Mar. 6,1916 
Flow through Weir Notches 
1055 
gate for the openings. The calibrated tanks and the wasteways on 
the weir box as well as the spill box are connected with the waste reser¬ 
voir, from which the water can be returned to the storage reservoir 
by either a 12-inch or a 5-inch horizontal centrifugal pump driven by 
electricity. The floors of the calibrated tanks and the waste reservoir 
are 19 feet lower than the coping of the storage reservoir. 
Some of the means used to secure accuracy in the experiments are 
as follows: The laboratory is so arranged that the centers of the storage 
reservoir, the headrace, the frame in the end of the weir box, and the 
channel from the spill box to the calibrated tanks all lie in the same 
straight line, thus permitting the water to approach and leave the device 
under experiment in a straight line. 
The three head gates between the storage reservoir and the head¬ 
race— 6 , 12, and 18 inches in diameter, respectively—permit a fairly 
accurate regulation of the water entering the weir box. 
Immediately below the head gates a series of two horizontal and 
two vertical baffles breaks up the eddy currents and reduces pulsations 
and wave action to such an extent that the water, before entering the 
weir box, is in a pondlike condition. 
In one side of the weir box, about 15 feet upstream from the bulkhead, 
is an overpour spillway which resembles a door 2 feet high and 3 feet 
long hinged at the bottom. The top of this spillway when in an upright 
position is slightly below the top of the weir box. Aprons of oiled 
canvas attached to the sides of the weir box and to the face of the door 
prevent leakage and compel the water to pass over the crest of the 
spillway. A 4-inch gate valve placed at the side of the spillway permits 
a still more careful regulation of the depth of the water in the weir box. 
Both the spillway and the gate valve can be adjusted by the hook-gauge 
observer on the opposite side of the weir box by means of screw controls 
operated by handwheels placed on the ends of long rods. By always 
having some water running over the spillway it was possible to keep 
the head upon the device under test constant throughout the duration of 
the experiment, usually from 20 to 40 minutes, depending upon the 
volume of water being run. 
The elevations of the water in the weir box and the spill box are 
observed in concrete gauge boxes built on the outside walls of the re¬ 
spective boxes. These gauge boxes are 1 foot by 2 feet by 4 feet deep, 
inside dimensions, and the water enters each of them through four 
1 -inch pipes. The gauge box for the weir box is located 10 feet upstream, 
and that for the spill box 7 feet downstream from the bulkhead. The 
pipes leading to the latter, however, take water from the spill box at a 
point only 3 % feet downstream from the plane of the weir. Each gauge 
box is equipped with an electric drop light and a Boyden hook gauge 
anchored in the concrete wall, and readings of the water level can be 
made to 0.001 of a foot. 
