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.
David McCullough Library E-book Box Set Page 102