Popular Science Monthly 



Holding the Hudson back while the lounda- 

 tion for the new piers was being prepared. 

 Hundreds of tons of steel and thousands of tons 

 of rock supported the sheet-piling cylinders 



SO that the (Irilhng and blasting coukl be 

 carried out close to the steel-sheet piling. 

 To obtain the necessary rigidity, the 

 smaller pockets were replaced by two 

 great circular units fifty-fi\x' feet in 

 iliamcter. These were filled with broken 

 rock, which made them stable. The 

 pressure developed in the cylinders made 

 them watertight. 



Along the stretch of cribbing a single 

 line of interlocking steel-sheet jiilings 

 had been <lri\en. When leakage oc- 

 curred at that i)oint it was suggesti'd 

 that the crevices be plugged by means of 

 fluid cement or "grouting." The hea\'\' 

 exj'iense of this remedy caused hesitation, 

 and resort was made to another exjiedi- 

 ent, this latter proving an effectise and 



cheap way of hailing the water. To 

 begin with, a timber i)ile twelve inches 

 in diameter was drivi-n down into the 

 space back of the old cribbing, and then 

 withdrawn, leaving a hole. This ca\ity 

 was filled with a wadding composed of 

 successive layers of earth, sawdust and 

 manure, driven down hard by the pile 

 which served the double purpose of 

 ramrod and plug. In this fashion, 

 a row of wooden pilings anil an eiiual 

 number of water-tight wads were dri\en 

 deep into liie underK ing earth, proving 

 .inipK' sutlicient to stop all leaks. A 

 little seepage, howe\er, came up from 

 tile bare ri\er bed, but a small pumj) was 

 sufficient to handle it. At Havana, 

 pumps had to work constantly, and at 



