SMALL WHIRLWINDS. O7 
and was lost to sight on the clear grass country. This was a good 
type of the calm weather whirl. From the fact of it being calm, 
and that the whirl did not disperse on my standing in it, I classi- 
fied it as caused by an ascending current of air. On January 24, 
1893, in the same spot as I have just described, I witnessed a fine 
specimen of the “windy weather” whirl. It revolved left handedly, 
and as the breeze was steady from N.N.W., I classified it as 
caused by an ascending current of air also. 
This whirl also crossed the road previously mentioned, and the 
dust was sucked upasbefore. At the height of about thirty feet, 
however, the head of the whirl was broken and dispersed, being 
carried bodily forward in a cloud of dust. Having noticed this 
as a general effect common to all whirls of this class, I formed 
the conclusion, as hitherto stated, that the directive force of the 
wind was greater than the rotatory force of the whirl, and that 
when this was the case the whirl would be dispersed. Many 
small whirls that I noticed only rose a few feet above the surface, 
and were dispersed by the wind before they had travelled many 
yards. Thus it may be concluded that whether a whirl is caused 
by an ascending current of air, or in an eddy caused by opposing 
currents, the force of the wind is an important item with respect 
to their existence. If the force of the wind be moderate to fresh, 
the eddy or whirl produced will be soon dispersed, as may be seen 
by those produced at street corners, etc., on windy days. If the 
force be greater, the whirls will be dispersed as soon as formed. 
In making this statement I refer principally to “variable” winds, 
for if two steady currents of air meet each other obliquely, there 
is no reason why eddies produced thereby should not exist till 
they disperse themselves. It must also be borne in mind that 
those destructive tornado hailstorms, which visit us periodically 
with high winds, belong to an entirely different section of cyclonic 
disturbances. — 
Thus it may be seen that to thoroughly investigate our second 
section is a difficult matter, and the result arrived at from my 
observations is that whirls which are caused by ascending currents 
G—June 7, 1893. 
