DUSTING COTTON FROM AIRPLANES. 29 
when the hopper was full, but usually when the valve was thrown 
open it took a few seconds for the dust to reach its maximum 
delivery, and in those few seconds the plane traveled a considerable 
distance. 
While these two hoppers were being tested and developed, the 
one which had been used in dusting the catalpa trees in Ohio 
arrived. This was immediately attached to a plane and tested in a 
few trial flights, but was found to be less suitable for cotton dusting 
than those which had already been constructed. The Dayton hopper 
had obviously been built to put out a large quantity of dust in a 
minimum time, without much regard to the regularity of delivery. 
When tried over a cotton field it was found that it at first fed rather 
slowly, and then, when perhaps one- fourth of the hopper's contents 
had been emptied out, it suddenly fed out the remainder in an 
enormous burst, providing a very inefficient distribution when regu- 
lar held flights are attempted. Furthermore, hanging this hopper 
on the side of the plane made the plane slightly side-heavy for such 
low flying, and since the hopper presented square corners to the 
air current and was not stream-lined in the slightest, it caused an 
unequal drag on one side of the plane. This interfered with flying 
somewhat, and was especially undesirable in that the interference 
was not regular in making turns, depending on which way the plane 
was banking. Further work with this type of hopper was therefore 
abandoned. 
DIRECTING PLANE OPERATION. 
In operating a plane the pilot is forced to keep a keen lookout for- 
ward and has very little chance to judge whether all portions of the 
field are being thoroughly treated, while the hopper operator is un- 
able to converse with the pilot when in flight and can not give any 
elaborate directions. Special arrangements were therefore made for 
directing the flight from the ground, and when actual field poison- 
ing was in progress one or more men were always placed in the cot- 
ton field which was being treated, provided with white flags 3 feet 
square attached to handles about 6 feet long. A system of wigwag 
signals was then used, by means of which the men on the ground 
gave the pilots directions for each crossing, and specified the exact 
points at which the crossing should be made. This seemed the only 
expedient which could be employed in the preliminary work. 
The method of directing the plane for effective dusting will al- 
ways be one of the most difficult problems in any attempt to use the 
airplane in commercial work, especially since a slight error in the 
airplane flight means so much cotton field area improperly treated. 
This problem will require a considerable amount of experimentation 
before it will be solved satisfactorily. Probably the care and effi- 
ciency of the pilot will always be a very important factor in deter- 
mining thoroughness of treatment. 
LEAFWORM CONTROL OPERATIONS. 
In the treatments of the cotton fields for leafworm control, those 
first infested received applications varying J n amount, and the re- 
sultant leafworm mortality served as a basis for later plans, the 
width of swath varying widely, depending on the field being treated, 
