Signal Tower — Mountain Common

Situated immediately E of the summit of Knocklackan, the large hill that dominates the N side of the island of Inishturk (192m OD). Located in an area characterised by unenclosed blanket bog with numerous modern turf drying stands located adjacent to the N. The signal tower is located on moderately sloping ground that makes up the ridge of Knocklackan. The signal tower has expansive views in all directions, except the W which is blocked by the summit of Knocklackan, and to the SE where an adjacent hill blocks the line of site. Located c. 854m to the ENE of the coastline at its closest point. The partially-ruined Shivel Head Signal Tower (MA084-001010-), located c. 11.2kms to the NE\NNW to the W side of Clare Island, is clearly visible from this site on Inishturk in good weather. The largely ruinous Cleggan Hill Signal Tower (GA009-007----), County Galway, located c. 15.5kms to the S, can no longer be seen from the site. The signal tower on Inishturk is located c. 1.95kms NN of a coastal promontory fort (MA104-002----), indicated as 'Dun Ooghmore' on the Ordnance Survey third ed. six-inch map of c. 1910, at Ballyheer to the S coast of the island, and c. NW of the ruinous ‘St. Columba’s Church’ (MA094-008001-) and graveyard (MA094-008002-). The remains of an early nineteenth-century (c. 1806) originally two-storey square-plan signal tower (int. dims. 4.25m N-S x 4.25m E-W; wall H 3.74m), built with randomly coursed rubble stone masonry. The signal tower now survives as a low, largely-collapsed ruin, and only the semi-basement level and sections of the ground floor remain upstanding. The walls of the tower face in the cardinal directions (N, S, E and W). The N part of the E wall is the best-preserved section of the building. The S wall and the S portion of the E wall are now mostly collapsed. The N wall features the lower parts of two ground floor window openings with remains of splayed embrasures. The S wall features only the lower section of a window opening, located close to the W corner. The external face of the W wall is plain. The external face of the E wall is plain apart from a centrally-located bulge on the external surface that originally housed the chimney flue, and by a square-shaped chute located close to the N corner that penetrates through the width of the wall. Internally, the N and S walls feature slots below the remains of the window openings, which would have originally held the ground floor timbers (floorboards, and possibly joists). The W wall is blank, and the E wall retains most of a central fireplace flanked by a complete square-headed alcove to the N and by the lower section of a partially-collapsed alcove to the S. A pair of substantial joist holes are located on either side of the central fireplace, set at the same height as the ground floor joist holes on the N and S walls. The internal opening of the square-profile chute is located at the base of the N alcove, set close to its N edge. Despite the fragmentary remains, enough evidence survives to orientate the building; the doorway would have been located to the centre of W side at first floor level, and bartizans would have been located over the NE and SE corners of the tower. The tower is built on a small rock-cut terrace cut into the hillside. The S side of this terrace is defined as an almost vertically-sided cut located adjacent to the S elevation of the tower (c. 1.2m S of wall edge; Wth E-W c. 8.2m), and it continues along the SW and SE corners of the tower for a short distance. The terrace is infilled with rubble from the collapse of the building. Apart from the rubble infilling the terrace and a low spread of rubble within the signal tower, there is an absence of collapsed rubble stone in the vicinity of the signal tower, suggesting this has been removed from the site. A small oval-shaped lime kiln (ext. dims c. 3.4m NE-SW x c. 3.1m NW-SE; int. dims of chamber c. 1.6m E-W x 1.5m N-S) is located c. 11.5m to the NW of the signal tower. The sub-circular chamber of this kiln survives as a well-defined ‘bowl’ with sides that slope inwards towards the top, and with a short flue extending to the SE. A lintel stone is present at the join between the flue and the bowl. A lime kiln is indicated on the Ordnance Survey six-inch first ed. map (surveyed 1837-1839) in this location. A concrete trigonometry pillar is located c. 6.5m NE of the signal tower. This is surrounded by a small modern cairn. This signal tower was part of a system of over 80 signal stations constructed by the British Board of Ordnance in the first decade of the 19th century to warn of the approach of a French invasion fleet. Signalling between sites was accomplished using a naval signal post. The system formed a continuous chain from Dublin Bay running clockwise all the way around the coast to Malin Head in County Donegal. It was abandoned by the mid-1810s when the threat of a French invasion diminished (Kerrigan 1995, 157-66). Compiled by: Stuart Rathbone Uploaded on: 07/07/22 Images: MA094-027----.01 N exterior MA094-027----.02 E exterior MA094-027----.03 S exterior MA094-027----.04 W exterior MA094-027----.05 N interior MA094-027----.06 E interior MA094-027----.07 S interior MA094-027----.08 W interior MA094-027----.09 Oblique view from the NW; trigometry station to foreground. MA094-027----.10 N (top) and W (bottom) exterior drawings MA094-027----.11 S (top) and E (bottom) exterior drawings MA094-027----.12 N (top) and W (bottom) interior drawings MA094-027----.13 S (top) and E (bottom) interior drawings MA094-027----.14 Plan of site MA094-027----.15 W exterior drawing MA094-027----.16 View of lime kiln looking NNW