404 NOTES ON DOCKS AND DOCK CONSTRUCTION. 



3 feet by 3 feet, was constructed, built in Portland cement, and 

 terminated with a stone cap ; stone corbels were also provided 

 to support the straight-edges on which to place the level staff. 

 On the stone cap a timber platform was constructed to carry 

 the weights. During the adjustment of these weights, the 

 platform was supported on folding wedges resting on a dwarf 

 wall surrounding the pier, and which also served to protect it 

 from injury. On the completion of the respective loads, the 

 wedges were removed, leaving the mass supported solely by 

 the pier. 



In order that the experiment should be made under con- 

 ditions approaching as nearly as possible those to which the 

 permanent work was subjected, provision was made for satu- 

 rating the ground by placing 3-inch pipes at each side of the 

 pier, by which to convey the water to the foundation. 



The experiment may therefore be considered to consist of 

 two parts, first, as regards resistance to compression with the 

 foundation dry; and secondly, when saturated, the ultimate 

 loads being the same in both cases. 



The results showed that the actual subsidence of the pier 

 with the foundation dry, and loaded with a weight of 8 tons 

 per foot superficial, was 0*02 foot, and with the foundation satu- 

 rated, slightly less, viz. 015 foot. On the removal of the load 

 before saturating the ground, the pier returned to its normal 

 condition. 



It was therefore clearly demonstrated that with a load of 

 8 tons per superficial foot no subsidence of an appreciable 

 character took place. Indeed, the slight difference observed 

 may be due as much to the compression of the material in the 

 pier as to the subsidence of the ground. 



Pressure on Ground under Dock Floors. The greatest intensity 

 of pressure on the ground under a dock floor is at the centre 

 when the ship is on the blocks. The weight is first distributed 

 over a width of the floor equal to the length of the blocl< 

 greater distribution being effected to the ground by the Jin-' 

 which would represent the direction of fracture through tin* 

 material composing the floor of the dock, supposing subsidence 

 from excessive weight to take place. 



Equipment. The equipment of a dock will vary with th<> 

 class of trade to be accommodated, or the purpose for which 

 the docks are established, whether for building and repairing 



