72 Report 8. A. A. Advaxcement of Science. 



Crete piles 12 ins. square, driven to a depth of 12 ft. below low water 

 •of spring tides. Slabs of concrete one foot thick reinforced with two 

 layers of expanded metal are laid upon the piles, the reinforcing bars 

 <jf the piles being carried through the same and connected with otliers 

 which were finally carried tluough the counterforts and face of the 

 abutments : horizontal lacings of wii-e are placed at intervals of 10 ins. 

 attached to the vertical rods. 



Piers. — The piers, eight in number, are each founded upon thiee 

 piles of concrete 15 ins. square. They are reinforced with four li^ in. 

 mild steel bars. These bars are protected with LV in. thickness of 

 concrete on the outsides. At intervals of 10 ins. horizontal wire 

 lioops are placed upon the \ertical bars. The piles are pointed in 

 shape and protected with an iron slioe. .\. 1 in. iron tube passes 

 through the centre of the pile to a hole in tlie iron shoe, through 

 which water is pumped wdiilst sinking the pile. As soon as tlie piles 

 are sufficiently seasoned for use (the specified time being tliirty days) 

 they are placed into position from the staging and sunk by water jet 

 to a depth of 15 ft. below the level of the river l^ottom. In forcing 

 the water through the tube in the pile a small direct-acting steam 

 pump is used. Tliis has the effect of putting the sand into suspen- 

 sion whilst the pumping is kept up, but immediately it has ceased 

 the sand settles around the pile. The time taken in lowering a pile 

 15 ft. by this method is from one to two hours. 



After this the piles are driven down by the impact of a oo-cwt. 

 ram, falling from a height of 2 ft. 6 in., eliding with a further fall 

 to 7 ft., so as to obtain the required resistance. To protect the head 

 of the pile whilst driving with the ram, a cap of iron is placed upon 

 the same, within which a pad of sawdust or jute is placed, and the 

 blow is delivered upon a timber shaft or "dolly" inserted in the 

 upper part of the "cap." When the above operation is completed, 

 the concrete surrounding and covering the vertical steel bars at the 

 head of the piles is broken off" until sufiicient length of tlie bars is 

 •exposed so as to connect the extension rods intended to pass through 

 the upper part of the piers. These extension lods are comiected with 

 the lower ones by a short length of gas tubing of sufficient diameter 

 to allow for the introduction of some fine cement grout around the 

 A'ertical rods. The whole of the system of reinforcement for the 

 upper part of the piers is afterwards finislied, enclosed within a mould 

 and filled up with concrete to the level of the underside of beam. The 

 whole of the pieis being complete and properl}' seasoned, the moulds 

 for longitudinal and transverse beams, crown of roadway, corbels ajid 

 side-walks were erected and reinforcement jilaced ready for concreting. 

 One span was filled in with concrete at a time and finished within one 

 long day, and the whole of the above members are therefore monolithic, 

 adding greatly to the strength of this part of the structure. 



The longitudinal beams, two in lunnber, under the roadway are 

 30 ins. by 12 ins., each designed to carry a live and dead load of 1050 

 lbs. per running foot, and are constructed as follows : The reinforce- 

 ment on the compression side of the neutral axis of the beam consists 



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