This primary source comes from the Records of the Patent and Trademark Office.
Full Citation: Samuel Morse's Telegraph; 4/11/1846; Utility Patent Drawings, 1837 - 1911; Records of the Patent and Trademark Office, Record Group 241; National Archives at College Park, College Park, MD. [Online Version, https://www.docsteach.org/documents/document/samuel-morses-telegraph, April 18, 2024]