284 Tornado in N. E. part of Ohio, Feb. 4, 1842. 



from a gun of two inches calibre into solid blocks of elm wood, 

 in the direction of the fibres, penetrated the following distances: 



With a charge of 2 oz. powder, velocity 800 feet per second, penetration 7 inches. 

 " 4 " 1200 " 15 " 



" 8 ' " 1600 " 20 " 



Dr. Hutton .estimates the resistance of elm timber 7^ times more 

 than that of firm earth. A pound ball with a velocity of 800 

 feet should then penetrate the earth 51 inches. The depth pen- 

 etrated being assumed to be as the square of the velocity, a pound 

 ball fired with the velocity of 550 feet would penetrate 24 inches. 

 The space penetrated is said to be as the specific gravity of the 

 ball. A wooden ball two inches in diameter, specific gravity .75, 

 fired with a velocity of 550 feet should then penetrate firm earth 

 2.4 inches. As this last result is a deduction from principles 

 somewhat doubtful, I desired to verify it by experiments of my 

 own. A six pounder was accordingly charged with 1:^ pounds 

 of powder. Two or three short pieces of oak board, three inches 

 wide and one inch thick, were added, and the gun pointed towards 

 a steep hill distant about a rod. The boards penetrated the ground 

 a few inches, were badly shivered and bounded some distance up 

 the hill. A second experiment was tried with nearly the same 

 result. The hill was of usually firm earth but not stony. The 

 greatest penetration did not exceed six inches. Velocity com- 

 puted 1000 feet per second. According to the former data, the 

 penetration should have been nearly eight inches. But the ground 

 at May field was saturated with water. I have no precise data for 

 estimating the allowance required by this circumstance. I judge 

 however that it would not increase the penetration more than 

 threefold. We arrive then at the conclusion that the clap-boards 

 at Mayfield were driven into the earth with a velocity of 1000 

 feet per second or 682 miles per hour. 



I do not by any means suppose that the velocity was the same 

 throughout the entire track. On the southeast half, probably the 

 velocity did not exceed three times the progressive motion of the 

 tornado. 



Let us now determine the directions of the wind. For this 

 purpose we measured the bearings of about seventy prostrate trees 

 extending across the track in the direction N O. We did not 

 attempt to measure the bearings of all indiscriminately, for this 

 would have been a hopeless task. The prostrate trees are only 



