50 BULLETIN 854, U. S. DEPARTMENT OF AGRICULTURE. 
The results of these observations are shown in Table 10. The 
data indicate that the use of reducers with tile flowing approximately 
full reduces the loss of head to practically nothing, while with tile 
flowing half full some loss of head occurs. Without reducers, the 
loss of head decreases with the decrease in slope. The variation in 
drop in the catch-basin did not materially affect the loss of head, 
which seems to be about equal to the grade through 15 feet length 
of drain. 
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