1874.] The Iowa and Illinois Tornado. 373 
so as to allow the tree to rest upon the ground. The 
broken timber, when sound, invariably presented the appear- 
ance of a broom. ‘The fibres of each year’s growth were 
loosened from the others and split. It was easy to obtain 
pieces ro feet long and as thin asa wand. This separation 
of the fibres had evidently been brought about by the ex- 
cessive straining and bending of the tree before it fell, Each 
year’s growth had apparently been snapped asunder by itself, 
beginning at the outside. The trees all lay as they had 
fallen, being, when once down, protected by the surrounding 
timber. If they had, after falling, been subjected to a wind 
from another direction, so as to break them off entirely, they 
' would have presented the precise appearances which have, 
by certain meteorologists, been attributed to the action of 
electricity. Many of these broken trees were 2 feet in 
diameter. When a tree, still standing, had its bark torn off 
at any point, an examination generally showed that the 
fibres of the tree were separated and perhaps partly severed 
at that point. 
The path of the tornado was exceedingly well marked 
among the young trees. It could be followed by the eye as 
far as the ground permitted. They were torn and bare, 
while all around was green. This barking of the young 
trees took place within much narrower limits than those 
within which grown timber was overthrown. Generally it 
did not extend over twenty to thirty yards in width, and 
was sometimes much less and even disappeared altogether. 
The trees exhibited the marks of the greatest violence on the 
side from which the storm came. The twigs were smashed 
and broken off, the bark partially removed, and even the 
timber bruised. These results were evidently the effect of a 
rush of missiles against the trees. 
The tornado at one point suddenly narrowed the path of 
extreme violence from 50 yards to 12 yards, at the same 
time changing its course to the south-east. This change of 
direction brought it toward Swan Creek, along the northern 
bank of which it had hitherto been raging. Just as it struck 
the creek the track was nearly S.S.E. Immediately there- 
after it turned nearly due east, following the creek. The bot- 
tom of the ravine, within which Swan Creek flows, is about 200 
yards wide, is surrounded by steep and lofty bluffs, and was 
covered with large trees. Among these trees the whirlwind 
raved with the utmost fury, developing an energy surpassed 
at no other point in its career. Trees from 3 feet to 4 feet 
in diameter were snapped or uprooted. Many large trees 
were broken off at a height of about 4o feet and left without 
VOL. IV. (N.S.) 3B 
