422 The Origin of the Great Cyclones. [October, 
limit reached by the S.E. trade in summer—a faét which is 
in remarkable contrast with the winter southern limit of the 
N.E. trade, which, as we have seen, does not attain a lower 
latitude than 3° N., or, as many observations give, 5° N. 
Besides this fact, we have in the S.E. trade a powerful 
and not a gentle wind. If we compare the average velocity 
of the South-East trades with that of the North-East, we 
shall find, according to the researches of the U.S. National 
Observatory, that ‘‘velocity of the North-East trades is 
from 14 to 18 miles per hour, that of the South-East from 
25 to 30 miles an hour.” Add to this the yet more signifi- 
cant fact, from the same authority, that ‘‘ The force of the 
trade-winds (S.E.) as determined by the average speed of 
2235 vessels sailing through them, is greater between 5° 
and 10° south than it is between 25° and 30° south,” and we 
have what amounts well nigh to a demonstration, that the 
South-East trades do violently overleap the Equator. Ex- 
periments also show that while the average force of the 
freshest trade-wind in the North Atlantic taken just abaft 
the beam of vessels is sufficient to propel them 6 knots an 
hour, that of the S.E. trade-wind is sufficient to propel 
them 8 knots an hour.* 
With the facts now before us, we are in a position to 
weigh and measure the wind-forces which meet and conflict 
in the torrid zone, and, as it is claimed, give the initial 
impulse to so many hurricanes or cyclones annually; and 
especially to those which are generated in the West Indies, 
and which subsequently come home to every American 
citizen whose habitation lies east of the Rocky Mountains, 
from the Gulf of Mexico to Lake Superior and Maine, and, 
I may also add, to every European. 
It is a marked trait in nature’s workings, that the most 
feeble and insignificant force may, and often does, work 
gigantic results. 
Scientific travellers tell us that, in their ascents of the 
Alps, far up amid its sublime and dreadful acclivities, the 
cautious guide is often so situated that he dares not open 
his lips to speak lest the faintest agitation of the air may 
dislodge immense masses of ice, and bury the party in an 
instant beneath the avalanche or storms of snow. It can 
be demonstrated by the laws of mechanics that the upward 
discharge of a single cannon will produce a cylindrical 
vacuum in the upright path of the projectile, and that, 
under a calm and still atmosphere, such a discharge will 
* Maury’s Sailing Directions, p. 853. 
