This was mentioned by D Morgan Rees in Elis Jenkins' Neath and District: A Symposium (Neath, 1974), p.162:
'One of the most interesting of the drawings of the works' buildings is 'A View of the Roof of the New Fitting Shop at Neath Abbey Iron Works', to a scale of 1/4 in. to 1 foot. This drawing, which is dated 20 October 1818 [sic], lists the Cast-iron stays, the Purlins, the King post of Wrought Iron, the Tie Beam of D°, the Centre Piece, D° the Principles, a piece of Timber under the Principles, a plan of Principles and Purlins. Each item is shown in fine detail in this ink and water-colour drawing'.