LOCK AND BRIDGE

The Department's description

Exterior description and setting

This single-chamber eighteenth century lock on the Lagan Navigation is aligned E-W situated at the E end of a cut through a curve of the river to bypass rapids. It measures 21.8m long by 4.7m wide (71ft 6in x 15ft 4in). The sides of the chamber are lined with masonry. The bottom section is of quarried rubble blackstone, brought to courses. Above this are larger squared sandstone blocks, with an admixture of blackstone rubble. Prior to the lock’s recent restoration, much of this sandstone had eroded away and been replaced with brick. During restoration, much of the brickwork was replaced with random sandstone blocks (of paler colour than the original) laid to regular courses; indeed, most of the N side of the chamber is of new sandstone and little of the brick repair work remains. The tops of the walls are coped with large dressed sandstone blocks. The original timber floor of the chamber and the original stone cill towards its upper (W) end have both been replaced with reinforced concrete during the recent restoration. Halfway along the N side of the chamber, a vertical galvanised steel escape latter has been let into the side of the wall (this is not an original feature).
There is a pair of replica timber lock gates at each end, each with its own counterweight beam and paddle sluice gate operated by a rack-and-pinon mechanism. Across the W face of each gate is a timber footway cantilevered out from the gate on galvanised steel brackets.

Spanning the chamber between the gates is a simple timber footbridge which was erected in the 1990s to facilitate access across it.
Immediately downstream from the lower gate is a small single arch masonry bridge by which horses towing the barges crossed from one side of the navigation cut to the other. The arch springs from the sides of the chamber and is of segmental profile with roughly dressed sandstone voussoirs. Its deck is strongly humped and the parapets are coped with concrete.

Approximately 3m downstream from the footbridge is a curved lagged mains water pipe which runs between concrete abutments on either bank. There was formerly also a second water pipe between the lower lock gate and footbridge which spanned the chamber at a much lower level. It was removed during the recent restoration work and replaced with a pipe under the lock.
At the time of survey, the navigation channel was blocked by a temporary earthen causeway which facilitated access to the contractors during the restoration of the lock house.

A tarmaced public footpath runs along each side of the lock. Immediately N is the former lock keeper’s house (HB25/17/004B).

Historical information

This is lock 3 of 12 on the Lagan Navigation between Stranmillis and Union Bridge, Lisburn. This section of canal was built between 1756 and 1763 by Thomas Omer for the ‘Corporation for Promoting and Carrying on an Inland Navigation in Ireland’. The navigation was subsequently extended as a canal to Lough Neagh, opening in 1794. It operated until 1954, when the upper (canal) section was closed. The Belfast-Lisburn section was not abandoned until 1956.

This lock is shown on all editions of the OS maps from 1834 onwards.

In 2003, the lock became a Scheduled Monument under article 3 of the Historic Monuments & Archaeological Object (NI) Order 1995.

This lock has recently been restored to operational order by Castlereagh Borough Council under the auspices of Lagan Valley Regional Park, with funding from the Heritage Lottery Fund.

References - Primary sources:
1. PRONI OS/6/3/9/1. First edition OS six-inch map, Co Down sheet 9 (1834).

References – Secondary sources:
1. Green, E.R.R. The Industrial Archaeology of Co Down, pp 70-75 (Belfast: HMSO, 1963).
2. McCutcheon, W.A. The Canals of the North of Ireland, pp 40-61 (Newton Abbot: David & Charles, 1965).
3. Delany, R. Ireland’s Inland Waterways (Belfast: Appletree Press, 1986).
4. McCutcheon, W.A. The Industrial Archaeology of Northern Ireland (Belfast: HMSO, 1980).
5. Blair, M. Once Upon the Lagan (Belfast: Blackstaff Press, 1981).

Criteria for listing: architectural interest

Not listed

Criteria for listing: historic interest

Not listed

Evaluation

Lock 3 is a single-chamber masonry lock built on the Lagan Navigation under the direction of Thomas Omer in the later 1750s.
Architecturally, the lock is a good example of its type, and understanding of how it worked has been enhanced by its recent restoration and reinstatement of replica gates. Immediately downstream from the lock is a small single arch masonry bridge by which horses towing the barges crossed from one side of the navigation cut to the other. It is enhanced by its setting and has group value with the adjacent lock-keeper’s house. The lock is also of local historical interest due to its association with the Lagan Navigation and Thomas Omer. The lock and bridge are protected as a scheduled monument, Scheduled Area (009500).