Correspondence with A. Auwers, Berlin, concerning Groombridge's Catalogue, 1901-1903, including copies of papers sent to him and Greenwich north polar distance observations and reductions.
Correspondence with Leopold Schulof, Paris, concerning catalogues and corrections, 1906-1908.
Correspondence concerning observations of heliometer comparison stars, 1898-1901.
Correspondence with Sir David Gill and H.H. Turner concerning the apparent rotation of bright stars with respect to faint ones, 1902.
Correspondence between H.H. Turner, Arthur Rambaut and the Royal Society concerning the re-reduction of Hornsby's observations and the Government Grant Committee, 1902.
Correspondence and other papers, 1904-1906, regarding the despatch of Breen's reductions of James Bradley's observations of 1743-1750 to A. Auwers, Berlin, and their return in 1906.
Correspondence with H.H. Turner concerning Oxford reference stars, 1906.
Correspondence with R.S. Ball concerning errata in the Cambridge Catalogue, 1906.
Errata in the Cape Catalogue sent to Greenwich, 1906.
Request from Kazam Observatory for the places of the stars from the 1900 Catalogue, 1906.
Correspondence with H.B. Hendrich, United States Naval Observatory, concerning the catalogue of zodiacal stars, 1907.
Request to the 'Berliner Jahrbuch', 1907, for the right ascensions of stars for 1910.
Correspondence with J.C. Kapteyn, 1907, regarding the spectrum of Groombridge, 1830.
Correspondence with E.C. Pickering, Harvard College Observatory, concerning photographic magnitudes, 1908.
Correspondence with Dr L. de Ball, Vienna, concerning the places of stars in the Greenwich Catalogue, 1909.
Correspondence with J.J. Cray, Worthing, concerning the stars to be observed for survey work in Egypt, 1909.
Letter from Christiana Observatory concerning the corrections for the Greenwich Catalogues, 1910.
Correspondence with A. Auwers concerning star places, 1911.
Correspondence with E.C. Pickering, Harvard College Observatory, concerning places for Jupiter's 8th satellite, 1911.
Letter from the Nautical Almanac Office regarding orbital motions of Sirius and Procyon, 1911.
Correspondence with Dr Schroeter, Austria, 1911, concerning the correct place for Groombridge 9144.
Correspondence with A. Auwers concerning the errors in the 1743 observations, 1911.
Correspondence with T.E. Heath concerning star tracks in space for 36,000 years, 1912.
Stereographs by T.E. Heath of tracks of the sun and stars from AD 1900 to AD 37900, 1912.
Correspondence with L. de Ball, Vienna, concerning places of stars in the Second 9-Year Catalogue, 1912.