Details
SU 6200 NE MAIN ROAD
(West off)
HM Naval Base
774-1/17/206 Block Mill & Nos 35 & 36 Stores
(Building No 1/153)
GV I
Alternatively known as: Brunel's Block Mill, HM NAVAL BASE
Two wood mills, block mill and pump house, disused. Of different builds, 1799-1806, planned by General Sir Samuel Bentham and probably designed by Samuel Bunce, architect, with James Sadler arranging the power system. Built above basin of 1691-8 by Edward Dummer which Bentham covered over and inserted a storage floor within in 1799. Later alterations. Red brick, some parts with blue headers, in English bond; ashlar dressings, and gauged brighter-red brick flat arches. Hipped slate roofs, north range roof altered to gabled roof, probably early C20. PLAN: 3 parallel ranges, the later block mill to the middle.
EXTERIOR: north and south ranges (the formerwoodmills) of 3 storeys with cellar, 3 x 11 bays; central block mill of 1 storey, 3 x 13 bays (projecting at east end), built in between the north and south ranges and with a walkway running across it to link the 2 latter at 1st-floor level. Windows are mostly replacement small-paned pivoting windows with flat brick arches and projecting stone sills. Board doors with small-pane overlights. Ashlar plinth and 1st-floor band. Stepped dentilled brick eaves band. Coped parapet to south range. West elevation: central door to ground floor of south range; 4 continuous doors to ground floor of north range and central loading door to upper floors, that on 2nd floor with wooden platform and crane. Central range has central sash and flanking doors set in round-arched recesses with continuous impost band; corniced pediment with small-paned lunette. East elevation: similar. Central range has bricked-up windows in recesses, 2 windows to left return, window and door to right return. South range has 2 old board doors on ground floor; north range 3 round- arched doorways to ground floor, the central one blocked, central loading doors to upper floors, and 16-pane sashes to 2nd floor. South elevation (south range): 2 entrances on ground floor; central loading doors on upper floors; lamp bracket on left corner at 1st-floor level.
INTERIOR: wooden columns, turned in central range, square and chamfered in north and south ranges, support large-scantling cross-beams, in south range probably original stair survives (in north-east corner) having large scantling plain balusters. Remnants of the former power transmission equipment include overhead shafting, pulley wheels and belts. Some fixed machinery (lignum vitae saw, treenail machine and cornering machine) remains on the first floor of the north range, and in the Wend of the S range is the frame of the c1800 Boulton and Watt beam engine. HISTORY: Bentham infilled the 1690s basin with a double tier of brick vaulting, the basin continuing in use as a reservoir (and still functioning as such today) with a storage floor above. This can be seen still, beneath the south range, having brick vaults carried by segmental- arched arcades, and a stone flag floor with drains. The C17 dock walling also survives, being formed of large blocks of tooled masonry, and with a projection at south-west corner (possibly the base for a sheerleg crane) and machinery for No.1 Penstock. The Mill was purpose-built for the innovatory block-making machinery, designed by Marc Brunel1801-1806 and constructed by Henry Maudslay. The innovation was highly successful. By 1806,45 machines and 10 men were producing 140,000 blocks a year (for ships' rigging), and the capital costs were recovered within three years. Built for both dock pumping and wood working, using the navy's first steam engine, the Block Mills is of international significance as the earliest application of steam-powered machine tools for mass production.
(Sources: Coad j: The Royal Dockyards 1690-1850: Aldershot: 1989: 31, 225-233 ; Lloyd DW: Buildings of Portsmouth and its Environs: Portsmouth: 1974: 70; The Buildings of England: Lloyd D: Hampshire and the Isle of Wight: Harmondsworth: 1985: 415; The Portsmouth Papers: Riley RC: The Evolution of the Docks and Industrial Buildings in Portsmouth: Portsmouth: 1985: 13-14; Winton j: The Naval Heritage of Portsmouth: Southampton: 1989: 104).
Listing NGR: SU6299200361
