ABR a i eit a ie Le 
On the Harrison ( Ohio) Tornado. 167 
which it was taken, it could not have ascended to a great beight. 
It entered the ground at an angle of about 45°; and if from this 
we estimate the velocity acquired from falling, to equal one-half 
of the whole there is still left a velocity of 500 feet per second 
due to the wind. ‘The effects of such a wind would be fearful 
indeed : it would move at the rate of 340 miles per hour. 
2nd. The involute form of the curve described by the wind as 
it approached the axis appears more marked in this than in the 
Brandon storm. ‘The plots of both Surveys indicate this, more 
especially that at the Graham place. At the same time the cy- 
cloidal curve is easily made out. The reverse action of the loop 
is clearly exhibited at the Graham place; the direct and reverse 
at Wakefield’s. Most of the prostrations at Wakefield’s on the 
right of the axis, were not made by the front of the storm, but 
took place when about one-half of the cycloid had passed over. 
Some of the trees were turned outward, showing that they stood 
till struck by the heel of the storm. 
' 3d. The plunging action of the tornado was a remarkable fea- 
ture. The ground west of the Whitewater was favorable for 
observing this, as it was intersected by deep ravines. Ascending 
slopes were touched lightly in general, or not at all; while the 
descending were often swept with fearful violence. I am not 
aware that this peculiarity has been mentioned by other observ- 
ers. ‘The explanation does not seem difficult ; but too much space 
has already been occupied to state it here. : 
In conclusion the writer would take the liberty to suggest to 
observers, that he has found it important to carry his observations 
beyond the track of greatest violence. hough no trees nor 
houses may be thrown down, yet valuable evidence to show the 
mode of action can oftentimes be obtained. 
Mr. Laird’s house in the vicinity of the Graham place, was on 
the left of the axis, but too far from it to suffer any injury. The 
wind was violent but left none of the ordinary marks which 
could determine its direction. Mr. Laird however stated to the 
door which had been locked, was violently driven in. The di- 
‘Tect and reverse stroke of the loop seem pointed out here. ‘The 
action of a tornado along the axis only, affords but confused data 
to elucidate the laws which govern it. 
