Portland Bill Lighthouse is a functioning lighthouse at Portland Bill, on the

Isle of Portland An isle is an island, land surrounded by water. The term is very common in British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct fr ...

Dorset Dorset ( ; archaically: Dorsetshire , ) is a county in South West England on the English Channel coast. The ceremonial county comprises the unitary authority areas of Bournemouth, Christchurch and Poole and Dorset. Covering an area of , ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. The lighthouse and its boundary walls are Grade II

Listed Listed may refer to: * Listed, Bornholm, a fishing village on the Danish island of Bornholm * Listed (MMM program), a television show on MuchMoreMusic * Endangered species in biology * Listed building, in architecture, designation of a historicall ...

. As Portland Bill's largest and most recent lighthouse, the Trinity House operated Portland Bill Lighthouse is distinctively white and red striped, standing at a height of . It was completed by 1906 and first shone out on 11 January 1906. The lighthouse guides passing vessels through the hazardous waters surrounding the Bill, while also acting as a waymark for ships navigating the English Channel.

History

The two original lighthouses, now known as the Old Higher Lighthouse and

Old Lower Lighthouse The Old Lower Lighthouse is a disused 19th century lighthouse on the Isle of Portland, Dorset, southern England. It is located along the eastern side of Portland Bill. The lighthouse, including its boundary walls and coastguard house, became ...

, operated as a pair of

leading lights Leading lights (also known as range lights in the United States) are a pair of light beacons used in navigation to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for position fixing. At nigh ...

to guide ships between Portland Race and The Shambles sandbank. They were constructed in 1716, both rebuilt in 1869, and decommissioned following the completion of the present lighthouse. At the turn of the 20th-century, Trinity House put forward plans for building a new lighthouse at Bill Point. They acquired the required land in 1903. The builders, Wakeham Bros. of Plymouth, began work on the foundations in October 1903. Chance & Co of Birmingham supplied and fitted the lantern. A pressurised vapour

paraffin Paraffin may refer to: Substances * Paraffin wax, a white or colorless soft solid that is used as a lubricant and for other applications * Liquid paraffin (drug), a very highly refined mineral oil used in cosmetics and for medical purposes * Alkan ...

lamp was used, placed at the centre of a large (

first-order In mathematics and other formal sciences, first-order or first order most often means either: * "linear" (a polynomial of degree at most one), as in first-order approximation and other calculus uses, where it is contrasted with "polynomials of high ...

) revolving

optic Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

; weighing 3.5 tons, this was made up of four asymmetrical

catadioptric A catadioptric optical system is one where refraction and reflection are combined in an optical system, usually via lenses (dioptrics) and curved mirrors ( catoptrics). Catadioptric combinations are used in focusing systems such as searchlights, ...

lens panels and a concave prismatic reflector. The lighthouse was completed in 1905 at a cost of £13,000, and the lamp first lit on 11 January 1906. A red sector light was provided in addition to the main light, shining from a window in the lower part of the tower, to indicate the position of The Shambles. The light was electrified in the mid-1950s. In 1940 the lighthouse was provided with an F-type

diaphone The diaphone is a noisemaking device best known for its use as a foghorn: It can produce deep, powerful tones, able to carry a long distance. Although they have fallen out of favor, diaphones were also used at some fire stations and in other situ ...

fog signal, sounding from a window part-way up the tower. Compressed air was provided to six cylindrical storage tanks by a pair of Reavell compressors, all located (together with a standby generator) within the base of the tower. These were connected at a higher level to the sounding tanks, which fed the compressed air to the diaphone itself, mounted behind its trumpet-like emitter which protruded through the window. Admission of air into the diaphone was controlled by a clockwork (later electric) coder, which caused the diaphone to sound a 3.5-second blast every 30 seconds. The 180 Hz note had an audible range of (which could be doubled under favourable conditions). The diaphone remained in regular use as an aid to navigation until 1995, when it was replaced by a high-frequency electric fog signal (sounding from another window, further down) in readiness for automation. On 18 March 1996, Portland Bill Lighthouse was demanned, and all monitoring and control transferred to the Trinity House Operations & Planning Centre in Harwich. The original Type F

was decommissioned in 1996, but in 2003 Trinity House restored it to occasional use for the benefit of visitors; (it was sounded regularly for half an hour on Sunday mornings, ''except'' when foggy, until 2017). In the early 21st century the lighthouse used a 1 kW MBI lamp together with the same rotating lens system that had been in use since 1906. (It flashed four times every 20 seconds with an intensity of 635,000 candelas and a range of 25 nautical miles.) The fog signal was used in times of bad weather; it gave a four-second blast every 30 seconds with a range of 2 nautical miles. In November 2018 Trinity House applied for (and obtained) planning permission to remove the lamp and optic from the lantern room as part of a programme of modernisation. It proposed relocating the lens array to the base of the tower, which led to the removal of the historic diaphone fog-signalling equipment, installed there in 1940 and still in working order, on the basis that this was 'the only available pacefor retaining the historic optic on-site'.

Present day

In 2019-2020 a new non-rotating LED light source was installed in the lantern room and a new omnidirectional fog signal was installed on the exterior lantern gallery (replacing the electric emitter installed in the 1990s). The two LED lanterns (one of which is used, the other kept on standby) have a reduced range of .

Tourist attraction

As Portland's prime attraction, the Portland Bill Lighthouse is open to the public for tours. A visitor centre is housed in the former lighthouse keeper's quarters. The original centre closed in 2013 due to lack of funding, however a new renovated centre opened in 2015. The tours operated at the lighthouse last approximately 45 minutes and visitors are able to climb the 153 steps to the top of the lighthouse.

Gallery

File:Portland Bill and Trinity House Obelisk.jpg, The lighthouse and the surrounding ex-quarried area. File:Bulbs In Portland Lighthouse BY ROBERT KILPIN.jpg, Lamps in Portland Bill Lighthouse File:Trinity House Flag on Portland Bill Lighthouse.JPG, Trinity House flag on Portland Bill Lighthouse, Dorset File:Foghorn on Portland Bill Lighthouse, Dorset.jpg, The diaphone foghorn emitter of Portland Bill Lighthouse File:Bill of Portland- the lighthouse lens (geograph 3643681).jpg, Fresnel lenses and prismatic mirror

References

External links