Foghorn
Encyclopedia
A foghorn or fog signal or fog bell is a device that uses sound to warn vehicles of hazards or boats of the presence of other vehicles in fog
gy conditions. The term is most often used in relation to marine transport. When visual navigation
aids such as lighthouse
s are obscured, foghorns provide an audible warning of rocks
, shoal
s, headlands
, or other dangers to shipping.
Audible fog signals have been used in one form or another for hundreds of years, initially simply bells
or gong
s struck manually.
At some lighthouse
s, a small cannon
was let off periodically to warn away ships, but this had the obvious disadvantage of having to be fired manually throughout the whole period the fog persisted (which could be for several days). In the United States
, whistle
s were also used where a source of steam power was available, though Trinity House
, the British
Lighthouse Authority, did not employ them, preferring an explosive signal.
Throughout the 19th century efforts were made to automate the signalling process. Trinity House eventually developed a system (the "Signal, Fog, Mk I") for firing a gun-cotton
charge electrically. However, the charge had to be manually replaced after each signal. At Portland Bill
, for example, which had a 5-minute interval between fog-signals, this meant the horns had to be lowered, the 2 new charges inserted, and the horns raised again every 5 minutes during foggy periods.
Clockwork systems were also developed for striking bells.
Captain James William Newton claimed to have been the inventor of the fog signalling technique using loud and low notes.
The first automated
steam
-powered foghorn was invented by Robert Foulis, a Scotsman who emigrated to Saint John
, New Brunswick
, Canada
. Foulis is said to have heard his daughter playing the piano
in the distance on a foggy night, and noticed the low notes were more audible than the higher notes: he then designed a device to produce a low-frequency sound, as well as a code system for use with it. After repeated representations to the New Brunswick legislature, Foulis's fog signal was installed on Partridge Island
in 1859 by a T. T. Vernon-Smith; Foulis himself was involved in legal battles over his invention for the remainder of his life.
The development of fog signal technology continued apace at the end of the 19th Century. During the same period an inventor, Celadon Leeds Daboll
, developed a coal-powered foghorn called the Daboll trumpet
for the American lighthouse service, though it was not universally adopted. A few Daboll trumpets remained in use until the mid 20th century.
All foghorns use a vibrating column of air to create an audible tone, but the method of setting up this vibration differs. Some horns, like the Daboll trumpet, used vibrating plates or metal reeds, a similar principle to a modern electric car horn
. Others utilised air forced through holes in a revolving cylinder or disk, in the same manner as a siren
. Semi-automatic operation of foghorns was achieved by using a clockwork
mechanism (or 'coder') to open the valves admitting air to the horns; each horn was given its own characteristics to help mariners identify their position.
One of the first automated fog bells was the Stevens Automatic Bell Striker.
Some later fog bells were placed under water, particularly in especially dangerous areas, so that their sound (which would be a predictable set, such as the number "23") would be carried further and reverberate through the ship's hull. See, White Shoal Light (Michigan)
. This was an earlier precursor to RACON
.
In the United Kingdom
, experiments to develop more effective foghorns were carried out by John Tyndall
and Lord Rayleigh, amongst others. The latter's ongoing research for Trinity House culminated in a design for a siren with a large trumpet designed to achieve maximum sound propagation, installed in Trevose Head Lighthouse
, Cornwall
in 1913.
, invented by John Northey of Toronto
, became the standard foghorn apparatus for new installations. Diaphones were powered by compressed air
and could emit extremely powerful low-frequency notes.
In 1982, the Dutch broadcaster VPRO
aired a live foghorn concert on national radio, relaying the sound of the foghorns in Emden
, Calais
, Nieuwpoort
, Scheveningen, Den Helder
, Lelystad
, Urk
, Marken
and Kornwerderzand
.
Since automation of lighthouses became common in the 1960s and 1970s, most older foghorn installations have been removed to avoid the need to run the complex machinery associated with them, and have been replaced with electrically powered diaphragm or compressed air horns. Activation is completely automated: a laser or photo beam is shot out to sea, and if the beam reflects back to the source (i.e., the laser beam is visible due to the fog), the sensor tells a computer to activate the foghorn. In many cases, modern navigational aids have rendered large, long-range foghorns completely unnecessary, according to the International Association of Lighthouse Authorities
.
s or torpedoes which are placed on the track and detonated by the pressure of the wheels of the oncoming train. The loud report of the explosion provides the indication to the driver that in most cases requires the train to be stopped immediately. During World War II
these devices were modified to detonate demolition charges during railroad sabotage
operations.
Fog
Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...
gy conditions. The term is most often used in relation to marine transport. When visual navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
aids such as lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....
s are obscured, foghorns provide an audible warning of rocks
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
, shoal
Shoal
Shoal, shoals or shoaling may mean:* Shoal, a sandbank or reef creating shallow water, especially where it forms a hazard to shipping* Shoal draught , of a boat with shallow draught which can pass over some shoals: see Draft...
s, headlands
Headlands and bays
Headlands and bays are two related features of the coastal environment.- Geology and geography :Headlands and bays are often found on the same coastline. A bay is surrounded by land on three sides, whereas a headland is surrounded by water on three sides. Headlands are characterized by high,...
, or other dangers to shipping.
Early fog signals
Bell (instrument)
A bell is a simple sound-making device. The bell is a percussion instrument and an idiophone. Its form is usually a hollow, cup-shaped object, which resonates upon being struck...
or gong
Gong
A gong is an East and South East Asian musical percussion instrument that takes the form of a flat metal disc which is hit with a mallet....
s struck manually.
At some lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....
s, a small cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
was let off periodically to warn away ships, but this had the obvious disadvantage of having to be fired manually throughout the whole period the fog persisted (which could be for several days). In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, whistle
Whistle
A whistle or call is a simple aerophone, an instrument which produces sound from a stream of forced air. It may be mouth-operated, or powered by air pressure, steam, or other means...
s were also used where a source of steam power was available, though Trinity House
Trinity House
The Corporation of Trinity House of Deptford Strond is the official General Lighthouse Authority for England, Wales and other British territorial waters...
, the British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
Lighthouse Authority, did not employ them, preferring an explosive signal.
Throughout the 19th century efforts were made to automate the signalling process. Trinity House eventually developed a system (the "Signal, Fog, Mk I") for firing a gun-cotton
Nitrocellulose
Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...
charge electrically. However, the charge had to be manually replaced after each signal. At Portland Bill
Portland Bill
Portland Bill is a narrow promontory of Portland stone, which forms the most southerly part of Isle of Portland, and therefore also the county of Dorset, England....
, for example, which had a 5-minute interval between fog-signals, this meant the horns had to be lowered, the 2 new charges inserted, and the horns raised again every 5 minutes during foggy periods.
Clockwork systems were also developed for striking bells.
Captain James William Newton claimed to have been the inventor of the fog signalling technique using loud and low notes.
Robert Foulis, the Daboll Trumpet
The first automated
Automation
Automation is the use of control systems and information technologies to reduce the need for human work in the production of goods and services. In the scope of industrialization, automation is a step beyond mechanization...
steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
-powered foghorn was invented by Robert Foulis, a Scotsman who emigrated to Saint John
Saint John, New Brunswick
City of Saint John , or commonly Saint John, is the largest city in the province of New Brunswick, and the first incorporated city in Canada. The city is situated along the north shore of the Bay of Fundy at the mouth of the Saint John River. In 2006 the city proper had a population of 74,043...
, New Brunswick
New Brunswick
New Brunswick is one of Canada's three Maritime provinces and is the only province in the federation that is constitutionally bilingual . The provincial capital is Fredericton and Saint John is the most populous city. Greater Moncton is the largest Census Metropolitan Area...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. Foulis is said to have heard his daughter playing the piano
Piano
The piano is a musical instrument played by means of a keyboard. It is one of the most popular instruments in the world. Widely used in classical and jazz music for solo performances, ensemble use, chamber music and accompaniment, the piano is also very popular as an aid to composing and rehearsal...
in the distance on a foggy night, and noticed the low notes were more audible than the higher notes: he then designed a device to produce a low-frequency sound, as well as a code system for use with it. After repeated representations to the New Brunswick legislature, Foulis's fog signal was installed on Partridge Island
Partridge Island, New Brunswick
Partridge Island is a Canadian island located in the Bay of Fundy off the coast of New Brunswick on the west side of the mouth of the Saint John River and Saint John Harbour.The island is designated as both a national and provincial historic site...
in 1859 by a T. T. Vernon-Smith; Foulis himself was involved in legal battles over his invention for the remainder of his life.
The development of fog signal technology continued apace at the end of the 19th Century. During the same period an inventor, Celadon Leeds Daboll
Celadon Leeds Daboll
Celadon Leeds Daboll, , was a merchant in New London, Connecticut, and from 1854-1861 was employed in the U.S...
, developed a coal-powered foghorn called the Daboll trumpet
Daboll trumpet
A Daboll trumpet is an air trumpet foghorn which had been developed by an American, Celadon Leeds Daboll, of New London, Connecticut. It was basically a small coal-fired hot air engine, which compressed air in a cylinder on top of which was a reed horn....
for the American lighthouse service, though it was not universally adopted. A few Daboll trumpets remained in use until the mid 20th century.
All foghorns use a vibrating column of air to create an audible tone, but the method of setting up this vibration differs. Some horns, like the Daboll trumpet, used vibrating plates or metal reeds, a similar principle to a modern electric car horn
Vehicle horn
A vehicle horn is a sound-making device used to warn others of the approach of the vehicle or of its presence. Automobiles, trucks, ships, and trains are all required by law to have horns...
. Others utilised air forced through holes in a revolving cylinder or disk, in the same manner as a siren
Siren (noisemaker)
A siren is a loud noise making device. Most modern ones are civil defense or air raid sirens, tornado sirens, or the sirens on emergency service vehicles such as ambulances, police cars and fire trucks. There are two general types: pneumatic and electronic....
. Semi-automatic operation of foghorns was achieved by using a clockwork
Clockwork
A clockwork is the inner workings of either a mechanical clock or a device that operates in a similar fashion. Specifically, the term refers to a mechanical device utilizing a complex series of gears....
mechanism (or 'coder') to open the valves admitting air to the horns; each horn was given its own characteristics to help mariners identify their position.
One of the first automated fog bells was the Stevens Automatic Bell Striker.
Some later fog bells were placed under water, particularly in especially dangerous areas, so that their sound (which would be a predictable set, such as the number "23") would be carried further and reverberate through the ship's hull. See, White Shoal Light (Michigan)
White Shoal Light (Michigan)
The White Shoal Light is a lighthouse located 20 miles west of the Mackinac Bridge in Lake Michigan. It is an active aid to navigation.-Overview:...
. This was an earlier precursor to RACON
Racon
A racon is a radar transponder commonly used to mark maritime navigational hazards. The word is a portmanteau of RAdar and beaCON.When a racon receives a radar pulse, it responds with a signal on the same frequency which puts an image on the radar display...
.
In the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, experiments to develop more effective foghorns were carried out by John Tyndall
John Tyndall
John Tyndall FRS was a prominent Irish 19th century physicist. His initial scientific fame arose in the 1850s from his study of diamagnetism. Later he studied thermal radiation, and produced a number of discoveries about processes in the atmosphere...
and Lord Rayleigh, amongst others. The latter's ongoing research for Trinity House culminated in a design for a siren with a large trumpet designed to achieve maximum sound propagation, installed in Trevose Head Lighthouse
Trevose Head Lighthouse
Trevose Head Lighthouse is a lighthouse on Trevose Head on the north Cornish coast at near Padstow. The tower is 27 metres tall, and has a range of , but, on a clear night, you can just spot the light from Pendeen Lighthouse, over away.-External links:*...
, Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
in 1913.
The diaphone
From the early 20th century a device called the diaphoneDiaphone
For Diaphone, the Noctuid moth species see Diaphone The diaphone was a noisemaking device best known for its use as a foghorn: it could produce deep, powerful tones able to carry a long distance...
, invented by John Northey of Toronto
Toronto
Toronto is the provincial capital of Ontario and the largest city in Canada. It is located in Southern Ontario on the northwestern shore of Lake Ontario. A relatively modern city, Toronto's history dates back to the late-18th century, when its land was first purchased by the British monarchy from...
, became the standard foghorn apparatus for new installations. Diaphones were powered by compressed air
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....
and could emit extremely powerful low-frequency notes.
In 1982, the Dutch broadcaster VPRO
VPRO
The VPRO was established in the Netherlands in 1926 as a religious broadcasting organization. Falling under the Protestant pillar, it represented the Liberal Protestant current...
aired a live foghorn concert on national radio, relaying the sound of the foghorns in Emden
Emden
Emden is a city and seaport in the northwest of Germany, on the river Ems. It is the main city of the region of East Frisia; in 2006, the city had a total population of 51,692.-History:...
, Calais
Calais
Calais is a town in Northern France in the department of Pas-de-Calais, of which it is a sub-prefecture. Although Calais is by far the largest city in Pas-de-Calais, the department's capital is its third-largest city of Arras....
, Nieuwpoort
Nieuwpoort
Nieuwpoort is the name of:* Nieuwpoort, Belgium** Battle of Nieuwpoort * Nieuwpoort...
, Scheveningen, Den Helder
Den Helder
Den Helder is a municipality and a city in the Netherlands, in the province of North Holland. Den Helder occupies the northernmost point of the North Holland peninsula...
, Lelystad
Lelystad
Lelystad is a municipality and a city in the centre of the Netherlands, and it is the capital of the province of Flevoland. The city, built on reclaimed land, was founded in 1967 and was named after Cornelis Lely, who engineered the Afsluitdijk, making the reclamation possible...
, Urk
Urk
Urk is a municipality and a town in the Flevoland province in the central Netherlands.Urk is first mentioned in historical records dating to the 10th century, when it was still an island in the Almere, a lake that would become part of the Zuiderzee in the 13th century after a series of incursions...
, Marken
Marken
Marken is a peninsula in the IJsselmeer, the Netherlands, located in the municipality Waterland in the province North Holland. It is an island, which nowadays is connected to the North Holland mainland by a causeway. Also, Marken is a well-known tourist attraction, well-known for its characteristic...
and Kornwerderzand
Kornwerderzand
Kornwerderzand is a settlement on the Afsluitdijk, a major dam in the Netherlands that links Frisia with North Holland. Kornwerderzand is located approximately 4 kilometers from the coast of Frisia, on a former artificial island which was created during the construction of the dam. The settlement...
.
Replacement of foghorns
International Association of Lighthouse Authorities
The International Association of Marine Aids to Navigation and Lighthouse Authorities is a non-profit organization founded in 1957 to collect and provide nautical expertise and advice.-Background:...
.
Railway fog signals
Fog signals have also been used on railway lines since the middle of the 19th century to indicate to the driver of a moving train that a broken down train, a work party or some other unforeseen hazard is on the line ahead. They are small explosive detonatorDetonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
s or torpedoes which are placed on the track and detonated by the pressure of the wheels of the oncoming train. The loud report of the explosion provides the indication to the driver that in most cases requires the train to be stopped immediately. During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
these devices were modified to detonate demolition charges during railroad sabotage
Sabotage
Sabotage is a deliberate action aimed at weakening another entity through subversion, obstruction, disruption, or destruction. In a workplace setting, sabotage is the conscious withdrawal of efficiency generally directed at causing some change in workplace conditions. One who engages in sabotage is...
operations.
External links
- Listen to Golden Gate Bridge foghorn
- a list of foghorn clips from San Pedro, CA.- Foghorn 1 is a good example of a diaphone.
- Terry Pepper, Seeing the Light, "Fog Signal Technology."
- Location of foghorns that can still be heard in UK