Threshing mill, 7 Legaterriff Road, Ballinderry Upper, Lisburn, Co Antrim, BT28 2EY

Threshing Mill

This detached three-storey water-powered threshing mill stands on Legaterriff Road north of the farmyard complex associated with The Grove. Built in 1836, as confirmed by a datestone on the south elevation, it represents a rare survival of a once-common rural industrial building. The mill began life as a corn kiln but was converted to water-powered threshing operation before 1857, with the present machinery dating from the late 19th or early 20th century.

The building is a two-storey structure over a basement, measuring 29 feet 9 inches long by 22 feet wide by 15 feet high, with a basement 6 feet 6 inches deep. It is aligned east-west at the foot of a gentle slope descending from the farmyard to the south. The walls are constructed of lime-rendered random rubble masonry with a brick eaves course, though rendering is missing in places. The pitched roof is laid with natural slate, though some ridge tiles and slates are absent. No rainwater goods survive.

Access is provided by square-headed timber-sheeted doors in the south and west elevations at ground floor level. The south door is a half door set within a segmental brick head, the brickwork a 20th-century repair using cement-rich mortar. The basement is lit by an opening on the west gable. Ground floor openings occur on the north and south walls. The top floor receives light from an opening in the apex of the west gable and through three small square openings along the north and south elevations. All these openings were originally shuttered, though their frames are now missing. The east gable contains no openings.

The datestone reading "AD 1836" is recessed into the south elevation directly above the western door.

The mill's water-powered mechanism is still substantially present. An external high-breastshot waterwheel is located in the centre of the north elevation, measuring 12 feet in diameter and 2 feet 7½ inches wide. The axle, hubs and rims are of cast iron, tied together with wrought-iron rods. Two sets of six timber arms originally drove the machinery, though most are now missing. The 36 angled buckets and soleplate were of timber and have largely disintegrated. A cast-iron segment spur gear attached to the inner arms drives a cast-iron bull nut at the 12 o'clock position. From this a cast-iron axle runs into the basement. The sluice gate that once controlled the water flow is missing. The mill pond directly behind the east gable has been infilled, as has the headrace in the vicinity of the mill. A partly culverted tailrace still runs west along the lane to an adjacent property.

The interior remains largely intact except for sections of floor and several minor ancillary machines. Original metal beams for the former kiln remain in place on the ground floor, their presence demonstrating the building's conversion from its original function. Substantial timber beams above these metal beams are too massive to suggest later reinforcement and likely date from the kiln period.

A metal shaft projects from the middle of the south elevation, its outer end supported on a vertical metal post mounted on a rubble masonry base. This originally drove a second shaft powering a woodworking lathe in an outbuilding immediately south of the mill, the shaft now gone.

Historical records show the building was erected as a corn kiln in 1836, appearing on the 1857 Ordnance Survey map as an outbuilding of The Grove alongside evidence of a watercourse from the Rooghan River and a pond, indicating mechanical power was already being applied. The conversion to threshing mill likely occurred before 1857. Valuation books cease to designate the building as a corn kiln from 1892 onwards, though they offer no alternative description. The property remained in the hands of the Peel family throughout the 19th century, with Mark Peel sole occupant in 1834 and sole proprietor by 1894. The present farmyard layout dates from the second half of the 19th century. By 1901 the complex had assumed its present form.

The waterwheel and machinery present stylistic characteristics more typical of late 19th and early 20th-century installations, suggesting the original threshing apparatus was replaced during this period, though the conversion from kiln to threshing mill occurred earlier. Such water-powered mills were once common in rural agricultural areas but have largely been demolished or stripped of their machinery, making this example of particular historical and industrial archaeological interest. Its position within the farmyard complex and group value with The Grove further enhance its significance as a reflection of the farming practices of a prosperous South Antrim farmer in the later 1800s.