Signal tower

The National Monuments Service's description

Situated towards the E end of a low ridge (195m OD) that runs between Slievemore to the E and Croaghaun to the W, the two mountains which dominate the western half of Achill Island. Site located c. 473m S\SSE of coastline at its nearest point. The ground slopes away moderately to the N, E and S, and rises slightly to the W. The surrounding area consists of unenclosed blanket bog with a disused quartz quarry located c. 480m to the E\ESE. The signal tower has unobstructed views to the N and S, but the views to the E and W are blocked by the adjacent mountains. The signal tower at Tarmon Hill Signal Tower (MA024-031----), located c. 12.6 kms to the N at the SW corner of the Belmullet Peninsula, and the signal tower at Shivel Head (MA084-001010-), located c. 22.3kms to the S\SSW at the W tip of Clare Island, are both clearly visible in good weather. This signal tower at Slievemore is located c. 600m WSW of a standing stone (MA042-014----) and c. 1.65kms E\ESE of an ‘unclassified’ megalithic tomb (MA042-012----).

An early nineteenth-century (c. 1806) originally two-storey square-plan signal tower, built of roughly coursed limestone rubble with flush roughly squared quoins to the corners. Slight batter to base of tower. The square signal tower survives as a partially collapsed ruin, and consists of the semi-basement level and fragments of the ground and first floor levels (int. dims. 4.25m N-S x 4.25m E-W; H 5.98m). Some sections of roughcast lime render survive to the exterior, particularly to the E elevation. The S and N walls feature the remains\lower sections of pairs of window openings at ground floor level, whilst the E wall features the distinctive shallow external bowing that indicates the presence of a chimney flue contained within the wall structure. Two square chutes pass through the E wall: a chute to the S of the wall that passes horizontally through the wall, emerging at the top of the semi-basement level at the SE corner of the building; and a chute at the N that slopes steeply upwards, emerging in the base of the N alcove. The W wall is plain. The internal face of the E wall at ground floor level features square-headed alcoves flanking a central shallow segmental-headed fireplace with roughly dressed and squared voussoirs over forming the arch. Some sections of lime plaster survive to the interior. The internal face of the S wall features the lower portions of the flared embrasures of two ground floor window openings. The internal face of the W wall is devoid of features. The internal face of the N wall is largely collapsed, with only traces of the flared outer edges of the ground floor windows and some of the joist holes for the ground floor remaining visible. These features allow for the tower to be orientated; the first floor doorway would have been located on the W wall, and bartizans would have protected the NE and SE corners. Two early twentieth-century photographs of the signal tower confirm this arrangement. One of the photographs shows the tower almost complete to full height at this time with a narrow rectangular machicolation over the doorway, and the rear of a bartizan over the SE corner. The bartizan appears to have had sides extending out at right angles from the tower’s walls with the outer face curving around the corner of the building. The second photograph shows that the upper parts of the N, W and S walls had collapsed by this time. The E wall had featured a first floor fireplace flanked by alcoves.

The signal tower is located to the E side of a rectangular enclosure (54m E-W x 27m N-S) defined by the low remains of a rubble stone wall with a simple entrance gap located one third of the way along the S wall. The wall stands in the base of a shallow ditch.

The foundation of a small oval hut (int. dims. c. 5m x 4m) are located within the enclosure to the S of the signal tower, which may post-date the use of the signal tower. The foundation of a rectangular building\structure (int. dims 7.2m E-W x 2.7m N-S), defined by a low rubble stone wall, is located at the NW corner of the enclosure. The foundations are likely the remains of a storage building used during the occupation of the signal tower. A partially-infilled vertically-sided oval pit (3.25m E-W x 2.7m N-S; D 0.7m) is located c. 12m W of the signal tower. The sides are now grassed over but occasional stretches of intact roughly coursed rubble stonework are visible. This pit may be the remains of a lime kiln and\or the socket for a signal mast.

The 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: 04/07/22

Images:
MA042-051----.01 Oblique view from NW
MA042-051----.02 Oblique view from NE
MA042-051----.03 N exterior
MA042-051----.04 E exterior
MA042-051----.05 S exterior
MA042-051----.06 W exterior
MA042-051----.07 Oblique view from SW
MA042-051----.08 N interior
MA042-051----.09 E interior
MA042-051----.10 S interior
MA042-051----.11 N exterior drawing
MA042-051----.12 E exterior drawing
MA042-051----.13 S exterior drawing
MA042-051----.14 W exterior drawing
MA042-051----.15 N interior drawing
MA042-051----.16 E interior drawing
MA042-051----.17 S interior drawing
MA042-051----.18 W interior drawing
MA042-051----.19 Plan of site
MA042-051----.20 View of enclosure
MA042-051----.21 View of entrance to S side of enclosure
MA042-051----.22 View of foundations of rectangular building to end NW of enclosure
MA042-051----.23 Oval hut to S end of enclosure
MA042-051----.24 Mast mount\lime kiln to W of tower

References

Rathbone, S. 2020. ‘The Construction, Survival and use of Signal Defensible Guard Houses in Connacht and Ulster’; unpublished PhD Thesis, Institute of Technology, Sligo

Kerrigan P.M. 1995 Castles and fortifications in Ireland 1485-1945. Cork. The Collins Press.