48 Mr. Redfield on the Rotary Action 
But on the arrival of the third quadrant, the prostrating 
power on the left side becomes more and more efficient by the 
ceasing of the backward and the accession of the progressive 
movement ; and at or near the line of fm, it again takes effect 
with rapid increase. The destructive force is also much aug- 
mented here by the greater velocity in the heart of the whirl, 
near its axis, and the impetus must rapidly increase in energy 
to its maximum effect, as at m 0, taking off any tree which 
may here remain, and carrying aloft, or sweeping onward, the 
objects previously prostrated on the line cx k. 
If a tree on the left side of the track falls on one previously 
thrown down by the tornado, the last fallen will also have the 
more onward direction, as on the other side; unless both have 
fallen in the second quadrant, where few prostrations occur.— 
The fourth quadrant, ‘for causes noticed in considering the 
Jirst, can have little prostrating effect, except perhaps on the 
small area near its axis. 
If we now conceive of our figure as applied only to the li- 
mits of prostration or destruction which constitute the visible 
path of the tornado, it becomes relatively unequal in its right 
and left-hand quadrants, the axis appearing greatly eccentric, 
and in the same degree, at least, as the /eft band or belt of 
prostrations is found narrower than that on the right of the 
axis. This apparent, but illusive form of the whirl, may be 
illustrated by fig. 5; which is drawn on the same lines with 
the preceding figure. 
