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 diaphone horn was based directly on the organ stop of the same name invented by Robert Hope-Jones, creator of the Wurlitzer organ. [1] [2] Hope-Jones' design was based on a piston that was closed only at its bottom end and had slots, perpendicular to its axis, cut through its sides; the slotted piston moved within a similarly slotted cylinder. Outside of the cylinder was a reservoir of high-pressure air. Initially, high-pressure air would be admitted behind the piston, pushing it forward. When the slots of the piston aligned with those of the cylinder, air passed into the piston, making a sound and pushing the piston back to its starting position, whence the cycle would repeat. [3] A modification of Hope-Jones' design was patented by John Pell Northey, head of the Northey Co. Ltd. of Toronto, Ontario, Canada, which manufactured pumps and small gasoline engines. [4] Northey added a secondary compressed air supply to the piston in order to power it during both its forward and reverse strokes and thus create an even more powerful sound. [5] The entire horn apparatus was driven by a compressor.
To manufacture the new equipment, Northey set up the Diaphone Signal Co. at Toronto in 1903. [6] It manufactured a range of diaphone models: the large "Type F", which created a tone of about 250 Hz, found worldwide use as a fog signal, especially in lighthouses. The mechanism of the diaphone created a noticeable low-frequency "grunt" at the end of each note produced, caused by the piston decelerating as the air supply was cut. As this low-frequency sound could carry farther, Northey's son Rodney redesigned the "Type F" model to sustain the second low tone, [7] creating the familiar two-tone fog signal, commonly used in lighthouses and lightvessels in the United States and Canada (as well as in a famous series of radio commercials for Lifebuoy soap). This version, known as the "Improved Type F" or later as the "F2T", was particularly common in installations on the West Coast of the United States and in lightvessels. [6] Installations in Europe generally used single-tone diaphones. [8]
Rodney Northey sold the Diaphone Signal Co. in 1932, when it was bought by a Buffalo, New York company, Deck Brothers, working under contract for the United States Lighthouse Service. [9] This company still exists, although it no longer manufactures diaphones. The European manufacturing rights were obtained by Chance Brothers of Birmingham in the United Kingdom, already a major supplier of Fresnel lenses and other equipment to lighthouse authorities.
In use, the diaphone was generally found to be reliable and suffered little from wear, as the lightweight piston floated on a cushion of air during oscillation. [10] Such wear as did occur tended to happen as a result of the piston becoming loose: as the pistons were custom-made [11] and the design to some degree affected the individual sound characteristics of the signal, the manufacturers supplied two spare pistons with each diaphone. [10]
The majority of diaphone installations were removed or became disused during the 1960s and 1970s. This was partly a result of automation of lighthouses, but it was also found that modern diaphragm horns would produce similar levels of volume to a diaphone while requiring much smaller and less powerful compressors. [12] By 1983, the last two-tone "F2T" type in full-time operation in the United States was at Edgartown, Martha's Vineyard. [11] A few survive in working condition in lighthouses around the world.
This considerably smaller device was produced by the Gamewell Corporation, of Newton, Massachusetts, for use as a municipal alarm, especially at fire stations, to alert firefighters and the public during emergencies. Many Gamewell diaphone systems remain in use today. [13] The Gamewell diaphone has a range of about six miles (9.7 km) under optimum conditions. [14]
The following installations are still functional and are demonstrated from time to time as tourist attractions.
A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines. There are two general types: mechanical and electronic.
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.
An organ pipe is a sound-producing element of the pipe organ that resonates at a specific pitch when pressurized air is driven through it. Each pipe is tuned to a specific note of the musical scale. A set of organ pipes of similar timbre comprising the complete scale is known as a rank; one or more ranks constitutes a stop.
Souter Lighthouse is a lighthouse located in the village of Whitburn, Tyne and Wear, 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'.
A steam whistle is a device used to produce sound in the form of a whistle using live steam, which creates, projects, and amplifies its sound by acting as a vibrating system.
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 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 Kewaunee Pierhead lighthouse is a lighthouse located near Kewaunee in Kewaunee County, Wisconsin. The lighthouse looks nearly identical to the Holland Harbor Lighthouse, except that it is colored white.
A fire alarm box, fire alarm call box, or fire alarm pull box is a device used for notifying a fire department of a fire. Typically installed on street corners, they were the main means of summoning firefighters before the general availability of telephones.
Ballast Point Lighthouse was a lighthouse in California, situated on Ballast Point, a tiny peninsula extending into San Diego Bay from Point Loma, San Diego, California. The lighthouse was torn down in 1960; the site is now on the grounds of Naval Base Point Loma. Ballast Point Lighthouse was the last lighthouse displaying a fixed light on the Pacific Coast. An automated light is left in its place and operates on a piling in the water off of the original site.
Point Sur Lighthouse is a lightstation at Point Sur 24.6 miles (39.6 km) south of Monterey, California at the peak of the 361-foot (110 m) rock at the head of the point. It was established in 1889 and is part of Point Sur State Historic Park. The light house is 40 feet (12 m) tall and 270 feet (82 m) above sea level. As of 2016, and for the foreseeable future the light is still in operation as an essential aid to navigation. Point Sur is the only complete turn-of-the-20th-century lightstation open to the public in California. Three-hour walking tours guided by volunteers are available on Wednesdays and weekends throughout the year.
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.
Hartland Point Lighthouse is a Grade II listed building at Hartland Point, Devon, England. The point marks the western limit of the Bristol Channel with the Atlantic Ocean continuing to the west. Trinity House, the lighthouse authority for England and Wales, have a lighthouse on the tip of the peninsula.
Low Head Lighthouse is in Low Head, Tasmania, about 7 kilometres (4.3 mi) north of George Town on the east side of the mouth of the Tamar River. It was the third lighthouse to be constructed in Australia, and it is also Australia's oldest continuously used pilot station. This light is now unmanned and automated.
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.