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the pocket being 7.5 ft., on the aver- age, above this floor, as the inshore end of the pocket is 3 ft. lower than the off-shore end. The pocket is car- ried directly by four longitudinal rows of 12 x 12:m. timbers, spaced 4 7 apart on centers in the rows. The two rows on each side of the center line are spaced 10 ft. apart transversely, in order to provide room between them for a standard-gage track to be laid on the floor over 'caps of the piles. The two compartments of the pocket are "each: 30 x 150 ft. mm: plan; and 12 ft. deep, each having a capacity of 2,500 cu. yd. The sides and ends of the compartments have 3 x 12-in. up- rights lined with 2 x 12-in. plank placed horizontally. The bottom of the compartment is built in the shape of two longitudinal hoppers, with the center line of each hopper over one of the two longitudinal standard-gage tracks laid on the floor over the pile caps. Two rows of 12 x 12-in. open- ings are placed in the bottom of each hopper, the openings being 10.5 ft. apart in the rows, and controlled by a double-lip under-cut operated by a hand lever from the track floor. These operating levers are at the sides of the track, where they can be reached without interference from a car on the track. The scows in which the crushed stone is delivered have horizontal belt conveyors placed under a row of open- ings in their docks, which conveyors deliver to a bucket elevator carried by a boom. The latter is arranged so it can be raised and lowered, and has sufficient length to enable the eleva- tor to deliver into the stone pocket. Two of the stone scows, each with a capacity of 600 cu. yd., are provided to insure a supply. The sand is hoisted into the sand pocket by means of a 34-yd. Hayward clam-shell bucket handled by a stiff- leg derrick traveling on top of the pocket. The derrick platform trav- els on "a rail on. top: of .each side of the pocket, and carries two derricks, one to serve scows on each side of the pocket. Each derrick is equipped with a 10 x 12-in. Lidger- wood engine, and can handle 35 cu. yd. of sand an hour. The cement used in the concrete is made in the mill of the Standard Port- land Cement Co., at Napa Junction, 6 miles from the work, and is delivered to the dock in a scow having a ca- pacity of 2,000 barrels. This scow is covered with a tight shed to protect the cement from the weather. A ce- ment storage shed, with a capacity of TAE Marine REvVIEw 12,000 barrels, has also been erected on the edge of the shore adjacent to the inner end of the sand and stone pocket: The cement scow is moored in the slip between the pocket and the stor- age shed, whereit can be reached bya 65-ft. boom stiff-leg derrick mounted on a section of the old earthfill cofferdam. The location of this derrick is such that' it can féach. cars on a track leading into the cement shed, or a 4 x 6-ft. hatchway in a floor over a 15 x 30-ft. working platform level with the floor of the pocket, at the inshore end of the latter. The derrick han- dles light wooden slings, capable of holding 40 sacks of cement. While the scow is at the work the cement re- quired in. the mixing plant is handled by the derrick directly to the work- ing platform at the end of the sand and stone pocket. The derrick is also used at the same time to deliver ce- ment from the scow to cars, on which it is carried into the cement shed. When the scow is away securing more cement, the stock in the shed is used. With this arrangement much of the cement has to be handled only once, while a stock adequate to insure against emergencies is available. The floor of the first story of the tower of the concrete mixing plant is level with the top course of timbers in the crib, and also with the floor car- rying the two tracks under the sand and stone pocket. Those two tracks extend from the end of the pocket up to the third story of the tower on an incline. The second story of the tower contains the concrete mixer, and the first story tracks leading out over the crib of the cofferdam. The whole concrete mixing and handling plant is designed to handle 2% yd. batches, and has been demonstrated to have a nominal average capacity of 100 cu. yd. per hour, with a force of 60 men, including the materials-handling crews and the concrete gangs in the cofferdam. A hopper car divided into two steel lined compartments, one for sand and one for stone, with a combined capac- ity of 2% yd. in the two compart- ments, is operated on each of the two tracks extending under the sand and stone pockets. Materials will be drawn first from one side and then from the other side of the pockets to avoid trimming in the latter. The two cars are handled along the tracks and up the incline leading to the third story of the mixer tower by a double- drum Lidgerwood hoisting engine in the three-story mixer tower beyond the head of the incline. After one compartment of a car is first filled with stone from the gates in the worked in the dock, one on each side 33 pocket, the car is pulled ahead and the other compartments filled with sand, marks in the hoppers indicating the amount of each required. The ce- ment is then added through an under- cut gate leading from the bottom of the working platform at the shore end of the pocket. One of these cement hoppers is placed over each track, only enough cement being stored on the platform to meet momentary fluc tuations. The loaded car is hauled up the incline and:-dumped by means of a gate in the bottom of each hopper of the car into a hopper under the track, the empty car running back down the incline by gravity. The gates under the sand and stone pockets and the car hoppers are so arranged that a loaded car can be delivered to the mixer tower on each track fast enough to insure the capacity of the mixing plant to be maintained, in case one track is out of service. A 214-yd. Ransome concrete mixer, specially arranged for this contract, is mounted in the second story of the tower, where it is fed directly by the hopper under the head of the tracks on the incline. This mixer is belt- driven by a 40-H. P. electric motor and discharges through the second floor into buckets on cars on the track be- low. Water is supplied to it from a measuring tank on the floor above, a quick-opening valve, operated from the floor below, controlling this tank. The gate on the track hopper supplying the mixer is also controlled from the same position, so one man feeds the mix- er and attends the motor. A second man handles the balanced discharge chute of the mixer. Two parallel standard-gage tracks extend the length of the cofferdam, 5.5 ft. on each side of the longitudinal center line. The concrete is discharged from: the mixer into 2%-yd bottom- dump buckets on flat cars on one of these tracks. These cars are hauled out on the track by a ©. W.- Hunt steel cable car haul. The engine driv- ing this car haul is placed under the shore end of the sand and stone pock- ets. The cable extends out on the loaded car track, around a_ sheave wheel at the end of that track and back on the empty car track. Each car is equipped with a clutch which is attached to the cable when the car leaves the mixer tower. As the speed 'of the cable is about as fast as a man walks, a rider is not required on the car, the clutch being released by a man along the track when the car reaches the desired position. Two gangs of concrete men are