Former Engine House and attached boiler houses and coal store, New River Head, Clerkenwell, London

Summary

Pumping engine house with attached boiler houses and coal store. Engine house built in 1768 under the supervision of Robert Mylne, Surveyor to the New River Company and extended by him in 1786. Remodelled and extended 1794-5 under William Chadwell Mylne, with subsequent additions and alterations of 1811-18 and 1845-9. Boiler houses rebuilt and coal store added 1845-9. The late-C19 lean-to structure to the east end of the coal store is not of special interest.

Description

MATERIALS: engine house in brown stock brick; 1840s additions in yellow stock brick, both with much C20 patching; stone cills and coping; slate roofs; 1840s cast-iron frames to most windows.

PLAN: the engine house has a D plan. The internal compartments are essentially as existing in 1794-5, with some breaches in the walls, and comprise the 2-chamber engine house of 1763 at the core minus its north wall; flanking engine chambers of 1786 and 1794-5 to the south-west and south-east and a large curved pump room to the north. Stair tower to west, conjoined single-storey boiler houses to south and east, and a single-storey coal store range to the east, all dating from 1845-9.

EXTERIOR: the engine house has plain brick banding between stages. The curved north elevation has a tall round-arched window with radial cast-iron glazing bars, an 1840s insertion. Upper windows have segmental arches. The east elevation has paired windows; round headed to the lower level and segmental to the upper. The blind south elevation incorporates at its centre the only outwardly visible element of the 1768 engine house; this has a blocked window (inserted in 1786 to light a short-lived stair). The flanking walls have flat, much rebuilt buttresses and upswept parapets. The west elevation retains brickwork from the 1786 extension including a pair of offset buttresses; the entrance was enlarged in the C20; above are segmental-arched windows. The stair tower has a string-course to the parapet and round-arched windows; the upper blind. Ground-floor entrance enlarged in the C20. The walls to all elevations have numerous curved iron tie-rods. The roof is surmounted by the octagonal brick structure which once supported a metal cylinder, now with a timber louvred cupola.

The boiler houses have low hipped roofs; that to the south-west with a glazed ridge. The west elevation has two windows with cambered gauged-brick arches; the lower part has been remodelled in the C20 with inserted openings. The south elevation is blind with three offset buttresses. The south-east boiler house has a series of inserted late-C20 louvred openings on the south side and a round-arched doorway on the east side. The north elevation adjacent to the coal store has been rebuilt. The coal store has a hipped roof with a glazed ridge. A brick lean-to structure along the south elevation was removed in the 1950s. The elevation has seven arcaded bays, now blocked; three with cast-iron windows. The north elevation has been altered and has a large opening with a concrete lintel.

INTERIOR: the engine house’s elaborate cast-iron stair of 1848–9 was supplied by Henry and Martin De La Garde Grissell of Regent’s Canal Ironworks, leading manufacturers of structural ironwork from c1841. Remnants from the 1845-9 stage include some substantial cast-iron girders, pocketed to carry the ends of floor beams in the west engine-house, and of I-section in the north chamber of Smeaton’s building, to support cisterns or condensation tanks for preventing steam loss. The boiler houses and coal store have light wrought-iron roof trusses but retain no fittings of interest.

History

The New River Head takes its name from the terminus of the New River, the 40-mile channel cut in 1604-3 to supply the City of London with water from springs in Hertfordshire, a civil engineering achievement vital to the development of the metropolis. It was directed by the City magnate, Hugh Myddelton, who became the first Governor of the New River Company (NRC) when it received its royal charter in 1619. From the high ground of rural Clerkenwell a network of wooden mains conveyed water to the cisterns of London. The site initially comprised a reservoir - the Round Pond - and a single building known as the Water House containing the stop-cocks and accommodation for the site supervisor; over time it expanded to some seven acres.

The engine house's complex evolution reflects the pace of technological advance and the challenge of supplying water to the expanding metropolis in the face of strong competition. In 1708, the NRC built a new reservoir, the Upper Pond, some 350m to the north-west in what is now Claremont Square, the higher ground providing a greater head of pressure to enable distribution to more distant areas in and around the West End. Water was pumped here from the Round Pond by a windmill whose base still survives, but this proved ineffective and was superseded c1720 by a horse engine. The problem of supplying the Upper Pond continued however and in 1766 the NRC engaged John Smeaton, a prominent engineer, who designed a Newcomen-type engine of unusually long stroke, his first steam engine, which was erected in 1768 under the supervision of Robert Mylne, Surveyor to the NRC. The engine house, a tall, heavily buttressed brick slab with two octagonal turret stacks, comprised two chambers housing a pump and a cylinder to the north and south respectively, plus a lean-to boiler house to the south. The engine proved inadequate however and had to be supplemented by a water wheel on the horse-engine site. In 1786 Mylne extended the engine house westwards to accommodate a new Boulton & Watt engine, plus a pump chamber and stair, located to the south-west and north-west respectively. Further extensions were added to the east and north in 1794-5, when Mylne remodelled the entire structure to create a symmetrical D-plan with a curved north elevation. A second Boulton & Watt engine (replacing Smeaton’s now-obsolete engine) was located in a chamber to the south east, and a pump to the north east, mirroring their 1786 counterparts, the pumps now housed in a unified curved chamber to the north. The 1763 core now contained a high-level cistern and stair in the north and south chambers respectively. Two chimneys rose from the south walls of the extensions and a second lean-to boiler house was added to the east shortly after. Further improvements took place from 1811-18 under William Chadwell Mylne, who succeeded his father in 1811, including the replacement of both engines with improved Boulton & Watt models. The 1786 stair, chimneys and south chamber stair were removed, the last making way for a 110’ tall chimney. The last major phase from 1845-9, again under Mylne, followed the successful introduction by Thomas Wicksteed of a Cornish engine for the East London Waterworks in 1838, and inventions enabling the compounding of old engines to work with high-pressure steam on the Cornish system. Accordingly, the Boulton & Watt engines were adapted to work new cylindrical boilers, and the two boiler houses rebuilt and enlarged. A stair tower was added to the west and a coal store to the north-east. Behind the chimney, above the north chamber which contained cisterns or condensation tanks, an octagonal brick structure was added to support a tall iron cylinder. The engines were replaced in 1897-8 and 1901-3.

In 1902-4 the NRC became part of the Metropolitan Water Board (MWB), and in 1915-20 the Round Pond was filled in and the Water House demolished to make way for the new MWB headquarters. In 1946 the waterworks became redundant; at this time the New River, by now running underground through north London, was terminated at Stoke Newington. The engine house chimney was removed in 1954 and the engines c1957 when a concrete floor was inserted. Water supply resumed on the New River Head site with the construction of the London Ring Main in 1986-94, served by a new pumping station.

Reasons for Listing

The former engine and attached boiler houses and coal store, New River Head, is listed at Grade II for the following principal reasons:
* Historic interest and rarity: as one of the principal structures of the New River Head complex, London’s first waterworks site, comprising at its core the remains of the earliest waterworks pumping engine house to survive nationally; the incrementally extended and remodelled engine house, as realised by 1818 under Mylne Senior and Junior, is also an early survival;
* Architectural interest: while evidence of machinery has largely been erased, the building’s well-documented evolution from 1768-1849 remains legible within the fabric and plan, reflecting the rapid pace of technological advance and obsolescence in that period; the cast-iron stair of 1848-9 is a fine example of its type;
* Group value: with several listed buildings on the site built by the New River Company and its successor the Metropolitan Water Board, in particular the windmill base which marks the earliest phase of powered pumping on the New River Head; such a grouping is unique in a waterworks site.

External Links

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