Correspondence concerning improved instruments, new techniques and inventions, and a proposed planetarium and cometarium. The new inventions include improved sextants and sea horizons; a micrometer; a paper on finding Greenwich Time, complete with a drawing; achromatic eyepieces; an improved quadrant; drawings of eye pieces; a heliotrope; and an illuminating process for telescopes. The correspondents include Sir B. Donkin, Sir C. Wood, Sir H.G. Ward, Sir W. Denison, J. Challis, C.B. Vignoles, B. Peirce, W.H. Smyth, the Earl of Rosse, J.F.W. Herschel, W.R. Dawes, Sir F. Beaufort and A. de Morgan. There are articles from 'The Times' on Sir J. South's telescope; 'The Daily Advertiser' and 'The Liverpool Times' on the Earl of Rosse's Telescope'; and 'The Athaeneum'. There are also catalogues of instruments, observations of Draconis with a zenith tube, and a map of Cardiff.