Tornado iii N. E. part of Ohio, Feb. 4, 1842. 283 



tance travelled estimated at three fourths of a mile, which is a 

 velocity of fifty two miles per hour. According to the best tes- 

 timony I could obtain, the tornado passed Chagrin River at a 

 quarter past four ; passed Painesville a quarter before five. Velo- 

 city seventeen miles in thirty minutes, or thirty four miles per 

 hour. 



I have obtained an independent estimate of the velocity, in the 

 following manner. Tlie tornado accompanied the change of 

 wind from south to west, which was experienced over a large 

 territory. This change of wind was at Hudson cotemporaneous 

 with the barometric minimum, and it is presumed to have ad- 

 vanced with nearly the same velocity. I have therefore sought 

 for barometric observations, and ha^re obtained them for the four- 

 teen following stations. The time of barometric minimum is 

 not in all cases the time of the lowest observation, but is obtained 

 by projecting the observations on paper and comparing the curves 

 at the different stations. 



From these data we find the progress of the wave to be in the 

 direction N. 62° 19' E., and velocity 30.05 statute miles per hour. 

 But the course of the tornado was N. 33° 30' E., inclined 28° 49' 

 to the p-ogress of the wave. The velocity of the wave in the 

 direction of the tornado's progress was then 34.3 miles per hour, 

 a result almost identical with the second estimate. The first es- 

 timate can only be regarded as a good guess. The tornado then 

 travelled a space equal to its breadth, at Mayfield, in seventy-five 

 seconds. 



The velocity of the wind's motion however at points of the most 

 destructive violence, was far greater than this. A tolerable idea 

 of its velocity may be gained from the distance to which light 

 objects were driven into the ground. Small pieces of clap-boards 

 with square ends were driven into turf land eighteen inches, and 

 with sharp ends two feet. What charge of powder is capable of 

 producing the same effect ? According to the experiments of Dr. 

 Hutton, (Tracts, Vol. 3, p. 214,) a pound ball of cast iron fired 



