DUSTING COTTOX FROM AIRPLANES. 23 
The plane would start in along one edge of the field and gradually 
work over to the other. Whether the plane was flying with the 
rows or at right angles to them seemed to make no important differ- 
ence in the behavior of the dust cloud. Usually the plane maneu- 
vered at an altitude of from 50 to 100 feet or more until the right 
point was reached for entering the field. It then dived down, and 
if possible reached the desired altitude of from 10 to 25 feet above 
the plants just before coming over the edge of the field. The plane 
was then leveled out and shot across the field at this elevation. At 
first the manner of leaving the field at the end of each trip whs 
based somewhat on the surrounding conditions, but it was soon 
found that the efficiency of the treatment could be considerably in- 
creased by "zooming" or turning upward sharply just as the plane 
reached the edge of the field. This is because the dust is carried 
back for some distance by the slip stream, and if the plane is zoomed 
as the feeder is closed the last dust, delivered is blown back into the 
edge of the cotton field, giving a heavy treatment for the row ends. 
In many instances, owing to the crude feeder attachments, the de- 
livery of dust did not begin quite quickly enough, and an area of 
50 feet or more at the edge of the field where the plane entered was 
thus left untreated. To correct this condition, after flying back 
and forth over a field in one direction until the field had been covered, 
the plane usually made one trip across each edge of the field at 
right angles to the previous course, thus making sure of getting an 
application on the row ends. This necessity could of course be 
eliminated with better feed-valve construction and more accurate 
control than was possible in this work. 
In treating a field extending along timber it was often possible 
to operate without difficulty by simply flying parallel to the timber 
line. In some instances, where a field was adjoined on two or more 
sides by timber, right-angle corners were presented. After a little 
experiment it was found possible to treat these in either of two ways. 
If the timber was not too high, the plane would fly directly at the 
timber line and zoom upward sharply so that the tail pointed down- 
ward and the dust was thus blown down in the corner of the field. 
AVhere this was not possible the plane was flown parallel to one 
side of the timber directly toward the right-angle corner and banked 
sharply into a climb so that the tail of the plane was again turned 
toward the corner. The backward blast of the propeller then blew 
the dust into this corner. It was thus found possible to treat any 
such situation which was encountered, even though the plane could 
not actually be flown over all of the cotton. 
Another problem which presented itself was the dusting of cotton 
immediately adjoining the cabins. In the district where these ex- 
periments were conducted, cotton is raised almost entirely on a tenant 
basis, each family having its quota of from 10 to 50 acres which 
is cultivated on some share basis. The average per family is 
somewhere between 20 and 30 acres. The home is usually either 
within, or closely adjacent to this area, and with its outbuildings and 
garden occupies a block of perhaps 100 by 200 feet. A considerable 
percentage of the cotton fields are dotted with these houses, or 
"cabins," which present obstructions to entering the field. On the 
other hand, the cabins are nearly always only one story high, and 
are usually the tallest portion of the obstruction, unless trees are 
