Geodetic equations based on the 'Longitude of Valentia' (Valencia) project. The papers include personal equations and geodetic formulae; a diagram of the triangulation employed; angles of places from Butser Hill, Hampshire, and other locations; abstract of latitudes, longitudes and azimuthal bearings; schemes and instructions for the reductions of the observations; and an account of the whole project in draft form by Airy, missing several pages.