Ministry of Defence Building L157 (Group C Incorporating Mills)

Details

ROYAL GUNPOWDER FACTORY TL3700 3/10022 MOD Building L157 (Group C Incorporating Mills) GV I

Gunpowder Incorporating Mills. 1861, converted for cordite incorporation c1898-9. English bond yellow brick with hipped slate roofs to Engine House and Boiler House; cross wings have brick walls separating the bays which continue as coped gables breaking through the felt and slate roof mid C20 replacement walling to originally wood and canvas side walls. T-plan: central Engine House with Boiler House at east end and cross wings on its north and south sides for gunpowder incorporating mills; these wings, originally of 2 bays, were each extended by the addition of a third bay soon after construction. One storey, with taller Engine House to centre. Chamfered brick plinth and brick dentil cornice to Engine House and Boiler House. Boiler House of 4x1 bays, the bays articulated by brick pilasters and each originally with segmental brick arches over windows with blind rectangular panels below (sills lowered and double doors inserted to easternmost bay in north elevation c1906-7); the windows were sashes except in the westernmost bay on both elevations where they were blind; wide doorway to east, with keystone to gauged brick semi-circular arch with fanlight. Engine House has semi-circular arched window with keystone to upper part of each elevation (glazed to north and south, originally blind and glazed 1906-7 to east and west); windows to lower part of north and south elevations inserted 1906-7. Interior: Boiler House has 9 trusses with wrought-iron tension rods, king rods, and decorative cast-iron compression members. The Engine House carried a steam engine to drive the edge runners in the incorporating mills. Cross wings have composite timber and iron roofs, 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. Cross-wing partition walls have I-section girders and blocked openings in gables which belong to shafting for machinery which was probably installed for cordite manufacture. There was an open verandah along the west front, from which cast-iron columns have survived. On the south side of the Boiler House was a coal yard containing a chimney at the centre of its west wall. The building was served by a tramline to the west. Incorporation - an extremely important process in gunpowder manufacture- involved the grinding and combination of saltpetre, sulphur and charcoal to form gunpowder. Waltham had pioneered many important developments in the process, and this building is the first steam-powered incorporating mill to have survived on the site (and most probably in the world); the drive shaft and machinery transmitting power to the mills was passed underneath the building to minimise the risk of explosion. The incorporating mills each consisted of pair of large heavy edge runners, of iron, which revolved on a large circular bed. The first and most complete of the incorporating mills to be built in the form of a T-shaped plan comprising a central Engine House, rear Boiler House and cross wings, thus providing a model for later incorporating mills on the site - L153 (qv) is an almost identical copy. (RCHME report, 1993).

Listing NGR: TL3773701167

Legacy

The contents of this record have been generated from a legacy data system.

Legacy System number:

352172

Legacy System:

LBS

Sources

Books and journals
The Royal Gunpowder Factory Waltham Abbey A Survey, (1994)

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