Caisson, 2002

When John Roebling designed the Brooklyn Bridge in the 1860's, it was an engineering marvel. One of the challenges was how to dig in the middle of the East River for the footings for the two towers. Roebling's solution was a "caisson," a huge airtight wooden box with an open bottom. The caisson was floated into the river and stones were piled on it until it hit the riverbed. Then workers went into the air-filled box and began digging. As they dug, the caisson sank deeper and deeper. The pressure of the water above was tremendous, and several of the workers, including Roebling himself, died of repeated decompression sickness, the condition scuba divers call "the bends."