John Ericsson was a Swedish-American inventor and mechanical engineer. He is perhaps best known for designing the Civil War ship U.S.S. Monitor, an ironclad warship with a revolutionary rotating turret. The John Ericsson papers consists of two letter-size folders of material and one oversize indenture. Included are letters, 1853-1879, written by Ericsson, primarily addressed to John O. Sargent.