Correspondence with tradesmen, including letters from booksellers; coal merchants; clock repairers; horologists; builders; chandlers; merchants; draughtsmen; machine repairers; stationers; opticians; the Kent Water Company; parcel carriers; engineers; chemists; decorators; journeymen; and the Phoenix Gas Company. The letters cover instructions; requests; accounts; bills; receipts; invoices; circulars; tenders; routine repairs; and adjustments and improvements to instruments. There are letters from J.D. Forbes, J. Glaisher and C. Brooke, and pieces on a gas conversion for the Royal Observatory using an old water supply.