#143 USS Cairo Engine and Boilers


Sole survivor of the fleet of river gunboats built by the Union during the US Civil War


The Cairo is the sole survivor of the fleet of river gunboats built by the Union during the Civil War with the object of controlling the lower Mississippi River. Designed by Samuel Pook and built by James B. Eads, it saw limited battle and was sunk on the Yazoo River in 1862 by newly developed electronically detonated mines, becoming the first craft ever sunk by this predecessor to torpedo technology. The 175-foot ironclad vessel had 13 guns. The Cairo was sunk within 12 minutes, burying much of its gear and armaments and thus preserving a unique view of the Civil War in the river silt for more than 100 years.

The propulsion system is the only known early example of the widely used "western rivers" steamboat engine, characterized by multiple fire-tube boilers with shared steam and mud drums and a two-cylinder noncondensing engine having a small bore, long stroke, and poppet valves. This engine was designed by A. T. Merritt. With a 22-inch bore and 6-foot stroke, it developed about 600 horsepower and drove a sheltered paddlewheel of 22-foot diameter and 15-foot width.

The Cairo was raised in 1964 and restored by the National Park Service. It, along with its artifacts, is exhibited at the Vicksburg National Military Park.

USS Cairo Engine and Boilers

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Landmark Location

Vicksburg National Military Park
3201 Clay Street
Vicksburg, MS 39180

Visiting Info

Regular hours: daily 8:30 am-5 pm

Ceremony Notes

June 1990

Comments from Visitors/Members

1994 Survey: Brian Blanche, 2/16/94--telephone number added (601-636-2199)

1992 Survey: Andrew C. Taylor, 3/6/92-- The attention to detail and the level of scrutiny that have gone into the restoration of the USS Cairo, including its engine and boilers, cannot be overemphasized. After walking across the gangway into the Cairo's hull, the port engine is easily accessed for close-up viewing. The National Park Service has put up individual placards that describe the separate functions of the boilers, the mud tank, and the engines.

The Cairo (pronounced "kay-roe") is surrounded by the Vicksburg National Military Park. The Civil War is dramatically documented throughout this part and the adjacent cemetery. This documentation serves to highlight the state of industrial development at the time of the Cairo's construction and provides an excellent background for a student of mechanical engineering history.

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