DUSTING COTTON FROM AIRPLANES. 
17 
In Figure 11 the behavior of the dust immediately after flowing 
from the hopper is noted, and in Figure 12 is seen particularly the 
decidedly spiral nature of the cloud following the plane. In Figure 
13 is shown, as well as possible, the tendency of the dust to blow to 
the left of the line of flight and downward. All of these effects were 
exceedingly important in the dusting operation. In fact, the down- 
ward tendency of the air current is probably one of the greatest con- 
tributing factors toward success in forcing the poison dust down 
among the plants, regardless of existing air currents. 
The effect of the backward blast of the slip stream was quite im- 
portant. The dust being delivered under the plane, instead of going 
directly to the ground, was blown backward from the point of deliv- 
FlG. 15. — Dusting plane in operation in " straightaway ** flight. This view shows the 
beginning of the trail of dust behind the plane. The plane i* operating about 2a feet 
above the plants near midday. The dust does not come in actual contact with the plant 
until about the point indicated bv a. See Figure 16 for remainder of dust cloud on this 
flight.) 
ery by this blast, and in some instances it was found that the dust 
was shot 100 feet or more to the rear of the point where it was 
dropped from the plane. The practical application of this point is 
illustrated in Figure 14, which shows the manner of starting the 
flow of dust in crossing a field of cotton. Instead of opening the 
hopper at the edge of the field, it is opened a short distance after the 
plane has passed into the field, and this backward blast shoots the 
dust back to the margin of the cotton. This is also of importance in 
connection with maneuvering for dusting difficult situations, as will 
be shown later. 
Figures 15. 16, and 17 probably illustrate as well as possible the 
behavior of the dust after it passes beyond the direct influence of the 
61070° --24 3 
