Correspondence with tradesmen, initials N-W, including letters from booksellers; clock repairers; horologists; draughtsmen; instrument makers; opticians; parcel carriers; engineers; chemists; journeymen; iron founders; electrical suppliers; and chart sellers. The letters cover various instructions; requests; accounts; invoices; bills; receipts; tenders; routine repairs; and adjustments and improvements to instruments. There are letters from C.V. Walker and J. Glaisher; discussions on the equatorial clock; diagrams of the London and Greenwich clocks; a plan of a screw-cutting lathe; and the plan for the hold-fast for the equatorial dome.