PRACTICAL ARBORICULTURE 147 
this grand gulf in a skiff, and remembers the efforts he was obliged to put 
forth to pull his craft out of the whirling waters. This is upon the same 
principle which we are endeavoring to show wherein the obstacles placed in 
the pathway of the wind will and do cause the same circular motion in the 
atmosphere as is seen in the moving waters. 
The whirlpool, or gulf, as it was termed, was described in 1811 in “The 
Navigator,” a periodical published in Pittsburg 
5 
It was noted on the map of 
a reconnoissance made in 1821, which is very nearly the same position as my 
memory recalls when I rowed through it during the fifties. When the “cut-off” 
was made, the Mississippi changing its course, this phenomenon was destroyed 
and its former location is now an island of sand. 
WHIRLPOOL PHENOMENON 
THE AFRICAN SIRCCCO 
originates in Egypt. Beginning on the Libyan desert, the heated current 
flows northwest; crossing the Mediterranean it reaches Malta, Sicily and Italy, 
traversing twelve to fifteen hundred miles of treeless, mountainless region, 
over desert and sea, having no obstruction until it reaches the Apennines, 
where it is deflected upward and mingled with the cold upper strata. 
THE AMERICAN SIROCCO 
is caused by the prevailing winds from southwest to northeast during July 
and August, passing over a vast tract of superheated sand and sandy soil, 
beginning in Mexico, traversing Texas, Indian Territory, Oklahoma, Kansas 
and Nebraska, reaching part of Iowa and Missouri. A region of plains with- 
out mountains, high hills or forests to break its continuity, the atmosphere 
takes up additional heat as it passes in succession over miles of hot and arid , 
sands—until its breath withers all vegetation with which it comes in contact. } 
Both man and beast suffer as well, the over-heated air being terribly oppres: 
