The Great Bridge (24 page)
Once the old dockwork was out of the way, a large basin was to be built to contain the caisson, open toward the river but bounded on three sides with new piling. Within this area the riverbed was to be dredged to a uniform depth of eighteen feet at high tide, or deep enough to keep the caisson afloat at all stages of the tide. The dredges made great headway at first, as long as there was only surface mud to contend with, but then they hit hardpan and boulders. “The character of this material was next to solid rock,” Roebling wrote. The dredges could make but the slightest impression upon it. “Recourse was necessarily had to powder,” and the blasting commenced at night, from about seven in the evening until daylight, when traffic was light on the river and few people were about the ferry slip. Holes were driven into the river bottom with steel-headed iron piles. Then blasting charges were packed into iron canisters and dropped into the holes by professional divers. When the divers were out of the way and the pile drivers hauled back to a safe distance, the charges were set off by electricity.
Three pile drivers were kept in action, and with a little practice the men had the work down to a neat system, setting off some thirty-five blasts every ten-hour shift. During the day the dredges moved in and cleared out the results of the night’s work.
A number of the boulders encountered were too large to be picked up by a dredge and had to be dragged clear—the divers assisting underwater. The whole process was about six times as expensive as normal dredging, but still quite effective, and it provided valuable knowledge of the ground the caisson would have to penetrate. On one side, for example, near the new piling, a dozen blows of the pile driver would sink an iron pile forty feet through soft clay, but in the center area it took a hundred blows to go three feet. Toward the ferry the clay gave way to boulders of all sizes, closely packed, with coarse sand in between, and at the open end of the basin, on the river side, all soft strata had been washed away, leaving hardpan.
As time passed, Roebling decided to concentrate the dredging along the lines of the caisson’s edges and frames; the parts in between could be removed later, he said, from inside the caisson. He also had two holes blasted to an extra depth to accommodate the water shafts.
The work went slowly now, and while the blasting and dredging provided valuable knowledge of the riverbed, that knowledge itself was a most sobering reminder of the magnitude of what they were undertaking. To sink a wooden box as big as a fair-sized railroad station straight down through such material, and underwater, keeping the thing absolutely level the whole time, and bringing it to rest finally—perhaps fifty feet down—and at the exact spot it was meant to be, was a very tall order indeed. And added to that, along toward the end of January, reports began coming in from St. Louis of a strange malady among the men working inside the Eads caisson.
James Buchanan Eads was an authentic American genius and one of the looming figures of the nineteenth century. Slim, leathery, highly opinionated, disliked by many, he had survived an extraordinary life on the Mississippi that had included a lucrative underwater salvage business, a financially disastrous attempt at glass manufacturing, and the building of a fleet of ironclad gunboats during the Civil War. These slow, squat, ugly warships, built before the
Monitor
or the
Merrimac
and nicknamed “the Turtles,” had played a decisive part in defeating the Confederates on the Mississippi, along with the rams built by Charles Ellet. Eads had not designed the ships himself, nor had he gone into battle with them as Ellet had with his rams, but he had organized everything, having timber cut in Minnesota and Michigan, iron armor rolled at St. Louis and Louisville, keeping four thousand men at work on a night-and-day basis, and financing much of the operation out of his own pocket. At the time Washington Roebling was distinguishing himself on Little Round Top, Eads’s gunboats were assisting Grant in the successful siege of Vicksburg.
In early 1870 Eads was approaching fifty. He was the sort of person who liked to play chess with two or three others at a time, and in a recent weight-lifting contest among some of his blacksmiths, he had come in second.
During his years in the salvage business Eads had worked with diving bells up and down the Mississippi and was said to know more than any man alive about the river’s treacherous currents and the character of its bottom. This had been an important factor when he presented St. Louis and New York financial backers with his radical proposal for a bridge over the Mississippi. But it was his unbridled self-confidence and his reputation as a man who could get things done that mattered most in the end. He managed to convince men who had worked with the country’s foremost engineers that he, James B. Eads, was the one man fit to bridge the Mississippi at St. Louis, that the bridge he wanted to build was the only answer, and this despite the very well-known facts that he had had no formal training as an engineer and that he had never once built a bridge before. Both Charles Ellet and John A. Roebling had prepared plans for suspension bridges at St. Louis back in the 1850’s. Later, the year before he died, Roebling had done an entirely new set of plans, combining both suspension cables and parabolic arches. But Ellet’s and Roebling’s ideas had been turned down. (The St. Louis people were fools, John Roebling wrote to his son.) Now Eads and his bridge were the talk of St. Louis.
The great need was for a bridge to carry a railroad and highway over the river without interfering with steamboat traffic. The Mississippi at St. Louis is about the same width as the East River. Instead of a heavy iron truss, the customary thing then for railroad crossings, or a suspension bridge, Eads had conceived a mammoth arched bridge, with arches of steel set on stone piers. He intended to span the river with just three of his steel arches, the biggest of which, the center span, would be longer than any arch of the time by several hundred feet. To avoid interfering with river traffic during construction, his assistant, an engineer named Henry Flad, had devised a cantilever system nobody had tried before. The halves of each arch would be built out toward one another from their respective stone foundations, like great jaws slowly closing over the river, which was the conventional way, except that here the temporary supports needed (until the jaws joined) would be supplied from
above.
The usual practice was to prop such arches up from below with temporary timber “falsework” that could be torn out once the bridge was finished. But since this would be impossible, obviously, if the river was to be kept clear, Eads would hang the arches from overhead cables attached to temporary wooden towers built above each of his stone piers.
So the design of the bridge, the material he intended to build it with, the way he planned to build it, just about everything about the bridge, was unorthodox and untried. And when he had first proposed it, Andrew Carnegie had decided that somebody who knew about things mechanical, as he said, had better look over the plans.
Carnegie’s interest in the bridge was twofold. He had been approached by Eads’s St. Louis backers to see if he might be interested in selling some of their bridge bonds. Also, it was a few years before this that he had organized his Keystone Bridge Company, one of the first to specialize in manufacturing iron railroad bridges. Carnegie enjoyed talking about his love of bridges. Like Thomas Pope and John Roebling he saw them, he said, as testimonials to the national spirit and professed great personal satisfaction in the part he played in building them.
The Keystone company was now being invited to come in on the St. Louis job as consultants and to handle the superstructure. So Carnegie, quite sensibly, asked for an opinion on the bridge from Keystone’s chief engineer and president, J. H. Linville, whom Carnegie described with customary enthusiasm as “the one man in the United States who knew the subject best.” This was an overstatement, but Linville was certainly among the finest men in engineering. He had been bridge engineer for the Pennsylvania Railroad before Carnegie hired him and the huge iron truss he had built over the Ohio at Steubenville in 1864 was considered the outstanding structure of its kind.
Linville asked that a set of Eads’s plans be sent to him. He examined them carefully, then, a little like the paleontologists who had been asked to give an opinion on the Cardiff Giant, he solemnly declared the subject preposterous. “The bridge if built upon these plans will not stand up; it will not carry its own weight,” he told Carnegie in private, and presently, in a formal statement, he called the bridge “entirely unsafe and impracticable” and said any association with it on his own part would imperil his reputation and was therefore out of the question.
Linville was quite wrong and Carnegie, who knew nothing about engineering, urged Linville to lead Eads “into the straight path.” Eads, however, was not about to be dissuaded or to have any outsider, regardless of reputation or connections, begin doctoring his bridge. In the end he would convince even Linville that he knew what he was doing. The Keystone company went to work on the bridge; Carnegie went off to London to sell a block of bonds to the American financier Junius Morgan, father of J. P. Morgan; and by the summer of 1867 Eads was confidently proceeding with the preparatory work for the first abutment beside the St. Louis waterfront. In neighboring saloons it was said that the bridge would take seven million dollars to build—and seven million years.
As things turned out the final cost would come to something near ten million, and seven years would go by before the job was completed. Once in use the bridge would be acclaimed by everyone, and by engineers especially. As one engineering historian would write, the bridge was “an achievement out of all proportion to its size,” something Washington Roebling thoroughly appreciated at the time Eads came over to visit the Webb & Bell yards.
Like every bridge engineer and every railroad official in the country, Roebling was keenly interested in the St. Louis bridge, but since Eads, along with everything else in his radical scheme, also planned to sink his piers by means of pneumatic caissons, Roebling perhaps more than anyone appreciated the full daring of the man and the tremendous importance of what he was attempting, not just to his own work at Brooklyn but to the whole future of bridge engineering.
When he first envisioned his bridge, Eads had originally planned to use coffer-dams to sink the two midriver stone piers upon which his great steel arches were to rest. But in April of 1869, he had returned from a trip to Europe, convinced he had a better answer. He had seen the French engineer Moreaux use a pneumatic caisson to sink piers for a bridge over the Allier River at Vichy and he came home full of faith in the technique and sure he could make it work at St. Louis, even though the Mississippi, as he knew better than anyone, was not the gentle Allier.
So through that summer of 1869 Eads and Roebling had been devising their own separate plans for the foundations of the two biggest, most important bridges of the age, each man working quite independently and with only his own judgment to go by. Eads, however, had his caisson in the water by mid-October, before the contract with Webb & Bell had even been signed, and by the time Eads arrived in Brooklyn, his caisson was already well on its way into the sandy bed of the Missssippi.
Of the two, Roebling was unquestionably the better educated on the development of caissons in Europe and the various ways they had been used. Eads had happened onto the technique almost by chance and took about the least time possible to educate himself. Roebling’s father had incorporated caissons in his plans from the start, knew much on the subject, and Roebling himself had taken great pains in his studies, spending close to a year in Europe for that specific purpose. Furthermore, unlike Eads, Roebling was a trained, experienced bridge engineer and was fluent in both French and German. Eads, who spoke only English, had had a difficult time conversing with some of the European engineers he met.
Still and all, Roebling doubtless appreciated that Eads was a man with a most uncommon gift for solving problems, a man of extraordinary originality and determination, a man, in fact, very much like his own father. Roebling also knew that what Eads was up against at St. Louis was far closer to his own situation in Brooklyn than anything the Europeans or McAlpine or anyone else had ever had to cope with. And most important, Eads, unlike Roebling, now had some working experience with caissons.
The caisson Eads had in operation was only about one-third the size of what Roebling was having built in Brooklyn, still it was bigger than any used by the Europeans. More significantly, by January 1870, the Eads caisson was already as deep as Roebling expected he would have to go on the Brooklyn side, and it was still descending steadily through Mississippi sand and mud that offered almost no resistance. By the end of January the trouble had begun.
From the very first Eads’s men had noticed certain peculiarities about working in the heavy atmosphere of the caisson. The most manly voices had a thin girlish sound, for example. It was impossible to whistle or to blow out a candle, as the men gladly demonstrated for the many visitors Eads liked to bring down. Some of the men mentioned a notable increase in their appetites. Others talked of trouble breathing or of a painful ringing in the ears. But by the time they were down forty feet there had been several clear cases of the mysterious sickness, a subject Eads and Roebling had both heard something about in Europe.
As early as 1664 an English doctor named Henshaw had published an essay proposing, ironically enough, that compressed air be used as a method of treating a variety of common disorders. In France and Germany, institutions sprang up offering the latest facilities for just such atmospheric treatment. Compressed-air “baths” were claimed to work miraculous cures and became something of a fashion, and particularly for curing indigestion. But the pressure in such baths was never much greater than normal.