Correspondence with tradesmen, including letters from booksellers; coal merchants; clock repairers; horologists; builders; merchants; draughtsmen; instrument makers; stationers; opticians; the Kent Water Company; parcel carriers; engineers; chemists; decorators; the Phoenix Gas Company; printers; journeymen; ironmongers; manufacturers of gas appliances; an upholsterer; and a picture framer. The letters cover instructions; requests; accounts; bills; receipts; circulars; tenders; invoices; routine repairs; and adjustments and improvements to instruments. There are letters from T. Jones, J. Glaisher and B. Donkin; letters concerning a proposed twenty-four hour electric clock outside the Royal Observatory; and correspondence with the Birmingham Plate Glass Company and the Electric Telegraph Company.