Letters and papers concerning new inventions; trials of existing and improved instruments, especially the transit circle, altazimuth and equatorial telescopes; improved techniques; and adjustments to various instruments. The correspondents include W.H.M. Christie, G.G. Stokes, J. Glaisher, Sir D. Gill, C.V. Walker, G.M. Whipple, W. De La Rue, W. Huggins, A.C. Ranyard, F.A.T. Winnecke, J.T.R. Robinson, A.V. Auwers, A. d'Abbadie, Y. Villarceau, J.R. Hind, W.B. Clarke and Sir W. Thomson. There are pieces on a new sidereal clock; a proposed spectroscope for Greenwich; instrument catalogues; the mechanism of governors for telescopes; recording sunspots; 'Summer's Method' of navigation in 'The Mercantile'; and various ways of finding longitude and determining a ship's place from observed altitudes by Sir W. Thomson in the 'Nautical Magazine'. There are also four photographs of telescopes.