FURMANFILMS Bay floor. :06 Drawing of cason w/ anchors Twenty-five ton concrete anchors held the cason in exact position in the swift tidal current. Additional 10 foot sections of each cell were then welded on and the whole pier expanded. Concrete was then poured around each pipe. Divers in hard hat suits like those in the lobby made the deepest dives ever attempted to inspect the seals at the bottom of the caisson. :09 Look inside and down one pipe This hole is only 60 feet, but they eventually went down over 200 feet and then anchored the whole thing to the bottom with 30 feet of concrete. :05 Ariel of cason :05 Central pier being built on top of cason Building the pier above the water was a simple task. For those who are curious, it is not solid, as it appears, but actually one single gigantic room. :15 Steel foundry Long before the piers were finished, steel was beginning to pour out of eastern mills. Millions of parts, the largest steel order ever made. 18% of all the steel produced in the United States in 1933 was for this one bridge. 18