16 
BULLETIN 1465. IT. 5. DEPAEIMEXT OF AGEICULTTJEE 
Plate 3. A. 
in the right-hand cylinder. The valve O admitted the water from 
the pipe L into the pipe Q and into the cylinder R. As the water 
rose in the cylinder the contained air was forced through the valve 
opening at D through the pipe V into the right-hand cylinder. When 
the water reached the float T it rose, closing the opening at U, thus 
stopping the flow of water into the cylinder. The valve O was then 
turned to direct the water into the right-hand cylinder; the valve Y 
was opened immediately after, and the water rushing into the right- 
hand cylinder forced the air back again into the left-hand cylinder, 
driving the water through the valve Y and the flexible pipe into the 
can. This operation was performed as fast as the pipes and caps 
of the cans and the ends of the flexible pipes could be flamed and 
changed, or as long as water remained in the tank. 
shows the watering machine in position to irrigate 
two cans. When the 
cans were submerged 
in the troughs, as 
shown in Plate 3, B. 
they were raised by 
the weighing frame 
and irrigated one at 
a time. 
WEIGHING THE CANS 
In weighing, the 
balance was hung 
from the pulley in the 
rope loop on the over- 
head shaft of the 
weighing frame, and 
an evener similar to 
the one used at the 
kettle but with longer 
side chains, was used 
to attach the balance 
to the cans. By turn- 
ing the crank and 
winding the rope 
about the shaft the 
weight of the can fell 
on the balance, and 
dial reading gave the 
The variation in the 
Fig. 6.— Diagrammatic curves of the steam pressure in the kettle 
and the temperature in the interior of a can of soil in a repress nt- 
ative steriliz it n. I:; : : , ling the steam-pressure curve the axis 
of ordinates indicates pounds; in reading the temperature carve 
it indicates i-rr-ef ?en::graie: and the axis of abscissas indicates 
time in hours for both curves 
when the can was free from the ground the 
weight of the can plus the weight of the evener. 
contents of the can could be.deterrnined bv referring to a tabulated list. 
TESTING THE SOIL AND WATER 
The samples of soil taken from the cans and the samples of water 
taken from the watering machine were tested bacteriologically for 
sterility. The samples were collected in sterile test tubes. A soil- 
decoction agar, made by extracting 200 grams of soil with 1.000 cubic 
centimeters of boiling water and adding 1 per cent of agar, was used 
in the soil test, as well as potato agar. Small quantities of soil taken 
on the end of a sterile spatula were introduced into the tube of 
