Pressure Filter Clayton and Holdroyd Original Patent Lithograph 1888

Pressure Filter Clayton and Holdroyd Original Patent Lithograph 1888


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DESCRIPTION:

On this original linen-backed lithograph from 1888, H. F. Clayton and G. H. Holdroyd patented a pressure filter. The filter-medium in the lower longitudinal cylinder is contained between two horizontal gratings. Above this cylinder are arranged hollow perforated cylinders, each of which communicates with the lower cylinder by a nozzle, upon which it is pressed by a top cap regulated by a hand-screw. Each of these cylinders are covered with either externally or internally with filtering-cloth.

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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