TQ 76 NE CHATHAM MAIN ROAD (West side) Chatham Dockyard 762-1/8/79 Nos.4, 5 and 6 Slip Covers and Machine Shop No.6 GV I Slip covers. 1845-47, by Messrs George Baker and Sons. Cast and wrought iron frame with corrugated iron sides and roof. PLAN: rectangular plan with aisles, connected into a single cover over the three slips. Each of one storey; 10-bay range. Three wide gables with the frame exposed and 4 stages, open at ground-floor beneath a continuous glazed stage, 6-light second and 4-light third stages, with corrugated sheet gables, sides and roof, and folding doors. A 3-bay left-hand section connects with the No.3 slip cover (qv) has iron posts to a corrugated-iron upper floor with 3 metal-framed windows. INTERIOR: composite iron frames have I-section cast-iron columns with vestigial Tuscan capitals, a wide semi-circular arch across the slips, with principal rafters which extending out over the aisles, and segmental arches each side over the aisles, with diagonal braces, connected longitudinally by light trussed purlins. Various attached fittings for line shafting, and supports to gantry crane by G BUTCHARD/GRAVESEND. HISTORY: covers for ship-building slips were introduced from c1814 because of the rapid deterioration of wooden ships exposed to the weather during construction. The earliest all-metal covers were built at Pembroke in the early 1840s. The Baker roofs differ however from earlier slip roofs in relying less on the cantilever effect of the outside aisle roofs. They managed moreover to double the distance between the frames established by earlier roofs to 9.5m, connecting them and supporting the roof by light trussed purlins. An exceptionally early example of a complete iron frame, and an important landmark in constructional history (Newman). Earlier iron roofs (demolished) had been closely modelled on the patterns of the Seppings wooden roofs. Brackets for travellers were inserted in 1863. Forms a fine group with the 1837 timber slip cover to the S (qv) and the larger 1855 slip cover to the N (qv) and the other iron covers in the steam Dockyard to the N, all manifesting the remarkable progression in the development of free-standing engineering frames. (Sources: Coad J: Historic Architecture of Chatham Dockyard 1700-1850: London: 1982: 182 ; Coad J: The Royal Dockyards 1690-1850: Aldershot: 1989: 114-115 ; The Buildings of England: Newman J: West Kent and the Weald: London: 1976: 206 ; Newcomen Society: Sutherland RJM: Shipbuilding and the Long-Span Roof: Paper read at Science Museum: 1989: 15-17). Listing NGR: TQ7595169499