Correspondence on instruments used in observing the transit of Venus. The correspondents include J.C. Adams, J. Challis, W. De La Rue, G. Forbes, Messrs C. Frodsham and Co., Messrs Dent and Co., J.H. Dallmeyer and C.J. Corbett. The papers include lists of clocks, with some of their rates; a list of telescopes used in the transit of Venus observations; plans of plate holders for photoheliographs; two photographs of the Corbett 6 1/3" Equatorial Telescope; drawings and a diagram from a newspaper concerning the transit of Venus model; a manuscript of a paper by G. Forbes on 'The appearances presented by the model transit of Venus, mounted at the Royal Observatory, with a cloudy sky'; a paper by W. De La Rue 'On a piece of apparatus for carrying out M Janssen's method of time - photographic observations of the transit of Venus'; and general correspondence on the lending and returning of instruments.