Screw Propellers Stead & Roberts Original Patent Lithograph 1888
On this original linen-backed lithograph from 1888, J. Stead and T. L. Roberts patented improvements to screw propellers. The blades, of which there are preferably four, are made of the shape shown, i.e., with their greatest breadth about the middle of their length.
All patent lithographs sold by Maymont Group are 100% ORIGINAL.
These documents are NOT reproductions or posters (patent art).
These are the original lithographs found in books obtained from the Patent and Trademark Office directly.
In the 1800's and early 1900's, inventors would submit a detailed drawing of the invention and/or improvements to the patent and trademark office. Once received and if approved, the Patent office would then send a letter of confirmation to the inventor and begin to take that drawing and etch it into stone in order to create and print this linen-backed lithograph. These documents are the original hard copies that were created by the patent office's artists, and act as patent examiner reference material. With that being said, these are 100% original and are the only physical copies in existence.
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