The Explainer General
Before work was begun, its designer, John A. Roebling, was making final surveys of the site. A docking ferryboat nudged a piling near him, driving a dirty nail into his foot. He died of tetanus 24 days later. His son, Washington Roebling took over the engineering project.
To sink the bridge tower foundations down to bedrock, workers excavated river silt inside two open-bottomed 3000 ton iron bases, caissons. High -pressure air pumps kept river water out. As the caissons were dug deeper beneath the river surface, air pressure grew higher; work became more dangerous. When they were digging near seventy feet deep, a few workers walked through the caisson air-lock at the surface, across the street to the tavern, and dropped down dead. The cause: nitrogen embolism—gas dissolved in blood under high pressure expanding rapidly at normal pressure. Scuba divers call it “the bends.” Washington Roebling, himself, was crippled this way but monitored the project through a telescope from his bed upriver. His brilliant wife, Emily Warren Roebling, managed construction on-site. Twenty to 30 bridge workers were killed in construction from nitrogen embolism, being struck by falling material, and by falls from the towers.
It was the longest suspension bridge in the world, with a river-span of 1595.5 feet. Anyone could cross: 1¢ for a pedestrian, 5¢ for a horse and rider, 10¢ for a horse and wagon, 5¢ for cows, 2¢ for sheep or hogs.
Only six days after its opening, the bridge was crowded with walkers when a rumor started that the bridge was collapsing! Strollers stampeded, killing 12, injuring 35 in the panic. Was the great bridge safe?
Months later, May 17, 1884, the great huckster and self-promoter P. T. Barnum set out to prove the solidity of the bridge “in the interest of the dear public.” Across the broad bridge paraded 21 elephants with Barnum’s famous African elephant Jumbo in the rear. They were followed by seven Bactrian camels (two-hump) and ten dromedaries (one-hump). Since elephant and camel fares had never been specified, no tolls were paid. The New York Times reported “…it seemed as if Noah’s Ark were emptying itself over on Long Island.”
If any doubts remained, Barnum’s ballyhoo proof put them to rest.
Jan Adkins is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.
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