U.S.S. Cairo Engine and Boilers

The Cairo is the sole survivor of the fleet of river gunboats built by the Union during the Civil War to control the lower Mississippi River. Designed by Samuel Pook and built by James B. Eads, the 175-foot ironclad vessel carried 13 guns. Its 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 with a small bore, long stroke, and poppet valves. Designed by A.T. Merritt, this engine had a 22-inch bore and 6-foot stroke, developed about 800 horsepower, and drove a sheltered paddlewheel 22 feet in diameter and 15 feet wide.

Vicksburg, Mississippi · United States