Correspondence and theories of J.C. Adams, A. d'Abbadie and Mr Sawitsch regarding geodesy. The papers includes a manuscript titled 'Observations made at Schiehallion June 1775' written by Dr Maskelyne and an assistant; a resumé of the career of Captain Basevi; plans of platforms for pendulums in a Russian observatory and in the Royal Society; a printed paper titled 'Gegenbericht an die permanente Commission der Europaischen Gradmessung' (Reply to the permanent European Commission on the size of the degree) by P.A. Hansen, with extracts from Italian newspapers; a galley proof of a paper on 'Gravitating Fluid Mass' by R.J. Adcock; papers on zetetic astronomy; and correspondence concerning pendulum experiments.