Correspondence with tradesmen, including letters from booksellers; coal merchants; clock repairers; horologists; builders; chandlers; merchants; instrument makers; opticians; parcel carriers; engineers; chemists; journeymen; decorators; bookbinders; the Post Office; machine makers; photographers; sculptors; picture framers; and the South Eastern Railway. The letters cover various instructions; requests; accounts; invoices; bills; receipts; tenders; circulars; routine repairs; and adjustments and improvements to instruments. There are also notes and letters from J. Glaisher, E. Dunkin, W.H.M. Christie and F.N.M. Moigno; correspondence on a spectroscope; and a German catalogue by the instrument maker G. Merz.