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's modern 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.
But 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.
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:
http://www.nps.gov/vick/u-s-s-cairo-gunboat.htm
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

The Engines of Our Ingenuity is
Copyright © 1988-2006 by John H.
Lienhard.