A foghorn or fog signal is a device that uses sound to warn vehicles of navigational hazards such as rocky coastlines, or boats of the presence of other vessels, in foggy conditions. The term is most often used in relation to marine transport. When visual navigation aids such as lighthouses are obscured, foghorns provide an audible warning of rock outcrops, shoals, headlands, or other dangers to shipping.
All foghorns use a vibrating column of air to create an audible tone, but the method of setting up this vibration differs. Some horns, such as the Daboll trumpet, used vibrating plates or metal reeds, a similar principle to a modern electric car horn. Others used air forced through holes in a rotating 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 sequentially open the valves admitting air to the horns; each horn was given its own timing characteristics to help mariners identify them. [1]
Audible fog signals have been used in one form or another for hundreds of years, initially simply seashell horns, fog bells or gongs struck manually.
At some lighthouses, a small cannon was let off periodically to warn away ships, but this was labor-intensive and dangerous. [2] In the United States, whistles 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 five-minute interval between fog-signals, this meant the horns had to be lowered, the two new charges inserted, and the horns raised again every five minutes during foggy periods.[ This paragraph needs citation(s) ]
Clockwork systems were also developed for striking bells. [3] Struck bells were developed throughout the 1800s with the use of a governor, including the use of a large triangle with 4-foot sides in Maine in 1837. Ships were required to carry bells, with an exemption for Turkish ships because Islam forbade the use of bells. [4]
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. Foulis repeatedly presented his concept to the Commissioners of Light Houses for the Bay of Fundy for installation on Partridge Island. While the Commissioners initially rejected Foulis's plan, one commissioner eventually encouraged Foulis to submit detailed plans to the Commission. For reasons unknown, the plans were given to another Canadian engineer, T. T. Vernon Smith, who officially submitted them to the Commissioners as his own. The foghorn was constructed at Partridge Island in 1859 as the Vernon-Smith horn. After protest by Foulis and a legislative inquiry, Foulis was credited as the true inventor, but he never patented or profited from his invention. [5]
Captain James William Newton in England claimed to have been the inventor of the fog signalling technique using loud and low notes. [6]
The development of fog signal technology continued apace at the end of the 19th century. [7] 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. [8] A few Daboll trumpets remained in use until the mid-20th century.
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 (see reference for details of the Trials of Fog Signals [9] ), installed in Trevose Head Lighthouse, Cornwall in 1913. One reporter, after hearing a steam-powered siren for the first time, described it as having "a screech like an army of panthers, weird and prolonged, gradually lowering in note until after half a minute it becomes the roar of a thousand mad bulls, with intermediate voices suggestive of the wail of a lost soul, the moan of a bottomless pit and the groan of a disabled elevator." [4]
One of the first automated fog bells was the Stevens Automatic Bell Striker. [3]
Some later fog bells were placed underwater, particularly in especially dangerous areas, so that their sound (which would be a predictable code, such as the number "23") would be carried further and reverberate through the ship's hull. For example, this technique was used at White Shoal Light (Michigan). [10] [11] This was an earlier precursor to RACON.
From the early 20th century an improved device called the diaphone, originally invented as an organ stop by Robert Hope-Jones [9] and developed as a fog signal by John Northey of Toronto, became the standard foghorn apparatus for new installations worldwide. Diaphones were powered by compressed air and could emit extremely powerful low-frequency notes.
The foghorn's musical connection extended beyond its use of pipe-organ technology. In 1982, for example, the Dutch broadcaster VPRO aired a live "foghorn concert" on national radio, relaying the sound of foghorns from Emden, Calais, Nieuwpoort, Scheveningen, Den Helder, Lelystad, Urk, Marken and Kornwerderzand, mixed with studio music by sound artist Alvin Curran. [12]
Since automation of lighthouses became common in the 1960s and 1970s, most older foghorn installations have been removed to avoid the need to run their complex machinery, 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 fog or precipitation), the sensor sends a signal to activate the foghorn. In many cases, modern navigational aids, including GPS, have rendered large, long-range foghorns completely unnecessary, according to the International Association of Lighthouse Authorities. [13]
The Nab Tower is a tower originally planned for anti-submarine protection in the English Channel in World War I. It was sunk over the Nab rocks east of the Isle of Wight to replace a lightship after the war, and is a well-known landmark for sailors as it marks the deep-water eastern entry into the Solent.
Souter Lighthouse is a lighthouse located to the North of Whitburn, South Tyneside, England.. Souter Point was the first lighthouse in the world to be actually designed and built specifically to use alternating electric current, the most advanced lighthouse technology of its day. The light was generated by a carbon arc lamp: first lit on 11 January 1871, it was described at the time as 'without doubt one of the most powerful lights in the world'.
Pendeen Lighthouse, also known as Pendeen Watch is an active aid to navigation located 2 kilometres (1.2 mi) to the north of Pendeen in west Cornwall, England. It is located within the Aire Point to Carrick Du SSSI, the Cornwall Area of Outstanding Natural Beauty and the Penwith Heritage Coast. The South West Coast Path passes to the south.
The Lizard Lighthouse is a lighthouse at Lizard Point, Cornwall, England, built to guide vessels passing through the English Channel. It was often the welcoming beacon to persons returning to England, where on a clear night, the reflected light could be seen 100 mi (160 km) away.
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 situations where a loud, audible signal was required.
The Pilot Island Light is a lighthouse located near Gills Rock, on Pilot Island at the east end of Death's Door passage, in Door County, Wisconsin.
The Turn Point Light Station is an active aid to navigation overlooking Haro Strait from the western tip of Stuart Island, San Juan County, Washington, in the northwest of the United States. The light marks a sharp turn in the shipping lanes at the transition between Haro Strait and Boundary Pass.
Coquille River Light is a lighthouse located near Bandon, Oregon, United States. It is currently maintained by the Oregon Parks and Recreation Department as a part of Bullards Beach State Park.
A Daboll trumpet is an air trumpet foghorn which was 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.
Start Point lighthouse was built in 1836 to protect shipping off Start Point, Devon, England. Open to the public in summer months, it is owned and operated by Trinity House. It has been designated by English Heritage as a grade II listed building.
Portland Bill Lighthouse is a functioning lighthouse at Portland Bill, on the Isle of Portland, Dorset, England. The lighthouse and its boundary walls are Grade II Listed.
Bull Point Lighthouse is a lighthouse on Bull Point, about one mile (1.6 km) north of the village of Mortehoe, on the northern coast of Devon, England. The lighthouse provides a visual aid to the villages of Mortehoe, Woolacombe and Ilfracombe, and warns of the inhospitable and rocky coast that lines the area.
A fog bell is a navigation mark used as an audible aid to navigation in seafaring, especially in fog and poor visibility. Floating navigation signs with bells are called bell buoys. On ships, the ship's bell is used for sound signals. Due to more suitable sound generators, but also the development and spread of radar, satellite navigation and electronic charting systems, fog bells have lost their importance for maritime navigation.
The Manana Island Sound Signal Station is an active fog signal station on Manana Island, Maine, United States. Established in 1855, it is one of the only separately managed fog signals in the United States, having been operationally independent of Monhegan Island Light for most of its existence. It is also home to the only known fog signal trumpet tower, built in 1889. The station was listed on the National Register of Historic Places as Manana Island Fog Signal Station in 2002.
Roche's Point Lighthouse is situated at the entrance to Cork Harbour, Ireland. A lighthouse was first established on 4 June 1817 to guide ships into Cork Harbour. The original tower was deemed too small and in 1835 was replaced by the larger present tower which is 49 feet high with a diameter of 12 feet. Roche's Point Lighthouse, and a number of other structures, are located on a headland of the same name.
The Duluth South Breakwater Outer Light is a lighthouse on the south breakwater of the Duluth Ship Canal in Duluth, Minnesota, United States. It forms a range with the Duluth South Breakwater Inner Light to guide ships into the canal from Lake Superior.
Point Atkinson Lighthouse is a lighthouse erected on Point Atkinson, a headland in southwestern British Columbia named by Captain George Vancouver in 1792, when he was exploring the Pacific Northwest in the ship Discovery. The first wooden lighthouse went into service in 1875 and was replaced by a reinforced concrete structure in 1914.
St Catherine's Lighthouse is a lighthouse located at St Catherine's Point at the southern tip of the Isle of Wight. It is one of the oldest lighthouse locations in Great Britain.
Dungeness Lighthouse on the Dungeness Headland started operation on 20 November 1961. Its construction was prompted by the building of Dungeness nuclear power station, which obscured the light of its predecessor which, though decommissioned, remains standing. The new lighthouse is constructed of precast concrete rings; its pattern of black and white bands is impregnated into the concrete. It remains in use today, monitored and controlled from the Trinity House Operations and Planning Centre at Harwich, Essex.
St Abb's Head Lighthouse stands on the cliffs at the rocky promontory of St Abb's Head, near the village of St Abbs in Berwickshire.
{{cite book}}: CS1 maint: location (link)Captain Newton also claimed to be the inventor of fog signalling by the interchange and repetition [sic] of loud and low notes.
| Types |
|  | ||||
|---|---|---|---|---|---|---|
| Fixtures | ||||||
| Maintenance | ||||||
| Locations | ||||||
| Categories | ||||||
| Global organizations | ||||||
