NOTES ON DOCKS AND DOCK CONSTRUCTION. 



set were driven, the 

 second tier or set was 

 put in, so that the top 

 edge was uniformly 

 level with the low- water 

 line of spring tides. 

 While the lower panels 

 were being driven, and 

 after they were down, 

 sacks of clay and gravel 

 and other material were 

 deposited both inside 

 and outside the dam. 



The remaining upper 

 panels were closed at 

 one operation, and in 

 order to accomplish this, 

 the whole were sus- 

 pended by tackles from 

 the overhead scaffolding 

 on each side of the dam 

 (Figs. 37, 39), so as to 

 be ready to be dropped 

 into place at slack 

 water. 



The first attempt to 

 close the dam was a 

 failure, owing to the 

 fracture of three of the 

 twin piles in driving. 

 The damage was made 

 good by driving addi- 

 tional piles in the spaces 

 between and adjoining 

 the broken piles. A 

 second attempt to close 

 the dam was success- 

 ful. The panels were 

 lowered at slack water 

 of the ebb tide. Imme- 

 diately the panels were 



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