Joseph Henry Letter to Stephen Alexander (April 26, 1861), by , , Smithsonian Archives - History Div, Letter from Joseph Henry, first Secretary of the Smithsonian Institution, to Stephen Alexander, his brother-in-law, April 26, 1861. In the letter, Henry describes the Civil War's effect on his daughters, Mary, Caroline, and Helen, and expresses worry about the unknown future of the United States. Henry and his family lived in the Smithsonian Institution Building, or "Castle," in the center of Washington, D.C., where many effects of the war were felt..