He worried about his mother, who was failing rapidly, and not the least of her troubles, his father wrote, was concern over his safety. He thought about the future, worried that he had forgotten everything he ever knew about engineering, puzzled over where he and Emily might settle once the war was over. He pondered the possibility of not following in his father’s footsteps. Trenton had no appeal, despite his father’s generous proposals. “The town is horribly dull,” he told her, “and I always get tired of it after being there a week.” When he daydreamed of home, it was nearly always of Saxonburg. “I have now more lasting memories of the first eight years of my life there, than I have of the intervening twenty,” he wrote. But there could be no going back to Saxonburg.
He grew a beard, changed the way he combed his hair to suit her, adopted two stray dogs, a family of kittens, a lizard, and took to sleeping with the blanket pulled over his face to keep off the flies, his feet sticking out at the bottom, a pose that inspired a fellow officer to do a pencil sketch, which Roebling included in one of his letters to Emily. In another letter, he told her, “I have been solacing myself all evening by playing on a fiddle, had a great time getting it, borrowed a bow from another man and stole the rosin from a sick horse; it did me good and so I played until the tips of my fingers began to ache…”
In November of 1864 his mother died and he hurried back to Trenton for the funeral; “…the greatest giver of us all [is] gone,” he told Emily. Then, at the end of the year, the war, for him, was over. He was commissioned lieutenant colonel, by brevet, as of December 6, for gallant conduct during the campaign before Richmond. By Christmas he was home to stay. In January, at Cold Spring, New York, he and Emily were married.
They lived in Trenton at first and he went back to the wire mill. But that lasted only a few months. In the early spring of 1865, just before the war ended, he left for Cincinnati to join his father on the Ohio River bridge and once he found a place to live, she came on. By the time the bridge was completely finished, they had spent nearly two years in Cincinnati, and his father had been back in Trenton the better part of that time.
In early 1867, when it appeared that the East River bridge at last had some serious support, his father had written to say he wanted him to go to Europe the following summer to make a study of pneumatic caissons, that Emily ought to go too, and that he would pay all their expenses. “Your kind offer…I accept with pleasure,” Washington Roebling wrote in answer; “Emily is especially delighted, to her the idea of going to Europe is something exceedingly grand.”
They sailed at the end of June, when Emily was a few months’ pregnant. They were in England for a number of weeks, then France later, and Germany, where the baby was born. In London they visited St. Paul’s, Parliament, Westminster, the Zoological Gardens. From their window at the Royal Hotel, he had watched construction of the Blackfriars Bridge and made a drawing of it to send his father.
He made flying visits to Telford’s bridge over the Menai Strait and Brunel’s bridge at Clifton, for a long time considered the most beautiful suspension bridge in the world. He did not think Telford’s towers very handsome, he wrote to John Roebling. The floor, very light in weight, had no strengthening truss. There was a stiff breeze blowing as he walked out on it and the vibrations were very strongly felt, he said. The towers for the Clifton Bridge he called remarkably ugly.
They visited Manchester and he spent several days looking over the noted steelworks of Richard Johnson & Nephew, where the wire for the Cincinnati Bridge had been made. They went to Birmingham, Sheffield, Newcastle, then on to Paris to see the Exposition, but left after a week because they were running low on money. One lady costs twice as much in Paris as two men, he explained to his father. The fair was considered the greatest international exhibition ever and among the American Commissioners was his Trenton neighbor and competitor in the wire business, Abram Hewitt. But Roebling thought little of the fair, nothing but “a great advertising show,” he said.
At Essen, Germany, to his astonishment, he was given the grand tour of the Krupp works, as though he were visiting nobility. On first arriving in Essen he had been told by several townspeople that an outsider had virtually no chance of visiting the works. He had spent one long night drinking wine with some of the young engineers employed there, hoping to win a friend who would open a few doors, but he had received only long faces whenever he mentioned the subject. Finally, figuring he had nothing to lose, he went directly to the main office, expecting to get nowhere and finding instead that they were eagerly awaiting his arrival. The management, he discovered, was well aware of the forthcoming East River bridge, knew all about his trip to Europe, and had already made up a sample eyebar for his personal inspection.
In all three countries he talked to bridgebuilders, wire manufacturers, visited iron works, filled his notebooks and letters with tens of thousands of words and hundreds of tiny freehand drawings and diagrams. He had an almost uncanny gift for observation and could commit vast quantities of information to memory, yet he never gave any sign of making a special effort along those lines. He would walk about a construction site or through a mill listening politely to his host, paying, it would appear, only the most casual attention to what he was being shown. Then he would return to a hotel room and write down a full description of what he had seen, with the most extraordinary memory for detail and great critical analysis.
After his return from Europe, for instance, while stopping over in Pittsburgh, he was invited to take a walk through Andrew Carnegie’s new Keystone Bridge works and that night, in private, at the Monongahela House, he had written his father a complete report of the entire Keystone operation, describing the different machines in use and how they worked, the production patterns followed, the personnel involved, the various products turned out and his opinion on their relative merits. The letter went on for pages, even in his minute hand, and it was all put down directly, with no apparent hesitation, no erasures or editing, and, apparently, with no special effort. At the close, after remarking that he found Carnegie and his brother “very pleasant people,” he told his father, “I could fill another letter of 20 pages to describe all I saw—still I keep it all in mind.”
The value of such a son was not lost on the father, and as the young man made his way across Europe, he sent off one letter after another, each taken up almost entirely with technical matters—on wiremaking, on the latest developments in metallurgy, Bessemer steel making in particular, and on caissons, which he spelled “cassoons” for some reason—and everything was set forth with the sort of clarity and thoroughness demanded by the exacting mind back in Trenton. By the time he and Emily and the baby were on their way home across the Atlantic in March of 1868, he knew more on the subject of pneumatic caissons than any American engineer.
The success of the bridge at Brooklyn, he and his father knew, would depend on the caissons. Everything hung on their success. If they could be sunk beneath the river properly and to the required depths—and they would have to be bigger by far than any caissons ever constructed before—then there seemed little doubt that the bridge could be built. If not, there would be no bridge, or at least not the one John Roebling had described with such persuasive language in the fall of 1867, when, as it happens, his son was still in Europe trying to determine just how the thing could best be done.
After returning home, Roebling busied himself at the Trenton mill, waiting for the New York politicians to settle their affairs. In 1868 his father finished the basic plans for the caisson, while he made another long tour at his father’s request, this time through the hard-coal regions of eastern Pennsylvania to see how wire rope could be used in mining operations. He and Emily were staying in the big house temporarily. His father had remarried. Ferdinand too was married by this time. Laura came visiting from Staten Island with her children. By fall the baby was walking.
When the word came from Brooklyn that the bridge was all set to go, he and Emily packed up and moved to the house on Hick
s Street.
In the months immediately following his father’s death, Roebling spent much of his time away from Brooklyn. He made repeated trips to Trenton, where he had his father’s estate to settle, as well as the wire business to look after. There were long family gatherings in the big house. It was agreed that Ferdinand would take charge of the business eventually and that Charles would come in with him as soon as he finished at Troy. But for the time being Washington would make the major decisions. Nobody foresaw any problems with that, but not very long afterward, at a time when Washington was having troubles enough in Brooklyn, a full-scale family fight developed over what to do about Charles Swan. Ferdinand did not want Swan made a partner, as his father had requested in his will. Washington said he should be. Swan quit and went off somewhere, leaving no word behind; plainly furious. But things were patched up eventually and Swan returned to work, on generous financial terms, but not as a partner.
It was also agreed, after some difference of opinion, that Washington was to be Eddie’s guardian. Roebling felt he had more than enough to cope with as things were, building his father’s bridge and looking after his own small family, without trying to be the father his father had never been to his troubled little brother. But the others felt differently, it appears, and so Eddie was packed off to Brooklyn, where Emily had a room prepared for him.
For Roebling, there was still more traveling to be done. He spent a day with Horatio Allen in Port Chester looking at dredging gear. He went to Albany to look at the black limestone and granite going into the foundations of the new state capitol, which had been engineered by William Jarvis McAlpine. He stopped at Kingston to visit a limestone quarry and to talk to the people there. He filled his small black leather notebook with pages of names, addresses, and reminders. “Find out where they get the broken stone at the Post Office…. Find out all about calcium light…. Find out who makes derrick forgings.” He went to Niantic, Connecticut, to look at granite and to Hallowell, Maine, to inspect the quarries of J. R. Bodwell. The infamous Tombs prison had been built of Bodwell’s stone, as had the coping of the huge new reservoir in Central Park, some of which had been built by William C. Kingsley. The quality of the granite, Roebling wrote in his notebook, was “very fine, very durable…the whitest granite known.”
His most vital concern, however, was the first giant caisson. In mid-August, immediately after Collingwood reported for work, Roebling had handed him rough drawings and a long written account of what was wanted, and Collingwood, Paine, and Hildenbrand had set to work on final plans, figured down to the last inch. The only one who could handle such an order, it was decided, was a shipbuilder, and on October 25, 1869, the contract was awarded to the firm of Webb & Bell, whose yards were up the river at Green-point. And if a date were to be picked to mark the beginning of the building of the bridge, it probably ought to be that one.
The caissons were the foundations of the great work, quite literally and figuratively, as everyone working with Roebling in Brooklyn was aware. There were also some among them who appreciated something that would be overlooked by most everyone as time passed—that it was Washington Roebling, more than his father, who was the closest thing to an expert on caissons and who had concentrated on how that part of the job ought to be handled. And perhaps this helped compensate some for the very obvious fact that he had never actually worked with a caisson before and that there were only two or three American engineers who had, McAlpine being one of them. In St. Louis Captain James B. Eads had just completed the first caisson for his bridge over the Mississippi. Still, to all but a handful of engineers, even the word “caisson” was unfamiliar.
With absolute, unqualified conviction John A. Roebling had proclaimed that his bridge would be the greatest in existence, the greatest engineering work of the age. All his son had to do now was build it.
PART TWO
8
All According to Plan
The foundations for the support of these large masses of masonry must be unyielding.
—JOHN A. ROBELING
THE EASIEST way to explain how the caisson would work, Roebling and his assistants found, was to describe it as a huge diving bell that would be built of wood and iron, shaped like a gigantic box, with a heavy roof, strong sides, and no bottom. Filled with compressed air, it would be sent to the bottom of the river by building up layers of stone on its roof. The compressed air would keep the river out, help support the box against the pressure of water and mud, and make it possible for men to go down inside to dig out the riverbed. As they progressed and as more stone was added, the box would sink slowly, steadily, deeper and deeper, until it hit a firm footing. Then the excavation could stop, the interior of the box would be filled in solid with concrete, and that would be the foundation for the bridge tower.
The idea was quite simple really. Furthermore, it had been used successfully in Europe for more than a generation, first in France, where the word “caisson,” meaning “chest,” had originated, then later in England and Germany. An air lock that enabled workers to get in and out of a sealed chamber filled with compressed air had been devised as early as 1831 by Lord Thomas Cochrane, the controversial British admiral, and in 1851 a pneumatic caisson had been used on a bridge foundation for the first time, for piers in the Medway River at Rochester, England. Seven years after that Brunel had taken a caisson down more than seventy feet to build a pier for his last and greatest railroad bridge, the Royal Albert over the Tamar at Saltash, Cornwall.
But the caisson Roebling intended to sink beneath the East River on the Brooklyn side would be bigger by far than anything used in Europe or the few that had been used in the United States, and the one for the New York tower, it was then thought, would have to go thirty to forty feet deeper than even Brunel had gone.
The caisson the Roeblings had designed, and which in the late fall of 1869 began slowly to take shape at the Webb & Bell yards, was to be built like a fort and launched like a ship. A gigantic rectangular box, 168 feet long and 102 feet wide, it was to have nine and a half feet of headroom inside and overhead a roof of solid timbers five feet thick, bringing the total height of the box to fourteen and a half feet. In area it would be more than half the size of a city block, more than half the size of the new St. Patrick’s Cathedral, for example. The sides of the box were to be V-shaped, being nine feet thick where they joined the roof and tapering to a bottom cutting edge of just eight inches. The inside slope of the V would be at an angle of about forty-five degrees and the entire cutting edge, or “shoe,” would be shod with a heavy iron casting and sheathed the whole way around with boiler plate extending up three feet, inside and out. A heavy oak sill two feet square would rest on the casting.
Driftbolts, screw bolts, and wood-screw bolts would be used to secure the whole immense mass. The V-shaped sides would be fixed to the roof with heavy angle irons. At the corners, timber courses would be halved into each other and strapped together. The roof itself would be built of five solid courses of yellow pine “sticks”—timbers a foot square—laid up side by side and bolted both sideways and vertically.
To make the box airtight the seams would be caulked with oakum to a depth of six inches, inside and out, and between the fourth and fifth courses of roof timber, across the entire top of the structure and extending down all four sides, a vast sheet of tin would be put down. The tin on the outside would be further protected by a sheathing of yellow pine and the spaces between timbers would be filled with hot pitch.
Since Roebling had learned that air under pressure of forty or fifty pounds (or about what would be needed inside the work chamber) will readily penetrate ordinary wood, he had selected a yellow pine from Georgia and Florida that was so pitchy that the 12-by-12 sticks would not even float. And finally, just to be sure, he planned to coat the whole inside with a specially concocted, supposedly airtight varnish.
Once the caisson was launched, ten additional courses of timber would be added to the roof, thereby making it a solid timber
platform fifteen feet thick, which would act like a colossal wooden beam for carrying and distributing the load of the tower.
As the work at Webb & Bell progressed on the raw and ungainlylooking structure, two air locks, two so-called supply shafts, and two water shafts were being built into the timber roof.
The air locks were made of half-inch boiler plate. They were cylindrical in shape, seven feet high by six and a half feet in diameter, or big enough to pack in about a dozen men, who would enter from the top, through an iron hatch about the size of a manhole cover. The hatch closed, an attendant stationed inside would open a valve near his feet, releasing compressed air from the work chamber below into the lock. As soon as a gauge on the wall of the lock showed the pressure there equal to that below, another hatch in the floor would be opened and the men, one by one, would climb down a ladder through an iron shaft, three a half feet in diameter, into the caisson itself.
When it was time to come out, the process would be reversed. They would climb up the shaft and into the air lock, the floor hatch would be secured, and another valve would be opened to release the air from the lock. When pressure in the lock decreased to normal atmospheric pressure, or 14.7 pounds per square inch, then the top hatch would be opened and the men would climb out. This way the loss of compressed air from the caisson each time a gang of men went in or out was no more than the volume of the lock.
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