Correspondence with tradesmen, including letters from booksellers; coal merchants; clock repairers; horologists; builders; chandlers; merchants; instrument makers; stationers; parcel carriers; engineers; chemists; journeymen; decorators; bookbinders; import agents; the Post Office; machine makers; customs; telegraph companies; the India Rubber Company; the Gutta Percha and Telegraph Works Company; the Kent Water Company; 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 weekly work reports by the Clerk of Works; a German prospectus for an astronomical theory by G.V. Schiaperelli; and notes by W.H.M. Christie and J. Glaisher.