DUSTING COTTON FROM AIRPLANES. 7 
special crank controls the elevation at which the feed regulator is set in 
the hopper, and this regulator remains at this point as long as the 
same feed rate is desired. The control of delivery is accomplished by 
a separate sliding valve operating across the bottom of the hopper. 
For convenience, the first hopper is termed the " hand-crank " type 
and the other is called the " air-suction " type. These two were left 
in the two planes throughout the experiments, and all field applica- 
tions were made with one or the other. The manner of operating 
them is shown in Figure 7. The operator stood upright in the rear 
Fig. 5. — Interior construction of air-suction hopper. Shows main air tube extending 
down through hopper, with box valve at its lower end fully raised. Also shows 
arrangement of auxiliary air tubes along the side to keep dust from clogging. 
cockpit behind the hopper and controlled the delivery of the dust. 
This was not a particularly pleasant position but sufficed for the 
preliminary experimental tests. 
THE DAYTON HOPPER. 
The hopper which had been used in the experiments at Dayton, 
Ohio, was shipped to Tallulah as soon as the tests were arranged. It 
arrived about the time the hoppers described above were completed, 
and was used in a few flights. As shown in Figure 8, this hopper 
was constructed to hang over the side of the plane to the right of 
and just in front of the observer's cockpit. The rate of feed was 
