Miscellaneous correspondence relating to optical instruments:

Correspondence with various engineering and optical instrument firms, 1919-1937, including estimates and accounts. There are sections on a double image star micrometer and diffraction grating for the Yapp 36-inch Refractor, 1936-1937; the grating for the 30-inch reflector, 1923-1925; and a new driving clock and various repairs to the 28-inch equatorial telescope and other instruments, 1919-1923.

Miscellaneous correspondence with scientists and instrument-makers concerning instruments at the Royal Observatory, including their design and the techniques used in their manufacture, 1923-1936.

Correspondence and papers, 1931-1939, regarding the purchase of a slit-less spectrograph from Adam Hilger Ltd of London for the 36-inch Yapp Telescope, including an initial specification and a specification of the spectroscope supplied to the Royal Observatory, Edinburgh; correspondence on the merits of various designs of spectrographs; and copies of accounts rendered by A. Hilger for payment.