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{{for multi|the organ pipe|Diaphone pipes|the linguistic term|Diaphoneme|the Noctuidae moth species|Diaphone (moth)}}
{{Use dmy dates|date=April 2020}}
[[File:Type B and Type F Diaphone Side by Side.jpg|thumb|A Type B Diaphone (Gamewell) in front of a Type F Diaphone fog horn (Diaphone Signal Co.) previously used in Cleveland, OH.]]
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 station]]s and in other situations where a loud, audible signal was required.

[[File:East Brother Light Diaphone Foghorn.oga|thumbnail|Sound of the diaphone at [[East Brother Island Light]], a lighthouse located at Richmond, California.]]

==History==
The diaphone horn was based directly on the [[organ stop]] of the [[Diaphone pipes|same name]] invented by [[Robert Hope-Jones]], creator of the [[Wurlitzer]] organ.<ref>Michael Lamm (Winter 2003) "Feel the Noise:  The art and science of making sound alarming," ''Invention & Technology'', '''18''' (3) :  22–27.</ref><ref>[http://www.terrypepper.com/lights/closeups/fogsignal/diaphone/diaphone.htm Seeing the Light:  "The diaphone fog signal" by Jeff Laser]</ref> 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.<ref>For the patents of Hope-Jones' diaphones that were used as foghorns, see:
*  Hope-Jones, R., "Sound-producing apparatus suitable for sirens, organs, etc.," British patent 26,738 (31 Dec. 1901).  See:  ''Patents for Inventions:  Abridgements of Specifications … Period – A.D. 1901-4.'' (London, England:  Patent Office, 1907) [https://books.google.com/books?id=SmhZAAAAYAAJ&pg=RA2-PA122 page 122].
*  Robert Hope-Jones, {{US Patent|702557}} "Sound-producing device suitable for sirens, etc.," (filed:  26 Nov. 1901; issued 17 June 1902).</ref>  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.<ref>For further information about John Pell Northey and the Northey Company of Toronto, see:
*  [http://www.smokstak.com/forum/showthread.php?t=77544 SmokStak:  The Northey Co., Ltd.]
*  [http://buzzcoil.brinkster.net/northey/page101.html Buzzcoil.Brinkster.net/Northey].</ref> 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.<ref>Northey's patents for diaphones:  
*  John  Pell Northey,  "Sound-producing device suitable for sirens or like instruments," {{U.S. Patent|736,428}} (filed:  22 Nov. 1902; issued: 18 Aug. 1903).  This patent mentions a second source of high-pressure air that caused the slotted piston to reciprocate.
*  John  Pell Northey, "Sound-producing device," {{U.S. Patent|973,960}} (filed:  5 June 1908; issued:  25 Oct. 1910).
*  John Pell Northey, "Sound-producing device," {{U.S. Patent|976,682}} (filed:  5 June 1908; issued:  22 Nov. 1910).
*  John Pell Northey, "Sound-signaling installation," {{U.S. Patent|1,619,585}} (filed:  8 June 1926; issued:  1 March 1927).
*  John P. Northey, "Sound-producing device," {{U.S. Patent|1,799,387}} (filed:  1 March 1929; issued:  7 April 1931).</ref> The entire horn apparatus was driven by a [[Gas compressor|compressor]].

To manufacture the new equipment, Northey set up the Diaphone Signal Co. at [[Toronto]] in 1903.<ref name=laser>Laser, J. ''[http://www.terrypepper.com/lights/closeups/fogsignal/diaphone/diaphone.htm Seeing the Light]'' accessed 2008-03-09</ref> It manufactured a range of diaphone models: the large "Type F", which created a tone of about 250 [[hertz|Hz]], found worldwide use as a [[Foghorn#Fog Signal|fog signal]], especially in [[lighthouse]]s. 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,<ref>Rodney V. Northey, "Sound-producing device," {{U.S. Patent|1,844,226}} (filed:  27 March 1931; issued 9 February 1932).</ref> creating the familiar two-tone fog signal, commonly used in lighthouses and [[lightvessel]]s in the [[United States]] and [[Canada]] (as well as in a famous series of radio commercials for [[Lifebuoy (soap)|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.<ref name="laser"/> Installations in Europe generally used single-tone diaphones.<ref name=douglas>Fox, F. [http://homepages.manx.net/fredd/diaphone.html Diaphone at Douglas Head Lighthouse] {{webarchive|url=https://web.archive.org/web/20080512090347/http://homepages.manx.net/fredd/diaphone.html |date=12 May 2008 }} accessed 2008-03-09</ref>

[[File:SplitRockFogSignal.jpg|thumb|right|Building housing the two diaphones of [[Split Rock Lighthouse]].]]

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]].<ref name=laser2>Laser, J. ''[http://www.terrypepper.com/lights/closeups/fogsignal/diaphone/diaphone.htm Seeing the Light]'' accessed 03-09-08. Northey sold the company as he required money to marry his [[Engagement|fiancée]].</ref> 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 lens]]es 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.<ref name=renton>Renton, A. ''Lost Sounds: the story of coast fog signals'', 2003, p.163</ref> Such wear as did occur tended to happen as a result of the piston becoming loose: as the pistons were custom-made<ref name=csm>[http://www.csmonitor.com/1983/0714/071446.html Bringing Back the Sound of San Francisco], ''Christian Science Monitor'', Jul 1983</ref> and the design to some degree affected the individual sound characteristics of the signal, the manufacturers supplied two spare pistons with each diaphone.<ref name="renton"/>

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 [[Air horn|diaphragm horns]] would produce similar levels of volume to a diaphone while requiring much smaller and less powerful compressors.<ref name=asme>American Society of Mechanical Engineers, ''Annual Proceedings of the Diesel and Gas Engine Power Division'', V. 33–34 (1961), p.18</ref> By 1983, the last two-tone "F2T" type in full-time operation in the United States was at [[Edgartown]], [[Martha's Vineyard]].<ref name="csm"/> A few survive in working condition in lighthouses around the world.

==The Gamewell diaphone==
This considerably smaller device was produced by the Gamewell Corporation, of [[Newton, Massachusetts]], for use as a [[Civil defense siren#Usage in the United States|municipal alarm]], especially at fire stations, to alert [[firefighter]]s and the public during emergencies. Many Gamewell diaphone systems remain in use today.<ref name=gamewell>{{cite web |url=http://www.gamewelldiaphone.com/history.php |title=The Gamewell Diaphone Web Site |accessdate=2008-09-03 |url-status=dead |archiveurl=https://web.archive.org/web/20080922233845/http://www.gamewelldiaphone.com/history.php |archivedate=22 September 2008}} The history of the Gamewell Diaphone. Accessed 2008-03-09</ref> The Gamewell diaphone has a range of about six miles ({{convert|6|mi|disp=output only}}) under optimum conditions.<ref name=gamewell2>{{cite web |url=http://www.gamewelldiaphone.com/diaphone_techinfo.php |title=The Gamewell Diaphone Web Site |accessdate=2008-09-09 |url-status=dead |archiveurl=https://web.archive.org/web/20081001222953/http://www.gamewelldiaphone.com/diaphone_techinfo.php |archivedate=1 October 2008}} Gamewell Diaphone Technical Information, accessed 2008-09-09</ref>
[[File:Saltaire VFC Gamewell Diaphone Test.webm|thumb|A noon test of a Gamewell Diaphone]]

==Working diaphone installations==
The following installations are still functional and are demonstrated from time to time as tourist attractions.
*[[DeTour Reef Light|Detour Reef Lighthouse]] near Detour, Michigan restored their original Type F2T diaphones to working condition and reinstalled them in the lighthouse, complete with new compressors and air tanks. <ref>{{Cite web|date=2011-05-05|title=DeTour Reef Light Original Foghorn Made Operational|url=http://drlps.com/old-foghorn-from-detour-reef-light-made-operational-by-chuck-feltner/|access-date=2021-07-19|website=DeTour Reef Light Preservation Society|language=en-US}}</ref> 
*[[East Brother Island Light]], [[Richmond, California]]<ref name=ebrother>http://ebls.org/?p=24 ''The East Brother Diaphones'', accessed 2008-09-04</ref> has a fully restored fog signal building with operational 2-tone Type F2T diaphones. 
*[[Grand Traverse Light]], [[Michigan]] has a working ''Type CC'' diaphone. 
*[[United States lightship Nantucket (LV-112)|Nantucket Light Ship]] museum in [[Boston]], [[Massachusetts]] sounded its restored diaphone for the first time on August 7, 2015.<ref>{{Cite news|last=Andersen|first=Travis|date=7 August 2015|title=Historic Nantucket Lightship shines bright in Boston|work=Boston Globe|url=https://www.bostonglobe.com/metro/2015/08/07/historic-nantucket-lightship-shines-bright-boston/dpLWXzwp8O9cOtB6uhezpN/story.html|access-date=19 July 2021}}</ref>
*[[Nash Point Lighthouse]], [[South Wales]], [[United Kingdom]]
*[[Portland Bill Lighthouse]], [[Isle of Portland]], [[United Kingdom]]: A ''Type F'' diaphone decommissioned in 1996, but restored in 2003 for the benefit of visitors.<ref name=DailyEcho>{{cite news|title=Blast from the Past|newspaper=[[Bournemouth Daily Echo]]|publisher=[[Newsquest|Newsquest Media Group]]|location=Bournemouth, Dorset, England|date=27 August 2003|url=http://www.bournemouthecho.co.uk/archive/2003/08/27/Dorset+Archive/5376521.Blast_from_the_past/|accessdate=2011-01-16}}</ref>
*[[Low Head Lighthouse]] in [[Low Head, Tasmania]] possesses the only working ''Type G'' diaphone (one of the largest models constructed) in the world. It has an audible range of up to 20 miles.<ref name=Findlay>{{cite web|author=Findlay B|title=The Low Head Fog Horn|publisher=Low Head Progress & Heritage Association|location=Low Head, Tasmania|year=2001|url=http://freepages.genealogy.rootsweb.ancestry.com/~barrowsr/Fog%20Horn%20at%20Low%20Head,%20Tas/The%20Low%20Head%20Fog%20Horn%20by%20Bruce%20Findlay.htm|accessdate=2011-01-16|url-status=dead|archiveurl=https://web.archive.org/web/20101027014331/http://freepages.genealogy.rootsweb.ancestry.com/~barrowsr/Fog%20Horn%20at%20Low%20Head%2C%20Tas/The%20Low%20Head%20Fog%20Horn%20by%20Bruce%20Findlay.htm|archivedate=27 October 2010}}</ref>
*[[Lindesnes Lighthouse]] in southern [[Norway]]. The last Sunday of July, Fog Horn Day is held at the lighthouse.

== External links ==
*  Animation of the operation of the Hope-Jones diaphone:  [http://gamewelldiaphone.com/technical-info/piston-stator-and-pitch-info/ Gamewell Diaphone]
*  Photographs of diaphone foghorn components:
**  [https://web.archive.org/web/20080512090347/http://homepages.manx.net/fredd/diaphone.html Douglas Head lighthouse, Isle of Man]
**  [http://www.hornwhistleboard.com/viewtopic.php?f=8&t=45 Horn & Whistle Board:  Diaphone foghorn]

== References ==
{{reflist}}
[[Category:Canadian inventions]]
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