ber. They looked like gnomes in an elfin world. We had been transformed into a real, live chapter of the Arabian Nights.
PASSING A BUCKET THROUGH THE AIR-LOCK. BEHIND THE LATTICE IS THE WORKMEN'S LADDER.
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.
