In the 1870s, constructing the Brooklyn Bridge required anchoring its massive masonry towers directly into solid bedrock below the East River. Chief engineer John A. Roebling and his son Washington implemented pneumatic caissons—enormous, bottomless wooden boxes weighed down by granite and submerged into the riverbed.
Compressed air was continuously pumped into these submerged chambers to keep water out, allowing workers known as 'sand hogs' to dig through mud and rock by hand. As the workers excavated below, the heavy wooden caissons gradually sank deeper until reaching bedrock. However, working under extreme pneumatic pressure came at a terrible cost.
When workers returned to normal atmospheric pressure too quickly, nitrogen gas dissolved in their blood formed painful, debilitating bubbles in their tissue and joints. The condition was dubbed 'caisson disease', now recognized as decompression sickness or 'the bends'. Dozens of workers suffered severe paralysis, and Washington Roebling himself was permanently incapacitated after spending long hours in the Brooklyn-side caisson.
To make matters worse, the interior of the caissons was filled with flammable gas for lighting, leading to frequent fires within the pressurized timber ceilings. Despite these nightmarish conditions, the caissons successfully reached their targets—the Brooklyn caisson was sunk 44 feet deep, while the Manhattan caisson went down 78 feet into the riverbed before being filled with thousands of tons of concrete to serve as permanent foundations.