U.S.S. Cairo

The Cairo is the sole surviving river gunboat from the fleet the Union built during the Civil War to control the lower Mississippi River. Designed by Samuel Pook and built by James B. Eads, the 175-foot ironclad carried 13 guns. Its propulsion system is the only known early example of the widely used Western Rivers steamboat engine, with multiple fire-tube boilers sharing steam and mud drums and a two-cylinder non-condensing 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 600 horsepower, and drove a sheltered paddlewheel 22 feet in diameter and 15 feet wide.

Vicksburg, Mississippi · United States