34 BULLETIN 115, U. S. DEPARTMENT OF AGRICULTURE. 
tion of a similar gate designed by the engineers of the California 
Development Co. The joists, floor, wings, cut-off, and walls are of 
redwood, and the other members are of Oregon pine. The whole 
structure, including the shutter — similar to the one in Plate I, c — 
contains 222 feet b. m. of lumber. These gates cost $20 to $25 in 
place. Two-inch material for the floor, sides, and sheet piling, in- 
stead of 1-inch, will be necessary for most lumber obtainable in 
States where redwood is not handled. The cracks should be battened 
for clear water, but the plans shown are for silted water. If the 
ground is eroded easily a cut-off and wings similar to but smaller 
than the front ones should be added at the lower end. Some of 
the water companies add an 8-inch weir board under the gate shutter 
to develop partial contraction and then measure the delivered water 
as an open-air or submerged orifice, as the case may be, using a 
coefficient of 0.62, but nearly all the gates deliver more than the 
rated amount of water, due to velocity of approach and imperfect 
contraction. 
On the gate as shown the floor extends under the side walls. A 
better practice is to let the side walls come outside of the floor. In 
such case the settling of the floor boards to a slight extent does not 
develop a crack through which water escapes and does damage, 
HEADGATE, LOW LINE LATERAL, ROCK CREEK CONSERVATION CO. 
The Low Line lateral of the Eock Creek Conservation Co. of Rock 
River, Wyo., receives water from the Bosler Xo. 3 ditch. It is 10 
miles long, 8 feet wide on the bottom at the head, and carries water 
1 feet deep on a grade of 2.61 feet per mile. The rated capacity of the 
lateral is 135 second-feet, to serve 10,000 acres of land. 
The structure, built in 1911, at the head of the lateral, also serves 
as a wagon bridge. (PL VIII, fig. 1.) Xo check structure is placed 
in the main ditch, as the lateral starts out down a slope so steep that 
drops are necessary, and it was desirable that the lateral headgate 
be placed as low in the main ditch as possible. The structure is of 
concrete with steel gate shutter and lift. 
The shutter is placed hi a vertical position at the line of the water 
side of the bank crest, A penstock 5 feet wide, with side walls 18 
inches thick sloping down on the top from the height of the bank 
to 4 feet above the floor, leads from the main ditch bottom to the 
shutter. The floor slants down 2 feet from the grade line of the 
ditch to the gate opening. The latter is 3 feet 7f inches high and 
3 feet 1 inches wide under a curtain wall 1 foot thick. 
The floor extends 15 feet downstream from the gate shutter and 
then drops 4 feet vertically into a water cushion 10 feet long. At 
the lower end of the latter a vertical raise of 2 feet makes the net 
