2. On the Diffraction Bands produced by Double Striated Surfaces

Extract

Having observed a series of serrated fringes in examining the colours produced by the fibres of the crystalline lens of fishes, the author was led to imitate them by the combination of grooves upon glass and steel surfaces, or of grooves taken from these surfaces upon isinglass or gums.

The interference bands thus produced were serrated or rectilineal, sometimes parallel and sometimes at right angles to the direction of the grooves, and varying in their magnitude and character according as they were exhibited on the colourless image, or on the diffracted spectra, or as they were produced at different angles of incidence, or at different distances of the grooved surfaces, or by different numbers of reflexion, or by different numbers and combinations of refracting and reflecting surfaces.