original hard to find unusually-shaped ornamental cast bronze eastlake style "brocade" pattern doorknob backplate with archtop

rare 1880's antique american eastlake style interior residential ornamental cast bronze vestibule door backplate fabricated by the p. & f. corbin co., new britain, ct. the popular "brocade" backplate was designed and patented by george s. barkentin in april of 1882. the hardware features a unique field pattern consisting of lightly incised circular rosettes. the surface patina is mostly uniform throughout. the oversized backplate with arch top retains the original swinging keyhole cover. salvaged from a chicago graystone residence undergoing demolition. backplate measures 8 1/2 x 2 1/2 inches.