The patent US405117A, granted to John E. Purdy and Daniel A. Sadgwar on June 11, 1889, is for a folding chair. The invention’s goal was to create a cheap, strong, and durable chair that could be folded into a very small, portable size for easy carrying and storage.
The Invention
The chair’s design focuses on a highly collapsible structure, reducing its size in both length and width.
- Seat Frame and Flexible Seat: The chair has a seat frame composed of two longitudinal strips (A A). A flexible material like canvas or carpet (B) is secured to these strips to form the seat.
- Two-Part Folding Legs: The core of the invention is its unique leg design. The chair has four legs, with a pair hinged to each end of the seat frame. Each leg is made in two sections (C C) that are hinged together at the middle. This allows the lower half of each leg to fold up against the upper half.
- Abutting Joints: When the chair is extended for use, the two sections of each leg abut against each other at a beveled joint, forming a stable, X-shaped support. This design is a key to its strength, as the weight is transferred directly onto the abutting surfaces of the legs and not the hinges.
- Multiple Hinges: The chair uses a series of carefully placed hinges to allow for its compact folding:
- Hinge
c: Hinging each leg to the seat frame, allowing the entire leg to fold flat against the bottom of the seat. - Hinge
c': A hinge at the intersection of each pair of legs, allowing them to fold together. - Hinge
c'': A hinge within each leg itself, allowing it to fold in half.
- Hinge
- Bracing: The legs are held in their extended position by a system of braces (
a''), which pivot and lock into a catch. When folded, these braces fit into a groove on the bottom of the seat strip, further streamlining the package. - Compact Form: The final folded chair is “a remarkably small and compact bundle.” Its length is reduced to that of the seat frame, and its thickness is only the width of the frame and two overlapping legs, making it “convenient for carrying in a bag or shawl-strap.”
Significance of the Invention and Inventor
John E. Purdy and Daniel A. Sadgwar were two African American inventors who developed a very practical and elegant solution to a common problem. Their patent is a notable example of ingenuity and design.
- Practical Innovation for Travel and Recreation: The late 19th century saw a rise in travel and outdoor activities. Folding chairs were in demand, but many were bulky. Purdy and Sadgwar’s design addressed this by creating a highly portable chair that could be easily carried by “artists, tourists, etc.” This focus on convenience made their invention well-suited for a society on the move.
- Smart Engineering: The most significant aspect of the design is the way it combines multiple folding points with a load-bearing, non-hinged joint. By having the weight press on the abutting legs rather than the hinges, the inventors created a chair that was both lightweight and strong, overcoming a common limitation of folding furniture.
- African American Inventors: John E. Purdy and Daniel A. Sadgwar were among the many African American inventors of the era who made significant contributions to technology and industry despite facing significant social and economic barriers. Their patent, like that of Granville T. Woods and others, is a testament to their talent and perseverance. It is a historical document that highlights the diverse origins of American innovation.
