only be increased in its in- 

 tensity, but will also be effective over a wider space ; and that 

 few, if any, of the prostrated bodies will be found to have been 

 thrown backward. 



In the case before us, as may be seen in the sketch, the pros- 

 trations are found to extend on the southern or right side of the 

 apparent axis to a distance nearly twice as great as on the left 

 side. The same general result has also been noticed in the tracks 

 of other tornadoes which I have examined. 



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

 line c c or axis of the tornado, owing to which the effect mentioned does not ap- 

 pear so obvious in the figure. 



Vol. xLi, No. 1.— April-June, 1841. 10 



