This primary source comes from the Records of the Office of the Chief Signal Officer.
National Archives Identifier:
525116Full Citation: Capitol of the United States, Washington, D.C; ca. 1860 - 1865; Mathew Brady Photographs of Civil War-Era Personalities and Scenes, 1921 - 1940; Records of the Office of the Chief Signal Officer, Record Group 111. [Online Version, https://docsteach.org/documents/document/us-capitol, October 13, 2024]