132 
HAROLD'S DISCUSSIONS. 
to rotating storms whose diameter is more than a 
mile at least, and use the word tornado for smaller 
and more destructive storms. This distinction is gen¬ 
erally made by scientific writers. 
“ Tornado ” comes from the Spanish word mean¬ 
ing to turn, and it has the same signification as the 
Greek word cyclone. I have often watched “ dust- 
whirls ” skip across fields or down the street. I re¬ 
member seeing a dozen or more at one time crossing 
a forty-acre field. The wind whirled about a central 
point, carrying with it straws and other light objects, 
whirling them round and bearing them ever higher 
and farther out, until their momentum carried them 
beyond the influence of the whirl. 
Fig. 67.—A dust-whirl moving contrary to the hands 
of a watch. 
The tornado is like the dust-whirl,” except that 
it is very much intensified. The air rushes up in the 
center with such force as to carry men, and even 
horses and other heavy objects, up to some distance 
above the ground. These, like straws, may be whirled 
