The Brooklyn Bridge
In the winter of 1852, John Roebling and his 15 year-old son, Washington were riding a ferry boat across the East River from New York to Brooklyn. John Roebling was an engineer. His specialty was building bridges. As he looked across the East River, he could picture the bridge he wanted there. For years after that, John tried to convince people that his plan for a bridge across the East River was a good one. But most people thought it was nearly impossible to bridge the wide and powerful river. John knew it would be difficult. There were many problems to be solved. The bridge would have to be strong enough to withstand the swift currents and powerful winds of the East River. It could not get in the way of the hundreds of boats that traveled on the river every day. It had to be so high that the masts of tall sailing ships could easily pass under it. And it had to be long. The East River was nearly half a mile wide at that point. But John also knew about a type of bridge that could solve all the problems. It was called a suspension bridge.
Every suspension bridge is different, but they all work in the same way. The roadway doesn't rest on supports. Instead it hangs in the air, suspended from thick cables. Only two towers are needed to hold up the cables, and they can be placed far apart to keep the river open for boat traffic. Finally in 1867 The New York Bridge Company made John A. Roebling engineer. In just three months he produced all drawings, cross sections, location plans, preliminary surveys, estimated cost, took sounding, and wrote his proposal. In June of 1869 John finished the design for the bridge. He and Washington climbed out onto the end of a pier to determine the exact location of the Bridge. He was so intent on what he was doing that he ignored the whistle of an aproaching ferry. Washington shouted a warning but his father couldn't move fast enough. The boat slammed into the pier, John's injury became badly infected and he died of lock jaw, a month later.
John's sudden death was a shock to everyone. Now Washington and his father's dream was in danger, and he was the only one who could keep it alive. Although he was young and inexperienced, he decided he had to carry on the work his father had started. He accepted the job of Chief Engineer of the Brooklyn Bridge. Washington began immediately. He had to build foundations under the water to support the bridge towers. If he built them on the muddy river bottom, they could slip, and the bridge would be unstable. He had to build them on a solid surface. He had to dig down through the mud to reach bedrock. To do this he used enormous caissons. The caissons sat on the river bottom and protected the workers inside as they dug. In 1871, the Brooklyn caisson reached solid bedrock at 44 ½ feet below the river, and the caisson was filled with concrete. The first foundation was finished. On the New York side of the river, the caisson...