46 
The method of inserting the injector is shown in figure 18. The 
hole should always begin at a distance of 3 or 4 inches from the 
plant and run horizontally downward to a point a little below the 
roots. To accomplish this, the injector must be inserted at an angle, 
as shown in the figure. Force it down until you think the point is a 
little below the roots, then let out the charge of liquid. In operat- 
ing the injector, first pull the piston up as far as it will go; this loads 
the measuring chamber between the valves; then push down the 
piston until it stops, and the instrument is ready to be pushed into 
the ground. Push it into the ground as far as desired, hold it there 
while you pull up the piston; by this operation you let the charge 
out of the lower chamber into the ground, and at the same time the 
measuring chamber is again filled. Hold the injector in, the ground 
I r lG. 18. — The McGowen Injector, and how to use it. 
a few seconds after the piston has been pulled up in order that all 
the liquid in the charge may have a chance to run out. Then pull 
the injector out of the ground, and quickly, with the foot, fill the 
