WALL SECTIONS ON PILE FOUNDATIONS. 129 



the result could be examined. The usual number of piles were 

 cut off at high water by a submerged saw, but only to the level 

 of low water, instead of at the proper depth. A diver, blind- 

 folded, then laid a mattress on the top of the piles in the 

 ordinary way, after which a concrete block was placed in its 

 proper position on the top of the mattress. The block was 

 subsequently removed at very low tide, which enabled the 

 mattress to be examined. The result was in every way satis- 

 factory, and proved that the weight of the block could, by the 

 use of the mattress, be well distributed on the pile heads. 



FIQ. 96. 

 FRONT VIEW. 



12' O" 



SIDE VIEW. 



o '--->,, 



PLAN 

 Pia 98. 



When the blocks were in their proper positions, the vertical 

 grooves came together, and were then filled with concrete in 

 bags well rammed down, so that a key or tongue was formed 

 between the two blocks. 



The upper part of the wall was constructed of granite ashlar 

 backed with concrete, the headers being all dovetailed at the 

 rear end so as to ensure a good grip with the concrete backing. 



At Glasgow, 1 a method of construction similar to the well- 



1 Description of Queen's Dock, Glasgow, by J. Deas, C.E. 



