54 
BULLETIN 194, U. S. DEPARTMENT OF AGRICULTURE. 
6 stops, up to 0.3, or 30 feet per hundred. Third. For very rough 
materials, for earth channels and for cobble-bottom ditches (fig. 8). 
The values of n range from 0.015 to 0.030 while the slopes cover all 
ranges likely to be encountered. On this chart the values of n cover 
m 
R-Hydraulic Radius. 
i i i i 1 1 1 ii 
yaraunc 
i i i j 1 1 1 1 
i i 1 1 1 ii 
1 1 1 1 1 j 1 1 1 1 1 1 1 1 
Depth of Channel in feet. 
Fig. 5.— Areas, in square feet; hydraulic radii, in feet and hydraulic economic dimensions 
(broken line) for channels having side slopes of H to 1. 
such a wide range that the guide lines through any particular zone 
have not quite the same slant, but the results obtainable from any 
of these charts are more accurate than the agreement between pre- 
liminary figures and results of tests made after construction. 
