One of Joseph Henry's Daughters as a Child, by Unknown, c. 1830s, Smithsonian Archives - History Div, One of the three daughters of Harriet Alexander and Joseph Henry, physicist and first Secretary of the Smithsonian Institution from 1846 to 1878. The Henrys had one son, William Alexander, born 1831, and three daughters, Mary Anna, born 1834, Helen Louisa, born 1836, and Caroline, born 1839..