Patterson's Spade Mill, 751 Antrim Road, Templepatrick, Co.Antrim, BT39 0AP

Patterson's Spade Mill is located six miles north of Belfast near Templepatrick, Co. Antrim, and represents the last working water-powered spade mill in the British Isles. Now in the care of the National Trust and open to the public, it demonstrates the workings and processes common to historic iron industries, with machinery covering the evolutionary development of mechanical and civil engineering over the past century.

The mill complex comprises three principal structures arranged around a working watermill site powered by the Ballymartin Water.

The main spade mill building is an attached single-storey multi-bay outbuilding with a central rectangular plan workshop aligned north to south, fitted with single-storey lean-to extensions to the east and west sides and further extensions attached to the south end. The central rectangular metalworking shop has a hipped slate roof with black clay ridge tiles, a central raised ventilation lantern, and a tall red brick chimney stack rising from the east party wall. The east lean-to is roofed in corrugated asbestos, whilst the west lean-to (now serving as a visitor centre) has a corrugated iron roof, both fitted with cast-iron rainwater goods. Throughout, the walls are constructed of rubble stone, finished externally with painted roughcast render except to the north elevations. Window openings are square-headed without cills, with replacement timber sliding sash and casement windows. Doors are square-headed, with double-leaf sheet-metal doors to the west lean-to and a single-leaf sheet-metal door to the south of the central block. The east lean-to has vertically-sheeted timber plank doors at either end, with the northern door opening onto steep steps that lead to a footbridge and sluice gate where the Ballymartin Water forms a steep torrent.

An original corn mill, built in 1832, survives as a fragmented double-height shell with no roof remaining. The ruin abuts the north end of the west gable of the metalworking shop, with a central double-height round-headed opening now blocked. The east gable is largely gone, and the north wall is almost entirely missing, with what remains supporting a raised path leading to the water gate beyond. The south wall is double-height with low-level openings to the east for original iron gears, now protected by a metal cage. Openings are formed with red brick headers and stone cills, fitted with unglazed multi-pane iron windows. An aqueduct—part concrete and part iron—carries water through the walls at the east side and projects through the south wall to power the turbine below. The iron aqueduct bears a plaque inscribed "Engineers, Portadown Foundry Ltd. Portadown." A door opening provides access to the main yard across a footbridge spanning the mill race running parallel to the south wall.

The mill manager's house is a detached three-bay two-storey building built circa 1850, facing south on an east-west axis. It features an attached L-plan front entrance porch and a single-bay two-storey return. The roof is hipped with natural slate and black clay ridge tiles, with a red brick chimney stack and cast-iron rainwater goods. The walls are finished in painted ruled and lined render with render quoins at all corners and a render plinth course. Window openings are square-headed with painted stone sills, fitted with single-pane timber sash windows with ogee horns. A roundel window opening serves the porch, and a square-headed door opening to the east side contains a timber panelled door opening into a small enclosed area.

A random rubble ruin built circa 1830 abuts the north-west corner of the main block, aligned east to west and divided from the west lean-to by the mill race and turbine. The site is elevated to the north, where remnants of earlier mill buildings remain.

The site is powered by water from the Ballymartin Water, which flows to a pond and race east of the buildings, feeding a short aqueduct to a water turbine added to the front of the beetling mill in 1917. A series of water-driven shafts, pulleys and belts through the main building and finishing shop drove the tilt hammer, grindstones and drills. The water-powered trip hammer is 150 to 200 years old. Access to the site is by a long lane and vehicular bridge crossing the Ballymartin Water.

William George Patterson opened Patterson's Spade Mill in 1919 on a site previously occupied by several different industries. A corn and flax mill operated from the 1830s; in 1832 a corn mill was built, which James Boyle noted in the 1838 Ordnance Survey Memoir was established as a paper mill in 1837, employing 19 people at that time. A paper mill is recorded on Griffith's Valuation Map of 1859, with William Sloan as lessor of a house, offices, paper mill, stepping stones and land, valued at £45. The 1836 Townland Valuation Map recorded the property valued at £16. 14s 0d with James Parker as the Immediate Lessor. A beetling mill operated from 1901. Patterson brought with him spade-making experience from two previous generations of mills. The spade mill reached peak production in the 1930s and '40s, employing over a dozen men. The mill remained in commercial production until 1990, when every other mill of its type had long since closed, a testament to the quality of spades produced here. The National Trust acquired the mill in 1992, restoring it by replacing the roof structure and furnace, and opening it to visitors in 1994.