36 REPORT—1840. 
lofty mountains ; and under what circumstances appear what are called 
tornadoes on land and waterspouts at sea. 
“ On visiting the path of a tornado, the trees on the extreme borders 
will all be found prostrated with their tops inwards, either inwards and 
backwards, or inwards and forwards, or exactly transverse to the path. 
The trees in the centre of the path will be thrown either backwards 
or forwards, or parallel to the path; and invariably if one tree lies 
across another, the one which is thrown backwards is underneath. 
Those materials on the sides which are moved from their places and 
rolled along the ground, leaving a trace of their motion, will move in 
a curve convex behind; those which were on the left hand of the path 
will make a curve from left hand to right, and those on the left hand 
of the path will make a curve from right hand to left; and many of 
these materials will be found on the opposite side of the path from 
that on which they stood on the approach of the tornado. Also those 
bodies which are carried up will appear to whirl, unless they arise from 
the very centre—those that are taken up on the right of the centre 
will whirl in a spiral from left to right, and those on the left of the cen- 
tre will whirl in a spiral upwards from right to left. On examining the 
trees which stand near the borders of the path, it will be found that 
many of the limbs are twisted round the trees, and broken in sucha 
manner as to remain twisted, those on the right-hand side of the path 
from left to right, and those on the left-hand side of the path from 
right to left. However, it will be found that only those limbs which 
grew on the side of the tree most distant from the path of the tornado 
are broken; for these alone were subject to a transverse strain. The 
houses which stood near the middle of the path will be very liable to 
bave the roof blown up, and many of the walls will be prostrated, all 
outwards, by the explosive influence of the air within, and those houses 
covered with zine or tin, from being air-tight, will suffer most. The 
floors from the cellars will also frequently be thrown up, and the corks 
of empty bottles exploded. _ All round the tornado, at a short distance, 
probably not more than three or four hundred yards, there will be a 
dead calm, on account of the annulus formed by the rapid efflux of air 
above, from the centre of the up-moving and expanding column. In this 
annulus the air will be depressed, and all round on the outside of it, 
at the surface of the earth, there will be a gentle wind outwards, and 
of course all the air which feeds the tornado is supplied from within 
the annulus. Nor is this difficult to understand, when the depression 
of the air in the annulus is considered, for any amount may be thus sup- 
plied by a great depression. Light bodies, such as shingles, branches 
of trees, and drops of rain or water formed in the cloud, will be car- 
ried up to a great height, before they are permitted to fall to the earth ; 
for though they may frequently be thrown outwards above, and may 
then descend to a considerable distance at the side, they will meet with 
an in-blowing current below, which will force them back to the centre 
of the up-moving current, and so they will be carried aloft again. 
« The drops of rain, however, will frequently be carried high enough 
to freeze them, especially if they are thrown out above so far as to fall 
