Correspondence with tradesmen, including letters from booksellers; coal merchants; horologists; builders; chandlers; merchants; draughtsmen; instrument makers; stationers; the Kent Water Company; parcel carriers; engineers; chemists; photographic suppliers; decorators; the Phoenix Gas Company; journeymen; an ironmonger; a manufacturer of gas appliances; and an upholsterer. The letters cover instructions; requests; accounts; bills; receipts; circulars; tenders; invoices; routine repairs; and adjustments and improvements to instruments. There are letters from J. Glaisher, J.D. Forbes, C.V. Walker and S.H. Christie, and a piece on N. Arnott's self-acting ventilator.