Correspondence on new techniques, requests for advice and new instruments. There are requests for transit circles from the Portuguese government, Upsala, Sweden, and Albany, U.S.A.; a description by Airy of the Greenwich transit circle; experiments with mercury and photography, including two early pictures of the Sun; improved sextants and clocks; a 'universal instrument'; and an account of the instruments used by the ancient Chinese astronomers. The correspondents include E. Dunkin, possibly I.K. Brunel, C. Pritchard, O.M. Mitchel, W. De La Rue, C.P. Smyth, M.J. Johnson, the Earl of Rosse and R.C. Carrington. There is also a photograph and drawings of an equatorial instrument.