Mew Head Lighthouse

In 1875 the Belfast Harbour Commissioners asked that the Copeland light be shifted to Mew Island, with the need for a new lighthouse being endorsed by the Board of Trade in 1881. Work on the light began in 1882, to a design by William Douglass. One of the key aspects of the design was to improve on the earlier oil powered light with its simple reflectors, by using gas burners in conjunction with a rotating glass Fresnel lens. The lighthouse was completed in 1884 and consisted of a 37-meter-high (121 ft) rubble stone tower, with a large glazed lantern room. This housed a substantial first-order optic, the largest type available at that time, from the French lens maker Barbier and Fenestre. This tri-form lens had three tiers of lenses each with its own set of 108 gas burners. The output from the light could be varied according to the number of jets used. On a clear night just 32 were lit in the lower tier, but in poor conditions such as fog all three tiers could be lit using 324 burners.

The contractor for the works was Thomas S. Dixon Co. of Belfast, who also built the adjacent keeper's house on the island; five other houses were built by H. Fulton on the mainland at Donaghadee to act as shore dwellings for the keepers and their families.The gas used in the light and the fog siren engines was generated by burning cannel coal in a gas plant alongside the tower and was stored in gasometers until used.

Ongoing problems with the first-order optic meant that it needed replacing, so it was decided to use the hyperradiant optic that had originally been designed for the Tory Island lighthouse, where it had been installed in 1887. Made by the same French manufacturer as the first-order lens, the hyperradiant is the largest type ever used for lighthouses, having a focal length or radius of 1,330 mm (52 in). Like the first-order optic it had a tri-form configuration, consisting of three tiers of lenses stacked above each other, with each tier having six panels, spanning 60 degrees.In the 1920s, it was removed from Tory Island, and re-engineered by Chance Brothers in Smethwick, where it was reduced in size to a bi-form system with two tiers. Two of the six bullseye panels were replaced by metal blanks, producing a light characteristic of four flashes of white light every thirty seconds. To enable the optic to turn freely it was mounted upon a circular bath of mercury known as a mercury float, providing an almost frictionless bearing. The redesigned light was then installed at Mew Island in 1928. It was lit using paraffin, making the coal plant redundant, the last in use at an Irish light. In 1969 generators were installed at the lighthouse, allowing the use of electric light to replace the paraffin burners, and an electric motor to replace the weight driven rotation system.

The hyper-radial lens, which weighed 10 t (9.8 long tons; 11 short tons), was carefully removed from the lighthouse in 2014 and transferred to the mainland by the ILV Granuaile. After restoration at the Commissioners of Irish Lights workshop in Dún Laoghaire, it was shipped back by Granuaile to Belfast to be put on display in "a new interpretive structure, made to resemble a lighthouse lantern room" on the waterside walkway in the Titanic Quarter. The majority of the £447,000 cost of the new structure was met by a Heritage Lottery Fund grant, with other contributions from Belfast City Council and Ulster villages.

A temporary light was displayed until 2015, when a solar powered LED system was commissioned that uses flashing illuminants to mimic the characteristic of the rotating lens. Its installation reduced the range from 24 nautical miles (44 km; 28 mi) of the hyperradiant apparatus to 18 nmi (33 km; 21 mi), and the focal height to 35 m (115 ft). In 2017, it was enhanced with an additional fixed light, changing the light characteristic slightly from four flashes every 30 seconds, with "A new low luminous intensity fixed light [that] will be combined with the existing flashing light of higher luminous intensity in order to assist with acquisition of the light during the eclipse period.