John A. Dahlgren Autograph Letter Signed (1863) - Sent to Mechanical Engineer Alexander Lyman Holley Civil War-dated ALS signed “J. A. Dahlgren,” one page, 7.5 x 9.5, May 9, 1863. Addressed from Washington, D.C., a handwritten letter to engineer Alexander Lyman Holley, in full: “As requested in one of your communications lately received, I enclose a paper in relation to Navy Guns, with brief remarks upon other prints connected with them generally.” Double-matted with an engraved portrait (bearing a facsimile signature) and a circular from the House of Representatives containing a “Letter from the Secretary of the Navy,” with an 1860 notice regarding Dahlgren an “armature of ships-of-war.” Framed to an overall size of 37 x 19; a window to frame backing reveals matting with additional Dahlgren-related material. In fine condition, with some light staining. Alexander Lyman Holley (1832-1882) was an American mechanical engineer, inventor, and founding member of the American Society of Mechanical Engineers (ASME). He was considered the foremost steel and plant engineer and designer of his time, especially in regard to applying research to modern steel manufacturing processes.