32 
The Colorado Experiment Station 
Earth Channels. 
Bed exceptionally smooth and of fine silt; very uniform in cross- 
section; perfectly straight alignment . 0.017 
Bed of hard, water-worn adobe . 0.022 
Bed of coarse gravel and small, loose stones . 0.024 
Banks of smooth clay; bottom of fine sand; grass over-hanging banks 
into water . 0.027 
Bed of hard, water-worn adobe; many fine roots projecting. 0.028 
Bed of fine silt, merging into clay; liberally sprinkled with large, 
loose stones . 0.030 
Bed of little gravel but composed mainly of smooth, rounded stones, 6 
inches or more in thickness . 0.032 
SIPHONS 
During the summer of 1913 a number of experiments were 
made to determine the coefficient of friction in wood stave pres¬ 
sure pipe under actual field conditions. By far the greatest diffi¬ 
culty encountered in the making of these tests was the determina¬ 
tion of the elevation of the mean water level at each end of the 
siphon, specially at the inlet where there was an eddying motion 
and boiling effect of the water. This was satisfactorily overcome, 
however, by siphoning water from the wood stave pipe, over the 
in-take wall and into a bucket which rested on a firm foundation. 
