Correspondence and research papers on optics, with associated calculations. The correspondents include, among others, W. Whewell, J.F.W. Herschel, B. Stewart, A. de Morgan, B. Powell, J.W. Lubbock, W.R. Hamilton and M. Faraday. There are papers concerning B. Powell's findings on forming spectrums, light rays in various conditions and refractive indices; W.R. Hamilton on quartz theory and polarity of the spectrum; J.D. Forbes on J.W. Cubbuch's radiant heat experiments; Airy's 'diffraction for an annular aperture' (various calculations and experiments on diffraction); M. Faraday's magneto-luminous experiments, with Airy's comments on such experiments and on magnetism in general; an optical illusion in fabric; a piece on H. Coddington's microscope and the construction of a microscope by E. Clarke; and W. Ritchie's improved manufacture of glass lenses, with H. Warburton's endorsement of the technique.