When it was completed in 1883, the Brooklyn Bridge was the largest suspension bridge in the world. It was the first bridge to be constructed using steel. The bridge links the boroughs of Manhattan and Brooklyn which were once two separate cities. The concept for the bridge came from Engineer John A. Roebling while stuck in ice on a ferry in Brooklyn. During construction of the bridge, over 20 lives were lost, including that of John Roebling. Most workers died of "the bends" from surfacing too quickly after being submerged in the deep caissons. Roebling's foot was crushed between an incoming ferry and a ferry slip. He died three weeks later. Roebling's son, Washington Roebling, continued the supervision of construction but was removed from a caisson suffering from the bends. He was partially paralyzed and confined to his bed. Roebling's wife, with Washington's guidance, supervised the completion of the project. The Brooklyn Bridge was built using entirely new techniques. Each cable contains 3,515 miles (5,657 km) of steel wire. The wires are galvanized with zinc to protect the cable from the elements. The bridge originally had two outer lanes designed for horse-drawn carriages, two middle lanes for cable cars, and an elevated center walkway. Poet Walt Whitman said that the view from the walkway was "the best, most effective medicine my soul has yet partaken.".