Correspondence with E.C. Pickering, Harvard College Observatory, 1884-1885.

Correspondence with Professor Newall and others concerning double stars and nebulae, 1892.

Undated memoranda and notes concerning double stars observed at Greenwich.

Undated listing of proper motions of astrographic reference stars from comparison with Carrington Catalogue 1850 in zones of N.P.D.

Correspondence concerning double stars and nebulae, 1896-1926.

Correspondence with various individuals concerning observations of double stars, 1896.

General correspondence concerning double stars, 1897, and a query on 1731.

Correspondence concerning double stars, 1898-1901, including M. Burnham on his catalogue and T.J.J. See on work on Capella (Alpha Aurigae).

Correspondence with E.E. Barnard concerning Capella (Alpha Aurigae), 1902.

General correspondence concerning double stars and nebulae, 1908-1911.

Correspondence with the Revd Espin, County Durham, concerning the discovery of a nebula in Ursa Major, 1913.

General correspondence concerning double stars, 1915-1926, including correspondence on the Vatican Observatory, and with E. Hertzsprung on double stars and a visit to Greenwich.

Correspondence with Sir A. Rumker concerning his paper on the distribution of secondaries in binary systems, 1913, with a copy of the paper.