Frictional Resistance in Artificial Waterways 25 
work. (Plate VIII.) The fall was about 19.5 feet to the mile. 
The cross-section is shown in Figure 7. A line of benches was 
established 600 feet apart, and on July 20 elevations of the water 
surface were taken opposite these places. The water was too swift, 
however, to wade, so that the discharge was measured at the rat¬ 
ing station at the head of the canal, two percent being arbitrarily 
deducted for seepage loss in transit, leaving the discharge 380 
second feet. 
Lateral No. i-c conveys the water down a steeper slope than 
do the other • two canals, causing drops to be constructed about 
every 1,300 feet, and thereby limiting the length of test section on 
this canal to 1,238 feet. The cross-section is shown in Figure 8. 
As on the other canals, the water was too swift for taking the cross- 
sectional elements in Jul), but benches were established about 400 ft. • 
apart and water surface elevations taken opposite these, while 
the gaging was done just below the drop at the head of the section 
where the current was not too swift to prevent wading. 
On October 5 and 6, 1912, other experiments were conducted 
upon these canals, which at the time carried only low heads, these 
being 85 second feet, 33 second feet and 23 second feet respectively. 
On Lateral No. 1 measurements of the discharge were made at 
both the lower and upper ends of the mile section, to determine the 
loss or gain, if any, by seepage. The results were as follows: 
Station Time Sec. Ft. 
.0+00 1130 P. M. 33-3o6 
52+80 3:00 P. M. 33-345 
For a small head the change is inappreciable, but with a large 
discharge it is believed that a deduction of two percent as used 
for the measurement in July, is sufficient to cover all loss by seep- 
Fig. 8. Lateral No. 1-c, Rio Grande System, Del Norte. 
age to the river in the two miles of section from the gaging sta¬ 
tion to the lower , end of the section tested. At this time, also, 
cross-sectional elevations were taken opposite the bench marks, the 
