John Ericsson (1803-1889), designer of USS Monitor Born in the Swedish province of Vermland, Ericsson first worked helping plan a Swedish canal. While working on the canal, he was tutored in math and the sciences. He joined the Swedish army at age 17 and did topographical surveying. In 1826 he moved to London, where he showed the breadth of his engineering genius by developing or improving transmission of power by compressed air, new types of steam boilers, condensers for marine steam engines (so ships could travel farther), placing warship engines below the water line (for protection against shell fire), the steam fire-engine, the design and construction of a steam locomotive.   His most enduring invention was the screw propeller, which is still the main form of marine propulsion. Early methods of applying steam power at sea-steam-driven oars, paddle wheels-were inefficient and, for warships, vulnerable to enemy attack. In 1839 Ericsson introduced propellers to vessels on the canals and inland waterways and commenced building a `big frigate` for the US Navy. He designed and built the Monitor for the Union Navy in 100 working days. It demonstrated its superior design-steam-propelled screw propeller, low in the water, a revolving gun turret, and iron construction rather than wood-by defeating the Confederate CSS Virginia (Merrimac). Back to History Index Image Country Year Description United States 1926 John Ericsson memorial 1803-1889.Builder of Monitor submersible Sweden 1976 John Ericsson