New Brunswick Tornado. 77 



of those examined by others, the course of rotation has been 

 found the same as in the case before us.* 



In order to make a just and satisfactory examination of the 

 effects of a tornado, it appears necessary to select portions of the 

 track where the extension of wood or single trees, on each side, 

 is found sufficient to mark clearly the exterior limits of the pros- 

 trating power, and where the effects on both sides of the axis are 

 also clearly developed. Our next care should be to ascertain, as 

 near as may be practicable, the line which separates the opposite 

 convergence of the two sides, noticed above as the axis or line 

 of convergence. We should then determine the general direc- 

 tion of this line and of the track at the place examined ; which 

 being done, we may proceed to measure the distance to which 

 the prostrations are extended on each side, and then carefully to 

 take the position and direction of prostration of each and of all 

 of the fallen bodies, noting with care, also, any other phenomena 

 which may serve to aid our inquiries. We may thus obtain val- 

 uable materials for future analysis ; and this course of investiga- 

 tion, if faithfully pursued, will, it is believed, remove all reason- 

 able doubt of the rotative action of these tornadoes. An exam- 

 ination of their probable origin, and the causes of their enduring 

 activity and violence, belongs not to the present occasion. 



New York, February 5, 1841. 



* As in the tornado which passed through Allegany county, New York, July 

 2.')th, 1838; described by Mr. Gaylord in the American Journal of Science, Vol. 

 xxxvii, p. 92. 



