Correspondence on instruments used in observing the transit of Venus. The correspondents include W.B. Birt, A.V. Auwers, A. de Morgan, W. De La Rue, W. Huggins, J.N. Lockyer, Miss Naylor, Mr Troughton and W. Simms. The papers include thermometer examination certificates issued by Kew Observatory; lists of instruments used in the transit of Venus observations; reports on the Altrincham (Naylor) and Hartwell (Lee) Equatorials; an illustrated single page catalogue of the theodolites made by Mr Troughton and W. Simms; diagrams from Airy on a 'Frame for Photograph Glasses'; and general correspondence on the lending and receiving of instruments.