26 
The Colorado Experiment Station 
channel being in such stable condition that it was believed that no 
appreciable change of cross-section had taken place from July to 
October. 
On April 24, 1913, two more experiments were made upon 
the Main canal and Lateral No. 1, there being no water in Lateral 
No. i-c. The discharges were 73 and 26 second feet, respectively. 
The results of these tests are shown in Table 8. These 
canals show a higher coefficient of roughness for low heads than 
for high, differing in this respect from the timber flumes on the 
Orchard Mesa Power Canal. In other words, these rough chan¬ 
nels gave a value for (n) which varies inversely as the hydraulic 
radius, which would indicate that the roughness in earth canals 
has a greater influence in retarding the flow of small heads of 
water than the same degree of frictional resistance exerts on high 
heads. In designing large canals in this class of materials, there¬ 
fore, the lowest values of (n) given in the table should be used, 
while for smaller channels use should be made of the greatest 
values of (n). 
BESSEMER CANAL, PUEBLO. This canal has been in 
operation about twenty-three years. From the few records avail¬ 
able as regards the original cross-sections, the bottom width was 
five and one-half feet, side slopes one and one-half to one, and 
maximum depth of water eight feet. As the canal was operated 
at high stages of water, a decided tendency was developed to de¬ 
posit sediment on the slope near the water surface, and to scour 
out at the bottom of the slope. In the sandy-loam, mesa soil, or 
in the extremely sandy soil of the river bottom near the headgate, 
the tendency has been to widen to a shallow channel with almost 
vertical sides. This tendency is less marked in the adobe or 
clayey soiN The diagrams of the cross-sections, Figures 9, 10, 
11 and 12, illustrate this. In cleaning the channels on mesa lands 
a section was adopted which seemed to be naturally formed by the 
water. This was gradually widened to 8 feet on the bottom, the 
sides adjusting themselves in a general way to a slope of from 1 
to 1, to 1% to 1, which section has seemed to maintain itself. The 
diagrams show a comparison of the original section, with the sec¬ 
tion worked to in cleaning the canal, and the section which the 
water seems inclined to establish. It has a high hydraulic radius 
and approaches an egg shape. 
Four sections of this canal were experimented upon with the 
idea of noting the change in the value of the coefficient with the 
variation of the kind of material composing the bed. In each of 
