The mechanics of conquering a river of such power and width proved challenging, but in an age when man lauded his ability to conquer nature, to move from agrarian sensibilities to industrial prowess, John Roebling ultimately tamed nature with nature. As David Nye asserts, "nineteenth-century Americans saw no irreconcilable contradiction between nature and industry; rather, they enjoyed contemplating the dramatic contrasts created by rapid progress" (39).
The first proposed scheme for a Brooklyn bridge lacked structural soundness. In 1811, Thomas Pope proposed a wooden, 1800-foot-long, 200-foot-high "Rainbow Bridge." These dimensions actually exceed the size of the Roebling bridge, and a material as light as wood never could have supported a span of such proportionsespecially over what is actually a turbulent tidal strait. Nevertheless, Pope plan's offered vision, a precursor to John's innovation (Trachtenberg, Bridge 27).
Thomas Pope's Rainbow Bridge
John incorporated awe-inspiring artistry and sublime eloquence with forward-looking technology. As Trachtenberg observes, he envisioned a Hegelian whole, where the engineering and architecture "intersected theoretical, physical, economic, and historical considerations" (Bridge 67-68). The primary technical benefit of a suspension bridge was the employment of a single span, unencumbered by supporting columns and, therefore, more open to navigation. More significant, given the formerly agrarian American setting, the suspension bridge operates on a basic principle of nature: the catenary curve. It forms when cables are draped, from anchorages on either shore, over two towers positioned in the river. Trachtenberg summarizes the efficacy of the structure: "Because they are extended, the cables are in tension, while the towers, resting upon foundations on the river bed, are in compression. Viewed theoretically, the structure was a unity of opposite forces, harmonizing tension and compression" (Bridge, 69). Above all, John stressed the importance of weight and stiffness: the longer the span, the greater the weight necessary for a more stable structure. Therefore, he reinforced the cables with a system of diagonal inclined stays, which extend from the top of the towers to sequential points on the roadway, each forming the hypotenuse of a right triangleanother feature gleaned from naturewith the roadway and the towers. This system, known as the trussing, can support the roadway even without the cables (Trachtenberg, Bridge 70-71).
The overall design, though Gestalt-like, works largely due to the interaction of individual technical feats mastered by Washington. Pneumatic caissons, for example, though unseen, provide the foundation of the project. Basically, upside-down, hollowed-out boxes made of wood and iron, they are constructed on land then launched into the river. Compressed air fills the inside space, keeping the water out and enabling men to enter, through specially designed air locks, to dig out the riverbed beneath. At the same time, another crew lays bricks on the roof. The combined effort causes the caisson to sink to the bedrock, where it is then filled with concrete, offering greater stability to the bridge than had it been planted at a lower depth. Europeans had employed the technique for years and, in St. Louis, Captain James Eads had begun sinking caissons when John Roebling was still presenting his plans to the New York Bridge Company. Washington, however, sunk substantially larger caissons (three times the size of that in St. Louis) to depths at least thirty feet greater than any in Europe. The 172-foot-by-102-foot New York caisson, for example, is grounded 78 feet and 6 inches deep. However, unlike that on the Brooklyn side, the New York caisson rests on sand. Washington, who agonized over the potentially deadly and costly decision, but halted digging there before reaching bedrock. The increased stability gained by further excavation, he was convinced, would not outweigh the toll on the lives of the workers, among whom the incidence of bends attacks were increasing, or the additional cost to the project (McCullough 293-294).
Workers bind the wire into cable
Similarly, Washington devised an intricate pattern for the wire laid in the cable, ensuring that no single wire endured a disproportionate amount of stress. Workers spun the wire into strands, then bound nineteen strands into a cable of fifteen and a quarter inches in diameter. The strands, however, were carefully arranged in four tiers of five, five, five, and four strands each. Seven strands, rather than one, forming the core (McCullough 408).
John Roebling's designs for the towers
Issues of practicality and safety aside, few bridges match the Brooklyn Bridge in its technological sublimity. Originally an esoteric, European theory, the sublime "is an essentially religious feeling aroused by the ocnfrontation with impressive objects" (Nye xiii). The American sublime, however, incorporated a decidedly democratic quality. Burke and Kant discuss the natural sublime, but in America this outlook crumbled under the weight of technological mastery. The tremendous effort of overcoming nature proved more easily impressive than the mere admiration of nature. Additionally, the more accessible American sublime, as John Roebling well knew, enabled one to apply Reason to the world. Ultimately a sublime structure, such as the Brooklyn Bridge, inspires awe and wonder. The experience, however, surpasses mere feeling: "the specific advantage of the sublime as a shared emotion," according to David Nye, "is that it is beyond words" (xiv). In America, where loyalties other than religion or politics, cannot bind, a pluralistic experience such as the technological sublime enables cohesion. Here it facilitates a common bond.
The Brooklyn tower rises
The bridge speaks volumes in its imposing, silence. The towers, for example, powerfully lift the roadway high above the tallest ships and bear the weight of the tremendous cables. However, each tower also boasts two Gothic arches through which the roadway passes. In uniting the past with the presentmedieval architecture enjoyed a revival in nineteenth-century Americathe gate-like towers offer an entrance to the future. The refined masonry of the towers adds to the monumental proportions. In comparison, the all-steel Manhattan Bridge, which can be spied just upstream from the Brooklyn span, is a work of bare utilitarianism and offers only an industrial aesthetic. Furthermore, the New York terminus faces city hall, and the entire bridge gleans a certain authority in its proximity to the municipality's center of government. Finally both the Brooklyn and New York anchorages were originally designed as treasury repositories, marking, as Trachtenberg notes, "a historical realitya shift of the center of civilization from Europe to America" (Bridge 75). In short, the Brooklyn Bridge satisfies Nye's definition of the American sublime as an "amalgamation of natural, technological, classical, and religious elements into a single aesthetic" (23).
Footbridge used wile laying wire
In addition to its symbolic presence, though, the Brooklyn Bridge invites visitors to participate in its greatness. John planned for five lanes across the span; the two outer lanes were designed for horse-and-wagon travel and the two the inner lanes for cable cars, but an elevated promenade, lined with electric lights from the start, also allows safe and scenic passage for pedestrians. Therefore, while locals and tourists can note, as does Nye, the "somber colors" that add to the overall effect of the bridge whereas bright colors would have ruined it, they can also sit on a bench and look out at the river. They can walk across the span, feel the gentle upward slope of the roadway, and watch as the opposing shore slowly comes into view. According to Nye, the roadway juxtaposed with the downward course of the cables adds beauty by avoiding "the banality of a merely horizontal span" (86). The bridge offers a unique opportunity to feel opposing forces at work. More important, it offered the experience to all. Lewis Mumford explains the effect of the finished structure: "This wasn't something that was exclusive to literary people, or to intellectuals. It was something that the ordinary man felt, too, because he walked back and forth across the bridge" (Burns).