Ask Greg: Mills




Greg Speed

Does a project sometimes lead in an unexpected direction?

In keeping with this month’s theme of industrial archaeology, here’s a story from a project I was involved in a few years ago that led us in an unexpected and extremely interesting direction. NAA was commissioned to carry out a fabric appraisal and desk-based assessment of a group of derelict mill buildings on the bank of the River Wear in Durham.

The main structure was a remnant of the 18th-century Bishop’s Mill, which in its heyday had been an impressive three-storey stone corn mill. In the 1960s, most of it was demolished leaving only a small structure covering the wheel-pit. To the rear, the 19th-century Logwood Mill (a stone lean-to shed), had been used to grind tropical hardwood to produce a fabric dye. The group of buildings also included a late 20th-century brick-built electricity substation. Not much of archaeological interest there, then!

However, things became much more interesting inside. No millstones, but lots of big pipework and electrical stuff, all connecting into the wheel-pit. Time for some research.

The Bishop’s Mill, first recorded in 1183 and used for grinding corn was, by the post-medieval period, one of eight mills found on the riverbanks around the town. By the middle of the 19th century, corn grinding was done by steam-powered mills, and the watermills gradually fell redundant. In 1848, a large parcel of waterfront land, including the Bishop’s Mill, was bought by William Henderson on which to build a carpet factory.

The carpet factory changed hands at the turn of the 20th century and continued to thrive into the second half of the 20th century. By the early 1930s, the mill complex became surplus to requirement and was sold off to an ice manufacturer named John Smith. He modernised the weir in the Wear, removed the milling machinery and replaced the millwheel with a water turbine and electrical generator to power the ice plant. The enterprise initially prospered, but by the late 1930s, the growth in domestic and commercial refrigeration made ice-making unprofitable. Smith, looking for continued returns from his investment, converted the site to an ice rink, which opened in 1940. Initially open air, the rink was subsequently covered by what was said to be the largest tent in the world, essentially a circus big top complete with supporting poles. The rink became popular with Canadian servicemen stationed in the area who introduced ice hockey to Durham, which must have been ‘interesting’ played around the tent poles! A storm in 1944 destroyed the tent, but after the Second World War it was replaced by a building that survived until recently, although for its final few years it was a bowling alley. The seating around the rink was said to have been built from war-surplus coffins! The success of ice hockey in Durham led Smith to build a second ice rink at Whitley Bay (which is still in use today) to provide the opportunity for lucrative local derbies between the ice-hockey teams Durham Wasps and the Whitley Bay Warriors.

Having discovered the history of the building, we were able to go back and make sense of the machinery in the Bishop’s Mill and Logwood Mill. A vertical driveshaft from Smith’s turbine emerged from the water-filled wheel-pit and was connected to a speed-reducing gearbox manufactured by David Brown and Sons of Huddersfield. Water flow was regulated by a series of concrete and steel sluices outside the building, while the turbine was controlled hydraulically via an oil-pressure governor manufactured by Gilkes of Kendal. A horizontal driveshaft from the gearbox passed into the Logwood Mill, where it powered a six-foot flywheel from which a belt-drive ran a 175kVA AC generator mounted on slide rails in order to tension the drive belt. The generator, built by the English Electric Co in Bradford, had been mounted on the concrete base of the original Logwood Mill’s saw bench. Presumably, all this machinery was installed to power the ice factory.

The flywheel was also connected via a sprag clutch to a compressor, which formed part of the ice-rink cooling system. The four-cylinder ammonia compressor system, manufactured by J & E Hall, appeared to have replaced a three-cylinder unit, which was found lying on the floor. Extensive pipework from this equipment ran back into the wheel-pit in the Bishop’s Mill, either as a heat-exchanger or for taking-up river water.

The mill buildings and the adjacent ice-rink building were cleared for redevelopment in 2014 and the site is now occupied by the Freemans Reach development housing the National Savings and HM Passport Office. However, during demolition, Beamish Museum recovered the water turbine and other machinery from the buildings. Recognising the historic ‘green’ credentials of the earlier hydroelectric plant on the site, and making use of the existing weir infrastructure, the new development incorporates a 20-tonne Archimedes screw hydro plant, which is capable of generating 100kW and supplies 75% of the electricity for the new development.

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