- Historic Sites
Mr. Eads Spans The Mississippi
The odds were all against him. His only credential seemed to be self-confidence—and who had ever heard of a steel bridge?
August 1969 | Volume 20, Issue 5
Back in St. Louis, Eads had soon begun work on a structure even more startling to rivermen than the socalled Submarines or the ironclads. In October, 1869, a huge, armored caisson, eighty-two feet long and sixty feet wide, was towed, rocking and swaying, to the site of the east pier, two thirds of the way to the Illinois shore. A flotilla of boats and barges waited, manned by 1,500 workmen and bristling with hoisting and pumping machinery. Lines, hoses, and cables were attached to the caisson. The caisson had no bottom, but its roof was extraordinarily thick, made up of several courses of heavy timber. Masons and carpenters clambered onto the massive roof and began to build the stone foundation of the pier. As they laid on limestone blocks and mortar, the weight caused the box beneath them slowly to submerge. One week after the caisson was launched, the cornerstone of the pier was laid. A few days later, the bottomless caisson struck sand.
Eads had provided seven air locks as entries to the working chamber for men and tools, and the carpenters and masons had constructed a spiral stairway through the center of the rising pier. Eads’s compressed-air workers—known today as sand hogs—descended the stair, entered an air lock, closed the door behind them, opened a valve, admitted enough air to equal the pressure in the working chamber, closed the valve, opened the opposite door, and entered the large, nine-foot-high chamber. Their task was to dig the mud and sand from under the caisson and shovel it into the lower end of a sand pump that Eads had designed to lift it to the surface and squirt it out into the river. Meanwhile the increasing weight of masonry above continued to press the caisson down through the river bottom toward bedrock.
As the caisson descended, the water pressure on its walls increased and had to be counterbalanced inside. The men worked well in the compressed-air atmosphere, but alter they left the chamber—sometimes while they were on the way home—several complained of acute stomach pains. One or two reported fleeting paralysis after emerging to the surface. After coming up from a depth of seventy-six feet, where the air pressure was thirty-two pounds per square inch, one man was doubled up with such severe abdominal pains that he had to be hospitalized. The men gave the strange ailment the name “the Grecian Bend,” after a contemporary fashion in women’s posture, and invented “cures” such as bands of zinc and silver around the wrists and ankles.
Eads, taking a more realistic view, noted that many of those suffering from the mysterious malady were underfed and alcoholic. He gave orders that only men in good physical condition should be employed in the working chamber. At the same time, he stopped night work and cut the working shift to three daytime watches of two hours each. These measures seemed to have some effect, and on February 28, 1870, the caisson was driven to bedrock at ninety-three feet below the directrix without further serious cases of “the bends.” Cannon boomed, and steamboats whistled up and down the waterfront.
The original working chamber was now bricked in till it was “the size of an Irishman,” at which point the last Irishman crawled out, the ladder was pulled up, and the last space bricked. But almost immediately the air lock had to be put back in use and a new working chamber created above the old one. The spring flood had caused the river to rise more rapidly than the upper part of the caisson could be filled in. Within days the air pressure had to be raised to forty-four pounds to match the increased water pressure.
Among the gang going down one morning was a new worker named James Riley. Squeezing down the narrow spiral stair in file, the men entered the air lock, waited for the pressure to equalize, and climbed down into the working chamber. At the end of two hours of hard work filling in the chamber, they re-entered the air lock, reversed the valves, and quickly reduced the pressure in the lock to normal. Stepping out, they climbed back to the surface. Riley told a fellow workman that he felt fine. The next moment he toppled over dead—America’s first caisson-disease fatality.
Horrified, Eads summoned his personal physician, a man named Jaminet, who fitted up an emergency hospital for other afflicted workers. Nevertheless, five more deaths took place in the next few days. Eads cut the working day to three one-hour watches. At Dr. Jaminet’s suggestion, he laid down strict rules on sleep and diet. This brought bitter complaints from the men, but the east pier was completed with no more fatalities.