Washington Roebling, the engineer in charge of building the Brooklyn Bridge, went down into one of its caissons in 1871 to see for himself the conditions his men were working in. He came out with an extreme case of what the workers called caisson disease, and he remained paralyzed for the rest of his life. He was neither the first nor the last victim. The disease had followed a new building method 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 a huge chamber filled with compressed air. It was used to build the piers and foundations that hold a bridge in place in a river. Men dug at the bottom while the air pressure kept the water out. The method was faster and cheaper, but it had a hidden cost. Workers in the caissons of this period labored at pressures as high as 55 pounds per square inch above normal, and the disease was common. Today it is called decompression sickness. When the pressure around a person drops quickly, nitrogen dissolved in the blood and tissues can form bubbles, causing joint pain, breathlessness, itching, confusion and seizures.
Roebling had started work in May 1870 on a bridge 1,600 feet long that would connect Manhattan and Brooklyn. Its caissons were larger than any built before, three times the size of those used for the bridge then being built across the Mississippi at St. Louis. The project had been planned 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 engineer. In 1840 he pumped compressed air into a chamber with an open bottom so that miners could dig for coal below the water level in the Loire Valley. His chamber produced the first known injuries from compressed air. Later, two doctors he hired, B. Pol and T. J. J. Watelle, recorded breathlessness, pain and itching in many workers leaving a caisson. Pol fell ill himself. The two men correctly linked the illness to the speed of decompression, and 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 deep below the Mississippi. Many men came out bent over in pain, a posture that reminded people of the Grecian Bend, a fashionable way for women to stand, so the sick men were said to have “the bends”. By the end of the project nearly a quarter of all workers had suffered from the disease, and 13 had died. A local doctor, Alphonse Jaminet, set up an infirmary on a barge beside the works, one of the first workplace clinics in America. He went down into the caisson himself and set standard rates for entering and leaving it. By modern standards his decompression was very fast, but controlling its speed at all was a step toward prevention.
At Brooklyn, the men were cared for by Andrew H. Smith, a doctor who specialized in diseases of the throat. He recorded 86 cases of caisson disease and treated them with morphine or atropine, but because the cause was still unknown he could do little to prevent it. He noticed that most of the men affected were overweight. A 2024 review in the journal Laryngoscope concluded that, although Smith misunderstood the disease, his strict standards and timely treatment allowed the bridge’s stone towers to be completed.
Roebling, meanwhile, was facing the limits of his own design. Worried by the rising number of injuries and deaths, he finally stopped the digging at 78 feet, short of the 100 feet thought necessary to reach bedrock. Against advice, he set the Manhattan tower on sand.
Someone else carried part of the work to the outside world. In May 1883, a Sacramento newspaper reported that representatives of mills hoping to work on the bridge had travelled to New York to consult Colonel Roebling. They were greatly surprised when Mrs. Roebling sat down with them and, using her knowledge of engineering, helped them with their patterns and solved their difficulties. The bridge opened that same month.
Abram S. Hewitt, who spoke for the city of New York, gave a speech about 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 the family had paid: the bridge’s planner had died, and the engineer who finished it had been left with a terrible disease.
The explanation came from the French scientist Paul Bert. He showed that the disease was caused by rapid decompression and recommended slower decompression, pure oxygen for minor symptoms, and immediate recompression for paralysis. These three practices are still the basis of treatment today.
None of this reached the men under the East River in time. Hewitt 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.