122 



watertight. A special gasket was placed around the pile at the bottom of the form 

 which sealed the latter and excluded the mud and water. This type, where thus well 

 constructed, has gi\en excellent ser\'ice. A recent inspection of Pier 34 disclosed only 

 minor flaws which were readily repaired. 



Fig. 43. (1) Holmes wooden stave cylinders being driven at Pier 34, San Francisco. 



(2) Outer end of Pier 34, San F'rancisco, during construction, showing Holmes cylinders. 



(Photo by Air. IIoii.'ard C. Holmes.) 



The Remov.able or Section.\l Form Type 



Methods of placing concrete in removable forms around a pile in place have been 

 in use for several years. The sections are short, especially adapting them to the con- 

 ditions of limited working space between water surface and the under side ot the wharf 

 floor, and permits such work to be carried out without the necessity of remo\ing the 

 floor or superstructure. Their chief application is to the salvaging of piles in place 



