There were notable exceptions, of course. One man named Mike Lynch went down with the very first shift to go into the caisson and would be the last man to come out. He not only never lost an hour’s time during the ten months he worked in the caisson, but he made a day’s extra pay in overtime. “He is strictly temperate and regular in all his habits,” William Kingsley noted, “and is none the worse for his long service in compressed air.”
That the turnover was so great is not surprising.
Amenities provided by the management were very few—about what was customary. Two unpainted frame sheds had been put up in the yard, with rows of pegs and hooks inside for the men to hang their clothes. (The temperature inside the caisson was such that most men went down wearing nothing but pants and a pair of company boots.) In front of the sheds were sets of washtubs, with hot and cold water. And that was about the sum of the comforts provided aboveground.
Inside the caisson itself there were generally a few dry spots where a man could eat his midday meal. And against one wall stood what was considered by all the world’s most extraordinary toilet. It was described in one of Roebling’s official reports as a pneumatic water closet and consisted of a wooden box with a lid and a large iron pipe that passed up through the timber roof. The box was kept about half full of water, and whenever its contents were to be discharged, a valve was opened and the pressure from within the caisson would blast everything instantly overhead in the form of a fine mist. This particular device was not installed until the work had progressed some little time, however, and until then the pools beneath the water shafts, or any convenient corner, had sufficed for the same purpose. When he came to describe the general working conditions, Roebling would note that the sense of smell was almost entirely lost in the “made air,” as he called it. “This,” he said, “is a wise provision of nature, because foul odors certainly have their home in a caisson.”
For an ordinary laborer the pay was two dollars a day. But after the caisson reached a depth of twenty-eight feet, it was decided to revise that. The bad air, the increased unpleasantness over all, and the widespread feeling that the deeper down they went the more hazardous the work, all called for a commensurate hike in wages, the management decided. So from that point on the pay was $2.25 a day.
Men kept quitting just the same, but for every one who did, there were at least a dozen anxious to take his place, most of them Irish, German, or Italian immigrants who were desperate for work of any kind, and many of them, like those who had gone into the Eads caisson, were thinly clothed and undernourished.
But for all the talk and worry there had been over caisson sickness, and for all the growing fear of it as pressure inside the caisson increased steadily, only a few so far had experienced any ill effects.
One pound of air pressure equals two feet of tidewater, so for every two feet the caisson was lowered, one pound had to be added to the pressure. Gauges in the engine room indicated the height of the tide and the pressure of the air. The greatest the pressure would ever be in the Brooklyn caisson was twenty-three pounds per square inch above normal atmospheric pressure, or nearly ten pounds less than it had been inside the Eads caisson the day James Riley fell dead. In St. Louis several more had died miserably, but there had been only mild symptoms in Brooklyn. A little paralysis in the legs was all. Only three or four men had been bothered in the slightest and none of the engineering staff so far.
Like Eads, Roebling noted that the ones who did have trouble were all new to the job. His way of alleviating their discomfort was to send them right out of the caisson. Now that he had seen something of the problem first hand and had spent as much time under compression as anyone on the job, Roebling was convinced that Eads’s system of shortening the hours was the best possible prevention and said he would follow that same system in the New York caisson. The thing to do, he said, was to “reduce the period that the human system is in contact with the exciting cause.” The increased quantity of oxygen inhaled under pressure was what did the damage, he thought. “That the system struggles against this abnormal state of affairs,” he said, “is shown by the fact that the number of inhalations per minute is involuntarily reduced from thirty to fifty per cent. It follows, therefore, that the shorter the period of exposure to compressed air the less the risk.”
But any change in the schedule would wait until the New York side, since the Brooklyn caisson was not going deep enough to produce anything like what was happening in St. Louis, where Eads had had a special hospital ship fitted up and had hired a full-time physician who prescribed special diets and set down strict rules about rest. Eads’s men by this time were permitted to work in the caisson only an hour at a time.
But the men in the Brooklyn caisson were having their troubles all the same. The work was a hazard to the health, it was agreed, and far more exhausting than anything any of them had ever done before. Collingwood said a full day inside would leave him feeling worn-out and in ill temper for days. And when the weather turned cold in the late fall, dozens of men began coming down with severe colds and bronchitis, caused by the abrupt drop in temperature inside the air lock. Every time they “locked out” at the end of the day, hot, tired, and dripping wet, the men would experience a sudden temperature drop, from at least 80 to 40 degrees. Roebling had steam coils installed in the air locks to keep the temperature the same as in the chambers below, but the men still had to face the chill open air once they emerged from the locks.
A hacking cough also became common among those who had been on the job any time. Candle smoke and the blasting were said to be the cause. Those who had been going down the longest could spit black and would still be able to do so several months after the work was finished.
But what plagued everyone most was the thought of all that weight bearing down overhead and the river outside and the unspoken fear that sometime, sooner or later, something was going to go wrong and they would all be drowned like rats or suffocate or be crushed to death. And then just to confirm how very tenuous was the balance upon which they were all trusting their lives, there occurred what would afterward be called “The Great Blowout.”
It happened at about six in the morning and on a Sunday, when only a few men were about, a fact the pious took to be more than a matter of coincidence. Eads had his men working seven days a week, it was noted, while Roebling kept the Sabbath. This was a sign, it was said, and thanks were given through Brooklyn and nowhere more fervently than in the Irish neighborhoods near the Navy Yard. Heaven only knew how many would have been left widows, people were saying, had it happened any other day of the week.
All at once in the very still early morning there had been a terrific roar. The few who actually saw the thing go off said it looked more like a volcano than anything else. It was as though the river had exploded, sending a column of water, mud, and stones five hundred feet into the air and showering yellow water and mud over ships and wharves and houses for blocks around. The column was seen from a mile off and the noise was so frightful that people began pouring out of their front doors and rushing pell-mell up Fulton Street. The whole neighborhood was on the run. Roebling described it as a stampede. “Even the toll-collectors at the ferry abandoned their tills,” he said.
Nobody was inside the caisson at the time and only three men were on top of it. One of them, a yard watchman, said later that the current of air rushing toward the blowing water shaft was so powerful it knocked him off his feet, ruining his Sunday suit. He had been struck by a stone after that and could remember no more. One of the other men leaped into the river, while the third tried to bury himself in a coal pile.
Then in an instant it was all over and everything was as silent as before. Both doors of the air locks fell open and for the first and only time the submerged caisson was flooded with daylight. The quiet lasted but briefly. Within minutes there was another rush of people heading down Fulton to see what had happened.
Roebling, Collingwood, and one or two of the others from the work fo
rce were on the scene almost immediately. They turned hoses into the open water shaft, closed the air locks, and in about an hour had a head thirty-one feet high back in the shaft and fifteen pounds of pressure back in the shaft and fifteen pounds of pressure back in the work chambers. When it was time to go down to take a look at the damage, Roebling led the way. “The first entry into the caisson was made with considerable misgiving,” he wrote. But incredibly none of the disastrous consequences he had feared had occured, as he reported later to the Board of Directors:
The total settling that took place amount to ten inches in all. Every block under the frames and posts was absolutely crushed, the ground being too compact to yield; none of the frames, however, were injured or out of line. The brunt of the blow was, of course, taken by the shoe and sides of the caisson. One sharp boulder in No. 2 chamber had cut the armor plate, crushed through the shoe casting, and buried itself a foot deep into the heavy oak sill, at the same time forcing in the sides some six inches. In a number of places the sides were forced outward. The marvel is that the airtightness was not impaired in the least.
His caisson had withstood the staggering blow of 17,675 tones dropped ten inches. By the way certain boltheads were sheared off, he could tell that the sides of the caisson—nine solid courses of timber—had been compressed two inches, such had been the impact. In the roof, however, there was not a sign of damage except for the slightest sag near the water shaft, where the support from the frames was the least.
With a little figuring Roebling concluded that once all the settling had stopped and before the compressed air was build up again inside the chambers, the caisson was carrying a total weight of twenty-three tons per square foot. This was an astonishing revelation. As never-racking as the whole episode had been, it had demonstrated just how large a margin of safety Roebling had built into the structure, since its ultimate load, once the bridge was built, would be only five tones per square foot. So he had built the caisson at least four times as strong as it needed to be.
Why the water shaft blew out was, needless, to say, a question of the gravest concern and the answer takes a little explaining.
The problem was that the weight of the columns of water in the shafts was not always the same. Particles of rock and earth were constantly washing out of the clamshell buckets as they were hauled up through the water shafts, and as a result a fine silt was held in suspension and this, in a column of water seven feet square by, say, thirty-five feet high, could and did increase the specific gravity of that column to a remarkable degree. But when the shaft was not in use for some reason or other, the silt would settle, the water would become less thick and weight less. So great would be the difference in the weight between a nearly cleared column of water and one still in use that the difference in the levels of the two (both of which were, of course, being supported by the same air pressure) would be about ten feet.
Outside, on the top of the caisson, such a disparity, in the level of the water in the shafts could be an alarming sight for anyone on duty who did not understand the reason for it. The impression would be that the lower of the two shafts was getting close to the danger level-that it might may blow out at any instant-and the immediate response would be to feed more water into the shaft as quickly as possible.
This is precisely what happened on more than one occasion and effect inside, naturally, was that the pool beneath one shaft would begin overflowing rapidly, which led those in charge below to assume the air pressure in the chamber was giving out. And since there was no direct communication between those above and those below, somebody had to scramble up through the air lock and find out what had gone wrong. On one such occasion it was discovered that the water in one shaft was above twelve feet from the top while the water in the other shaft was twenty-one feet from the top and despite the fact that a heavy stream of the water was pouring into the shallower shaft. The water was immediately shut off when it was known what was happening below and samples of water were taken from each shaft. Water from lower shaft was found to weight eighty-five pounds per cubic foot, which was twenty-one pounds more than the water from the other shaft.
On the Sunday of the blowout, apparently the sediment in one shaft had settled to such an extent that the water no longer weighed enough to contain the pressure inside. The normal precaution had been to keep a small stream of the water playing into the shaft to make up for just a likelihood during the days when the work was halted and no dredging was going on. But this time had not been done. Sounding very much like his father, Roebling said “To say that his occurrence was an accident would certainly be wrong, because not one accident in a hundred deserves the name. In this case it was simply the legitimate result of carelessness, brought about by an overconfidence in supposing matters would take care of themselves”
Trusting matters to take care of themselves was something this extremely competent young man had seldom done in his life. He had had the contrary attitude drummed into him since childhood and from here on more than ever, he would insist on the strictest attention to every detail and to safety precautions especially, and he would come down hard on anyone caught taking such matters lightly. The thing to fight against, he told the men, was the kind of carelessness that comes from familiarity with the job.
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 i
t 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.
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