DAHLGREN, JOHN ADOLF (18o9-187o), admiral in the U.S. navy, was the son of the Swedish consul at Philadelphia, Pa., and was born in that city on Nov. 13, 1809. He entered the navy in 1826, and saw some service in the Civil War in command of the South Atlantic blockading squadron, but was chiefly notable as a scientific officer. His knowledge of mathematics caused him to be employed on the coast survey in 1834. In 1847 he was transferred to the ordnance department. In this post he applied himself to the improvement of the guns of the navy. He was the inventor of the smooth bore gun which bore his name, but was from its shape familiarly known as "the soda water bottle." It was used in the Civil War, and for several years afterwards in the U.S. navy. Dahlgren's guns were first mounted in a vessel named the "Experi ment," which cruised under his command from 1857 till They were "the first practical application of results obtained by experimental determinations of pressure at different points along the bore, by Colonel Bomford's tests—that is by boring holes in the walls of the gun, through which the pressure acts upon other bodies, such as pistol balls, pistons. etc." When the Civil War broke out, he was on ordnance duty in the Washington navy yard, and he was one of the three officers who did not resign from Con federate sympathies. His rank at the time was commander, and the command could be held only by a captain. President Lincoln insisted on retaining Commander Dahlgren, and he was qualified to keep the post by special act of Congress. He became post-captain in 1862, rear-admiral in 1863, and was in command of the Wash ington navy yard when he died on July 12, 187o.
A memoir of Admiral Dahlgren by his widow was published at Boston in 1882. (D. H.)