Miscellaneous scientific works and correspondence on comparisons of Earth currents; the Australian telegraph; the Earth's axial wobble; various earthquakes, including the Sussex earthquake of 1864; a paper by G.P. Bond on a new form of the achromatic object-glass; T.W. Webb's paper on Dr Draper's telescope; observations of the spectra of stars from a balloon ascent by J. Glaisher; a French article by Camile Flammarion on spectral analysis from 'Le Siècle', 12 January 1866; 'Discrimination of organic bodies by their optical properties' by G.G. Stokes; work on lighthouse illuminations; J.F.W. Herschel's paper 'on light' (double refraction and polarization); a piece from 'The London Review' on the relation of light and colour; and a method of squaring the circle by W. Houlston, with various literary quotations and other ways of squaring the circle. The correspondents include A. de Morgan, W.H. Miller, E.J. Routh, E. Sabine, A. Martin, G.E. Paget, J.F.W. Herschel, D. Brewster, W. Huggins, the Earl of Rosse, W. De La Rue, R.S. Newall, C. Pritchard, E. Guest, Lord Wrottesley, R.I. Murchison, C. Lyell and C.F. Varley.