GATE STRUCTURES FOR IRRIGATION CANALS. 51 
regardless of moderate fluctuations in the supplying stream, the inlet 
pipe is set below the headgate and the outlet carried to a lower level. 
This is possible only where a diversion dam of some sort is used and 
the outlet pipe discharges into the stream below the diversion dam, 
and where this water is lower than the proposed water in the canal 
below the gate. Only one lever is used, connected to the gate at one 
end and the counterweighted tank at the other. When more water 
than is desired enters the canal it fills the well through the inlet pipe, 
raises the tank, and lowers the gate until equilibrium is established. 
If the supply falls then the water in the well gradually passes out 
through the outlet pipe, the tank falls, raising the gate, and thus 
allowing more water to enter. 
The operation of these gates in the Turlock district is practically 
instantaneous and allows the canals to be run with larger heads of 
water than would otherwise be safe. 
Where the level of the water, and consequently the volume, in a 
side lateral or consumer's delivery is to be held constant the inlet pipe 
is placed at the desired level in the lateral, but the double system of 
levers operates on the check gate as before. This system could be 
used to insure uniform deliveries to consumers and would protect 
the banks above the check also, because the rising water above the 
check would increase the delivery to the side lateral, flow into the 
well, raise the tank, lower the counterweight, and lift the check gate 
sufficiently for the excess water to pass on down the canal. 
The particular structure shown in figure 14 combines both an au- 
tomatic check and a drop located on lateral No. 7, which carries 
about 200 second-feet of water. The height of the open ends of both 
inlet and outlet pipes may be adjusted, as they can be swung about 
on the threads of the elbows. About two-thirds of the way up these 
two pipes the gage rods are attached. The slots in the rods are 
slipped over staples set in the concrete walls near the top and pad- 
locks through the staples over the bars lock the device. 
The bucket or tank hanging in the well is made of No. 16 gal- 
vanized iron, 44 inches in diameter and 5 feet high, the top lapping 
over a J-inch round pipe stiffener and riveted thereto. Two straps 
of I by 1J inch iron pass completely around the bucket at right 
angles to each other and are brought together 2 feet above the rim. 
The concrete counterweight hung below the intersection of the 
lines of the two levers is of convenient shape and weighs about 300 
pounds more than that portion of the gate to be lifted by it. 
The automatic radial gate is built up of double 1-inch Oregon pine. 
Before being set in the concrete the ends of the pipe axle are bored 
and 12-inch pins thrust through them, which prevent the axle turn- 
ing in the concrete. 
