The attached note states this iron was found in the debris of the Patent Office fire of 1877. There is considerable damage - the slug, wooden handle and bottom half of the iron are missing.
Patent Models are very collectible and rare. To learn more about the history of Patent Models in the United States, and about the destruction suffered after two fires in the US Patent Office, see the following article by Donald W. Hogan. Unwanted Treasures of the Patent Office. American Heritage Magazine, Volume 9, Issue 2, February 1958.