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No. 2266:
The Cairo Rises

Today, ghosts in a river. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

The Monitor and Merrimack fought in 1862, about a year after our Civil War began. The South scuttled the Merrimack as they retreated from Norfolk. The Monitor sank in a storm off North Carolina. But the Union built a series of Monitor-class gunboats and made good use of them during the rest of the War. America kept on making them, right up to the First World War. 

While she built more Monitors, the Union was not about to put all her eggs in that basket, back in 1862. The Monitor design was still radical. In 1861, the Union had already adopted a more conservative ironclad design -- the so-called city class boat -- and she was now using it to assert control of the Mississippi Basin.

The city class Cairo was built by the same James Eads who built the monumental St. Louis Bridge after the War. A hundred and fifty feet long with a six-foot draft, these boats were driven by a protected interior paddle and jacketed with 122 tons of 2-1/2-inch iron plate. None had the Monitor'smodern gun turret, and they presented a slightly higher profile. Outwardly they looked more like the Confederate Merrimack.

The Cairo was launched early in 1862. For eleven months she saw action up and down the rivers, but nothing of real military importance. Then her rash young captain, Thomas Selfridge, took her up the Yazoo River, just off the Mississippi near Vicksburg. He meant to clear Confederate mines.

Cairo's dishwareBut when he came under Confederate fire he turned the boat, and hit a mine. The Cairo sank in 36 feet of water. Her crew escaped and, since the smokestacks stuck out above the surface, Union forces tore them off to hide the Cairo, and prevent Confederates from salvaging her. River mud soon filled in what was left, and there she lay for a century. 

Civil-War historians went looking for the Cairo in the late 1950s. They found her, and restoration began. The last of her reached land in 1965 and, what a rich view of Civil-War America her remains provide! Here's a river ironclad, armed, primed, and ready for combat, just as she'd been. Yet, while this is an artifact of military history, even more, it's a brilliant snapshot of mid-19th-century life -- all the commonplace texture: boots, combs, photographs, medical instruments, dishware. 

Cairo sewing and medicineWe can visit the reconstructed Cairo at the Vicksburg National Military Park. She makes a great example of one of the many sidetracks in the technology of modern naval slaughter. Rivers would not be major naval battlefields of the future. Unlike of things to come. 

But this byroad of human ingenuity, quite apart from either its purpose or its lack of influence, is beautiful and exciting. As we trace the sophisticated form, structure, engines, and drive systems, we are privileged to enter a forgotten memory of another world.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Here's the short history of Cairo on the Government site:

Anonymous authors, U.S.S. Cairo: The Story of a Civil War Gun Boat.Washington, D.C.: National Park Service.

This is a greatly rewritten version of Episode 280


Below: Cairo's prow, armor, and drive system. All photos by JHL

Cairo's prow

Cairo's armor

Cairo's drive system