44 Origin, Extension and Continuance of Prairies. 
A TORNADO. it 
We have stated that hurricanes and whirlwinds, by their irl 
upon the forests, are chiefly instrumental in forming prairies. 
It is believed that hurricanes are not so frequent and so violent as 
formerly. For the last twenty-five years particularly, they have dimin- 
ished in number and energy. The signs of hurricanes, previous to 
the year 1805, would indicate in their case, a frequency and violence 
unequalled in any subsequent period. 
“Tn the year 1805 it happened to the writer to be roving on that 
most beautiful lawn, extending from, Kaskaskia to Illinois, and which 
is called the American bottom. There was the most charming alter- 
nation of prairie, and woodland, and while he was musing on the 
causes which gave rise to forests of grass, or cane; and of stu- 
pendous oaks and cotton’ *~woods, he was roused, and his attention di- 
rected toascene of unequalled grandeur and horror. It was a whirl- 
wind that had ct ossed the Mississippi, and was making i its way through 
the swamp, until it was near the ‘charming prairie, which at that mo- 
ment afforded rest and comfort toa solitary pedestrian. By the irres 
sistible force of the wind, whole forests were ina moment twisted 
from the ground, and when thrown from the mouth of the vortex, 
such was the violent collision of tree against tree, that they were 
pounded into billets and splinters. A sound of universal distress burst 
forth from every quarter, and earth and sky appeared to be blended. 
In a twinkling the tornado scooped up a lake, with two or three feet 
of mud which lined its bottom. In one instant more, it tore away 
a house with its stone” chimney. In another moment thirty or forty 
horned cattle, and fifteen or sixteen horses, disappeared with incon- 
ceivable quickness. The whirlwind twisted off almost every spear 
of a wheat field, and bore it away with the fence, cattle, horses, lake, 
trees, house, and whatever was in the way. For more than a mile _ 
the heavens were black, and filled with the wreck of the = ie 
In this tornado, as well as many that had before occurred in 
ge on a smaller scale, there was nothing to justify a belief with 
Mr. Dunbar, “of a vortex with a central spot in a state of profound 
calm 5” or of Dr. Franklin, who supposed the “vortex of a whirl- 
wind to be a true vacuum.” 
From the lake to the house, was about two hundred yrds between 
which stood a huge cotton-wood tree of at least seven feet in diamée- 
ter, and more than one hundred feet in height. It was observed, 
_ when the vortex had nearly or quite reached the tree, that the leaves _ 
