10

Fire

When the perfected East River bridge shall permanently and uninterruptedly connect the two cities, the daily thousands who cross it will consider it a sort of natural and inevitable phenomenon, such as the rising and setting of the sun, and they will unconsciously overlook the preliminary difficulties surmounted before the structure spanned the stream, and will perhaps undervalue the indomitable courage, the absolute faith, the consummate genius which assured the engineer’s triumph.

—THOMAS KINSELLA, in
The Brooklyn Eagle

A SECOND contract was signed that October with Webb & Bell to build the New York caisson, according to plans drawn up during the summer. This time the caisson would be slightly larger and there were to be a number of important modifications. Roebling had decided to make the water shafts round instead of square, for example; he wanted the air locks positioned differently; and the entire interior would be lined with boiler plate, as fire protection, Roebling having realized by this time how very inadequate were the preventive measures he had specified in the Brooklyn caisson. With a caisson that might have to go twice the depth of the Brooklyn caisson, he wanted none of the anxieties there had been over fire.

In November actual construction of the New York caisson got under way at Webb & Bell yards on the other side of the river, while the Brooklyn caisson continued steadily downward. Things were proceeding very nicely now. In the middle of the month Harper’s Weekly published a spectacular double-page view of lower New York and Brooklyn, as though seen from the air (“an unprecedented piece of engraving”), and there, bestriding the East River, bigger and grander by far than anything in sight, was the finished bridge. “This bold and peculiarly American design is not yet wholly beyond the scope of debate,” wrote the editors, whose offices on Pearl Street looked out on the spot where the New York tower would stand. But the beautiful engraved view, placed in the magazine so it could be easily removed and saved by the reader, suggested quite clearly, if their words did not, that they had every confidence in successful results. And for the technical community, Scientific American announced about the same time that “the rapidity with which the work has proceeded is evidence that it is conducted by a man who is fully competent to conduct this greatest engineering feat of modern times,” implying, it would seem, that there had been some doubts about that.

By the end of the month the Brooklyn caisson had reached a depth of almost forty-three feet, or very nearly as far as it would have to go. Another two feet, maybe even less, another ten days would do it, Roebling told the others. In the drafting room, plans were being drawn up for brick piers, ten feet square, that he had decided to build throughout the interior of the caisson, once it was at rest, to provide absolutely solid support for the mounting load overhead during the time it would take to fill the vast chambers with concrete. An order had already been placed for a quarter of a million bricks.

So the end of this first momentous step seemed very near indeed, when, on the morning of Friday, December 2, about the time most people were on their way to work, the news swept through Brooklyn that the caisson was on fire.

The fire had been discovered about nine thirty the previous evening. It had started several hours before that, as near as anyone could judge, in a seam where the frame between chambers No. 1 and No. 2 joined the roof. Every other seam in the roof had long since been pointed with cement, but this one for some unknown reason had been overlooked and the highly inflammable oakum caulking put in when the caisson was being built had been left exposed. In chamber No. 2, just below the place where the fire was discovered, a workman named McDonald had nailed a wooden box about head high, where he evidently stored his dinner pail, and during the change of shifts at three, in order to see into the box, he must have held his candle against the seam just long enough to start the oakum burning.

There had been four or five fires in the caisson before this one, in the summer when the men were still unfamiliar with working in compressed air. But none of those early fires had amounted to very much. They had been put out quickly by the men themselves, without any help from the fire department, or any public knowledge that they had ever happened. The pressure then was still comparatively mild and there was still plenty of river water in the chambers to drown fires with. But the need for extreme caution in such an oxygen-charged atmosphere had been pretty clearly demonstrated, and particularly if one imagined the same thing happening when the caisson got down to a depth where the river would be sealed out. Roebling wanted no chances taken. In the time since, he had had steam pipes introduced, as well as fire extinguishers and a couple of hoses that could throw an inch-and-a-half stream at sixty-five pounds of pressure. Two men had also been assigned to do nothing but watch over all the lights.

Because the fire began directly above the frame, it had remained undetected until the frame itself had burned through near the roof. But once it was discovered, there was a sudden, loud panic among the eighty men inside the caisson at the time. Tools were thrown down, wheelbarrows were overturned in a rush for the ladders. But that had ended quickly enough. Charles Young, the foreman, got the men under control. Nobody left the caisson and Young ordered some of the men to start packing wet clothes, rags, and mud into the cavity where the fire was burning to shut off the draft of compressed air as much as possible.

The charred opening of the cavity was only about as big as a fist, but inside it looked to be about seven feet long and maybe a foot or more wide and it was all a mass of flame. Men tried throwing buckets of water up into it. Then steam was turned into it for fifteen or twenty minutes. The fire extinguishers were tried after that: two big cylinders of carbon dioxide under several hundred pounds of pressure were discharged into the fire in an effort to smother it. But none of this had any noticeable effect. The instant the steam or the fire extinguishers were turned off the timbers would ignite again.

About ten o’clock, or half an hour after the fire was discovered, Roebling was sent for, and by the time he had come down through the air lock, the hoses had been put into service and were enough to extinguish all the fire, or at least all anyone was able to see. Still, as Roebling noticed immediately, a violent draft of compressed air was rushing through the aperture. He had most of it stopped with cement, but kept the water steadily playing into it for the next two hours, the force of the water being greatly enhanced by the draft.

In the meantime, Farrington, the master mechanic, had also been sent for and Roebling put him to work drilling holes into the roof to see how far the fire had penetrated. Several holes bored up to two feet showed no signs of fire. Others were then bored a foot deeper and they too showed nothing. But this work went terribly slowly and the tension for everyone was agonizing. Time was lost lengthening out augers, as Roebling told the story later, and the draft carried the chips up into each hole as it was being drilled. There was also the anxiety of knowing that every new hole meant the introduction of another draft of compressed air into the yellow pine and even a small draft of such air, they all realized, would have about the same effect on smoldering wood as a huge bellows.

It was a strange, unnatural kind of fire they were fighting. There was no flame to be seen now and in the dense atmosphere of the caisson, charged already with lamp smoke and blasting powder, it was impossible to see or to smell whether the cavity was smoking. There was no telling either what damage was being done out of sight, or to what depths the compressed air might force the fire into the fifteen layers of timber overhead, in just the way a great weight might force a spike into wood.

Roebling worked feverishly with a few hand-picked men; the rest he had get back to their regular duties. He did not intend to lose a night’s work unless he absolutely had to. His own efforts for the next several hours would be described as “almost superhuman” by those who were there.

The question of flooding the caisson came up. To put the fire out some less drastic, simpler way would be immensely preferable, Roebling said, but if they were to find that the fire was not out, as it appeared to be, then, he said, it was only a matter of time until the entire foundation would be destroyed. The fire would eat through the immense pine roof like a hidden cancer, destroying one course of timber after another, until the structure was so weakened that the vast weight overhead (now about 28,000 tons, Roebling calculated) would come crashing through.

The problem with flooding, however, was comparable to that of a blowout. Even if water could be substituted for the compressed air as rapidly as the compressed air was allowed to escape, the caisson would lose a considerable, perhaps vital, part of its support. During one of the earlier fires the river had been allowed to rush under the shoe as air was released and a uniform pressure had been maintained until the fire was out. Moreover, the load being borne then was quite light, comparatively speaking. But now the water would have to be poured down the water shafts from above. The supply might be limited, more than likely it would be variable, and so there was a chance the air might get out before the water reached the roof. In that event, of course, the caisson and all it carried would drop suddenly and the blow would probably be enough to destroy all supports.

To compound the problem, one water shaft was resting on several boulders at that particular moment. It had been capped above earlier, drained, and a gang of men were busy that same night digging the boulders out. But if the caisson were to be flooded immediately and settled abruptly as a result, even if only a foot or so, the water shaft would smash down on the boulders with such force as to wrench it permanently out of kilter. And this, quite likely, would leave the caisson leaking so badly that it could never be inflated again.

About three in the morning, water began to drip from the charred seam for the first time, suggesting that the compressed air had driven water into every possible crevice above, that the timber was now totally saturated for fifteen feet up, and that the fire was at last out.

Roebling was so exhausted he could barely stand. He had been in the caisson much of the previous day and had gone home that evening completely played out. The air was also bothering him a good deal. The men now urged him to leave. Then, about five o’clock in the morning, having decided that the fire was out, he had what appears to have been an almost total physical collapse. The accounts there are do not say exactly what his condition was, only that he had to be helped up through the air lock.

Apparently the sharp night air revived him some at first, but then suddenly he felt the beginnings of paralysis. In a matter of minutes he was unable to stand or walk. Nearby, Charles Young, the foreman, who had also been carried up through the lock about the same time, was in an equally bad state.

Roebling was driven directly home in a carriage just as it was turning light. For the next three hours he was rubbed vigorously all over with a solution of salt and whiskey. It was the best way to restore circulation they believed. He was conscious the whole time and he was in no pain apparently. After a bit, with a little help, he was able to get up and walk about, but he was very weak.

At eight, or thereabouts, a man was at the front door with a message. Fire had been discovered again deep in the caisson roof. Roebling dressed and returned immediately to the caisson.

He was down only a few minutes this time. The carpenters had drilled four feet into the overhead timbers and discovered that the whole fourth course of pine was a mass of living coals. The caisson would have to be flooded, Roebling said. It was a last-ditch decision and he made it on the spot, without any hesitation.

In his absence the men working on the boulders beneath the water shaft had succeeded in removing them, so that at least was one worry he could forget about. He ordered the men all up to the surface. An alarm was sounded in the yard and it was only a matter of minutes after he himself had come up out of the air lock that fire engines were clanging through Brooklyn toward the river with hundreds of people chasing after them.

The time was just about nine. Rumors were everywhere. People were saying there had been a terrible explosion beneath the river, that the caisson had been ripped apart, that half the men had been killed and the rest were still trapped below. At the ferry slip, along Fulton Street, Water and Dock, noisy crowds gathered, everybody trying to find out what was happening and nobody able to see very much. The best view, as usual, was from one of the ferries. But hundreds of people worked their way right into the bridge yards, mingling among swarms of firemen who were rolling out hoses from what appeared to be every last fire engine in Brooklyn. On the river, a New York fireboat and two tugs were being brought up alongside the caisson.

“The crowd dispersed, re-gathered, looked here and peered down there to discover the dread destroyer,” the Eagle reported later in the day, “but to the general eye no fire was seen.”

Men, muddied by splashing liquid clay, dampened by the streams of bursting hose, made their difficult way over all obstacles, climbed upon the elevation whence the water shaft is accessible, and looked down, only to see the unrevealing surface of the column of muddy water, with which the shaft is filled. Others again, climbed upon the platform about the air lock, up and down in which the huge rubber pipes go, and in pursuit of knowledge under difficulties, climbed down as far as they might.

Before the morning was out it seemed the whole of Brooklyn had been down to the river’s edge. A double line of police was needed to keep back the crowd. “Everybody was there,” the Eagle said, “and there was considerable lively calculations going on. Persons in every walk of life wandered about the spot, Senators, merchants, laborers. To most of them the whole thing was a mystery.”

It was in truth the damnedest fire anyone could remember seeing. There was no flame, nothing to be seen burning, not even much smoke. In some respects the scene was more like that following a mine disaster, the trouble all concealed below, unexplained and out of reach, except here there was no anguish over human suffering, not even much indication that things were serious. Were it not for rumors and the anxious looks of a few officials, no one would know there was any particular trouble below. The idea that there was even a fire had to be taken pretty much on faith.

About the closest thing to real excitement the whole morning was the bursting of a hose that sent up a spectacular plume of spray “upon which the sunlight played,” said the Eagle, “forming a beautiful, clearly marked rainbow, with a fainter one reflected on the mist and spray from the streams.”

A grand total of thirty-eight streams were pouring into the water shafts by ten o’clock, eight from the fireboat, five from the tugs, the rest from fire engines, including two or three brought over on the ferry from New York. One tug alone was pumping eight thousand gallons a minute and estimates were that inside the caisson the water was rising across the entire interior about eighteen inches an hour. But even at this rate it would be another five hours anyway before the chambers were flooded to the top, and therefore it would be that long or longer until the water did any good, since the fire was all in the roof. So fire, fed by compressed air, would be eating through the timberwork with nothing to restrain it until at least three in the afternoon, which accounted for the “degree of anxiety” noted “on the faces of those familiar with the character of the works.”

This same reporter singled out William Kingsley standing “conspicuously above all the others” and wrote, “He appeared calm and collected and preserved well his equanimity, but a few words of conversation with him showed him to be anxious for the work.” Collingwood, who had not been in the caisson since the day before, was also interviewed and talked of the grave dangers involved with flooding it. Roebling, who remained on hand through the whole morning, would say only that he thought everything would turn out satisfactorily, but that naturally the work would now be delayed some.

By half past three the caisson was entirely filled with water. The compressed air had been replaced without any sudden loss of support. The total quantity of water required was 1,350,000 gallons, which if not quite enough to float a battleship of the day was fairly close to it.

A careful watch had been kept on the pressure gauges during the whole operation; when it appeared that the air was escaping too rapidly, the compressors were started up again. When the water got to within two feet of the roof, the valves used for releasing air were closed off and the balance of the air escaped slowly through leaks and two small pipes. At one point during this stage, pressure dropped suddenly and inexplicably from nineteen to ten pounds.

After the caisson was flooded, the water in the shafts was kept ten feet above tide level, where it stayed with only a little feeding, indicating how very watertight the caisson had become at forty-odd feet below the river.

Still, the prospects looked dim. That night George Templeton Strong, the noted diarist of the time, wrote, “Caisson of the East River bridge was severely damaged by fire yesterday. I don’t believe any man now living will cross that bridge.”

The caisson remained flooded for the next two days, during which time there was an inquiry conducted by the Brooklyn fire marshal. Some of the New York papers, on their editorial pages, questioned what sort of management had allowed such an accident to occur. The Herald said the damage done would cost $250,000. Incredibly, the World implied the fire had been an act of sabotage, that directly or indirectly, it had been the doing of someone connected with the ferry company. The Eagle ridiculed such speculation and worried about what effect the whole incident might have on the morale of the men who had to carry on with the work. But after the fire marshal’s hearing on Saturday, everyone calmed down considerably and it was pretty well concluded that much too much had been made of very little. Collingwood and Farrington both said they did not think the damage would run to more than five hundred dollars. Collingwood thought they had been set back two days at most. C. C. Martin said, “All that the fire has done is to burn little spaces between the beams, very probably very small ones which will not in that mass of timber affect the stability of the structure in the slightest.”

It was also reported by one of the assistant foremen that the man named McDonald, who supposedly started the whole thing, had not been seen or heard from since.

Roebling had testified separately earlier in the day. He was still feeling some paralysis, he said. He too thought the damage had been minor and reported that the caisson had settled only two inches during the flooding, which he said was less than the average daily rate of descent. He left no doubt at all that this highly precarious operation had been very successfully executed and would perhaps prove even beneficial to the caisson in the long run, since the timbers had been getting too dry.

Monday morning the air pressure was restored, the water pushed out in about six hours. It all ran out over the tops of the water shafts. When Roebling and the others went down inside, everything seemed to be in good order, beyond a few blocks crushed and some posts thrown over. The structure itself appeared tighter than before due to the swelling of the timbers.

The fire marshal went into the caisson a little later with C. C. Martin and reported that he watched Roebling and the others at work, checked things over, and said that if he had not been told differently, he would never have known there was any fire at all. There was not the least sign of fire below, he said, except through one small opening and he concurred that the damage had been very slight.

Work was resumed immediately. The brick piers, about a third of the way built by then, were finished in another two weeks and the caisson was lowered the final two feet to rest upon them.

The day before Christmas the men began filling the work chambers with concrete. To save time and cut the quantity of concrete needed by a third, the shoe of the caisson was allowed to sink into the ground three feet deeper than the average level of the caisson floor, which meant that headroom inside was reduced from nine and a half feet to six and a half feet.

The concrete consisted of one part Rosendale cement, two of sand, and four of a fine gravel from the Long Island beaches, where it had been washed perfectly clean by the surf. Outside the caisson the weather by now had turned so cold that the concrete had to be mixed below. So like the bricks for the piers, cement, sand, and gravel were all brought down through the supply shafts, which for some several weeks had been functioning quite flawlessly.

The shafts were iron tubes forty-five feet long and twenty-one inches in diameter, with doors at top and bottom. When the upper door was open, the lower door would be held shut by the pressure in the caisson and locked by two iron clamps worked by levers. Any material needed below would simply be dumped down the shaft and the upper door, which closed up, not down, would be pulled shut. Then compressed air would be allowed to enter the shaft from below, closing the upper door tighter still. As soon as the shaft was filled with compressed air, the lugs on the lower door would be removed, the door would fall open, the contents in the shaft would drop into the chamber. The system was fast, uncomplicated, and quite safe so long as the attendants responsible for it used their heads.

But it was only two weeks after the fire that again something went wrong. Every so often a load of bricks would get jammed in a supply shaft and the usual method of breaking the jam was to drop a weight down on a rope. But this time the men above decided instead to dump in a second load, then signaled for the men below to open the lower door while they neglected to close the upper door. The second load loosened the first, the two together landed on the lower door with a force greater than the air pressure against it from inside, and since the lugs on the door had been opened as directed from above, the door fell open.

Instantly there was an enormous, earsplitting rush of air out of the caisson. Stone and gravel shot from the shaft as if from a cannon. The men on the top dove for cover or fled as fast as their legs would carry them. Had any one of them had the least presence of mind, he could have closed the shaft instantly and had everything locked up tight quite simply by just reaching over and pulling at the rope connected to the upper door. It would have taken no effort whatever. The explosion of air from below would have slammed the door shut. But nobody did that.

Roebling was one of those trapped inside the caisson at the time. The noise, he said, was so deafening that no voice could be heard. Water was pouring in from the water shafts. The lights went out. The air, he said, was full of a dense, impenetrable mist. Men were stumbling all over one another, running in terror, smashing into pillars, tripping and falling in the pitch-darkness, nobody sure where he was going.

In an instant the water was up to their knees. The river had broken in, they all thought.

“I was in a remote part of the caisson at the time,” Roebling wrote, “half a minute elapsed before I realized what was occurring and had groped my way to the supply shaft, where the air was blowing out. Here I joined several firemen in scraping away the heaps of gravel and large stones lying under the shaft, which prevented the lower door from being closed.” It took from two to three minutes for them to clear the door. Then they had it shut and everything was all over. Fifteen minutes later the pressure was restored.

Roebling had kept his head under the most nightmarish conditions, and when nobody else had. He had analyzed the situation in an instant and moved swiftly to put a stop to it. In the eyes of many, it was as commendable a demonstration of cool command as anything he had done on a Civil War battlefield.

Later, in his formal report to the directors, he wrote:

The question naturally arises, what would have been the result if water had entered the caisson as rapidly as the air escaped? The experience here showed that the confusion, the darkness and other obstacles were sufficient to prevent the majority of the men from making their escape by the air-locks…Now it so happens that the supply shafts project two feet below the roof into the air chamber; as soon, therefore, as the water reaches the bottom of the shaft it will instantly rise in it, forming a column of balance and checking the further escape of air. The remaining two feet would form a breathing space sufficient for the men to live, and even if the rush of water were to reduce this space to one foot, there would be enough left to save all hands who retained sufficient presence of mind.

It is not known whether he had realized this before the supply shaft blew out.

Again, as after the “Great Blowout,” an examination was made to determine what effect the impact of sudden weight had had upon various internal supports and particularly on the new brick pillars. By the time Roebling and the others got the supply shaft door closed, pressure in the chamber had dropped from seventeen to four pounds. He reckoned, therefore, that for several minutes the weight on the pillars was twelve tons to the square foot. Still, they showed no signs of strain, which was the clearest demonstration possible of their capacity to bear up under the load they were designed for and proof certainly that Roebling had been right to put them in. More important, the subsoil beneath the pillars, on which the bridge was to bear, had also withstood this same tremendous pressure.

But Roebling would be granted precious little time to take pride in the way things were being handled. Work on the masonry above had stopped because of the weather. Eleven courses of stone had been laid up within a wooden cofferdam, the top of the stonework being about even with the river at high tide. But the people manning the dump carts were still about, along with a number of others who looked after this or that piece of equipment, and they had begun noticing a strong smell of turpentine that seemed to be coming from air bubbles being forced up through the caisson. Large deposits of frothy reddish-brown pyrolignic acid, or “wood vinegar,” as the men called it, had also been found, indicating, as Roebling said, “that a destructive distillation of wood had been going on.”

Acting on what he called very unpleasant suspicions, Roebling quietly ordered Farrington to start drilling into the roof again. About two hundred borings were made to determine for everyone’s satisfaction just how extensive was the internal damage from the fire.

Most of it seemed to be confined to the third and fourth courses of timber, as had been expected, but as nobody had imagined, it also extended out laterally in every direction, in some places as much as fifty feet, or about five times farther than anyone had judged earlier. Equally disturbing was the discovery that the compressed air was rushing out of every bore hole, which meant that any attempt to cut into the roof to make repairs would result in an enormous drain on pressure.

Roebling decided, however, that if the air chamber were filled in with concrete around the edges, the pressure might now be released entirely with no harm. He had decided, in other words, that he could trust the brick pillars to support everything. So if maintaining pressure was no longer the vital concern, then holes as large as need be could be cut overhead and the damaged areas seen to properly.

Still, as he wrote, “It was very desirable…to gain time and do as much as possible at once, while air pressure was yet on.” It would be necessary therefore to plug the boreholes and at the same time compensate somehow for the honeycomb of charred pine they all pictured overhead.

Accordingly cement grout was injected into all two hundred boreholes. It was no easy task and it took quite some time. Roebling had a cylinder and piston fixed to a quarter-inch pipe. The cylinder was filled with liquid cement, placed under a borehole, the pipe inserted, then the cement forced up the hole by a screw jack. The technique worked well for the most part. The cement could be forced a good ten feet into the timber and appeared to spread out laterally to some distance. But the moment it met any resistance, all the water would be squeezed out, and to budge the charge another inch became impossible. So a thinner mixture was tried and it was found that the suction of compressed air alone, through the holes, was enough to draw this up the pipe and into the timberwork.

By the time they were finished, six hundred cubic feet of cement had been pumped into the caisson roof. The leaks had been stopped and a number of new boreholes in the area of the trouble failed to reveal a single place without its own vein of hardened cement. “We already flattered ourselves that this filling might answer every purpose…” Roebling wrote.

But just to be sure, he had a great hole, six feet across, cut into the roof through five layers of timber, directly over the spot where the fire had originated. And by opening up the roof this way they discovered that they had been exceedingly proficient in their work and that it had been a great mistake. The cement had indeed filled every crack and crevice, but most of the timber beneath the cement was covered with a layer of soft, brittle charcoal, anywhere from one to three inches thick.

It was a crushing revelation. It meant that every last bit of the cement put in so laboriously would have to come out, and any charcoal there was would have to be found and scraped away. There was no other alternative Roebling said. The caisson roof, the timber platform upon which the bridge tower would stand, had to be absolutely, permanently solid. He could take no chances on that. He could no more let it go this way then he could launch a ship with rotten timbers.

The immense, painstaking job of restoration that followed took a force of eighteen carpenters three full months to complete, working night and day. It was like gigantic dentistry, as someone said. To say that the work was extremely disagreeable, as Roebling did in his report to the Board of Directors, was to greatly understate the situation.

Not until the cement was all chopped out did anyone realize the full extent of the fire. Instead of one opening into the roof, five had to be cut, slowly, laboriously, each one three to four feet square and five feet deep or more. Above the original opening it was found that the fire had not only turned the third and fourth courses of timber to charcoal, but it had burned right through the sheet tin between courses four and five, destroyed the fifth course and made a start on the sixth. To judge by the traces it left, the fire had advanced mainly as a slow, intense charring that expanded equally in all directions. But in numerous places it had been strangely erratic, due no doubt to the multitude of leaks that fanned it. Roebling noted, for example, that a single 12-by-12 timber would be burned away for thirty feet, while one just like it directly alongside would be untouched. And since the courses had been laid up at right angles to one another, the fire had had opportunity to branch off in a zigzag pattern, jumping from one timber to another, heading off left or right, up or down.

Damaged timbers were carefully scraped clean and all jagged edges were squared off with chisels. Every foot of burned wood was cut out. New cement was rammed into the smaller places, while new timber was cut to size (in lengths of eight to ten feet usually), rammed into all the larger openings with a screw jack, and securely bolted.

The burned channels that wandered laterally between the big vertical openings were generally about two by three feet in dimension. All such channels had to be gouged out by hand, then filled in in the same manner. The men worked like coal miners along such veins, inching forward on their backs or sides, with barely enough room to move, digging out charcoal instead of coal, imprisoned in a mountain of wood instead of earth. For hours at a time a man would be confined to a single spot, unable to turn around, his only light a little bull’s-eye lantern, and breathing candle smoke, cement dust, and powdered charcoal. Because the air pressure had been greatly reduced by the openings that had been cut, the ventilation was dreadful and the heat remained near 90 degrees.

“After everything was filled up solid,” Roebling wrote, “a number of five-foot bolts were driven up from below so as to unite both the old and new timber into a compact body.” He also had forty iron straps bolted against the roof from below, and inside the air chamber, directly under the line of the fire, he had great square blocks of traprock set in the concrete that was being put down over the rest of the chamber floor.

When the repairs were at last completed Roebling reminded everyone that there were still eleven perfectly sound layers of timber above the first four. And in his final report he stated, “From the faithful manner in which the work was done it is certain that the burnt district is fully as strong, if not stronger than the rest of the caisson.” Most people believed him.

The fire and its aftermath had been a sobering experience. It had delayed the work two, possibly three months. With the payroll running about eleven thousand dollars every two weeks, this meant a loss of some fifty thousand dollars at least, on that score alone. The fire had done much to reinforce the arguments of the skeptics, of whom there were still plenty on both sides of the river. This said one New York paper was the “main mischief” of the whole unhappy affair. But it had also been a brutal physical and mental ordeal for many of the men, and for Roebling in particular, whose strength had never quite returned since the night he collapsed in the caisson. He was a changed man after that, his assistants would say later.

Had he decided early that night to flood the caisson, in spite of the boulders beneath the water shaft, then things might have gone differently. But if he ever speculated about that, it was only in private.

The last repairs were completed on March 6, 1871. Five days later the air chamber was completely filled with concrete. During the final few weeks of sinking the caisson, several fresh-water springs had been encountered, and now, much to everyone’s astonishment, the water came right up through six feet of concrete in such quantity that it filled the water shafts clear to the top. The water was perfectly fresh, without a trace of salt, so it was all coming from directly beneath the caisson. The shafts were drained, therefore, and they too were filled with concrete. The air locks were removed and these empty spaces were also filled with concrete.

So by mid-March the Brooklyn caisson was permanently in place. The hardest, most treacherous and uncertain part of the work, the sinking of the caissons, was half done. No lives had been lost, no one had been seriously injured. Every man on the engineering staff had proved himself worthy of the faith Roebling had in him, and none had quit.

Work on the Brooklyn side from here on would be of the sort everyone had been anticipating. There would be something actually to see now, to watch grow and change from one day to another. The Brooklyn tower, it was commonly said, would be the greatest structure in the world except for the Pyramids. “America has seen nothing like it,” Thomas Kinsella wrote on the editorial page of the Eagle. “Even Europe has no structure of such magnitude as this will be. The most famous cathedrals and castles of the historic Old World are but pygmies by the side of this great Brooklyn tower. And it is our own city which is to be forever famous for possessing this greatest architectural and engineering work of the continent, and of the age.”

Such grandeur was still several years off, everyone knew, but it was not so very difficult to picture. “Think of Trinity Church as big at the top of the steeple as at the ground,” said Kinsella, “and one solid mass all the way up, and we get some idea of what this great Brooklyn tower is to be…the fame of the Roeblings and the boast of Brooklyn forever will be that, where Nature gave no facilities for a suspension bridge, and seemed indeed to place a veto upon the idea in these low and shelving shores, the genius of the father designed, and the consummate inherited and acquired ability of the son executed, in spite of all obstacles, this most novel and unparalleled masterpiece….”

But not until June 5, when the Eagle published Washington Roebling’s annual report to the directors of the Bridge Company, did the people of Brooklyn and New York get a fair idea of what exactly had been accomplished to make the tower possible. Except for the flurry of excitement when the fire was discovered, almost nothing about the details of the work or the setbacks experienced inside the caisson had appeared in the newspapers. Roebling’s report filled seven and a half columns. It was straightforward, unadorned, and it was read with enormous interest. People were utterly astonished to learn all that had taken place beneath their very noses. “We are not partial to long official reports,” the Eagle said by way of introduction, “but this one is exceptional in the thrilling interest of the story.” Roebling was praised for his modesty by the editors and lauded for his own personal heroism in such a way that it seemed they too were realizing for the very first time the extent of what had happened down at the end of Fulton Street. In 1870, when the caisson was making its slow, tedious descent, the English translation of Jules Verne’s Twenty Thousand Leagues Under the Sea had appeared in America, with its adventures of the strange genius Captain Nemo. Now the Eagle wrote: “The adventures of Colonel Roebling and his twenty-five hundred men under the bed of the East River are as readable, as he tells them, as any story of romance which has issued from the imagination of the novelist.”

What Colonel Roebling and his men might run up against on their next descent was now, naturally, a matter of much popular interest. On one side of the river a tower of imperishable granite would be rising straight into the sunlight, while on the other side, mortal men would be descending beneath the tides and into the earth. It was quite a picture to keep in mind for anyone crossing the river to clerk in a countinghouse or sit the long day at a sewing machine.