Public domain
Reproduction of a patent grant. This particular one [happens] to be dedicated to the free use of the people
From the collection of Library of Congress. Free to download, adapt and use — no permission needed.
Credit lineReproduction of a patent grant. This particular one [happens] to be dedicated to the free use of the people. 1940-01-01. Harris & Ewing. Harris & Ewing Collection, Library of Congress. Public domain.