146 JOURNAL OF THE 



A path 6 c runs east and west as in the figure. I had set fire to the 

 dry leaves in the drain and it was burning from a to d, about 75 

 yards, the flames often mounting up 10 feet. While this was going 

 I rapidly spread fire along on the north side of the path from a to 6, 

 about 75 yards, so as to burn up the pine straw covering the ground 

 up to the dotted line, say 20 feet. This fire spread to the north, its 

 northern border (the blazing straw) maintaining its east and west 

 direction, the wind blowing all the time from due east. After the 

 blaze had got 6 or 8 feet from the path, and everything was going 

 on to my satisfaction, I stopped at the path to look at it, when be- 

 hold! there was a little tornado following the blaze from east to 

 west whirling around from left to right. In two or three seconds it 

 eith^^r lost its force or ascended out of reach of the blaze. Then 

 there was another and another in rapid succession until I counted 

 about thirty, and the straw was all consumed. They were devel- 

 oped so rapidly that I was unable to get a good view of one until 

 it had moved a few feet, when the flame in its axis was rushing up 

 above the normal height of the blaze. 



Now for the conditions : The east wind, heated by the fire in the 

 drain from a to d^ did not blow along on or near the surface of the 

 earth north of the burning pine straw, hence the air there was drawn 

 towards the partial vacua south and east of it. Over the ground 

 covered by the burnt pine straw, and bounded on the north, as well 

 as I could judge, by the line of blazing straw, the east wind was 

 blowing. Hence, as the cool air on the north rushed to the blaze 

 and came in contact with the heated northern border of the east 

 wind, the consequent check to its velocity on that side, produced 

 the series of whirls from left to right. 



B. F. GRADY. 



Albertson^s, iV. C, August, 1886. 



