(ĕr'ĭksӘn), 1803–89, Swedish-American inventor and marine engineer, b. Värmlands co., Sweden. He moved to London in 1826, and entered the railroad locomotive Novelty in a contest in 1829, only to be defeated by George Stephenson's Rocket. Ericsson's outstanding role in the development of the screw propeller (he patented one in 1836) for ships was responsible for his coming to America in 1839 to build for the U.S. navy. The U.S.S. Princeton, completed by him in 1844, was the first warship with a screw propeller. Unfortunately, one of the ship's guns, which he did not build, exploded and killed several dignitaries, and he was blamed unjustly for the disaster.
Ericsson is chiefly remembered as the designer and builder of the Monitor, a radical departure from previous types; and its fortuitous conflict with the Virginia during the Civil War, less than five months after its keel was laid, caught the imagination of the people and made Ericsson a hero (see Monitor and Merrimack. With his associates he was busy the remainder of the war designing and building other ironclad vessels, and after the war he built monitors for other governments until the type was abandoned. He also constructed gunboats for Spain, and worked on a “destroyer” with successful devices for releasing torpedoes underwater, but he could not interest the U.S. government in it.
Ericsson made many other contributions to engineering, notably in ordnance, in marine engines, and in caloric or heat engines. In his late years he did experimental work in solar physics.