overall design. In June 1869, while conducting these surveys, Roebling sustained a crush injury to his foot when a ferry pinned it against a piling. After amputation of his crushed toes, he developed a tetanus infection that left him incapacitated and resulted in his death the following month. Washington Roebling, John Roebling's 32-year-old son, was then hired to fill his father's role. When the younger Roebling was hired, Tammany Hall leader William M. Tweed also became involved in the bridge's construction because, as a major landowner in New York City, he had an interest in the project's completion. The New York and Brooklyn Bridge Company—later known simply as the New York Bridge Company—was actually overseen by Tammany Hall, and it approved Roebling's plans and designated him as chief engineer of the project. Construction Caissons Construction of the Brooklyn Bridge began on January 2, 1870. The first work entailed the construction of two caissons, upon which the suspension towers would be built. The Brooklyn side's caisson was built at the Webb & Bell shipyard in Greenpoint, Brooklyn, and was launched into the river on March 19, 1870. Compressed air was pumped into the caisson, and workers entered the space to dig the sediment until it sank to the bedrock. As one sixteen-year-old from Ireland, Frank Harris, described the fearful experience:The six of us were working naked to the waist in the small iron chamber with the temperature of about 80 degrees Fahrenheit: In five minutes the sweat was pouring from us, and all the while we were standing in icy water that was only kept from rising by the terrific pressure. No wonder the headaches were blinding. Once the caisson had reached the desired depth, it was to be filled in with vertical brick piers and concrete. However, due to the unexpectedly high concentration of large boulders atop the riverbed, the Brooklyn caisson took several months to sink to the desired depth. Furthermore, in December 1870, its timber roof caught fire, delaying construction further. The "Great Blowout", as the fire was called, delayed construction for several months, since the holes in the caisson had to be repaired. On March 6, 1871, the repairs were finished, and the caisson had reached its final depth of ; it was filled with concrete five days later. Overall, about 264 individuals were estimated to have worked in the caisson every day, but because of high