This primary source comes from the Records of the Patent and Trademark Office, 1836 - 1978.
National Archives Identifier:
7451803Full Citation: Patent Drawing for T. A. Edison's Magneto or Dynamo Electric Machine; 6/14/1881; Records of the Patent and Trademark Office, 1836 - 1978, Record Group 241. [Online Version, https://www.docsteach.org/documents/document/patent-drawing-for-t-a-edisons-magneto-or-dynamo-electric-machine, May 2, 2024]