THE FLOW OF WATER IN IRRIGATION CHANNELS. 9 
On the work done by the writer and S. T. Harding, wherever the 
meter was used on a rod the latter rested on a foot piece which in turn 
rested on the bottom of the channel. For use in wooden flumes a 
small 4-pronged plug was made to screw up into the rod and project 
out below the foot piece about 0.01 foot. This was easily forced 
down into the soft pine or redwood composing the floor and pre- 
vented the foot from skidding out beneath the meter under the 
pressure of water. A guy wire made of piano wire was used in high 
velocities, whether the meter was held on a cable or on a rod. This 
guy was equipped with a turnbuckle so that it could be adjusted in 
length and would hold the meter so that the latter took a position in 
the vertical plane through the front edge of the gauging bridge. 
Meter stations. — As it was desirable to measure the discharge in 
canals near the reaches to be tested for the value of n, it was neces- 
sary to provide some form of footbridge for small canals and a cable 
station for canals of such widths that a temporary footbridge was 
impracticable. For small canals a piece of clear Oregon pine, 2 
inches by 8 inches, 16 feet long, was found to make the best bridge. 
It would span a ditch about 14 feet wide without bending appreci- 
ably under the weight of one man. In a few cases standard wading 
methods were used. Where ditches were slightly wider than this 
and quite shallow a light tower of wire-trussed 2 by 2 pieces carried 
the end of -the plank out over the water while measurements were 
made in the verticals between the bank and about 3 feet from the 
tower. The plank was then changed to the other side of the canal 
and the tower placed in the portion of the canal previously measured, 
and the meter measurements in the verticals resumed. Thus at no 
time did the meter approach closer than about 3 feet to the tower, 
and the legs of the latter were so small that but little water was 
disturbed by their presence. In order to measure canals up to about 
90 feet in surface width a portable meter station was provided as 
follows : 
A rating car was constructed like the body of a fiber steamer 
trunk. The covering had no hinges, but was held by trunk fasteners 
and twin locks, one on each side. When the cover was off iron arms 
carrying 6-inch sheave wheels and hinged to each end of the car were 
raised to a vertical position. Coiled in the bottom of the car was 
carried 130 feet of high-grade haulage cable, three-eighth inch in 
diameter. Steel standards, turnbuckles, pins, and all other acces- 
sories also were packed in the car during moves from place to place. 
This equipment assembled into a meter station, as shown in Plates 
IX and XII. 
Hook gauges. — Two gauges of the Boy den type were used for deter- 
mining the fluctuation in the surface elevation of the water through- 
out the experiments. They were not as well adapted for deter- 
