2 BULLETIN 789, U. S. DEPARTMENT OF AGRICULTURE. 
D=diameter of bin or diameter of inscribed circle in feet. 
H=height in feet of grain above point in question. 
uw’ =coefficient of friction of grain on bin walls. 
W=weight of grain in pounds per cubic foot. 
V =vertical pressure of grain at depth H in pounds per square foot. 
L=\lateral pressure of grain at depth H in pounds per square foot. = 
oe ratio of lateral to vertical pressure. 
e=base of Naperian logarithms. 
Notre.—Both V and FZ are assumed to be constant at all points on 
a horizontal plane. 
LX iw 1 
For round and for square bins or other bins of the form of a regular 
polygon, the hydraulic radius = is equal to 2 and the formula becomes 
DxW ie 
VaxExe( 1 ea) 
L=kV 
VALUES OF yx’ AND k. 
Numerous experiments have been made with various grains in bins 
constructed of different materials to determine values for the factors 
py’ and k. The results of several of these experiments are given in 
the appendix. é 
PRESSURE FACTORS FOR WHEAT IN ROUND OR OTHER REGULAR 
CONCRETE BINS. 
By taking y’ equal to 0.4167, an average value for wheat on con- 
crete, and k equal ‘to 0.6, an accepted value for wheat in concrete 
bins, the product 4xk xu’ becomes equal to 1.0, and with W equal 
to 50 pounds, the formula simplifies to 
V=50x Wigs = 
V = 
or 7 =50 (ie = 4) 
ep 
