Denge
Encyclopedia
Denge is a former Royal Air Force
site near Dungeness, in Kent
, England. It is best known for the early experimental acoustic mirror
s which remain there.
The acoustic mirrors, known colloquially as 'listening ears', at Denge are located between Greatstone-on-Sea
and Lydd
airfield, on the banks of a now disused gravel pit. The mirrors were built in the late 1920s and early 1930s as an experimental early warning system for incoming aircraft, developed by Dr William Sansome Tucker
. Several were built along the south and east coasts, but the complex at Denge is the best preserved.
hemispherical reflector.
mar2005.jpg)
Acoustic mirrors did work, and could effectively be used to detect slow moving enemy aircraft before they came into sight. They worked by concentrating sound waves towards a central point, where a microphone would have been located. However, their use was limited as aircraft became faster. Operators also found it difficult to distinguish between aircraft and seagoing vessels. In any case, they quickly became obsolete due to the invention of radar
in 1932. The experiment was abandoned, and the mirrors left to decay. The gravel extraction works caused some undermining of at least one of the structures.
The striking forms of the sound mirrors have attracted artists and photographers. British artist Tacita Dean
created a film inspired by the complex. The band Turin Brakes
featured the mirrors on some of their album covers. The object appeared in the music video
for Blank & Jones
' "A Forest".
secured £500,000 from the Aggregates Levy Sustainability Fund and from the EU's Interreg programme under the Historic Fortifications Network, as administered by Kent County Council
. This money was spent to restore the damage caused by the gravel works, as well as to install a swing bridge which now is the only means of access, reducing the monument's exposure to vandalism. The site is now only accessible during guided tours, or by wading through the water close to the swing bridge which is only waist deep.
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
site near Dungeness, in Kent
Kent
Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...
, England. It is best known for the early experimental acoustic mirror
Acoustic mirror
An acoustic mirror is a passive device used to reflect and perhaps to focus sound waves.- Overview :Prior to World War II and the invention of radar, acoustic mirrors were built as early warning devices around the coasts of Great Britain, with the aim of detecting airborne invasions...
s which remain there.
The acoustic mirrors, known colloquially as 'listening ears', at Denge are located between Greatstone-on-Sea
Greatstone-on-Sea
Greatstone is a beach-side town, the third town up from the "point" of the Romney Marsh area.It is situated near the largest town there, New Romney in Kent, England. Permission was given in the 1920s for a company to construct large numbers of homes and facilities; only a small number were built...
and Lydd
Lydd
Lydd is a town in Kent, England, lying on the Romney Marsh. It is one of the larger towns on the Marsh, and the most southerly town in Kent. Actually located on Denge Marsh, Lydd was one of the first sandy islands to form as the bay evolved into what is now called the Romney Marsh...
airfield, on the banks of a now disused gravel pit. The mirrors were built in the late 1920s and early 1930s as an experimental early warning system for incoming aircraft, developed by Dr William Sansome Tucker
William Sansome Tucker
Major William Sansome Tucker, DSc, OBE was a British pioneer in acoustical research. He was born in Kidderminster, the son of William Tucker, an artist painter, and his wife Anna....
. Several were built along the south and east coasts, but the complex at Denge is the best preserved.
Denge complex
There are three acoustic mirrors in the complex, each consisting of a single concreteConcrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
hemispherical reflector.
- The 200 foot mirror is a near vertical, curved wall, 200 feet (60m) long. It is one of only two similar acoustic mirrors in the world, the other being in MagħtabMagħtabMaghtab is a village in Malta. Maghtab is mostly known for Malta's largest landfill. Since Malta joined the E.U it has been closed down.-Zones in Maghtab:*Bajjad*Bingjala*Ġebel San Pietru*Ġjovadu*Ghallis*Ghallis Island*Ħatja il-Bajda*Il-Widna*Il-Mejjieli...
, MaltaMaltaMalta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...
.
- The 30 foot mirror is a circular dish, similar to a deeply curved satellite dish, 9 m (30 ft) across, supported on concrete buttresses. This mirror still retains the metal microphone pole at its centre.
- The 20 foot mirror is similar to the 30 foot mirror, with a smaller, shallower dish 6 m (20 ft) across. The design is close to that of an acoustic mirror in KilnseaKilnseaKilnsea is a hamlet in the East Riding of Yorkshire, England, in an area known as Holderness. It is situated approximately south of the village of Easington, on the north bank of the Humber Estuary.It forms part of the civil parish of Easington....
, East Riding of YorkshireEast Riding of YorkshireThe East Riding of Yorkshire, or simply East Yorkshire, is a local government district with unitary authority status, and a ceremonial county of England. For ceremonial purposes the county also includes the city of Kingston upon Hull, which is a separate unitary authority...
.
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
in 1932. The experiment was abandoned, and the mirrors left to decay. The gravel extraction works caused some undermining of at least one of the structures.
The striking forms of the sound mirrors have attracted artists and photographers. British artist Tacita Dean
Tacita Dean
Tacita Dean is an English visual artist who works primarily in film. She is one of the Young British Artists, and was a nominee for the Turner Prize in 1998.-Life and work:...
created a film inspired by the complex. The band Turin Brakes
Turin Brakes
Turin Brakes are a modern folk duo, comprising Olly Knights and Gale Paridjanian, hailing from Balham, London. They had a UK top 5 hit with their song "Painkiller ".-1999–2003:...
featured the mirrors on some of their album covers. The object appeared in the music video
Music video
A music video or song video is a short film integrating a song and imagery, produced for promotional or artistic purposes. Modern music videos are primarily made and used as a marketing device intended to promote the sale of music recordings...
for Blank & Jones
Blank & Jones
Blank & Jones is a Cologne, Germany based Trance duo, consisting of the members Jan Pieter Blank , known as Piet Blank; René Runge , better known as DJ Jaspa Jones; and the producer Andy Kaufhold...
' "A Forest".
Restoration
The mirrors are in the process of being transferred from the aggregate quarry owner to become part of a nature reserve. In 2003, English HeritageEnglish Heritage
English Heritage . is an executive non-departmental public body of the British Government sponsored by the Department for Culture, Media and Sport...
secured £500,000 from the Aggregates Levy Sustainability Fund and from the EU's Interreg programme under the Historic Fortifications Network, as administered by Kent County Council
Kent County Council
Kent County Council is the county council that governs the majority of the county of Kent in England. It provides the upper tier of local government, below which are 12 district councils, and around 300 town and parish councils. The county council has 84 elected councillors...
. This money was spent to restore the damage caused by the gravel works, as well as to install a swing bridge which now is the only means of access, reducing the monument's exposure to vandalism. The site is now only accessible during guided tours, or by wading through the water close to the swing bridge which is only waist deep.