Correspondence with tradesmen, including letters from booksellers; coal merchants; clock repairers; horologists; chandlers; merchants; machine repairers; instrument makers; stationers; opticians; the Kent Water Company; parcel carriers; engravers; engineers; chemists; photographic supplier; decorators; the Phoenix Gas Company; journeymen; picture framers; bookbinders; assayers; gas fitters; slaters; and manufacturers of glass, metal fittings, stoves, porcelain and telegraph wire insulation. The letters cover instructions; requests; accounts; bills; receipts; circulars; tenders; invoices; routine repairs; and adjustments and improvements to instruments. The volume includes letters from J. Glaisher and C.V. Walker; a leaflet, in French, of mathematical equations; and plans for a corrugated partition at the Royal Observatory.