ary Henry (1834–1903) was the second child and eldest daughter of Joseph Henry. She was twenty-seven when the war began, unmarried, and living in the Castle with her family. A photograph of her reveals a comely young lady, who, given her father’s prominence, would seemingly have had many opportunities to meet prospective suitors. Yet she never married. Between 1858 and 1868, Mary kept a diary, and her entries offer glimpses of how the Smithsonian functioned during the war years. She recounts the ongoing scientific activities of her father and the changes the city of Washington experienced as it coped with an escalating Union army in its midst. She wrote about the grandeur of the camps—the colorfully uniformed soldiers and the splendor of the officers—and about death and disease and the mud and squalor that invariably followed an army. Her descriptions of her brother’s fatal illness and last hours are especially poignant against the backdrop of war and underscore the frailties of the human condition in every time and age. See more