Powder Mills — Ballincollig (muskerry East By., Carrigrohane Par.),great Island

In 1793 Charles Leslie built two incorporating mills W of Cork City to manufacture black gunpowder. British Board of Ordnance purchased mills in 1804; under its control mills were extended, and present canal dug; also worker's houses erected and adjacent Ballincollig Cavalry Barracks built. Mills abandoned by 1828 but purchased and re-opened in 1830s by Tobins of Liverpool; later amalgamated into Curtis and Harvey (Bielenberg, 1991, 88-91; Kelleher 1993; Lucy 1988). At peak in mid 1870s mills said to have employed up to 500 people. Now owned by Cork County Council which has restored one incorporating mill and built visitor centre nearby. Entire complex stretches 2.5km along S bank of River Lee, covering an area of 52.6ha. It can be divided into three areas: Refining Area: small off-centre area associated with initial refining of raw materials; Incorporating mills at E end; Finishing Area: structures associated with post-incorporating processes at W end. All structures are ruinous, some are overgrown and inaccessible; for locations see Map 15. Unless otherwise stated, structures listed are shown on 1828 map of complex by Board of Ordnance; reference is also made to a map of the complex made in 1876. The main canal, recently restored, takes a curving course along full length of complex, providing safe route for transport and water for numerous millraces serving individual units. Canal is taken off River Lee at W end of complex; Leslie's original straighter canal survives in part. Refining Area: Here raw materials used in manufacture of gunpowder (saltpetre or potassium nitrate, charcoal and sulphur) were processed. Ancillary structures included craftsmen's workshops, saw mills, a weigh-bridge, stores, offices and stables. Main surviving buildings are: Saltpetre Refinery (R): Overgrown brick-built structure (long axis E-W). Long 2-storey structure to N. Straining Shop (Q): Remains of one-storey stone-built structure (long axis N-S), brick addition. Sulphur Refinery (S): Remains of one-storey structure immediately north of saltpetre refinery. Workshops (V): Line of three small stone-built one-storey structures (long axis E-W) built close together, comprising carpenters' and millwrights' shops. Brimstone (sulphur) store (U): Remains of two-storey stone-built structure (15m N-S; 6m E-W); E side collapsed. Charcoal Mill (W): Two-storey stone-built rectangular structure (16.5m WNW-ESE; 7m NNW-SSE); gable-ended. Central brick-lined wheel-pit (Wth 1.6m) which housed low breastshot waterwheel. New Saw Mill (T): Built in mid-9th-century, replacing earlier saw mill to W which does not survive. Stone-built, roofless, two-storey rectangular structure (15m N-S; 7m E-W); brick window surrounds; gable-ended. Interior contains octagonal brick-lined pit containing octagonal iron cistern which houses remains of downward axial flow turbine, made in Hive Iron Foundry (Cork) in 1855; according to Rynne (1993a, 93) earliest known example of its type. Charcoal Burning House (P): Roofless stone-built square structure (int. c. 11m N-S; 11m E-W), remains of brick-arched vaults on W side with brick chimney (H c. 6m). Addition to S. Named 'Cylinder House' on 1828 and 1876 maps. Incorporating Mills: Here refined saltpetre, sulphur and charcoal (green charge) were ground together to produce 'mill cake'. This was a highly dangerous process and special measures were introduced to contain damage in the event of an explosion: each pair of mills was separated from next by massive gabled 'blast walls', all of which survive. According to Hamond and Hegarty (1987, 12, 13), 'The incorporating mills can be divided into two groups each with its own millrace; mills 1-3 at western end of complex, remaining 9 pairs lying to east (mills 4-12)...Mills 1 and 2 are earliest...having been erected by Leslie in 1793...with takeover of complex by Tobin in 1833 the mills extant (nos. 1, 2, 5-9, 11; correction pers. comm. Hamond) were quickly recommissioned...Mill 3 dates to 1840s...erected, along with mill 10, by Tobin in his first phase of expansion. During 1850s mills 4 and 12 were also added'. Most mills had a breastshot water wheel (mainly metal) ranging in diameter from 16-21ft, and from 4-5ft in width (Rynne, forthcoming); mills 1 and 2 were breast-fed paddle wheels (pers. comm. Hamond). Each water wheel drove two mills, one on either side of wheel pit. The buildings were constructed entirely of wood to minimise damage and make rebuilding easier in the event of an explosion. Each mill contained two limestone edge runner stones, driven through a train of cast-iron bevel and spur gears and rotating about a metal pan resting on a horizontal limestone bedstone. According to Hamond and Hegarty (ibid., 13), valuation books of 1834 state that mill at wheel-pit no. 3 measured "7.77m (25.5ft) long; 6.55m (21.5ft) broad by 3.35m (11ft) high", similar to what was found during excavation at Mill 1 by C. Rynne; recently reconstructed. Brick-lined millraces link canal to wheel-pits to N; many bedstones (diam. c. 2.5m), mostly limestone, are still in position adjacent to wheel-pits; also numerous pairs of limestone runner stones (diam. c. 2m; c. 0.7m thick) stand or lie in vicinity. On N bank of main canal, to S of wheel-pits, are four circular charge houses which stored 'green charge' prior to incorporation. Western charge house (int. diam. 4.8m) has conical slate roof and gabled porch on S side; recently restored. Finishing Area: Wooded area covers western two thirds of complex, stretching c. 2km from Refining Area to Inishcarra Bridge (9615). Buildings here are associated with the finishing process; the mill cake mixture was very volatile and consequently buildings were scattered over a large area in managed woodland designed to absorb blast damage. The mill cake was taken to the press house and pressed dry; next it was crushed in the corning/granulating mill; this produced dust which was removed in the dusting house. Grains of gunpowder were then coated in black graphite in the glazing houses. Gunpowder was dried on shelves in drying houses adjacent to stove house. Finished powder was packed and stored in magazines (Rynne forthcoming). Most of buildings interconnected by main canal or minor off-shoots from it; many were powered, where necessary, via millraces taken from canal. The surviving buildings, described in sequence from W to E, represent several phases of use and may not have been in use contemporaneously. Press house (B): Stone-built oval structure (10.2m E-W; 4m N-S; H c. 4m). Broken round-arched ope to E; remains of wall project to W. Shown on 1828 map with rectangular structures to N and S; marked 'Dusting House' and 'Press House'. Disused by 1876. Dusting house (D): Overgrown oval stone-built structure (10.5m N-S; 4m E-W; H c. 5m); walls taper inwards with height. Lower level solid with earthen fill. Circular opes on 1st floor. Series of holes for pipes c. 3m above ground level. Remains of square structures to E and W (c. 8m E-W; 8m N-S; H c. 0.8m). Shown similarly to (B) above on 1828 map; marked as 'Dusting House' on map of 1891. Corning mill (C): Low overgrown remains of irregular-shaped stone-built structure (c. 12m E-W; 6m N-S). Millrace (dry, approaches from W), skirts around structure on W, S and E sides. Press house (E): Not examined due to overgrowth. Granulating/Corning mill (F): Heavily overgrown area, some walls and probable wheel-pit (Wth 1.05m) visible. Press house (G): Heavily overgrown remains of one-storey structure; pillar-like remains may represent divisions between windows. Structure shown here on 1842 map and named 'Corning House' probably not present structure. Magazine (H): Built in sunken area in N bank of canal; area enclosed by retaining wall on N, E and W sides, quay along canal to S; steps lead down to sunken area at S end of W wall. Rectangular stone-built one-storey structure (int. 5.85m E-W; 6.1m N-S); round-headed S gable with brick-arched ope leads onto qua