Ministry Of Defence Building L149 (Group E Incorporating Mills)

ROYAL GUNPOWDER FACTORY TL3700 3/10020 MOD Building L149 (Group E Incorporating Mills) GV II* Building in two main phases, the core built c1869 as "Pellet Powder Buildings" comprising an Accumulator House, Engine House and Boiler House; converted into incorporating mills in 1877-8. English bond yellow brick with red brick dressings; slate roofs. T-shaped plan: originally a roughly square plan. In 1877-8 the coal yard walls were demolished, the rest of the structure; a new Boiler House was built at the rear of the Engine House and a new coal yard was formed which incorporated the earlier chimney; 3-bay cross wings for incorporating mills added to north and south; Pump House added between 1878 and 1895, extended c1904, on north side of Boiler House. One storey, with taller Engine House to centre having brick dentil cornice and pilasters. Accumulator House has datestone 1887-8, probably recording a rebuilding, semi-circular arched doorway, paired semi-circular arched windows to each elevation with false machicolation pattern of bricks above and to corbelled-out cornice. 1877-8 Boiler House of 4xl bays, the bays articulated by pilasters and the 3 eastern bays on the north and south elevations each containing a pair of semi-circular arched windows with red brick heads and drops, in a style similar to that of the Accumulator House; rubbed red brick semi-circular arch to eastern end. Cross wings each of3 bays, the original insubstantial walling having been replaced. Pump House, added to centre of north elevation of the Boiler House, has semi-circular headed windows to north elevation and square windows to east and west sides. Interior: Boiler House has trusses with wrought-iron tension rods, decorative cast-iron compression members and cast-iron ventilators. Cast-iron columns on the outer west side of the cross wings originally formed part of an open verandah which had ends of corrugated iron. Composite timber and iron roofs to cross wings, the relatively insubstantial fabric being easily replaced should an explosion occur; a drenching apparatus, erected over each pair of runners, would also have been activated. The original gearing for the incorporating mills survives in a chamber below ground level, the manufacturing process being identical to that carried out in L157 (qv), upon which the later incorporating mills were modelled. The accumulator provided hydraulic power to press gunpowder in pellet forms, which resulted in more consistent performance and was particularly important component of the technology of the large-bore guns being developed in this period. (RCHME report, 1993).

Listing NGR: TL3774301289