This primary source comes from the Records of the Patent and Trademark Office.
National Archives Identifier:
4531653Full Citation: Drawing of Improvements in Magneto-electric Telegraphs; 8/4/1863; Records of the Patent and Trademark Office, Record Group 241. [Online Version, https://www.docsteach.org/documents/document/drawing-of-improvements-in-magnetoelectric-telegraphs, March 28, 2024]