Correspondence regarding accounts held with various instrument-makers:

Correspondence with Troughton and Simms, 1898-1909, including a summary of the annual cost of cleaning instruments.

Correspondence with the Improved Electric Glow Lamp Company concerning the re-silvering and polishing of mirrors, 1899-1900.

Correspondence with Victor Kullberg concerning an estimate for the cost of repairs to Osler's anemometer, 1903.

Correspondence with Peter Heele, manufacturer of scientific instruments, concerning an instrument he wished to sell but which the Royal Observatory rejected, 1904.

Correspondence with Negretti and Zambra concerning a defect in a thermometer made by them and its repair, 1907.

Correspondence with the '"Vega" Societe Anonymede photographie' concerning a dark slide for observing the Sun, 1907.

Correspondence with Troughton and Simms concerning the late delivery of orders and an order for aluminium alloy rods, 1907-1908.

Correspondence with Siemens Brothers and Co. concerning a previous order and containing a new order for tungsten wire, 1913.

Bills and accounts from Troughton and Simms for the annual cleaning of instruments at the Royal Observatory, 1898-1909.

Correspondence with Elliott Bros. concerning the repair of 'The Wheatstone bridge and Galvanometer', 1914.

Correspondence with Sir Howard Grubb, Dollond and Co., Newton and Co., and Adam Hilger Ltd concerning the purchase of a small flat mirror for determining the flexure of instruments, 1914-1915.