US Patent 519,333 for a window frame and sash design, co-patented with Albert B. Harrington.
On May 8, 1894, Margaret Knight received US Patent 519,333 for an improved window frame and sash mechanism, developed jointly with Albert B. Harrington. This invention addressed practical issues in the construction and functionality of window frames, likely improving ease of operation, sealing, or structural durability.
This patent stands as further evidence of Knight's extraordinarily diverse inventive output. By the mid-1890s, in her mid-fifties, she had already secured patents in paper manufacturing, domestic goods, and shoe machinery; this venture into architectural hardware shows her continued willingness to apply her mechanical reasoning to entirely new domains of everyday life and construction.
Collaborative patents such as this one, shared with a named co-inventor, were relatively common in Knight's later career, suggesting she often worked within engineering partnerships or consulting arrangements rather than solely as an independent inventor. Though this particular patent did not achieve the widespread commercial fame of her paper-bag machine, it forms part of the broader mosaic of a working inventor's life — one in which not every patent becomes a landmark, but each represents genuine problem-solving and technical contribution across the built environment of industrializing America.