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 sarqe 

 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. 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- 



