Miscellaneous correspondence and some related papers on pure mathematics and other subjects. The correspondents include, among others, J.G.S. Lefevre, J. Phillips, G. Cayley, H. Ellis and F. Beaufort. There is material on integrated equations; squaring the circle or the quadrature of the circle; a calculating machine; the tides and the Moon; an experiment to show the rotation of the Earth by means of a pendulum, with a paper by B. Powell for the Royal Institution of Great Britain; a piece by E.H. Rowland in 'The Carlisle Journal' on the rotation of the Earth; other pendulum experiments; a machine for measuring the Earth's revolutions, with a watercolour picture; J. Ferguson's fortifications and defences in Southern England; and writing by C. Lyell on the movement of shingle. There is also a letter by Airy to 'The Examiner' on the economic depression in 1847.