Decompression sickness—more commonly known as “the bends”—is a dangerous condition that can affect people who spend time under water and then rise to the surface too quickly. While under water, divers breathe oxygen that is at a higher pressure than the surface pressure, to equalize the pressure of the surrounding water. If the diver stays under water too long and doesn’t ascend gradually enough, the gases that have dissolved in his body (nitrogen bubbles in the blood) can be emitted too quickly—much like a soda bottle that has been shaken and uncapped. The results can cause debilitating pain and death.
This was a real problem during the construction of the Brooklyn Bridge (which began in 1870). To build the longest suspension bridge in the world (over a mile from end to end), workers had to first anchor the bridge’s two immense towers into the bedrock beneath the East River. I’ve always wondered how they accomplished this. (You can read more detail here to learn about the process.)
So to drill down, under water, the engineers constructed a huge, watertight box, called a caisson, which was sunk to the river bottom—with workers inside it. Compressed air was pumped in to keep the water out. Then the floor was ripped out so that the workwoodeers could dig up the river bottom.
Working conditions inside the box were, as you might imagine, abysmal. Workers breathed hot air, under tremendous pressure, while standing in a few inches of frigid water. Working shifts were limited to two hours at a time, because it was so debilitating. The laborers were mostly Irish, German, and Italian, and they worked by the light of calcium lamps, drilling through stinking mud and basalt at rates of fewer than six inches a week.
The water was deeper on the New York side of the river, and laborers frequently suffered from the bends—terrible cramps, blood spurting from the mouth and nose, and bizarre contortions of the body. A great many laborers died from the bends.
The construction company hired a doctor to investigate the deaths, and he urged a five- to six-minute exit procedure (not enough time, but it certainly would have helped). But the company was in a hurry to finish construction so workers had a two-to-three-minute exit procedure—and kept dying.