58 
BULLETIN 37G, U. S. DEPARTMENT OF AGRICULTURE. 
EFFECT OF AGE UPON THE CARRYING CAPACITY OF WOOD-STAVE PIPE. 
Some manufacturers and hydraulicians have contended that wood- 
stave pipe becomes smoother with length of use, and that therefore 
the capacity of the pipe increases with its age. 
In order to study this question the writer prepared figure 5. This 
chart shows that, judging by available experimental data, there is 
no definite law between age and change in capacity, but unfor- 
tunately the results of but one test are accessible on any pipe older 
than 7 years. That pipe (No. 31, Ogden, Utah), although 24 years 
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Fig. 5.— Diagram showing lack of relationship between age and carrying capacity. Numbers correspond 
with those in column 1, Tables 2 and 3. Ages taken from column 4, Table 3. Relative capacities taken 
from column 18, Table 3. 
old at time of test, shows a capacity only about 3 per cent greater 
than the discharge computed by the new formula. 
CAPACITY OF WOOD-STAVE PIPES. 
In the following pages the design of wood-stave pipes is con- 
sidered with reference to carrying capacity alone. Such structural 
features as thickness of staves, banding, cradles, etc., do not come 
within the scope of this paper. 
The total loss of head necessary in the conveyance of a given 
quantity of water will be the sum of the velocity head, h v ; the entry- 
head, he; and the friction head, h f , or its equivalent per unit length; 
