Whirlwinds produced by the Burning of Cane-Brakes. 73 



coal is used. This smoke also far surpassed, in its dense, 

 deep black colour, any thing ordinarily observed. 



The cane-brake visited by Mr Olmsted covered a space of 

 25 acres, and w^as set on fire at the part most distant from 

 him. " Whirlwinds were now observed in the hottest part 

 of the fire. They did not unite in one column, but were 

 scattered throughout the fire, and several were formed at 

 the same time. The first were on a comparatively small 

 scale. Their height was from 30 to 40 feet. To these suc- 

 ceeded others on a larger scale, until they reached the height 

 of more than 200 feet, and the flame and smoke which formed 

 their columns were perfectly distinct from the general mass 

 which arose from the fire. They appeared rather to increase 

 in size and frequency toward the latter part of the ' burn- 

 ing,' and many were formed on the ashes after the fire had 

 to a great extent gone down. 



" Among the whirlwinds there were several points of dif- 

 ference, by which they might be classed under four heads. 

 The most common one was that which was stationary over a 

 part of the fire which was hotter than the neighbouring por- 

 tions. A second variety was that which had a progressive 

 motion, and advanced over the burnt track, throwing up ashes 

 and cinders, and thus making its course through the fire. Some 

 of these emerged from the flames. This was probably the 

 case with a number, although, having nothing to mark them 

 after leaving the fire, they became invisible. One, however, 

 passed near enough to us to be observed, and attracted our 

 attention by its rustling sound, and by the leaves which it 

 carried up. This was about 15 or 20 feet high. At the 

 time this passed us we had moved from our first station, 

 and were about 300 yards from the fire. These whirl- 

 winds differed from the others in form, being very wide 

 at the top, and contracting to a point at the bottom, like a 

 top or a spindle ; or, more exactly, they were of the form 

 of the upper cone of an hour-glass. An interesting pheno- 

 menon which attended some of the whirlwinds might render 

 it proper to arrange them under a third class. In these the 

 flame was violently whirled at the base ; then above suc- 

 ceeded a dark interval, where the flame seemed to be ex- 



