Washington Roebling, the engineer in charge of building the Brooklyn Bridge, went into one of its caissons in 1871 to inspect for himself the conditions his men were working in. He came out of it with an extreme case of what the workers called caisson disease, and he was left paralyzed for the rest of his life.
Roebling was not the first person the disease had struck, and he would not be the last. It had followed a new method of building from the coal fields of France to the great rivers of the United States, and in the 1870s nobody knew what caused it.
A caisson, from the French word for “box”, was an enormous chamber filled with compressed air and used to build the piers and foundations that anchor a bridge in a river. Men dug at the bottom while the pressure of the air held the water out. The method made construction faster and cheaper, but it carried a hidden cost. Inside the caissons of this period, workers labored at pressures as high as 55 pounds per square inch above normal air pressure, and the disease was common. Today it is called decompression sickness. When the pressure around a person falls quickly, nitrogen dissolved in the blood and tissues can form bubbles, causing joint pain, breathlessness, itching, confusion and seizures.
Roebling had begun work in May 1870 on a bridge 1,600 feet long that would connect Manhattan and Brooklyn. Its caissons were larger than anything built before: at 16,000 square feet, they were three times the size of those used for the bridge then going up across the Mississippi at St. Louis. The project had been conceived by his father, John A. Roebling, who died during the early work.
The first person to use a pressurized chamber for work was Charles-Jean Triger, a French civil engineer and geologist. In 1840 he pumped compressed air into a chamber with an open bottom to mine coal in the Loire Valley, forcing water out so that miners could dig below the water table. The device was used for about two weeks, with shifts of seven to ten hours, and Triger went down through the airlock before every shift to check the air and the working conditions. His chamber produced the first known injuries from compressed air.
Triger later hired two physicians, B. Pol and T. J. J. Watelle, who examined and cared for 64 laborers on a project at Douchy in northern France, reportedly run at three and a half times normal atmospheric pressure. They recorded breathlessness, joint and muscle pain and itching in many workers leaving the caisson. Pol fell ill himself, and recovered only after a night of severe chest pain, paralysis and vomiting. The two men correctly linked the severity of the illness to the speed of decompression, but wrongly believed it came from a lack of oxygen in the blood. Even so, in 1854 they were the first to suggest that putting a patient back under pressure might treat it.
At St. Louis, the caissons of the bridge designed by James Eads were sunk toward bedrock 100 feet below the surface of the Mississippi. By the time they reached 60 feet, the men were complaining of joint pain, partial paralysis of the legs, headaches and itching. Many came out bent over in pain, a posture that reminded people of the Grecian Bend, a fashionable way for women to stand, and so the stricken men were said to have “the bends”. As one caisson neared its greatest depth of 93 feet, six men died. By the end of the project nearly a quarter of all workers had suffered from the disease: there were 30 hospitalizations, 13 deaths, and two men permanently disabled.
In 1870 Alphonse Jaminet, a local physician, set up an infirmary with cots and blankets on a barge beside the works, one of the first on-site workplace clinics in America. He required laborers to stay in his care for “at least one hour after work, while drinking three-quarters of a pint of strong beef tea.” Jaminet went down into the caisson himself, and on coming back up suffered ear pain and extreme chills, which led him to advise men to dress warmly as the pressure was released. He mistakenly blamed the bends on compressing the men too fast, but he set standard rates for both entering and leaving the caissons. By modern standards his decompression was very quick, but controlling its speed at all was a step toward prevention. He published an account of his experience in 1871.
At Brooklyn, the care of the men fell to Andrew H. Smith, a physician who specialized in diseases of the throat. He recorded 86 cases of caisson disease, with joint pain, headache, itching, shortness of breath and paralysis. He treated them with morphine or atropine, but because the true cause was still unknown he could do little to prevent the illness. He did notice that most of the men affected were overweight, and that every death was described in “obese” patients, an observation later used to support the conclusion that obesity raises the risk. Smith published his report in 1873. A 2024 review in the journal Laryngoscope concluded that although Smith was wrong about how the disease worked, his strict standards and timely interventions allowed the masonry towers of the bridge to be completed.
Roebling, meanwhile, was confronting the limits of his own design. As digging continued, he grew concerned at the rising number of injuries and deaths, and he finally stopped the work at 78 feet, short of the 100 feet thought necessary to reach bedrock. Against the advice he was given, he set the Manhattan tower on sand. The writer Joel Cook later described him as an invalid for years after he fell ill.
Someone else carried part of the work to the outside world. In May 1883, a Sacramento newspaper reported that representatives of mills hoping to bid for work on the bridge had travelled to New York to consult Colonel Roebling. According to the paper, they were greatly surprised when Mrs. Roebling sat down with them and, through her knowledge of engineering, helped them with their patterns and cleared away their difficulties. The bridge opened that same month.
Abram S. Hewitt, chosen to speak for the city of New York, gave an address on the bridge that was printed in Popular Science Monthly in July 1883. He said that “the name of Mrs. Emily Warren Roebling will thus be inseparably associated with all that is admirable in human nature.” He also spoke of the price paid by the family: “Death, indeed, was the fate of its great projector, and dread disease the heritage of the greater engineer who has brought it to completion.”
The explanation came from the French physiologist Paul Bert, who was conducting numerous experiments with barometric pressure in 1870. He showed that the disease came from rapid decompression, noticed that symptoms were often delayed by ten to thirty minutes, and recommended slower decompression, pure oxygen for minor symptoms, and immediate recompression for paralysis. Those three practices remain the basis of treatment today. In 1908 the experiments of J. S. Haldane led to a recommendation of staged decompression.
None of that reached the men in the East River in time. Even the electric light, Hewitt observed, was perfected too late for use in the caissons. He asked his audience to remember, along with the engineers, “the unnamed men by whose unflinching courage, in the depths of the caissons,” the bridge had been built.