Marked Norwalk Lock Company Sept. 3, 1873. But patent #142,451 by H.H. Elwell for stem design has the date Sept. 2, 1873. Made of Silica Diatite patent #85018, Dec. 15, 1868 by  J.M. Merrick. Found with rose patent #113,842,  December 10, 1873 also by H.H. Elwell. Marking is visible on rear of knob and inside the rose.Shown in the 1876 Norwalk catalog page 262 as Grape Vine Pattern. Made with Silica stem (below) and with cast iron stem. Click on each photo below to view additional images and information.