DUSTING COTTON FROM AIRPLANES. 21 
in the early morning and three in the late afternoon. Any attempt, 
at low flying during the middle of the day is dangerous on account 
of rough air. and the air temperature is such that the motors o 
heat very badly in a short time. 
ADHESION" OF POISON TO PLANTS. 
To determine the amount of arsenic which adhered to the cotton 
plants, a series of plants were collected in a line parallel to and 
directly under the path of the plane, and in parallel lines at varying 
distances on both sides of the path of the plane. Chemical anal 
of these plants shewed not only the amount of poison present on the 
plants directly under the plane, but also the uniformity of distribu- 
tion and the width of spread. 
The first series of records of this sort were used in checking 
a flight made at -i o'clock in the afternoon between 15 and 20 feet 
above the cotton plants, with a breeze blowing approximately S 
miles an hour at right angles to the path of the plane. The heavies' 
distribution of poison was of course found immediately under the. 
plane, but there was a strip 45 feet wide on the down-wind side or' 
the path of the plane which showed a fairly uniform dosage of poi- 
son. Practically this entire strip showed an arsenic recovery as high 
as is normally obtained from a hand gun feeding about 10 pound- 
to the acre operated directly over a row of cotton plants in the early 
morning when the plants are moist. This result was all the more 
surprising because it was almost impossible to see any poison on these 
plants, which still showed a higher content when analyzed than l is 
considered necessary for weevil control. Further analyses only 
confirmed these, although the series made was by no means complete, 
and the results are somewhat sketchy. 
From the results of the analyses, together with the observation- 
made on worm control, however, it seems quite obvious that an aston- 
ishing amount of the poison adhered to the plants over a very wide 
path under atmospheric conditions such that it would be considered 
absolutely impossible to make the dust stick to the plants with the 
best of present ground dusting machines. The exact cause of thi- 
adhesion is a complicated matter which is now under invest igal 
MANIPULATION OF PLANES. 
On the two properties on which these test- were made was found 
almost every conceivable type of field as regards the difficulties 
presented for airplane dusting. In the center of each property 
were some cotton fields absolutely open, without obstructions of am 
sort surrounding them. Around the margins were the fields ex- 
tending along the timber line, which was sometimes very irregular. 
Other fields consisted of small clearings of only a few acres tucked 
back into the timber and in some cases surrounded on three sides 
by trees 50 to 60 feet or more in height. In still other field- which 
had been cleared within comparatively recent years a few deadened 
tree trunks were still standing, forming snags which were difficult 
to -ee while flying and which had to be very carefully avoided. 
Typical fields along an irregular timber line and containing o 
sional high snags are shown in Figure 18, which illustrates als< 
interspersed planting of cotton and other crops, since Fields 2j and 
