Wolf Rock Lighthouse

In 1790, the Corporation of Trinity House received a patent of the Crown to build a lighthouse on Wolf Rock. The rights were leased to a Lt. Henry Smith; but (such were the technical challenges of the venture) the project was transferred to the less exposed location of the Longships, where construction of a lighthouse proceeded.[10] On Wolf Rock, rather than a lighthouse, Lt. Smith went on to build a 6.1 m (20 ft) high wrought iron daymark, 10 cm (4 in) in diameter and supported by six stays. A metal effigy of a wolf was placed on top; but by 1795 the daymark was washed away.

In the late 1830s John Thurburn built a beacon, which was completed on 15 July 1840,[11][12] and in November of that year was wrecked by storms when the pole and globe on its top were washed away[13] and not replaced until 1842[14] but they were once more washed away in a storm on 9 October 1844.[15] Trinity House engineer James Walker constructed a 4.3 m (14 ft) high cone-shaped beacon, which took five years to build. Made of iron plates and filled with concrete rubble this was completed in 1848,[16] it can still be seen next to the lighthouse.

In April 1860, Trinity House applied to the Board of Trade for funds to build a lighthouse on Wolf Rock.[17] Approval was given and Walker, as engineer-in-chief, drew up designs for a 117 ft (36 m) masonry tower, tapering in diameter from 41 ft 8 in (12.70 m) at the base to 17 ft (5.2 m) at the top. Details of the design followed closely that of other Walker-built lighthouses: the recently completed Bishop Rock and Hanois lights, and the Smalls (which was then nearing completion). While his designs were inspired by Smeaton's third Eddystone Lighthouse, Walker introduced new innovations, not least the use of vertical as well as horizontal dovetail joints (first achieved at Les Hanois at the suggestion of Nicholas Douglass, and likewise incorporated into the design of Wolf Rock).[18]

Nicholas's son James Douglass was appointed as resident engineer, and in July 1861 he arrived (fresh from completing his work as resident engineer for the Smalls lighthouse) and surveyed the rock.[18] The following March work began on excavating the foundations. In October 1862, James Walker died (at the age of 81). James Douglass replaced him as engineer-in-chief to the Trinity House; James's younger brother, William Douglass, then became resident engineer at Wolf Rock.[19]^:ch4 William himself laid the first stone of the new tower on 6 August 1864. Masonry construction was completed on 19 July 1869.[20] The finished tower was topped by a lantern storey manufactured by Chance Brothers of Smethwick to James Douglass's design. The lantern had previously been exhibited at the Paris Exhibition of 1867 as an example of the latest in lantern technology, using curved rather than flat panes of glass and helical rather than straight glazing bars.[21]

Engineering drawing of the 1869 optic and sectional view of it within the lantern, alongside a chart showing location in relation to other lights.

James Chance of Chance Brothers had designed a large (first-order) rotating multi-panel optic for installation in the tower, 2.58 m (8 ft 6 in) high by 1.73 m (5 ft 8 in) diameter.[22] In order to differentiate the light from the nearby St Agnes lighthouse (which displayed a white light) and from Les Hanois Lighthouse (which displayed a red light) it was resolved that the Wolf Rock light should revolve and flash alternately red and white; in order to achieve the required characteristic it was planned to install 'ruby' coloured panes of glass over half the panels on the optic (with the intervening panels left clear).[23] It was known, however, that the intensity of a light was reduced when shone through coloured glass, so Chance conducted experiments to measure the precise difference.[23] It was concluded that the comparative intensity of clear glass to red was 21 to 9 (i.e. more than double); therefore the red-covered panels on the optic were made wider than the others by the same proportion, in order to maintain an even intensity across the colour-change.

The light first shone in January 1870 and flashed red and white as planned.[24] The completed optic (which together with its pedestal stood 20 feet (6.1 m) high) was described by Douglass as "probably the most perfect for the purpose that has yet been constructed";[25] it continued in use for the next hundred years. The optic was rotated by a clockwork drive, that required winding every four hours.[22] A 7-cwt bell, hung from the lantern gallery, was sounded in fog; driven by a separate clockwork mechanism, it rang three times every fifteen seconds.[26]

The Wolf Rock was the site of a hake (Merluccius merluccius) fishery in the 1870s, especially by fishermen from St Ives with 400 employed in October 1879.[27]

In 1904, a reed fog signal was installed; it remained in use until after the Second World War.[26] (The bell was initially retained for standby use, but was decommissioned in 1906.)[28] In 1955 electrification came to Wolf Rock Lighthouse: a 15 kW tungsten filament lamp was installed in place of the oil lamp, within the old optic, and a set of diesel generators were installed (which powered not only the light but also a new diaphone fog signal).[29] Then, in 1972 Wolf Rock became the first lighthouse in the world to be fitted with a helipad (a smaller fourth-order revolving optic having replaced the original in the meantime);[30] this greatly eased the challenge of getting keepers to and from the lighthouse in heavy seas. The last keepers left Wolf Rock in July 1988, when the lighthouse became fully automated;[5] an electric emitter replaced the diaphone fog signal at this time.[26] Fifteen years later the lighthouse was converted to solar power, with photovoltaic cells being installed around the exterior of the helideck support structure.[22]