On the reproduction and ruling of diffraction gratings

Abstract
New methods of copying ruled diffraction gratings are described. Copies of gratings can be made in hardened gelatine, and the technique of preparing such gratings and their advantages over pyroxyline replicas are discussed. Replicas on flat glass coated with gelatine can also be made from gratings ruled on cylinders. Cylinders ruled on a lathe are not sufficiently accurate but a method is described by means of which periodic errors can be eliminated.