Theories of the Sun, Moon and planets, including letters from C.E. Delaunay on lunar acceleration; lunar theory and tables; an enquiry by Airy on the state of Delaunay's investigations after his death, with a letter of reply from A. d'Abbadie that includes a report on Delaunay's death; letters from J.C. Adams on some points of Delaunay's lunar theory; letters from M. Souillant on his theory of Jupiter's satellites; correspondence and calculations on the transit of Venus, 1882; a letter from Mr Ince on the number of days between midsummer 606 and midsummer 1866; tables of epochs of the Sun and Moon; a note on Kruger's determination of the mass of Jupiter; C. Pritchard's calculations on the retardation of the Earth's rotation; and letters by H. Breen, S. Newcomb, U.J.J. Le Verrier, J.R. Hind, Mr Todhunter, etc., on other matters to do with the Sun, Moon and planets.