St. Nicholas/Volume 40/Number 6/With Men Who Do Things

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THE FIRE IN THE CAISSON. “DANNY REACHED FOR THE SIGNAL ROPE.” (SEE PAGE 540.)

WITH MEN WHO DO THINGS

BY A. RUSSELL BOND

Author of “The Scientific American Boy” and “Handyman’s Workshop and Laboratory

Chapter III

ONE HUNDRED FEET BELOW BROADWAY

Immediately after breakfast, on the next day, we went down-town to see how foundations are sunk to bed-rock in lower New York. The place we wished to investigate was inclosed by a high board fence, but projecting far above it was a confusion of derricks, concrete mixing-machines, bucket elevators, enormous wooden boxes, and curious, cylindrical objects from which, every once in a while, would come the sound of a whistle signal, followed by a loud gasp of escaping air. The lid of dry, white sand would be drawn forth and dumped into a hopper; then the bucket would be swung back into the yawning mouth of the cylinder, and an attendant would swing a lever, closing the lid. Thereafter, there would be a number of toots of the air whistle, and we could see the bucket cable pay out or in, in accordance with the signal.

It all seemed very mysterious, and whetted our curiosity. We sought out Mr. Squires without further delay. He proved to be a very approachable man, the kind that had n’t forgotten that he was once a boy. “If Dick Hotchkiss sent you here, you may have anything you wish.

Will explained that we were anxious to know how foundations are sunk.

Photograph by Brown Brothers.
SWINGING THE BUCKET UP TO THE AIR-LOCK—THE IRON BLOCKS ARE USED TO KEEP THE CAISSON DOWN.

“Simply a case of dig, dig, dig,’ said Mr. Squires, “until we get to rock; when we get down to water, we keep it out of the excavation with compressed air.”

“How do you do that?”

“On the same principle as the diving-bell. You know, if you plunge a tumbler mouth down into a basin of water, the air trapped in the tumbler will keep the water from filling it completely. If enough air were pumped into the tumbler, it would be possible to keep out every drop of water. We do that very thing in building foundation piers. First we make a big diving-bell, called a caisson. It is a large box of wood, or steel, or concrete, with the top and bottom open. At the bottom, the box has fairly sharp cutting edges; about seven feet up from this cutting edge, there is a horizontal partition called the ‘deck.’ This is made very strong, because it has to carry the weight of the whole concrete column while the digging is going on. ‘Sand hogs,’ as we call them, get into and out of the working chamber under this deck through a tube, or ‘shafting, as it is called. They dig away the soil and gravel below, constantly undermining the caisson, so that it gradually sinks into the earth. As the caisson is sunk, the concrete pier is built up on its deck, and its weight helps to force the cutting edges into the ground. As the work progresses, new caisson sections are added on top, and the shafting is extended for the sand hogs and excavating material.”

“But where does the water come from?” I asked.

Photograph by Brown Brothers.
AT WORK ON THE FOUNDATIONS OF A SKY-SCRAPER. IN THE FOREGROUND IS A NARROW WOODEN CAISSON.
“The lower end of New York is built over a deep layer of sand and porous soil that is saturated with water from the river. About fifty feet below the curb, in this part of New York, we come to water; then we have to put on the air-pressure to keep it out. The first thing we must do is to put an “air-lock” on the shafting, so as to let the men in and out without losing the pressure. The lock is just a cylinder with a hinged lid, or door, at the top and bottom. One or other of those lids must be closed all the time, to hold the pneumatic pressure in the caisson. The bottom door is closed when the top door is open to let the men in. After they enter the lock, the lock-tender lifts the upper door shut, and turns a valve to let the compressed air in. All the time, the bottom door is kept closed by the air-pressure in the shaft below, but, as air is let into the lock, its pressure at length equals that in the caisson, and, there being nothing to hold up the bottom door, it swings open of its own weight, so that the men can go on down to the working chamber.”

Photograph by Brown Brothers.
GOING DOWN TO WORK IN THE SAND BUCKET. MEN ARE SUPPOSED TO USE THE LADDER.

Could we go down into one of the caissons, asked Will.

“Oh, no, that is entirely out of the question,” said Mr. Squires. Then, as he saw the disappointment in our faces, he explained: “There is n't anything to see down there, and it is pretty dirty work.”

“We don’t mind the dirt,’ I interrupted.

“Well, I don’t know,” said Mr. Squires, hesitating. “You say Dick Hotchkiss sent you to me? That settles it then, if you really want to go. Come on to the sand-hog house, and I Il see if I can rig you out in boots and oilskins. But hold on. When did you have breakfast? Eight o'clock? You did n’t have a very substantial meal, did you?”

We told him what constituted our usual morning fare.

“That ’s not enough,” he said. “Run over to that restaurant, and fill up with all you can eat.”

That seemed like an odd preliminary to our work. “It ’s like feeding the prisoners just before they are to be executed,” I remarked.

Photograph by The Foundation Company.
SETTING UP THE FORMS AND REINFORCING BARS FOR CASTING A CONCRETE WORKING CHAMBER.

“But,” Mr. Squires explained, “down there you will take in three times the usual amount of oxygen with every breath. Your ‘innards’ are going to work under forced draft, and so you must have plenty of fuel aboard. It is one of the rules that the men cannot go under pneumatic pressure except on a full stomach.” So we repaired to the nearest restaurant, and filled our bunkers with broiled steak and apple-pie.

“Now we shall see the doctor,’ said Mr. Squires.

“The doctor!’ we both exclaimed; “why, we are not ill!”

“Certainly. Every one has to undergo a physical examination before entering a caisson.”

All this preliminary was most impressive. For the first time it occurred to me that there might really be some danger, but, shucks! what did I care about dangers as long as I could feel good, solid earth beneath me.

The doctor was such a serious-looking man that we never, for a moment, imagined he might play a joke on us. He felt of my pulse, looked at my tongue, listened to my heart, and then thumped and pounded me unmercifully all about my chest and back, to see if I were perfectly sound. I tell you I was sore before he got through with me! I ached all over, but found some consolation in the thought that Will’s turn was coming next. After Will had stood the test, the doctor began in a clerical tone to sermonize on the awful hazard we were inviting upon ourselves. He told us that we were to enter a chamber where the air was compressed to over three times the density of the atmosphere. “On every square inch of your body,” he said, “there will be a pressure of thirty-five pounds above the ordinary pressure of the air, and thirty-five pounds on every inch means 5000 on every square foot, or about fifty tons on your whole body. Think of that, young men, fifty tons! Why, that would smash you as flat as a griddle-cake if you did not take air of the same pressure inside your body, so that it would press out and counteract the outside compression. The weakest spots are your ear-drums. You will have to look out for them. They are liable to burst unless you can get compressed air up your Eustachian tubes. The only way to do it is to take a long breath, and then, holding your nose and keeping your mouth shut, blow for all you are worth.”

I began to suspect that we were providing a lot of fun for these men, but they were both so insistent about it, that we had to practise blowing so that we should know how to do it when in the air-lock. I learned afterward that that bit of practice was the only really important item in the whole farcical examination. The doctor explained how men who did n’t heed instructions were affected with a dreadful malady known as the “caisson disease.”

“In its very mildest form,” he said, “you are seized with cramps and shooting pains from which you can get no relief. Every bone in your body will ache so that you cannot sleep. In the more serious stages, you become paralyzed. There is one simple test of your condition. Can you whistle? Yes? Well as long as you can whistle, you are all right, but if, after you have been in awhile, you experience any difficulty, it means trouble. Your lips are losing their sensitiveness, a slow paralysis is coming on.”

At this, Mr. Squires had a terrific coughing-spell, but there was not even the flicker of a smile on the doctor’s face as he waved us off.

Mr. Squires led the way up a ladder to a platform surrounding one of the cylinders we had seen. Just as we reached it, there was a sudden blast of air, the trap-door at the top opened, and out came a load of sand. We climbed into the lock, and the lock-tender closed the upper door. The lock was a large chamber about ten feet in diameter, lighted by an electric bulb. At the bottom, there was a trap-door. Mr. Squires warned us against standing on it. The lock-tender turned a valve and let the compressed air rush into our chamber with a loud, hissing noise. The noise was so deafening, we could n’t talk, but Mr. Squires motioned to us to follow his example of taking in deep breaths, and blowing with nose and mouth tightly shut. I felt a little queer as the pressure came on, but was in no distress. The pressure on my ear-drums was far from pleasant. I looked at Will, and could n’t help laughing. He was following directions so conscientiously, taking in copious breaths, and blowing until his cheeks were distended like balloons.

Suddenly, the trap-door below us dropped open with a clang that echoed and reëchoed down the yawning well that seemed to run to the very center of the earth. The well was pear- shaped, with a latticed partition dividing it into two shaftings, the smaller one for the workmen, and the other for the sand bucket. The trap-door opened into a chamber with a narrow ledge to stand upon, and we had to climb down into it and then over to the workmen’s shafting. Mr. Squires then pulled a whistle cord, in response to which the lock-tender swung the bottom door shut.

A ladder led down the workmen’s shafting, which was lighted with a few electric lamps. We could see the shafting tapering with the perspective until it formed but a tiny hole where it passed into the workmen’s chamber, a hundred feet below. In the murky darkness, we could barely make out the forms of men in the cham-ber. They looked like gnomes in an elfin world. We had been transformed into a real, live chapter of the Arabian Nights.

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PASSING A BUCKET THROUGH THE AIR-LOCK. BEHIND THE LATTICE IS THE WORKMEN'S LADDER.

I tried to speak to Will, but my voice sounded so high and nasal that I could scarcely tell what I was saying. Mr. Squires had already started down the ladder, and we scrambled after him. It was a long, tedious descent, and I wondered how we should ever get up again. Somehow, I felt a peculiar exhilaration. It seemed easier to do things in that atmosphere.

THE WORKING CHAMBER OF A CONCRETE CAISSON HAS A STEPPED ROOF.

When, at last, we reached the bottom of the shafting, we wriggled down a rope ladder to the ground. The working chamber was rectangular, measuring about ten by fifteen feet; five sand-hogs were at work. They had dug a wide hole in the sand at the center of the chamber, and were extending it toward the sides. Mr. Squires explained that they would dig to the edge of the chamber, undermining the edges of the caisson if necessary, so that they would sink into the ground. The deck, a foot or so above our heads, was made of heavy timbers, and supported a concrete pier that extended in a solid mass eighty feet above us. The shaft was getting so deep that the weight of the concrete was no longer enough to force it down, and tons of pig-iron were loaded on top to overcome the friction of the earth on all sides of the caisson.

“Nowadays,” said Mr. Squires, “caissons for deep building foundations are nearly always made of steel or concrete. We happen to be using wooden caissons here because the contract for this job was not let until the last moment. The wreckers had already removed the old building that stood on this property, and we had to start operations at once. There was no time to build concrete caissons, or wait for steel ones from the mill. It does n't take long to build a timber caisson, and lumber is always at hand.”

It was damp in the chamber, and water dripped from the ceiling; but the sand floor was quite dry. The air forced all the water out of the sand. It was hot in there, too. Mr. Squires explained that compressing the air heated it, and if they did not use a special cooling system, the temperature in the working chamber would be simply unbearable.

My! how those men worked. “You see, they are taking in such a lot of oxygen at each breath,” said Mr. Squires. “Take them out in the open, and they are too lazy to do a thing. “Once a sand-hog, always a sand-hog, the saying goes. They are simply unfit for work unless stimulated with oxygen. They can only work two hours at a time in this pressure. It is dangerous for them to be in any longer.”

Mr. Squires turned on his heel and started off, whistling. As if of one mind, Will and I puckered our mouths for a whistle, but the sound failed to come. In alarm we tried again, and yet again, but without avail. Thoroughly frightened, we ran after Mr. Squires, and told him that we had symptoms of paralysis; we could n't whistle.

“Try harder!” he urged. “Sometimes if you put forth a little effort, the symptoms disappear.” We blew and blew, until we were red in the face. He looked genuinely concerned, and, calling to one of the men, said: “Here, Pat, take these two boys to the doctor at once, and tell him they can’t whistle.”

Pat grinned from ear to ear as we made for the ladder and began climbing like mad. I thought we should never reach the lock. A hundred feet up was three times as much as a hundred feet down. Try running up to the ninth floor of a building, and then imagine how much harder it would be to make that same ascent up a vertical ladder. What if the paralysis spread to our arms and legs before we got to the top! We were pretty well fagged before we reached the lock and scrambled through the lattice, but the rich oxygen we took in with every breath sustained us wonderfully. Pat was not far behind us. He shouted to us to get down out of the way of the trap-door, then he gave the signal, and presently the door fell open.

We dragged ourselves into the lock and the door closed behind us; then we waited an interminable time for the compressed air to be let out. The chamber filled with fog as the pressure was reduced, and, after a time, the upper door clanged open, and we jumped out into the sunshine.

A shift of sand-hogs gathered around the door of the doctor’s shack as we were ushered in.

“Docther,’ said Pat, “these bhoys is afflicted with serious symptims. Their whistlin’ orgins is paralyzed.”

“Most distressing, most distressing,” replied the doctor. “You will have to get them a tin whistle, Pat.’ The guffaws of laughter that greeted this prescription were disconcerting, to say the least. We were completely taken in. How should we know that it is very difficult to whistle in air as dense as that in a caisson, and that only by considerable practice can one acquire the art of making “lip music” under pressure? However, there was nothing to do but to laugh with the rest, and make the best of the joke. The doctor made us stay in his office for a half-hour or so, to keep us from becoming chilled, and made up for the prank he had played upon us by recounting some very curious adven- tures he had had. Presently Mr. Squires came in, and we had to go over the whole story again.

THE WORKING CHAMBER:OF A WOODEN CAISSON.

“It was one on us, all right,” said Will, with a forced laugh; “but you sent us out before we had seen half there was to see. You will have to answer questions now. What do you do when the caisson is sunk all the way down to rock?”

“We blast out a good footing if the rock is tilted.”

“What! You blast rock down in that small chamber!”

“Oh, yes, the sand-hogs all get out of the chamber when the charge is set off. We have a trap-door at the bottom of the shaft. The men all climb into the shaft and pull up the trap-door, then the gang boss sets off the charges with electricity.”

“But after you have finished blasting, what then?”

“Oh, then we just fill in with concrete. The concrete is laid round the cutting edges first. The filling then proceeds toward the center. Then we work up the shaft, filling up the hole behind us until the entire pier is built up solid. What next?” asked Mr. Squires.

“I can’t think of anything more; can you, Will?”

“No, not without going in again,” he replied.

“You can go down with Danny Roach in one of the narrow coffer-dam caissons, if you like,” he answered. “We find it necessary to build a solid wall all the way down to rock on two sides of the building, because we expect to have a pretty deep cellar, and the adjacent buildings were built on floating foundations. Not many years ago, foundations used to be made that way. Piles were driven into the mud and sand as close to one another as possible, and then upon them was built a grillage of iron rails, that is, the rails were piled in tiers that crisscrossed one above the other, and upon this grillage the columns of the building were supported. That form of foundation is pretty good until some one digs a deep hole near by, then, under the weight of the building, the quicksand oozes into this hole, and the building settles badly, sometimes dangerously.

In Chicago, most of the buildings are supported on floating foundations, because the sand is so deep that it is impossible to get down to rock. A man can’t work at much more than 110 feet below water-level, because the pressure would be over 47 pounds per square inch. Some Chicago buildings are constantly sinking. For this reason, scores of hydraulic jacks are placed under the columns, and now and then the building is jacked up to its original level. We have to run a wall all around our foundations to keep the quicksand out of our subcellar. But run along with Danny Roach. He ’ll explain the whole thing to you. He knows more about real caisson work than any other man alive.”

Danny Roach, a big, broad Irishman who looked in at the doorway just at that opportune moment, seemed only too glad to show us around. The caisson we entered was only five feet wide by twenty feet long. A group of sand-hogs were digging away the sand. It seemed peculiarly sticky material. Our feet sank into it as if it were soft mud, and yet, apparently, it was dry when we picked up a handful.

“Tricherous stuff thot,’ said Danny Roach; “if there wuz no pressure on it, it wad be the wurst koind of quicksand.”

There was a man in the chamber puttying leaks in the caisson, close to the deck, with clay and oakum. He carried what I thought was a torch, but it proved to be only a common wax candle. The rich oxygen in the caisson drew out the flame to a length of four or five inches. It was wonderful how things burned in that air.

“Hey! luk out there,” called out Danny Roach. “Kape that candle away from thim timbers, or yez ‘ll have thim afoire.”

“Could you really set that damp wood afire?” asked Will.

“Sure, if there was a laik, the outpourin’ air wad suck the flame through the hole, and we wad have the wurst koind of a foire. Luk out, ye fool of a man!” yelled Danny Roach. The man stumbled, clutched at something to save himself from falling, and, as luck would have it, tore down the electric-light wires, broke the circuit, and, instantly, we were in darkness. Even his candle was extinguished, for he fell upon it and snuffed out the blaze. The only light was a brilliantly glowing ember in Danny Roach’s pipe. Once, when I was a child, I had read of a young chap who crawled into a hollow log after a rabbit, and was trapped in there by the inwardly pointing splinters. I did n’t get over it for weeks, and now that same feeling of horror seized me. It was all I could do to keep from venting my panic in a yell. I don’t know about Will, but I venture he was thinking about the blessed sunshine just then. Presently some one scratched a match; it blazed up brilliantly. A candle was lighted, and the match was tossed carelessly aside. Almost immediately there was a flare of light like the flash of gunpowder.

“The o-akum!” cried Danny Roach.

There was a big pile of it in the center of the working chamber. It burned fiercely, and the heat was intense. We saw that the deck would be ablaze in another instant, if something were not done to quench the fire; and if the deck gave way, might not the mass of concrete above crush through and mash us as if we were so many flies? But the chances were we would be burned to death before that happened. All this went through my mind like a flash.

In the meantime, Danny Roach had taken in the situation. There was a bucket nearly filled with sand standing beside the burning oakum and almost enveloped in the flames. He reached for the signal rope, gave a signal, in response to which the bucket was lifted three feet off the ground, then, rushing through the flames, he kicked the trip of the bucket. A ton of sand poured out over the blazing oakum and smothered the fire. Danny Roach’s clothes were afire, and he rolled around on the ground, trying to quench the flames. It was with difficulty that we extinguished the blaze, and poor Danny was very painfully burned. He was placed as tenderly as possible in the sand bucket, and, with the gang boss attending him, was hauled up to the surface.

The rest of us climbed up the shaft, which was filled so full of smoke that we could scarcely breathe. We came so near smothering in the lock that we signaled to the lock-tender to let the air out as fast as he could. I tell you what! we were glad to get out of that stifling atmosphere.

Poor Danny Roach had done his duty so quickly, that we scarcely realized what a hero he was. The doctor was doing his best to relieve the man’s suffering until the ambulance arrived, but told us that the brave fellow would have to spend a week at least, in the hospital.

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