John Augustus Roebling was the foremost designer and builder of suspension bridges in the nineteenth century.
John Augustus Roebling (born Johann August Röbling on June 12, 1806 in Mühlhausen, Thüringen; died July 22, 1869 in Brooklyn, NY) was the foremost designer and builder of wire suspension bridges in the nineteenth century. His crowning design was the Brooklyn Bridge over the East River in New York. It was Roebling’s development of a method for manufacturing wire rope by spinning it in place and his understanding of stress factors and the methods that would be needed to counteract wind and lateral swaying that made the construction of long suspension bridge spans possible. Such has been the worldwide impact of wire rope that Roebling was later inducted into the National Inventors Hall of Fame. Roebling was a man of varied interests, including music and philosophy, but primarily he was the founder of two business enterprises upon which he focused his attention: his civil engineering firm and his wire rope manufactory. Both firms became successful due to Roebling’s attention to detail and his ability to select assistants wisely. Among the latter were his sons, two of whom also studied civil engineering and expanded the manufactory into one of the premier facilities of its kind in the world after Roebling’s death.
The youngest of five children, Johann August Röbling was born on June 12, 1806, in the town of Mühlhausen in the Prussian province of Thüringen (now the Free State of Thüringen in the center of modern-day Germany). The family could trace its ancestry in the region back to the sixteenth century. The Röblings were strict Lutherans and John Augustus was baptized in the twelfth-century church Divi Blasii. Roebling’s father, Christoph Polycarpus, was a tobacconist who was successful enough to take on apprentices, and the family lived above his shop. His mother, Friederike Dorothea, was five years older than her spouse and by most accounts more ambitious than her husband, who seemed content with sleepy town life in Mühlhausen. Roebling likely acquired his lifelong work drive from Friederike, who scrimped and set aside money for her son’s education.
Young Roebling attended public schools in his home town until age fifteen when his mother arranged for him to be tutored for three years at Erfurt by a famous German mathematician, Dr. Ephraim Saloman Unger. The goal of this special tutoring was to prepare him for a civil service career. To attain such an occupation, the first step required was to pass a surveyors’ examination, thereby becoming officially certified as a surveyor (Feldmesser). Once he held the Feldmesser certificate, he was permitted to attend lectures at the Berlin Building Academy (Berliner Bauakademie) which qualified him to work as a Bauconducteur building public structures such as roads and bridges. During the year he spent in Berlin, he also attended a few lectures at other nearby schools where he learned French, perfected his artistic skills, and was inspired by the philosopher Hegel.
Roebling’s course of study at the Berlin Building Academy included engineering and architecture under Martin Friedrich Rabe, foundation construction and bridge building under Johann Friedrich Dietleyn, and hydraulics and dike construction under Johann Albert Eytelwein, who was “the leading authority on river and harbor works” and was conducting research into the comparative value of using cast iron and wrought iron for bridge construction at the time. From the start, bridge construction was Roebling’s favorite subject and he especially enjoyed Dietleyn’s lectures on five small suspension bridges that had recently been constructed in England. These bridges used chains of iron bars to suspend the roadway. Dietleyn had translated into German “excerpts of [French engineer Louis] Navier’s Memoire [sur les Pont Suspendus],” which Roebling no doubt studied. Dietleyn also discussed the construction of a chain bridge built in Pennsylvania in 1796 by James Finley and a wire suspension bridge over the Schuylkill Falls in Philadelphia in 1816.
Many years later Roebling summarized his higher education and early employment in Germany with these chronological curriculum vitae notes:
Went to Dr Ungers Mathematical Institute in Erfurt in June 1820 at the age of 15.
Passed my 1st Examination & returned to Mühlhausen in 1823.
Remained there 1 year, went to Berlin 1824.
Went to Westphalia (built Military Road) 1825.
Remained there 4 years & returned to Mühlhausen 1829.
Worked out my Thesis & Plans for 2nd Examination and left for the U.S. in May 1831.
For unknown reasons, Roebling never took the crucial second examination. Instead, he and his older brother Carl became caught up in a plan to relocate away from Prussia.
The year 1830 was one of social and political unrest in France and elsewhere in Europe. With the overthrow of Charles X that summer, the Bourbon dynasty, which had been restored after the ultimate defeat and second exile of Napoleon Bonaparte, was finally swept away. Later that summer Belgium emerged as an independent nation. To the young Roebling brothers and those of similar inclination it seemed only a matter of time before the changes overtook Germany. However to their dismay, the revolution in Prussia was suppressed almost before it began. Indeed, the repressive Prussian government went to extreme lengths to bolster the status quo. It soon became harder for skilled workers and trained technicians to leave Prussia without an official permit, which, needless to say, would be hard to come by for those wishing to emigrate. Despite the new anti-emigration regulations, John Augustus Roebling and his brother first began thinking seriously about emigrating during this time period.
The country of choice for the young men was the United States. A friend of Roebling named Johann Etzler, who was a trained engineer, had returned from the United States to Mühlhausen on a visit and was singing the praises of the New World. Toward the end of 1830, John Augustus Roebling, his brother Carl, and Etzler decided they would organize a group to immigrate to the United States. Personal savings and monies acquired through the sale of property covered the passengers’ costs. As for John and Carl Roebling, their mother, Friederike, provided them with money that she had been saving for years.
The Roebling brothers, Etzler, and the small group of like-minded émigrés left Mühlhausen for the port of Bremen on May 11, 1831, and sailed for the United States on the August Eduard later in the month. Roebling and six others paid 75 thaler (roughly fifty-eight U.S. dollars at the time or about $1,500 in 2010$) for cabin passage. The rest of the group traveled in steerage. Instead of the planned six-week voyage, it took eleven weeks to cross the Atlantic due to storms, calms, and headwinds. The August Eduard docked at Philadelphia, Pennsylvania, on August 3, 1831. Roebling and his fellow “colonists” spent a few weeks in that city before embarking on the 300-mile, four-week journey to Pittsburgh. However, as time passed, the group splintered and dwindled.
After scouting out territory in the Pittsburgh region, Roebling eventually bought land in western Pennsylvania that had formerly been part of the estate of Robert Morris, one of the financiers of the American Revolution. The area totaled 7,000 acres, but Roebling’s initial purchase was 1,600 acres, including a farmhouse, at $1.37 ($35 in 2010$) per acre. Roebling paid $1,000 (equal to $26,000 in 2010$) in cash with the balance to be paid in two subsequent installments. The land purchase was made on behalf of John Augustus Roebling, his brother Carl, another brother, Hermann Christian, and their friend Ferdinand Baehr, the latter two remaining in Germany. Johann Etzler led many of the Mühlhausen immigrants elsewhere to settle, but the Roebling brothers and the seven-member Grabe family moved onto the land that Roebling had purchased. The tiny group hunkered down in the farmhouse for the winter and purchased a team of horses, two plows, a cow, and supplies.
Meanwhile Roebling continued writing letters to friends and family in Mühlhausen hoping to encourage others to emigrate. The strategy worked. In May of 1832, the seemingly incredible amount of $6,000 (approximately $160,000 in 2010$) was transferred to Roebling by another group of approximately 30 immigrants led by Ferdinand Baehr. They arrived during the summer. By that time, Roebling had surveyed the land and drawn up a plan for laying out a village on a hillside. Main Street ran in an east-west direction and individual lots ran down the slope of the hill to Water Street. The lots, which Roebling envisioned as farmsteads, were divided into six-by-twelve-acre plots, and the original houses, all communally raised, were either log cabins or blockhouses. The settlement was originally called Germania, but the name was soon changed to Saxonburg.
Perhaps due to its isolated location in western Pennsylvania, Roebling intended for Saxonburg to be a farming village, though he himself had no agricultural experience. Some of the houses along Main Street served as both residences and businesses. Within five years of its establishment Saxonburg boasted “a weaver, a grocer, a blacksmith, a cabinetmaker, about six carpenters, a tanner, a miller, a baker, a shoemaker[,]” two tailors, a brewer, and even an artist. Additional farmers also arrived in the community. The village was nominally Lutheran, but there was no minister until 1844 when Roebling installed Julius Riedel, who was his son’s tutor, as the village minister. However this did not sit well with the Lutheran synod in Pittsburgh, which soon after deposed Riedel. Nevertheless, the incident is illustrative of how Roebling’s fellow villagers were willing to accept his authority in matters both religious and secular.
This period in Roebling’s life was marked by an optimism that was tempered by the deaths of a family member and a mentor, as well as setbacks in his personal life. A letter from home soon after Roebling’s arrival in the United States informed John Augustus and his brother of the death of their mother. Friederike Roebling had traveled to Bremen to see her sons off but when their ship sailed she suffered a heart attack from which she never recovered. Another letter told Roebling of the death of his former professor Georg Wilhelm Friedrich Hegel. Lastly, he was briefly engaged to a young woman, Helena Giesy, whose family lived near Pittsburgh. However when she and a brother joined a religious community that planned to relocate to Missouri, Roebling chose to remain in Pennsylvania, thus breaking the engagement.
In 1833 yet another group of immigrants arrived at Saxonburg, and this faction included a former tailor from Mühlhausen, Ernst Herting, and his family. Soon Roebling was keeping company with Herting’s daughter Johanna. They married in 1836, and on May 26, 1837, their first child, Washington Augustus Roebling, was born. John Augustus and Johanna Roebling eventually had nine children together.
In addition to the birth of his first child and his naturalization as a United States citizen, the year 1837 witnessed a tragic event in Roebling’s life, the death of his brother Carl. Carl died during the summer of 1837 and left behind a widow and two children. Carl’s death affected John Augustus Roebling’s plans for the future. Since purchasing the land in western Pennsylvania and laying out the plot for Saxonburg, Roebling had primarily devoted his attention to farming. Unfortunately, the farming land that he had selected was of poor quality, and while other Saxonburg residents prospered somewhat as farmers, Roebling was unsuccessful. Carl’s death left John Augustus with an extended family to support and made him even more discouraged by his agricultural pursuits. He finally made a decision that he no doubt had been considering for some time. Roebling decided to loosen his ties to Saxonburg now that it was a well-established community and return to the profession for which he had trained. Securing a job as an engineer, however, was not so easy in 1837. The United States had experienced an economic panic earlier in the year and had entered a period of economic depression that would last for five years.
It is unclear why Roebling had been so intent on living out Thomas Jefferson’s ideal of the yeoman farmer when he first arrived in the United States instead of immediately pursuing employment for which he had professional training. His sense of responsibility towards his fellow immigrants from Mühlhausen may have had something to do with it. Not dissuaded by his failure at farming, or by his initial inability to secure steady engineering employment due to the ongoing economic depression, Roebling took to poring over technical and engineering journals and books and designing and inventing various apparatuses. An excellent draughtsman, he illustrated his own patent applications. Among the machinery Roebling designed during this period were a new boiler for steamships, a steam-powered tractor that operated plows and reapers, a self-acting gauge, and a radial engine. Working with an inventor in Philadelphia, he took out a joint patent for “submarine propellers,” underwater propellers that could move steam-powered vessels through the water. Roebling was also the inventor of a spark-arrester for locomotives, which prevented sparks from the locomotives’ wood-burning stoves from setting fire to trees, fields, and houses along the tracks, a serious and very-real hazard at the time.
Fortunately for Roebling, he eventually found employment in the field of canal engineering and construction. The 1820s and 1830s witnessed a frenzy of canal-building in the United States set in motion by the opening of the Erie Canal in upstate New York in 1825. As luck would have it, an old schoolmate wrote to Roebling inquiring whether he was interested in joining the engineering staff working on the Sandy and Beaver Canal in Ohio. Roebling jumped at this opportunity and temporarily left the farm in the capable hands of Johanna. Roebling’s employment was brief due to the hard times. Pennsylvania, where the first short canal in the United States had been constructed in 1797, eventually began building its own system of inland waterways known collectively as the Pennsylvania Canal. By the end of 1837, Roebling had secured a job working on the construction of a feeder canal that would deliver water from the Allegheny River to the Pennsylvania Canal. His duties included “determining location, line and grade, and staking out the work for excavation and masonry construction.” Eventually his excellent training and engineering skills came to the attention of his superiors, and Roebling was placed in charge of a group of engineers whose duty it was to survey portage routes across the Allegheny Mountains. These routes would connect the central Juniata Section of the canal with the western sections. In all, Roebling was employed for about two years on these aspects of the Pennsylvania Canal construction project.
Roebling’s next job involved surveying railroad routes for the State of Pennsylvania. These routes went over the Alleghenies to connect Harrisburg and Pittsburgh. While he was working on these surveys, Roebling met and befriended Charles L. Schlatter, who was the chief engineer on the project. Schlatter soon promoted Roebling to his principal assistant. He held the post for two years from 1839 to 1840. As principal assistant he organized his own crews, and employed some of the men from Saxonburg. Even as he was practicing his profession, Roebling continued to file patent applications for transportation and agricultural inventions in his spare time.
During the same time period, Charles Ellet, who had studied at the École Polytechnique in Paris, was making a name for himself with various wire-suspension bridge proposals, including a thousand-foot span across the Potomac River, one over the Mississippi River at St. Louis, Missouri, and another over the Schuylkill River at Fairmount in Philadelphia. Though nothing came of the first two bridge proposals, the Fairmount proposal was well received by the citizens of Philadelphia and it bolstered Ellet’s growing reputation as a bridge designer. Roebling, working in western Pennsylvania, wrote to Ellet, whom he assumed, mistakenly, was older and more experienced than he, on January 28, 1840, about employment. “Should you at some future period,” he wrote Ellet, “be desirous of engaging an Assistant [sic] for the construction of suspension bridges, who is competent for the task, and who at the same time would execute with pleasure all the necessary drawings, please bear me in mind.” Ellet’s response was perfunctory, and Roebling soon realized that he had no chance of working as the former’s assistant. In time the two would become rival bridge builders.
In the meantime, Roebling decided to promote publicly his own ideas about engineering and bridge building. He authored an article on suspension bridges that appeared in the American Railroad Journal: “Some Remarks on Suspension Bridges, and on the Comparative Merits of Cable and Chain Bridges.” He also wrote to Andrew Young, the local contractor selected by the county commissioners to build the Schuylkill suspension bridge, to offer his assistance after the contract had been awarded. Young accepted his offer, possibly because Young had no experience in bridge design or construction, but Charles Ellet and his allies on the county board, which had final say over contracts, used every means possible to return the project to Ellet’s control. Young’s contract was rescinded by late spring of 1841, and Ellet was back in charge of the bridge’s design and construction work. Roebling received the unfortunate news from Young on his thirty-fifth birthday.
The loss of the Fairmount Bridge project spurred Roebling to pursue work in a different, but related, field. The Pennsylvania Canal used a series of stationary steam engines and inclined planes, rather than a costly system of hydraulic locks, to haul canal boats on flatbed rail cars over the crest of the Allegheny Mountains. The project was known as the Allegheny Portage Railroad. Roebling was familiar with the inclined-plane system due to his railroad route surveying work in western Pennsylvania and knew of the hazards of using hemp rope, which sometimes frayed and snapped under tension, to link the steam engines and rail cars. Roebling decided that wire rope would be stronger, more flexible, and longer-lasting than hemp. He returned to his Saxonburg farm, purchased a quantity of wire from an iron monger in Beaver Falls, Pennsylvania, and built a ropewalk to manufacture wire rope. Roebling initially enlisted friends and neighbors to twist the wire strands into rope, but later created machinery to mechanize the process. He set up his manufactory while continuing to work on railroad surveys and maps for the State of Pennsylvania. The end result of his wire rope experiments was that in 1842 Roebling was granted patent number 2720 for “Methods of Manufacture of Wire Rope.” Before he was granted the patent, however, he had already received an order for one-inch thick wire rope, 600 feet in length, to draw boats from a river basin to the base of the Portage Railroad.
The big test for Roebling’s wire rope came when he proposed to demonstrate its superiority to hemp rope on one of the inclined planes of the Portage Railroad. Despite his second-hand exposure to the political scheming associated with the Fairmount Bridge project, Roebling was still naïve enough that he failed to understand that money was at stake if his design proved successful and that powerful political and commercial forces were opposed to his new product. He undertook the demonstration at his own expense, but the wire rope was sabotaged and broke during the test. Fortunately the sabotage was discovered and a Roebling supporter, James Potts, who served as the collector of canal tolls, intervened on his behalf with the president of the Pennsylvania Canal Commission, John B. Butler. The cut wire rope was repaired and a new test proved the superiority of wire rope over hemp rope. Within a few years wire rope replaced hemp rope on seven of the other nine inclined planes of the system. Soon other applications were found for wire rope in collieries, on ships, and in dredging operations. The lead article of the November 1843 issue of the American Railroad Journal contained Roebling’s discussion of the still-revolutionary product. By the time of that publication, he was secure enough in his profession that incoming and outgoing correspondence referred to him as “John A. Roebling, Civil Engineer.”
Nevertheless the backers of hemp rope would not go down without a fight, and soon supporters on both sides of the wire-versus-hemp-rope issue were trying to gain the upper hand on the various inclined planes of the Pennsylvania Canal system. For a time it looked like the supporters of wire rope would lose the fight, but the main supporter of hemp rope accepted a position outside the canal system and his underlings lost their impetus to carry on the fight. By 1845, wire rope was installed on the last two inclined planes of the Allegheny Portage Railroad.
Even as he was struggling to have his invention accepted by the engineering community, Roebling was thinking of improvements to the basic design. As far back as 1841, when he was just starting to create wire rope, Roebling had applied for a patent on a process that would alter the wire rope by wrapping it with annealed wire to form a cover over the strands and thus create a cable. Wire cable could be used for suspending bridges, and bridge building was constantly on Roebling’s mind. By the mid-nineteenth century, revolutionary changes were occurring in the design of bridges. Iron began to replace gradually stone and wood as the material of choice, and new truss designs, especially for railroad bridges, began to come into vogue. Despite innovations in truss bridge design, Roebling, who avidly kept up with new developments in the field, remained a confirmed disciple of the suspension bridge, though not all of his bridges utilized that design. Roebling became a trend-setter in bridge design and pioneered innovative applications of iron, and later steel, in his projects.
The first suspension structure Roebling designed and constructed was the world’s first suspension aqueduct over the Allegheny River at Pittsburgh. The aqueduct itself was part of the Pennsylvania Canal system. The previous aqueduct had been so damaged by ice during the winter of 1843-1844 that it had to be torn down, and an invitation for proposals had been issued for a replacement design. Roebling completed the design studies and testing of models at his home in Saxonburg, and then presented his work in Pittsburgh to engineers and others in charge of the project. His bid was the lowest of the forty-four submitted, and he was awarded the contract, which stipulated that the work had to be completed within nine months. The timing of the contract meant that six of the nine months would be during late fall, winter, and early spring, which added complexity to the project. Roebling also had to pay canal tolls for shipments of aqueduct construction materials, which further complicated matters and cut into his profit margin. Nevertheless, Roebling and his workforce, many of whom had been recruited from Saxonburg, completed the project on time in May of 1845. He accomplished the feat by stringing the large suspension cables for the bridge in place, “wire by wire, in their final position.” This innovative method would become de rigeurin suspension bridge construction. He also patented a new form of anchorage design, in which the chains that gave strength to the structure were “permanently sealed and protected” by the masonry of the anchorage. Water was let into the finished aqueduct on May 22, 1845. Of the $62,000 (approximately $2 million in 2010$) spent on the project, Roebling netted about $3,500 (nearly $100,000 in 2010$).
By the time he completed the Allegheny Aqueduct project, Roebling had become a regular contributor to the American Railroad Journal, and he published another article in that periodical describing the aqueduct’s construction and his innovations with wire cable and anchorage design. He wrote: “The plan of this work therefore is a combination which presents very superior advantages, viz. great strength, stiffness, safety, durability and economy… This system, for the first time successfully carried out on the Pittsburgh aqueduct, may hereafter be applied with the happiest results to railroad bridges, which have to resist the powerful weight and great vibrations which result from the passage of heavy locomotives and trains of cars.” The aqueduct lasted until 1861, when it was abandoned at the beginning of the Civil War.
Even before the Allegheny Aqueduct was officially opened, Roebling had embarked on his next project, a road bridge. His design was chosen to replace the Smithfield Street Bridge in Pittsburgh, a wooden structure over the Monongahela River that had been destroyed by fire on April 11, 1845. The bridge linked settlers in the outlying areas south of the river with the city. Roebling shifted his work crew from the Aqueduct to the site of the Smithfield Street Bridge and planned to commence work on the bridge on May 1, 1845. Although Roebling’s proposal had already been approved, and a contract signed, he realized that the new bridge should be ten feet higher than the previous one when he began onsite planning work. The proposed change set off a debate among merchants in Pittsburgh. Some feared that a higher bridge would allow ships to float underneath the structure and bypass Pittsburgh altogether. In the end, the toll-bridge company financing the construction work deemed the $10,000 (approximately $300,000 in 2010$) price of Roebling’s proposal too expensive. To save money he converted the old bridge abutments into cable anchorages. The new Smithfield Street Bridge opened officially in February of 1846. Roebling was paid $55,000 (equal to nearly $1.6 million in 2010$) for the project, but realized no profit because he had submitted a low bid in order to secure the bridge contract.
Of the bridge Roebling wrote to D. K. Minor, editor of the American Railroad Journal: “The bridge surpasses the expectations even of its friends, and has silenced the opposition forever… The stiffness promised for the Monongahela [B]ridge has been fully attained, and pleases the public much—as many prophesied differently.” Roebling later wrote and illustrated another article for the American Railroad Journal about the bridge’s construction. The bridge was not without its defects, but it remained in service for thirty-five years. A new bridge replaced it in 1883. Despite his success with the Smithfield Street Bridge, Roebling later lost out to rival Charles Ellet on a contract to build a bridge over the Ohio River at Wheeling, Virginia.
During the next five years Roebling was extremely busy expanding both his professional reputation and his personal fortune. First he contracted with the Delaware and Hudson Company to construct four aqueducts. After inspecting the Allegheny Aqueduct, the engineers of the Delaware and Hudson Canal Company approved his aqueduct designs and authorized the construction of two aqueducts. He was later authorized to construct two additional aqueducts. The first of the quartet, the Delaware Aqueduct, was completed at the end of 1848. Roebling completed a smaller suspension aqueduct over the Lackawaxen River, a tributary of the Delaware River that flows though northeastern Pennsylvania, in the spring of 1849. Soon after, in April of 1849, he began working on the High Falls Aqueduct over the Rondout River in New York and the following summer he began work on the Neversink Aqueduct in New York. The latter employed nine-and-one-half-inch cables, the largest then in use. Both aqueducts were completed in the latter half of 1850. The speed with which these aqueducts were completed was made possible by a patented process that Roebling developed for building suspension bridges: a “method for putting the bridge cable together, on site, by running out the wires separately, two at a time.” For this he received U.S. patent number 4995 in 1847.
Though aqueduct construction kept Roebling employed profitably, his true desire was to construct a suspension railroad bridge. Roebling understood that railroad transportation would soon supplant canal transportation in the United States. Back in 1847 he had read a paper before the Pittsburgh Board of Trade titled, “The Great Central Railroad from Philadelphia to St. Louis.” The paper was subsequently published in the American Railroad Journal along with a companion piece by Roebling titled, “Location of the Central Railroad Through Pennsylvania.” In these articles Roebling showed that he understood the relationship between railroads and the opening up of commerce and, ultimately, the creation of municipal wealth. In 1850 he also published an article in the New York Journal of Commerce arguing on behalf of the necessity of a transatlantic telegraph cable. Roebling, of course, was not the only one arguing for such a cable, but, again, he was on the side of technological progress, as one might expect from a student of Hegel.
At about the time he began working on the aqueducts for the Delaware and Hudson Canal Company, Roebling recognized that his other company, the wire-rope factory, had outgrown its home in tiny, rural Saxonburg. The factory not only needed to expand, but it needed better access to river and rail transportation. The operation in Saxonburg required loading the wire rope onto wagons and hauling it approximately ten miles to the southeast to Freeport, Pennsylvania, where it was then transferred to a local canal for shipment. At the suggestion of New York industrialist Peter Cooper, Roebling decided to move the factory and his family to Trenton, New Jersey. He purchased twenty-five acres of land about a mile from the center of Trenton for $3,000 (approximately $85,000 in 2010$). The site was near both the Delaware and Raritan Canal and the Camden and Amboy Railroad. The expanded factory required new machinery, and since wire rope manufacturing was still in its infancy, it was up to Roebling to design the proprietary manufacturing equipment for which he received patents. Partial operations began in Trenton in October of 1849.
Meanwhile Roebling’s family had relocated successfully to Trenton as well. Roebling’s third son, Charles Gustavus, was born in the city in December of 1849. It must also be pointed out that the successful move to Trenton, both for the factory and the family, could not have been accomplished without Charles Swan, who was not only Roebling’s trusted assistant and superintendent of the factory but his closest confidant and, indeed, the family’s confidant. Roebling and Swan corresponded frequently regarding important business and family matters, and he trusted Swan to carry out important assignments, especially during Washington Roebling’s youth.
In 1845, Major Charles B. Stuart, a civil engineer who later went on to become New York’s first state engineer and surveyor and eventually engineer-in-chief of the United States Navy, first broached the idea of a railroad bridge over the Niagara River that would link the Rochester and Niagara Falls branch of the New York Central Railroad with the Canada’s Great Western Railway. The new international connection would facilitate the transfer of goods and passengers between the United States and Canada and expand commercial markets in both nations. Stuart himself was not a bridge engineer so he circulated a letter outlining his ideas throughout North America and Europe. Most engineers of the time thought his notion impractical and only four men responded positively: Samuel Keefer, Edward W. Serrell, Charles Ellet, and John Roebling. In 1846, the Niagara Bridge Company was chartered by the New York State Legislature and the Ontario Provincial Parliament, and the following year an invitation was sent out for proposals. Ellet, with his superior publicity and self-promotion skills quickly got the jump on his rivals. With Stuart as his ally, he was awarded the contract in November of 1847. The decision represented a setback to Roebling who was determined to construct a railroad bridge. Ellet’s contract called for the construction of a combination railroad and carriage bridge over the Niagara River, below Niagara Falls. The sum to be paid out was $190,000 (or the equivalent of $5 million 2010$), and the completion date was stipulated as May 1, 1849.
Despite a flurry of promotions, Ellet managed to accomplish little in one year other than the construction of a wooden suspension footbridge that was later reinforced to accommodate light carriage traffic. When he and the bridge company fell into a dispute about tolls on the footbridge it was decided mutually to cancel the contract. The bridge company and Ellet severed their connection on December 27, 1848, with just a little over four months remaining before the stipulated completion date of the railroad bridge. Construction of the bridge remained suspended for the next two years, but eventually Roebling signed on to build the bridge. Under his supervision construction began in earnest in 1851.
While work proceeded on the Niagara Railroad Bridge, with Roebling carefully overseeing all important phases of the project, he entered into a contract in 1853 to build a bridge over the Kentucky River for the Lexington and Southern Kentucky Railroad. However a brief economic slowdown during 1853-1854 caused the railroad to go bankrupt and work was halted on the project. Commenting on the project, Roebling noted that, “The progress of the Ky. [sic] Bridge is a little doubtful on account of money matters. Several lines have stopped, thousands of men are thrown out of employment in Ohio and wages reduced from 1.25 to 80 cs. p. day. Laborers will be very plenty next winter, and I also think Iron will be a little lower.” In fact, Roebling’s factory at Trenton also felt the economic pinch. The State of Pennsylvania suspended payment for wire rope. This caused Roebling enough consternation over his bank credit that he instructed assistant Charles Swan to “open with Mrs. Roebling my safe and the iron box with the small brass key, and take out of the morocco pocket book my Certificate of Stock of $5000 of the Pennsylvania R.R. Co, and deposit it in bank if necessary.”
In 1854, as work continued on the Niagara Bridge, a cholera epidemic broke out in the villages near the bridge site. Soon it spread to Roebling’s crew, and work on the bridge nearly came to a halt. Roebling and those who did not catch the disease spent the better part of the summer tending to those who did. By early August the epidemic abated and work resumed on the bridge. The Niagara Railroad Bridge was completed the following March and the first train passed over it on March 16, 1855. Roebling had successfully designed and overseen construction of the world’s first suspension railroad bridge. The bridge remained in service until 1897 when it was decommissioned due to heavier locomotives, bigger freight cars, the need for two sets of railroad tracks on the bridge, and a desire for electrified trolley cars to cross the span. Nevertheless, the Niagara Railroad Bridge was an engineering marvel of its time.
On April 18, 1856, Roebling signed the contract to construct the Covington and Cincinnati Bridge. The idea for a bridge across the Ohio River had been kicking around for decades. In fact the Covington and Cincinnati Bridge Company had been in existence for ten years. Roebling himself had surveyed the site in 1846, but politics and financing problems had caused delays in the project. In 1856, after Roebling had presented his second report on the feasibility of the bridge, the political will and financial backing for the project had finally materialized. Roebling’s increasing reputation as the nation’s premier designer and builder of suspension bridges helped generate interest in the project. “While negotiations [between Roebling and the board of directors of the Covington and Cincinnati Bridge Company] were underway, the company called for bids on furnishing the stone and timber required for the foundations of the towers. At the same time a committee was appointed to buy the right of way required for the bridge on the Ohio side.” The contract called for construction to be complete within three to four years, and Roebling began work on the structure in late August of 1856.
The proposed timeframe for the bridge project proved too optimistic. Unforeseen problems at the site and poor weather conditions caused delays. Water filled the excavations on the Cincinnati side due to the pit being lower than the water table. This was compounded by the annual autumn rains that raised the river’s level. Necessity being the mother of invention, Roebling managed to design pumps fashioned from wood and powered by the engine of a nearby steamboat that ejected the water and mud and allowed the work to proceed. The faltering economy also hindered work on the project. Roebling continued to push forward construction of the bridge despite the economic depression that began in August of 1857, but as bank after bank in Ohio and the East failed it became apparent that the bridge company itself was in financial trouble. During these years Roebling sent letters to Charles Swan that effectively instigated a period of hunkering down, both for the wire rope business and for the family in Trenton. Meanwhile construction on the bridge came to a halt in 1859. In December of 1860 the stockholders, at Roebling’s suggestion, worked out a plan to issue preferred stock for approximately $500,000 (equal to $13.5 million in 2010$) in an effort to keep the project moving forward. However, in the intervening years since construction on the bridge had halted, prices had increased. The onset of the Civil War in 1861 brought shortages of workers, especially skilled workers, and material, as well as rumors and threats of raids by Confederate troops.
As the Covington and Cincinnati Bridge project languished during 1857, Roebling signed a contract to design and construct a bridge over the Allegheny River at Sixth Street in Pittsburgh to replace an old, unsafe, covered bridge. In the spring of 1858 as construction of the bridge was proceeding he was joined by his son, Washington, who had recently graduated from Rensselaer Polytechnic Institute with a degree in civil engineering. It was Washington Roebling’s first bridge job and such was Roebling’s faith in his son’s ability that he often left him in charge of the project while he made frequent trips to Cincinnati in connection with the Covington and Cincinnati Bridge project. Work on the Allegheny Bridge continued smoothly, and the four-span bridge was opened for traffic on May 2, 1860. It served the City of Pittsburgh and the surrounding region for more than 30 years. In 1892 the bridge was decommissioned and replaced due to the exigencies of late-nineteenth-century transportation requiring a larger, electrified structure.
As he continued to oversee work on the Covington and Cincinnati Bridge during the early 1860s, Roebling experienced both personal tragedy and joy. First, Johanna Roebling died in November of 1864. A few months later, however, Washington Roebling, who had resigned his commission in the U.S. Army to take on the job of assistant chief engineer, joined him in Cincinnati. Together they completed the eleven-year-old bridge project. The Covington and Cincinnati Suspension Bridge opened to foot traffic on December 1, 1866, before it was fully finished. Nearly 50,000 people crossed the bridge on the first day, and approximately 120,000 more people crossed the bridge the next day. On January 1, 1867, the bridge was opened for carriage and wagon traffic. The finishing touches, overseen by Washington Roebling, were not complete until July 1867. With a span of 1,057 feet and twelve-and-a-half inch diameter cables it was Roebling’s largest, most magnificent structure to date. In 1975 it was listed on the national register of Historic Places, and named a National Historic Civil Engineering Landmark in 1983. Also, on June 27, 1983, the bridge was renamed the John A. Roebling Suspension Bridge.
In February of 1867, John Roebling married for a second time. His new wife was Lucia Cooper of Trenton, New Jersey, but little is known about her other than “two years later she still had not been fully accepted by the family, nor would she be.” By the time of this marriage, Roebling was already deeply involved in his next project, the East River Bridge connecting New York with Brooklyn (later simply referred to as the Brooklyn Bridge).
Supposedly, John Roebling first began thinking of a bridge to span New York’s East River in 1852 when he and his son, Washington, were stuck in ice on a ferryboat in the East River. New Yorkers and Brooklynites, however, had been thinking, mostly fancifully, about a bridge for decades. At any rate Roebling first seriously considered the possibility in 1857, but the travails of the Covington and Cincinnati Bridge project occupied his attention over the next decade. In 1865 his thoughts again turned to a bridge over the East River. Roebling revised his earlier estimate and now put the price of the span at four million dollars ($55 million in 2010$). It wasn’t until two years later, with a bridge company and its attendant committees in place, that Roebling, on May 16, 1867, was named chief engineer for the project. His hiring took effect a week later at a salary of $8,000 per year (approximately $110,000 in 2010$).
Roebling threw himself immediately into surveying, design studies, and cost estimates, which needed to be revised upward from his 1865 figure. His report, complete with drawings, was ready on September 1, 1867. While he was involved in the frenzy of work, Washington Roebling was in Europe studying “the pneumatic method of sinking caisson foundations.” The younger Roebling also inspected steel mills in Germany and England as potential sources of steel wire for the cable spans.
Roebling’s design proposal for the East River Bridge met with initial opposition from some of the nation’s most prominent engineers. The span, nearly 1,600 feet in length, was approximately fifty-percent longer than the Covington and Cincinnati Bridge, and some experts felt that such a span would be challenging to build. Furthermore, Roebling suggested the bridge be built using steel wire cables instead of iron, but at the time steel was, by and large, an untested metal in bridge construction. Also, the projected cost of the project had risen to seven million dollars by 1867 (nearly $110 million in 2010$). To allay public and professional concerns, Roebling suggested that a panel of prominent engineers be convened to review his plans. After two months of investigation, the panel, which included one of his staunchest critics, voted unanimously to endorse Roebling’s plan. Simultaneously, three U.S. Army engineers reviewed his proposal, which they too approved with the single caveat that the clearance of the span be increased to 135 feet instead of the proposed 130 feet, possibly due to concerns over tidal variations in the East River. Finally, the federal government formally approved the bridge plan in 1869.
Roebling was in the process of preparing to commence construction work on the East River Bridge when disaster struck on June 28, 1869. He was standing on piles at the Fulton Ferry slip in Brooklyn while performing a final project survey and either failed to notice an incoming ferryboat or assumed he was on secure footing. The ferry crashed into the fender, which then set the piles in motion and crushed Roebling’s right foot. He was immediately taken to Washington Roebling’s home at 137 Hicks Street in Brooklyn Heights where the toes of his right foot were amputated. Roebling endured the procedure without anesthetic. Despite the prompt surgery, tetanus set in and Roebling lingered for a few weeks until he died on July 22, 1869.
Roebling was a wealthy man at the time of his death. In his will he left the wire rope company to his four sons. He made bequests totaling approximately $80,000 (equal to more than $1.25 million in 2010$) to distant relatives and some charities. Roebling divided the remainder of his estate equally among his second wife and seven children. The bequests, however, revealed a quirk in Roebling’s nature. He had kept a careful accounting of the expenditures he had made for each of the children throughout their lives and these sums were deducted from their individual bequests.
John A. Roebling was an iconoclast, an extreme one at times. He was also a dreamer whose dreams, infused with the practicality of his engineering background, often came to fruition and made him one of the most celebrated bridge builders and civil engineers of his era. When Roebling strayed briefly from his engineering background and sought to establish himself as a farmer he failed miserably. Yet he did not fail in the establishment of the small town of Saxonburg. Its success, and a good deal of his later success, was due in part to his ability to convince others of the integrity of his projects. Roebling led a small group of émigrés into the wilderness of western Pennsylvania and encouraged more to immigrate while still a young man in his twenties. Later some of these immigrants joined him in his wire-rope manufactory and on his construction sites.
Much has been made about the strength of Roebling’s personality. About him, fellow civil engineer Charles B. Stuart wrote, “One of his strongest moral traits was his power of will, not a will that was stubborn, but a certain spirit, tenacity of purpose, and confident reliance upon self….” Many times Roebling relied on his famous willpower to pull himself up from the throes of illness. As he entered middle age, essentially the beginning of his bridge-building career, Roebling became even more of a grim and determined figure. Always away from his family on engineering projects, he grew more distant from his loved ones, sending most of his correspondence to them via his trusted assistant Charles Swan. Work was all, even to the extent that he did not return home during his first wife’s fatal illness. Furthermore, Roebling was a brutal man, even by the standards of the time, who doled out punishment to his children.
During his time as the titular leader of Saxonburg, Roebling acted in a paternalistic manner towards those over whom he had authority. This included not only his family, but also the workers on his bridge-building crews and in his wire rope-making factories, first in Saxonburg then in Trenton. Indeed, his first Trenton home was open to his factory workers. His extended sense of pater familias, while physically distancing himself from his actual family, was not the only seeming contradiction in his personality. Roebling the civil engineer, the student of Hegel with his belief in the natural progress of humanity and rule of just law, later embraced the transcendentalism of American philosopher Ralph Waldo Emerson. After the death of his first wife he also embraced spiritualism. As for organized religion, Roebling was not a strict practitioner. During his Mühlhausen days he, his parents, and his siblings practiced Lutheranism, which carried over to his Saxonburg period. Later he was influenced by Presbyterianism and even Episcopalianism. Roebling’s disinterest toward organized religion has been attributed to his preference for intellectual pursuits, but he nevertheless came to embrace a Swedenborgian form of Christian spiritualism later in life.
Roebling was a metaphysical and social philosopher in his own right. His philosophy encompassed nature, metaphysics, and American life. In his reminiscences Washington Roebling mentioned his father’s unpublished 1,000-page treatise titled: “Roebling’s Theory of the Universe.” Roebling’s other philosophical writings include: “The Truth of Nature”; “The Harmonies of Creation”; “A Few Truths for the Consideration of American Citizens”; “A Few Truths for the Consideration of the President of the United States, October 1861”; and “The Condition of the U.S. Reviewed by the Higher Law.” These writing aside, it is Roebling’s technical achievements, and to a lesser extent his technical writings, for which he is rightly celebrated.
As the owner of both an engineering firm and a wire-rope manufactory, Roebling’s initial style was to oversee the day-to-day functions of the project site and the operations of the manufactory in Saxonburg when needed. Yet, he understood that micromanagement had its limits if both businesses were to expand. Thus by the end of his career, though he made the important business, construction, and design decisions himself, he trusted others, including his oldest son Washington, not to veer from the path of perfectionism he had laid out. According to at least one contemporary account, Roebling was more than ready to hand over the supervision of the construction of the Brooklyn Bridge to Washington at the time of his death. Roebling did not live to see any of the innovative European technologies, such as caissons and steel cables that Washington Roebling employed in the bridge’s construction, but these new applications of technology certainly embodied his father’s innovative character.
John Augustus Roebling’s two most outstanding traits were his creativity and his commitment to perfection in his work. He adapted his European training and experience to the problems he encountered in the United States. Roebling’s training included not only what he had learned firsthand at the Berlin Building Academy but also what he gleaned from earlier practitioners and theorists of suspension bridge building such as Frenchman Louis Navier and Americans James Finley and Charles Ellet. He also adapted and improved earlier ideas about wire rope, cable spinning, stiff roadways, and anchor stays for most of his suspension projects. Most importantly, as Roebling advanced in his bridge-building career he made technical changes with each bridge and aqueduct. He adapted each structure to its environment, and was not content to stand on past successes.
Roebling entrepreneurial inclination also shaped the course of his life. He managed to carve out two careers that nicely dovetailed with one another: civil engineer and wire rope manufacturer. The success of his manufactory no doubt owed much to his success as a bridge builder and his proof of the efficacy of iron (later steel) wire rope and cables. Roebling’s success, however, also depended on the assistance of fellow German émigrés. His Saxonburg neighbors helped him set up his wire-rope business, which provided the basis of his wealth. After Roebling’s death, his sons took over management of the firm, renamed John A. Roebling’s Sons Company, and expanded it into one of the world’s premier suppliers of iron and steel rope and cables during the twentieth century. As both engineer and entrepreneur, John Augustus Roebling left a physical and commercial legacy for future generations.
 After immigrating to the United States he anglicized his name to John Augustus Roebling. Thüringen is spelled Thuringia in English.
 Alan Trachtenberg, Brooklyn Bridge: Fact and Symbol, Second Edition (Chicago: The University of Chicago Press, 1979), 41.
 Nele Güntheroth, “The Young Roebling, Biographical Notes,” in John A. Roebling: A Bicentennial Celebration of His Birth, 1806-2006, Theodore Green ed. (Reston, VA: American Society of Civil Engineers Press, 2007), 8.
 Steinman, 12.
 Two of the bridges were eventually destroyed by strong winds.
 Emory L. Kemp, “Roebling, Ellet, and the Wire-Suspension Bridge,” in Margaret Latimer, Brooke Hindle, and Melvin Kranzberg, eds., Bridge to the Future: A Centennial Celebration of the Brooklyn Bridge, (New York: The New York Academy of Sciences, 1984), 55. See also Seth Goldman, “John A. Roebling: Engineer-Philosopher,” 2007 (accessed May 13, 2011).
 The Schuylkill Bridge collapsed in 1817.
 Güntheroth, 8.
 All 2010 dollar conversions in the article, unless otherwise noted, are based on Samuel H. Williamson, “Seven Ways to Compute the Relative Value of a U.S. Dollar Amount, 1774 to present,” MeasuringWorth, 2011, using the Consumer Price Index.
 Roebling described the hardships of the trip in the cumbersomely titled (in translation) “Diary of my Journey from Mühlhausen in Thuringia via Bremen to the United States of North America in 1831, written for my Friends.” It was privately printed in Eschwege, Hesse, by a cousin of Roeblin and later republished in Trenton, New Jersey in 1931 to mark the centennial of Roebling’s immigration.
 The group first took a boat north on the Schuylkill River to Reading, traveled west to Harrisburg by canal boat, then continued up the Susquehanna and Juniata Rivers to Huntingdon, 125 miles from Pittsburgh. The last segment of the trip to Pittsburgh involved an overland passage along “rough and hilly wagon roads.” Steinman, 32-33.
 Using the more liberal Nominal GDP Per Capita calculation, the amount is equivalent to nearly 3.5 million dollars in 2010$. Samuel H. Williamson, “Seven Ways to Compute the Relative Value of a U.S. Dollar Amount, 1774 to present,” MeasuringWorth, 2011, using Nominal GDP Per Capita.
 Saxonburg is now a sister city of Mühlhausen.
 Southeast Butler County local historian, Drenda Gostkowski, e-mail to author, August 26, 2011.
 McCullough, 47.
 Riedel had also married a sister of Roebling’s wife, Johanna.
 W.A. Roebling, “Early History of Saxonburg,” Butler County Historical Society, Butler PA, 1924, n.p.
 The group ultimately settled in the Oregon Territory
 W.A. Roebling, “Early History of Saxonburg,” Butler County Historical Society, Butler PA, 1924, n.p.
 Laura (b. 1840), Ferdinand (b. 1842), Elvira (b. 1844), Josephine (b. 1847), Charles (b. 1849), Edmund (b. 1854), William (b. 1856), and Hannah (n.d., died in infancy).
 The Conewago Canal was constructed to bypass the Conewago Falls on the Susquehanna River. It proved unprofitable for investors.
 Steinman, 50.
 Quoted in Steinman, 58.
 Roebling’s patent reflected the fact that he was the first person in the United States to create wire rope. Wire rope had been invented in Germany in the early 1830s by Wilhelm Albert.
 R. McCullough and W. Leuba, The Pennsylvania Main Line Canal (York, PA: The American Canal and Transportation Center, 1962; H.M. Cummings, “John A Roebling and the Public Works of Pennsylvania,” Bulletin 28 (Department of Internal Affairs, Harrisburg, PA), 1954.
 Roebling was not the first to employ wire to suspend a bridge roadway, but his ideas on wire rope manufacture and usage were the most ambitious and successful. See Steinman, 78.
 One of the more notable examples of timber bridge construction was the Portage Viaduct over the Genesee River, designed by Silas Seymour and completed in 1852. Fire destroyed it in 1875. Afterward it was rebuilt using iron, then steel. See Eric DeLony, Context for World Heritage Bridges: A Joint Publication with TICCIH, 1996 (accessed October 1, 2013).
 Steinman, 84.
 Steinman, 87. The Allegheny Aqueduct Bridge consisted of seven spans of 162 feet each with stone piers and towers. There were two wire cables, seven inches in diameter and each cable consisted of 1,900 parallel wrought iron wires, each of these slightly more than one-eighth of an inch thick. The cables stretched from the anchorage on one shore to that on the other. The aqueduct’s flume was sixteen-and-one-half feet wide at the top, fourteen feet wide at the bottom, and eight-and-one-half feet deep; on each side of the flume were eight-foot-wide towpaths for mules; the weight of the water was greater than 2,000 tons.
 Quoted in Steinman, 88.
 There are two points of interest regarding the design of Roebling’s first bridge. The first is that he used a system of two small pendulums (parallel iron bars) suspended from the top of iron towers to which the cables of the adjoining spans were attached. Second, the bridge had what is known as “inclined stays” to prevent the bridge from swaying. It was 1,500 feet long between abutments, and consisted of eight spans with sixteen cables, each four-and-one-half inches in diameter. The bridge also had sidewalks that were placed outside of the cables. Furthermore, the cables were “cradled,” that is they were five feet closer together at their lowest points than at the tops of the towers. Like the inclined stays, cradling the cables also increased resistance to swaying and lateral disturbances.
 Quoted in Steinman, 97.
 Ellet’s bridge was completed in 1849 but collapsed under heavy winds in 1854. At the time the bridge was built the territory comprising what is now the State of West Virginia was still part of the Commonwealth of Virginia,
 R.M. Vogel, Roebling’s Delaware and Hudson Canal Aqueducts (Washington, D.C.: Smithsonian Institution Press, 1970).
 Brooke Hindle, “Spatial Thinking in the Bridge Era: John Augustus Roebling versus John Adolphus Etzler,” in Bridge to the Future: A Centennial Celebration of the Brooklyn Bridge, ed. Margaret Latimer, et al. (New York: The New York Academy of Sciences, 1984), 138.
 This interconnection was understood early on. In the late 1820s the business and political elite of Baltimore pushed for the construction of what became the Baltimore & Ohio Railroad, linking that city with the Ohio River, hoping to turn their metropolis into a point of departure for domestic trade. Other cities, such as Charleston, South Carolina and Louisville, Kentucky also clamored for railroads as did businesspeople in Boston. See Craig Miner, A Most Magnificent Machine: America Adopts the Railroad, 1825-1862 (Lawrence: University Press of Kansas, 2010), 1-18.
 Some have criticized Hegel as being reactionary toward the end of his life.
 Gostkowski, August 30, 2011; W.A. Roebling, “Early History of Saxonburg,” Butler County Historical Society, Butler PA, 1924, n.p.
 Roebling and his wife did not conduct correspondence regarding family matters.
 The more liberal Nominal GDP Per Capita calculator produces a conversion of $78 million in 2010$. For big projects like this, the higher number probably comes closer to approximating the real value of the project in the context of the times. Samuel H. Williamson, “Seven Ways to Compute the Relative Value of a U.S. Dollar Amount, 1774 to present,” MeasuringWorth, 2011, using Nominal GDP Per Capita.
 This was the first suspension bridge over the Niagara River.
 Ellet’s bridge-building career effectively ended in 1855 when the bridge he designed and built at Wheeling, Virginia (now West Virginia) collapsed. Ellet erected “a temporary single-line bridge” at the site that summer, but the bridge was eventually rebuilt in 1860 by William K. McComas. Kemp, 53,
 The anchorages and towers were already in place when work stopped. During the Civil War, Washington Roebling, an engineer in the Union army, tried to build a bridge using the towers and anchorages, but military and government red tape impeded his project, and nothing came of it.
 Steinman, 168-169.
 Steinman, 168.
 Cholera was a serious problem in the United States in the nineteenth century, but this seems to be the only time it affected a Roebling worksite.
 Roebling’s design of the Niagara Railroad Bridge differed from the Monongahela Bridge in the use of stiffening trusses to prevent swaying. The bridge, with a railroad track on the upper level and a regular roadway on the lower level, was 821 feet long and weighed approximately 1,000 tons. The levels were suspended using four cables of wrought iron wire, each ten inches in diameter with 3,640 wires per cable. In his initial report of the completed bridge Roebling presciently mentioned the use of steel cables, but in the United States steel cables lay in the future. It would be Roebling’s son, Washington, who would introduce their usage as chief engineer of the Brooklyn Bridge.
 Steinman, 230.
 The majority of Roebling’s construction projects were done in his home state of Pennsylvania. Two notable exceptions were the Covington-Cincinnati Bridge over the Ohio River and the Brooklyn Bridge.
 Roebling’s original bridge (made of wood and iron), with exception of the stone towers and original iron cables, was totally rebuilt by Wilhelm Hildenbrand in the 1890s. See J.F. Gastright, “Wilhelm Hildenbrand and the 1895 reconstruction of the Roebling suspension bridge,” Northern Kentucky Heritage, 2000.
 McCullough, 97.
 It was referred to officially as the New York and Brooklyn Bridge, though informally, even before construction began, people began referring to it as the Brooklyn Bridge. The name was made official in 1915.
 Steinman, 300.
 The more liberal Nominal GDP Per Capita calculator produces a conversion of $673 million in 2010$. Samuel H. Williamson, “Seven Ways to Compute the Relative Value of a U.S. Dollar Amount, 1774 to present,” MeasuringWorth, 2011, using Nominal GDP Per Capita.
 In this report, Roebling also predicted the construction of the Williamsburg Bridge.
 Steinman, 306.
 When adjusted for using the Gross Domestic Product (GDP) these costs seem even more amazing than the simple conversions. For example, the preliminary cost of the Brooklyn Bridge when using the 1867 GDP of the Unites States would translate to the equivalent $1.5 billion in 2010 currency.
 Charles B. Stuart, Lives and Works of Civil and Military Engineers of America (New York, NY: D. Van Nostrand, Publisher, 1871), 325, quoted in McCullough, 41.
 Roebling was a lifelong practitioner of hydropathy, the popular nineteenth-century regimen of imbibing large quantities of water and taking daily cold baths.
 Trachtenberg, 61-63. Roebling took an antislavery position almost from the time of his arrival in the United States, refusing to go along with a splinter group of immigrants who had traveled as part of his original group when they relocated first to South Carolina, then Alabama. See Steinman, 34.
 See McCollough, 99.