2012:576 - CALEDON MILL, Tyrone

This report was commissioned by Consarc Conservation Ltd, a Belfast-based firm of conservation architects on behalf of the Caledon Regeneration Partnership Ltd, owners of the site under review. It focuses on excavations carried out in and around the early 19th-century steam engine house associated with the now-demolished Caledon Mill.

The project was carried out over a three-week period from 15 February to 7 March 2012. The excavations were carried out by JE Restoration, a two-man team comprising Seamus McElory and his assistant Terry McQuaid. Day-to-day monitoring was carried out by the writer, and the project was administered by Jonathan Baird of Consarc Conservation. The project was implemented through South West Action for Rural Development (SWARD), and part-funded by the European Union and the Department of Agriculture and Rural Development under axis 3 & 4 of the Northern Ireland Rural Development Programme 2007-2013.

Caledon Mill was built in 1823 by Du Pré Alexander, 2nd Earl of Caledon, to grind wheat into flour. Initially it was powered by water, but in the early 1830s an auxiliary steam engine was installed in a purpose-built house on the gable of the existing mill. Milling ceased in 1879, but operations restarted in 1882 with the spinning and weaving of wool under Sherrard, Smith & Co trading as Caledon Woollen Mills. Turbines were installed in place of the two waterwheels in the 1890s. The steam engine was superseded by a gas engine sometime before 1914. The woollen mill stopped in 1930 and lay idle thereafter. It was requisitioned by the Army as a store in 1940. Some of the smaller components of the steam engine were removed during this period. In 1985, the derelict remains of the various mill buildings were demolished. Fortunately, the engine house and engine escaped this fate and are now, along with the base of the chimney from the boiler house, the only survivors of what had been one of the largest mills in the region. The Caledon Regeneration Partnership now wishes to restore the engine house and erect a visitor centre on the site of its adjoining boiler house. Consarc Conservation was commissioned to draw up plans for this scheme, part of which entailed the examination of the engine house and remains of the steam engine.

The objectives of the investigative works were four-fold:
(1) Stabilisation of the wall heads of the engine house in order to make it safe for subsequent internal investigation;
(2) Removal of the debris from inside the building to reveal all the machinery and enable it to be assessed and surveyed;
(3) Salvaging of items relating to the building and engine from the debris;
(4) Selective archaeological trenching of the area east of the engine house to establish the extent of the boiler house.
All debris was removed by hand and inspected for artefacts of potential interest. Where found, these were put into temporary storage in the nearby Wool Store for cleaning, recording and labelling.

Although most of the roof had long collapsed, most of its twisted remains survived and were salvaged. Its frame comprises three trusses, each of which is made up of (1) two cast-iron rafters, (2) two wrought-iron tensioning rods along the bottom of the truss, (3) two diagonal wrought-iron rods between each tensioning rod and top of the central post, (4) two diagonal cast-iron struts between each tensioning rod and rafter, and (5) a central rolled-iron upright post. The bottom ends of the trusses are bolted to cast-iron wall plates which were affixed to the eaves. A small section of the timber floor at the top of the engine house also survived and was salvaged. Up to 1m of debris was removed by hand from the ground floor. This comprised mostly fragments of roofing slate, slate battens, dislodged stones and bricks, wall eaves’ copings and internal plaster, timber from the beam floor and miscellaneous pieces of iron from the roof trusses and engine. All worked pieces of timber and all fragments of metal were salvaged. The floor was found to be flagged with sandstone, many of which still survived, and also partly covered with cast-iron plates, of which only one survived.

The basement comprises four separate spaces, all of which were also excavated. Significant finds included bell-cranks, shaft brackets, bearing covers, pipework and gaskets, staircase newel posts and sundry roof components. In addition, the in situ remains of parts of the steam engine were also revealed: the hot and cold wells and their associated pumps, and also the condenser, injector and connecting pipework.

The area east of the engine house was trenched to determine the extent of the boiler house. This proved inconclusive as this entire area had been comprehensively demolished right down to the foundation level of the boiler house in the mid-1980s. The area immediately west of the engine house was also excavated. The basal remains of the mill’s gable were found to extend several metres beyond the north-west corner of the engine house. A large cast-iron spur gear, formerly driven by the steam engine, was also uncovered. The former mill race along the south side of the engine house was infilled with debris when the mill was demolished. This material was partly excavated to ascertain the stability of the retaining wall along this side of the race and to salvage any significant items. Several fragments of roof truss were found and are of particular significance as they could only have come from the boiler house, the framing of which appears to have been identical to that of the engine house.

Sufficient structural remains of the engine house and its fixtures and fittings survive to enable an authentic reconstruction of its roof, walls, windows, doors, internal floors, and staircases. On the basis of what survives, the feasibility of restoring the steam engine merits further investigation. All its principal components survive and whilst many of the smaller items have disappeared, those discovered through this excavation could be reused or form the basis for the fabrication of replica components.