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			{{short description\|Physicist and engineer}}
	'''Daniel Gabriel Fahrenheit''' (] ] – ] ]) was a ] ] and ] who worked most of his life in the ]. The ] ('''°F''') scale of ] is named after him.
			{{Use dmy dates\|date=October 2015}}
			{{Infobox scientist
			\| name = Daniel Gabriel Fahrenheit
			\| image = Fahrenheit small.jpg
			\| image_size = 180px
			\| birth_date = 24 May 1686 (14 May ])
			\| birth_place = Danzig, ]<br>(present-day ], Poland)
			\| death_date = {{Death date and age\|df=yes\|1736\|9\|16\|1686\|5\|24}}
			\| death_place = ], ]
			\| residence =
			\| field = ] (])
			\| work_institutions =
			\| alma_mater =
			\| known_for = ]<br />]<br />]<br />]<br />]
			\| influences =
			\| influenced =
			\| prizes =
			\| footnotes =
			\| signature = Daniel Gabriel Fahrenheit Signature.svg
			}}
			'''Daniel Gabriel Fahrenheit''' ] ({{IPAc-en\|ˈ\|f\|ær\|ə\|n\|h\|aɪ\|t}}; {{IPA\|de\|ˈfaːʁn̩haɪt\|lang}}; 24 May 1686 – 16 September 1736)<ref>{{Cite EB1911\|wstitle=Fahrenheit, Gabriel Daniel \|volume=10 \|page=126}}</ref> was a <!-- Please do not include nationality without a prior discussion on talk page.-->], ], and ] maker, born in ] to a family of ] extraction. Fahrenheit invented thermometers accurate and consistent enough to allow the comparison of ] measurements between different observers using different instruments.<ref>{{Cite journal \|last=Dorsey \|first=N. Ernest \|title=Title of the Article \|journal=Journal of the Washington Academy of Sciences \|volume=36 \|issue= \|date=15 November 1946 \|page=363}}</ref> Fahrenheit is also credited with inventing ]s more accurate and superior to ] at the time. The popularity of his thermometers led to the widespread adoption of his ] attached to his instruments.<ref name="Grigull, Ulrich 1966 pp. 9">Grigull, Ulrich (1966). ''Fahrenheit, a Pioneer of Exact Thermometry''. (The Proceedings of the 8th International Heat Transfer Conference, San Francisco, 1966, Vol. 1, pp. 9–18.)</ref>

	== Biography ==		== Biography ==
			=== Early life ===
			]]]
			Fahrenheit was born in Danzig (Gdańsk), then in the ]. The Fahrenheits were a German ] merchant family who had lived in several ] cities. Fahrenheit's great-grandfather had lived in ], and research suggests that the Fahrenheit family originated in ].<ref>{{cite book \|author=Kant, Horst \|title=G. D. Fahrenheit / R. -A. F. de Réaumur / A. Celsius \|year=1984 \|publisher=B. G. Teubner \|url=https://books.google.com/books?id=XYKtGQAACAAJ \|access-date=14 June 2008}}</ref> Daniel's grandfather moved from ] in ] (then in the ]) to Danzig and settled there as a merchant in 1650. His son, Daniel Fahrenheit (the father of Daniel Gabriel), married Concordia Schumann, the daughter of a well-known Danzig business family. Daniel was the eldest of the five Fahrenheit children (two sons, three daughters) who survived childhood. His sister, Virginia Elisabeth Fahrenheit, married Benjamin Krüger and was the mother of Benjamin Ephraim Krüger, a clergyman and playwright.<ref>See the .</ref>

			As a young adult, Fahrenheit "showed a particular desire for studying," and was scheduled to enroll in the ].<ref name="momber" />{{rp\|111}} But on 14 August 1701, his parents died after eating poisonous mushrooms.<ref>{{cite journal \|last1=Meyer \|first1=F.A. \|title=Daniel Gabriel Fahrenheit aus Danzig \|journal=Westpreussen Jahrbuch \|date=1952 \|issue=1951–1952 \|pages=138–141}}</ref> Fahrenheit, along with two brothers and sisters, was placed under guardianship. In 1702, Fahrenheit's guardians enrolled him in a bookkeeping course and sent him to a four-year merchant trade apprenticeship in ].<ref name="star" />{{rp\|1}}
	Fahrenheit was born in ] (Gdańsk) in ] on ] ]. The Fahrenheits were a merchant family who had moved from one ] city to the Polish. Fahrenheit's great-grandfather had lived in ], although research suggests that the Fahrenheit family originated in ].<ref>Horst Kant, ''G.D. Fahrenheit / R.-A.F. de Réaumur / A. Celsius'', 1984.</ref> Daniel's grandfather ''Reinhold Fahrenheit vom Kneiphof'' moved from ](Kniepawa) (])(Królewiec)) to Danzig and settled there as a merchant in 1650. Father Daniel Fahrenheit married Concordia (widowed name, ]), daughter of the well-known Danzig business family of ]. Daniel Gabriel was the eldest of the five Fahrenheit children who survived childhood (two sons, three daughters).

			Upon completing his apprenticeship, Fahrenheit ran off<ref name="momber" />{{rp\|111}} and began a period of travel through the ], Sweden, and Denmark in 1707. At the request of his guardians, a warrant was issued for his arrest with the intention of placing him into the service of the Dutch East India company.<ref name="star" />{{rp\|3–4}}
	Upon the accidental early death of his parents, by consumption of poisonous mushrooms, Gabriel had to take up business training as a merchant in ]. However, his interest in natural sciences caused him to take up studies and experimentation in that field, and after travelling around, he settled 1717 in ] with the trade of ], making ]s, ]s, and ]s. From 1718 onwards, he gave lectures in ] in Amsterdam, and became a member of the ] in 1724. Fahrenheit died in The Hague.

			===Work with thermometers, Fahrenheit scale===
			By around 1706, Fahrenheit was manufacturing and shipping barometers and spirit-filled thermometers using the {{ill\|Florentine temperature scale\|wd=Q130551159\|s=1\|v=sup}}.<ref name="momber">{{cite journal \|last1=Momber \|first1=Alfred \|title=Daniel Gabriel Fahrenheit.; sein Leben und Wirken \|journal=Schriften der Naturforschenden Gesellschaft in Danzig \|date=1890 \|volume=7 \|issue=J }}</ref>{{rp\|116}} In 1708, Fahrenheit met with the mayor of Copenhagen and astronomer, ], and was introduced to ] and his methods for making thermometers. Rømer told Fahrenheit that demand for accurate thermometers was high.<ref name="star" />{{rp\|4}} The visit inspired Fahrenheit to try to improve his own offerings.<ref name="middleton">* {{cite book \|author=Middleton, W. E. Knowles \|title=A History of the Thermometer and its Use in Meteorology \|year=1966 \|location=Baltimore, Maryland \|publisher=Johns Hopkins Press}}{{rp\|71}}</ref> Perhaps not coincidentally, Fahrenheit's arrest warrant was dropped around the time of his meeting with Rømer.<ref name="star" />{{rp\|3–4}}

			In 1709, Fahrenheit returned to Danzig and took observations using his barometers and thermometers, traveled more in 1710 and returned to Danzig in 1711 to settle his parents' estate. After additional travel to Königsberg and Mitau in 1711, he returned to Danzig in 1712 and stayed there for two years. During this period he worked on solving technical problems with his thermometers.<ref name="star" />{{rp\|4–5}}

			Fahrenheit began experimenting with mercury thermometers in 1713.<ref name="star" />{{rp\|26}} Also by this time, Fahrenheit was using a modified version of Rømer's scale for his thermometers which would later evolve into his own ]. In 1714, Fahrenheit left Danzig for Berlin and Dresden to work closely with the glass-blowers there.<ref name="star" />{{rp\|5}} In that year ] wrote about Fahrenheit's thermometers in a journal after receiving a pair of his alcohol-based devices, helping to boost Fahrenheit's reputation in the scientific community.<ref name="middleton" />{{rp\|74}}

			In addition to his interest in meteorological instruments, Fahrenheit also worked on his ideas for a mercury clock, a ], and a ] around 1715. He struck up a correspondence with ] about some of these projects. From the exchange of letters, we learn that Fahrenheit was running out of money while working on his projects and asked Leibniz for help obtaining a paid post so he could continue his work.<ref name="star" />{{rp\|5–7}}

			In 1717 or 1718, Fahrenheit returned to Amsterdam and began selling barometers, ]s, and his mercury and alcohol-based thermometers commercially.<ref name="star" />{{rp\|8}} By 1721, Fahrenheit had perfected the process of crafting and standardizing his thermometers.<ref name="star" />{{rp\|24}} The superiority of his mercury thermometers over alcohol-based thermometers made them very popular, leading to the widespread adoption of his Fahrenheit scale, the measurement system he developed and used for his thermometers.<ref name="Grigull, Ulrich 1966 pp. 9"/>

			===Later life and controversy ===
			Fahrenheit spent the remainder of his life in Amsterdam. From 1718 onward, he lectured in chemistry in Amsterdam. He visited England in 1724 and was elected into the ] on May 5.<ref>{{Cite web \|url=http://www2.royalsociety.org/DServe/dserve.exe?dsqIni=Dserve.ini&dsqApp=Archive&dsqCmd=Show.tcl&dsqDb=Persons&dsqPos=0&dsqSearch=((text)%3D'fahrenheit') \|title=The Royal Society Archive catalogue \|access-date=26 November 2010 \|archive-url=https://web.archive.org/web/20111127053001/http://www2.royalsociety.org/DServe/dserve.exe?dsqIni=Dserve.ini&dsqApp=Archive&dsqCmd=Show.tcl&dsqDb=Persons&dsqPos=0&dsqSearch=((text)%3D'fahrenheit') \|archive-date=27 November 2011 \|url-status=dead }}</ref> In August of that year, he published five papers in ] for the Royal Society's scientific journal, '']'', on various topics. In his second paper, "Experimenta et observationes de congelatione aquae in value factae", he provides a description of his thermometers and the reference points he used for calibrating them. For two centuries, this document was the only description of Fahrenheit's process for making thermometers.<ref name="middleton" />{{rp\|75}} In the 20th century, ] uncovered correspondences between Fahrenheit and ] which cast considerable doubt on the veracity of Fahrenheit's article explaining the reference points for his scale and that, in fact, Fahrenheit's scale was largely derived from Rømer's scale. In his book, ''The History of the Thermometer and Its Use in Meteorology'', W. E. Knowles Middleton writes,
			{{Blockquote
			\|text=I believe that much of the confusion has resulted from believing that meant exactly what he said , and discounting the natural tendency of an instrumentmaker to wish to conceal his processes, or at least to obfuscate his readers.<ref name="middleton" />{{rp\|75}}
			\|author=W. E. Knowles Middleton
			\|title=''The History of the Thermometer and Its Use in Meteorology''
			}}

			From August 1736 to his death, Fahrenheit stayed in the house of Johannes Frisleven at ] in The Hague in connection with an application for a ] at the ]. At the beginning of September, he became ill and on the 7th his health had deteriorated to such an extent that he had ] Willem Ruijsbroek come to draw up his will. On the 11th, the notary came by again to make some changes. Five days after that, Fahrenheit died at the age of fifty. Four days later, he received the fourth-class funeral of one who is classified as ], in the ] in The Hague (the Cloister or Monastery Church).<ref name="star">Star, Pieter van der: . Rodopi Publishers, Amsterdam 1983.</ref><ref>{{cite web \| url=http://www.kloosterkerk.nl/bezoek-de-kerk/en/ \| title= The Kloosterkerk \| publisher=The Kloosterkerk \| access-date=16 September 2017}}</ref><ref>Zuiden, D.S. van: , in: "Oud-Holland", pp. 123-130, Binger Publishers, Amsterdam 1913</ref>]

	== Fahrenheit scale ==		== Fahrenheit scale ==
			{{main\|Fahrenheit}}
			According to Fahrenheit's 1724 article,<ref name="ftempsc"/><ref>Fahrenheit describes, in Latin, these numerical choices in the following paper: {{cite journal \|author=Fahrenheit, D. G. \|title=Experimenta et Observationes de Congelatione aquae in vacuo factae \|journal=Philosophical Transactions of the Royal Society \|volume=33 \|pages=78–84 \|year=1724 \|doi=10.1098/rstl.1724.0016 \|issue=381–391 \|doi-access=free }}</ref> he determined his scale by reference to three fixed points of ]. The lowest temperature was achieved by preparing a ] of ], water, and a salt ("] or even sea salt"), and waiting for the ] to reach ]. The thermometer then was placed into the mixture and the liquid in the thermometer allowed to descend to its lowest point. The thermometer's reading there was taken as {{not a typo\|0 °F}}. The second reference point was selected as the reading of the thermometer when it was placed in still water when ice was just forming on the surface.<ref name="why32">{{cite web\|url=http://www.physlink.com/Education/AskExperts/ae64.cfm?CFID=21412834&CFTOKEN=55577927 \|title=Why does the Fahrenheit scale use 32 degrees as a freezing point? \|access-date=9 May 2008 \|last=Heath \|first=Jonathan \|publisher=PhysLink}}</ref> This was assigned as {{not a typo\|30 °F}}. The third calibration point, taken as {{not a typo\|90 °F}}, was selected as the thermometer's reading when the instrument was placed under the arm or in the mouth.<ref name="Burdge2014">{{cite book\|last=Burdge\|first=Julia\|title=Chemistry: Atoms First\|url=https://books.google.com/books?id=2XVzCgAAQBAJ&pg=PA11\|access-date=16 September 2017\|date=10 January 2014\|publisher=McGraw-Hill\|isbn=9780077646479\|page=11}}</ref>

			Fahrenheit came up with the idea that mercury boils around 300 degrees on this ]. Work by others showed that water boils about 180 degrees above its freezing point. The Fahrenheit scale later was redefined to make the freezing-to-boiling interval exactly 180 degrees,<ref name="ftempsc">{{cite web\|url=http://www.sizes.com/units/temperature_Fahrenheit.htm \|title=Fahrenheit temperature scale \|access-date=9 May 2008 \|date=10 December 2006 \|publisher=Sizes, Inc}}</ref> a convenient value as 180 is a ], meaning that it is evenly divisible into many fractions. It is because of the scale's redefinition that normal mean body temperature today is taken as 98.6 degrees,<ref>{{cite journal \|doi=10.1001/jama.1992.03490120092034 \|title=A Critical Appraisal of 98.6°F, the Upper Limit of the Normal Body Temperature, and Other Legacies of Carl Reinhold August Wunderlich \|year=1992 \|last1=MacKowiak \|first1=Philip A. \|journal=JAMA: The Journal of the American Medical Association \|volume=268 \|issue=12 \|pages=1578–80 \|pmid=1302471}}</ref> whereas it was 96 degrees on Fahrenheit's original scale.<ref>{{cite journal \|last1=Elert \|first1=Glenn \|title=Temperature of a Healthy Human (Body Temperature) \|url=http://hypertextbook.com/facts/1997/LenaWong.shtml \|access-date=4 December 2008 \|doi=10.1046/j.1471-6712.2002.00069.x \|year=2002 \|journal=Scandinavian Journal of Caring Sciences \|volume=16 \|pages=122–8 \|pmid=12000664 \|last2=Forsberg \|first2=C \|last3=Wahren \|first3=LK \|issue=2}}</ref>
	Fahrenheit needed to associate a scale with his ]s in order to use them to record temperature. His initial work with a temperature scale was based on three benchmarks. His low temperature mark was the coldest ] attainable under laboratory conditions at that time: a mixture of water, ice, and ]<ref>Fred Senese: ''Why isn't 0 °F the lowest possible temperature for a salt/ice/water mixture?'', 2005 </ref>. Fahrenheit defined that as 0 °F (approx. -17.8 °C). Next was the freezing point of water, which he set at 32 °F. Finally, he defined the human body temperature as 96 °F.

			The ] was the primary temperature standard for climatic, industrial and medical purposes in English-speaking countries until the 1970s, presently mostly replaced by the ] long used in the rest of the world, apart from the United States, where temperatures and weather reports are still broadcast in Fahrenheit.<ref>{{cite web \|url= https://www.livescience.com/39916-fahrenheit.html \|title= Fahrenheit: Facts, History & Conversion Formulas \|first= Kim Ann \|last= Zimmermann \|website= ] \|date= 24 September 2013 \|access-date= 16 September 2017}}</ref>
	Later, with the aid of a ] thermometer that could measure higher temperatures, Fahrenheit adjusted his scale<ref>John H. Lienhard </ref> so the high end was the boiling point of water, which he put at 212 °F. With the adjustment, normal human body temperature moved to the now familiar ] °F. Fahrenheit's final temperature scale has 180 degrees between the freezing and boiling points of water.

			==See also==
	The Fahrenheit scale was widely used in Europe until the switch to the degree ] scale. It is still used for everyday temperature measurements by the general population in the ] and less so in the UK.
			* ]
			* ]
			* ]

	==References==		==References==
			{{Reflist}}
	<references/>

			==Further reading==
	{{BD\|1686\|1736\|Fahrenheit, Gabriel}}
			* {{cite book \|author=Bolton, Henry Carrington \|title=Evolution of the Thermometer, 1592–1743 \|year=1900 \|publisher=The Chemical Publishing Company \|location=Easton, Pennsylvania \|pages=–79 \|url=https://archive.org/details/evolutionthermo01boltgoog}}
	]
			* {{cite journal \|author=Fahrenheit, D. G. \|title=Experimenta circa gradum caloris liquorum nonnullorum ebullientium instituta (Experiments done on the degree of heat of a few boiling liquids) \|journal=Philosophical Transactions of the Royal Society \|volume=33 \|issue=381 \|pages=1–3 \|year=1724 \|url=http://web.lemoyne.edu/~giunta/fahrenheit.html \|doi=10.1098/rstl.1724.0002\|doi-access=free }}
	]
			* {{cite journal \|author=Fahrenheit, D. G. \|title=Experimenta et Observationes de Congelatione aquae in vacuo factae \|journal=Philosophical Transactions of the Royal Society \|volume=33 \|pages=78–84 \|year=1724 \|doi=10.1098/rstl.1724.0016 \|issue=381–391\|url=https://zenodo.org/record/1432206 \|doi-access=free }} (Latin)
	]
			* {{NDB\|4\|746\|747\|Daniel Gabriel Fahrenheit\|Klemm, Friedrich}}
	]
			* {{Cite news\|pmid=775856\|last=Kops\|first=J\|publication-date=Feb 1976\|year=1976\|title=Who was G.D. Fahrenheit? \|volume=26 \|issue=2 \|periodical=Zdravotnická Pracovnice\|pages=118–19}} (Czech)
	]
			* {{Cite ADB\|6\|535\|535\|Fahrenheit, Gabriel Daniel\|Lommel\|ADB:Fahrenheit, Daniel Gabriel}}
			* {{NDB\|4\|746\|747\|Daniel Gabriel Fahrenheit\|Friedrich Klemm}}
			* {{cite book \|author=Middleton, W. E. Knowles \|title=A History of the Thermometer and its Use in Meteorology \|year=1966 \|location=Baltimore, Maryland \|publisher=Johns Hopkins Press}}
			* {{cite news\|pmid=3543477\|last=Sorokina\|first=T S\|publication-date=Oct 1986\|year=1986\|title=Creators of medical thermometry (on the 300th anniversary of the birth of Gabriel Daniel Fahrenheit—24 May 1686 and on the 350th anniversary of the death of Santorio Santorio—22 February 1636)\|volume=64\|issue=10\|periodical=Klinicheskaia Meditsina\|pages=147–51}} (Russian)
			* {{cite book \|title=Fahrenheit's Letters to Leibniz and Boerhaave \|editor=Van Der Star, P. \|publisher=Editions Rodopi \|year=1984}}

			==External links==
	]
			{{Commons category\|Daniel Gabriel Fahrenheit}}
	]
			* Letter from Daniel Gabriel Fahrenheit () to ], 7 May 1736 n.s., {{in lang\|de}}
	]
	]		* {{cite EB9 \|wstitle = Gabriel Daniel Fahrenheit \|volume= VIII \| page=847 \|short=1 }}
			* {{cite web \|title=Why isn't 0°F the lowest possible temperature for a salt/ice/water mixture? \|author=Senese, Fred \|year=2005 \|url=http://antoine.frostburg.edu/chem/senese/101/solutions/faq/zero-fahrenheit.shtml}}
	]
			* {{in lang\|la}}
	]

	]
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Latest revision as of 04:16, 27 October 2024

Physicist and engineer

Daniel Gabriel Fahrenheit

Born	24 May 1686 (14 May Old Style) Danzig, Polish–Lithuanian Commonwealth (present-day Gdańsk, Poland)
Died	16 September 1736(1736-09-16) (aged 50) The Hague, Dutch Republic
Known for	Precision thermometry Alcohol thermometer Mercury-in-glass thermometer Fahrenheit scale Fahrenheit hydrometer
Scientific career
Fields	Physics (thermometry)

Signature

Daniel Gabriel Fahrenheit FRS (/ˈfærənhaɪt/; German: [ˈfaːʁn̩haɪt]; 24 May 1686 – 16 September 1736) was a physicist, inventor, and scientific instrument maker, born in Poland to a family of German extraction. Fahrenheit invented thermometers accurate and consistent enough to allow the comparison of temperature measurements between different observers using different instruments. Fahrenheit is also credited with inventing mercury-in-glass thermometers more accurate and superior to spirit-filled thermometers at the time. The popularity of his thermometers led to the widespread adoption of his Fahrenheit scale attached to his instruments.

Biography

Early life

Location of Fahrenheit's birth in Gdańsk

Fahrenheit was born in Danzig (Gdańsk), then in the Polish–Lithuanian Commonwealth. The Fahrenheits were a German Hanse merchant family who had lived in several Hanseatic cities. Fahrenheit's great-grandfather had lived in Rostock, and research suggests that the Fahrenheit family originated in Hildesheim. Daniel's grandfather moved from Kneiphof in Königsberg (then in the Duchy of Prussia) to Danzig and settled there as a merchant in 1650. His son, Daniel Fahrenheit (the father of Daniel Gabriel), married Concordia Schumann, the daughter of a well-known Danzig business family. Daniel was the eldest of the five Fahrenheit children (two sons, three daughters) who survived childhood. His sister, Virginia Elisabeth Fahrenheit, married Benjamin Krüger and was the mother of Benjamin Ephraim Krüger, a clergyman and playwright.

As a young adult, Fahrenheit "showed a particular desire for studying," and was scheduled to enroll in the Danzig Gymnasium. But on 14 August 1701, his parents died after eating poisonous mushrooms. Fahrenheit, along with two brothers and sisters, was placed under guardianship. In 1702, Fahrenheit's guardians enrolled him in a bookkeeping course and sent him to a four-year merchant trade apprenticeship in Amsterdam.

Upon completing his apprenticeship, Fahrenheit ran off and began a period of travel through the Holy Roman Empire, Sweden, and Denmark in 1707. At the request of his guardians, a warrant was issued for his arrest with the intention of placing him into the service of the Dutch East India company.

Work with thermometers, Fahrenheit scale

By around 1706, Fahrenheit was manufacturing and shipping barometers and spirit-filled thermometers using the Florentine temperature scale. In 1708, Fahrenheit met with the mayor of Copenhagen and astronomer, Ole Rømer, and was introduced to Rømer's temperature scale and his methods for making thermometers. Rømer told Fahrenheit that demand for accurate thermometers was high. The visit inspired Fahrenheit to try to improve his own offerings. Perhaps not coincidentally, Fahrenheit's arrest warrant was dropped around the time of his meeting with Rømer.

In 1709, Fahrenheit returned to Danzig and took observations using his barometers and thermometers, traveled more in 1710 and returned to Danzig in 1711 to settle his parents' estate. After additional travel to Königsberg and Mitau in 1711, he returned to Danzig in 1712 and stayed there for two years. During this period he worked on solving technical problems with his thermometers.

Fahrenheit began experimenting with mercury thermometers in 1713. Also by this time, Fahrenheit was using a modified version of Rømer's scale for his thermometers which would later evolve into his own Fahrenheit scale. In 1714, Fahrenheit left Danzig for Berlin and Dresden to work closely with the glass-blowers there. In that year Christian Wolff wrote about Fahrenheit's thermometers in a journal after receiving a pair of his alcohol-based devices, helping to boost Fahrenheit's reputation in the scientific community.

In addition to his interest in meteorological instruments, Fahrenheit also worked on his ideas for a mercury clock, a perpetual motion machine, and a heliostat around 1715. He struck up a correspondence with Leibniz about some of these projects. From the exchange of letters, we learn that Fahrenheit was running out of money while working on his projects and asked Leibniz for help obtaining a paid post so he could continue his work.

In 1717 or 1718, Fahrenheit returned to Amsterdam and began selling barometers, areometers, and his mercury and alcohol-based thermometers commercially. By 1721, Fahrenheit had perfected the process of crafting and standardizing his thermometers. The superiority of his mercury thermometers over alcohol-based thermometers made them very popular, leading to the widespread adoption of his Fahrenheit scale, the measurement system he developed and used for his thermometers.

Later life and controversy

Fahrenheit spent the remainder of his life in Amsterdam. From 1718 onward, he lectured in chemistry in Amsterdam. He visited England in 1724 and was elected into the Fellow of the Royal Society on May 5. In August of that year, he published five papers in Latin for the Royal Society's scientific journal, Philosophical Transactions, on various topics. In his second paper, "Experimenta et observationes de congelatione aquae in value factae", he provides a description of his thermometers and the reference points he used for calibrating them. For two centuries, this document was the only description of Fahrenheit's process for making thermometers. In the 20th century, Ernst Cohen uncovered correspondences between Fahrenheit and Herman Boerhaave which cast considerable doubt on the veracity of Fahrenheit's article explaining the reference points for his scale and that, in fact, Fahrenheit's scale was largely derived from Rømer's scale. In his book, The History of the Thermometer and Its Use in Meteorology, W. E. Knowles Middleton writes,

I believe that much of the confusion has resulted from believing that meant exactly what he said , and discounting the natural tendency of an instrumentmaker to wish to conceal his processes, or at least to obfuscate his readers.
— W. E. Knowles Middleton, The History of the Thermometer and Its Use in Meteorology

From August 1736 to his death, Fahrenheit stayed in the house of Johannes Frisleven at Plein Square in The Hague in connection with an application for a patent at the States of Holland and West Friesland. At the beginning of September, he became ill and on the 7th his health had deteriorated to such an extent that he had notary Willem Ruijsbroek come to draw up his will. On the 11th, the notary came by again to make some changes. Five days after that, Fahrenheit died at the age of fifty. Four days later, he received the fourth-class funeral of one who is classified as destitute, in the Kloosterkerk in The Hague (the Cloister or Monastery Church).

Fahrenheit scale

Main article: Fahrenheit

According to Fahrenheit's 1724 article, he determined his scale by reference to three fixed points of temperature. The lowest temperature was achieved by preparing a frigorific mixture of ice, water, and a salt ("ammonium chloride or even sea salt"), and waiting for the eutectic system to reach equilibrium temperature. The thermometer then was placed into the mixture and the liquid in the thermometer allowed to descend to its lowest point. The thermometer's reading there was taken as 0 °F. The second reference point was selected as the reading of the thermometer when it was placed in still water when ice was just forming on the surface. This was assigned as 30 °F. The third calibration point, taken as 90 °F, was selected as the thermometer's reading when the instrument was placed under the arm or in the mouth.

Fahrenheit came up with the idea that mercury boils around 300 degrees on this temperature scale. Work by others showed that water boils about 180 degrees above its freezing point. The Fahrenheit scale later was redefined to make the freezing-to-boiling interval exactly 180 degrees, a convenient value as 180 is a highly composite number, meaning that it is evenly divisible into many fractions. It is because of the scale's redefinition that normal mean body temperature today is taken as 98.6 degrees, whereas it was 96 degrees on Fahrenheit's original scale.

The Fahrenheit scale was the primary temperature standard for climatic, industrial and medical purposes in English-speaking countries until the 1970s, presently mostly replaced by the Celsius scale long used in the rest of the world, apart from the United States, where temperatures and weather reports are still broadcast in Fahrenheit.

References

Chisholm, Hugh, ed. (1911). "Fahrenheit, Gabriel Daniel" . Encyclopædia Britannica. Vol. 10 (11th ed.). Cambridge University Press. p. 126.
Dorsey, N. Ernest (15 November 1946). "Title of the Article". Journal of the Washington Academy of Sciences. 36 (): 363.
^ Grigull, Ulrich (1966). Fahrenheit, a Pioneer of Exact Thermometry. (The Proceedings of the 8th International Heat Transfer Conference, San Francisco, 1966, Vol. 1, pp. 9–18.)
Kant, Horst (1984). G. D. Fahrenheit / R. -A. F. de Réaumur / A. Celsius. B. G. Teubner. Retrieved 14 June 2008.
See the Fahrenheit and Krueger genealogies.
^ Momber, Alfred (1890). "Daniel Gabriel Fahrenheit.; sein Leben und Wirken". Schriften der Naturforschenden Gesellschaft in Danzig. 7 (J).
Meyer, F.A. (1952). "Daniel Gabriel Fahrenheit aus Danzig". Westpreussen Jahrbuch (1951–1952): 138–141.
^ Star, Pieter van der: Daniel Gabriel Fahrenheit's Letters to Leibniz and Boerhaave. Rodopi Publishers, Amsterdam 1983.
^ * Middleton, W. E. Knowles (1966). A History of the Thermometer and its Use in Meteorology. Baltimore, Maryland: Johns Hopkins Press.
"The Royal Society Archive catalogue". Archived from the original on 27 November 2011. Retrieved 26 November 2010.
"The Kloosterkerk". The Kloosterkerk. Retrieved 16 September 2017.
Zuiden, D.S. van: Het Testament en de Inboedel van Daniel Gabriel Fahrenheit, in: "Oud-Holland", pp. 123-130, Binger Publishers, Amsterdam 1913
^ "Fahrenheit temperature scale". Sizes, Inc. 10 December 2006. Retrieved 9 May 2008.
Fahrenheit describes, in Latin, these numerical choices in the following paper: Fahrenheit, D. G. (1724). "Experimenta et Observationes de Congelatione aquae in vacuo factae". Philosophical Transactions of the Royal Society. 33 (381–391): 78–84. doi:10.1098/rstl.1724.0016.
Heath, Jonathan. "Why does the Fahrenheit scale use 32 degrees as a freezing point?". PhysLink. Retrieved 9 May 2008.
Burdge, Julia (10 January 2014). Chemistry: Atoms First. McGraw-Hill. p. 11. ISBN 9780077646479. Retrieved 16 September 2017.
MacKowiak, Philip A. (1992). "A Critical Appraisal of 98.6°F, the Upper Limit of the Normal Body Temperature, and Other Legacies of Carl Reinhold August Wunderlich". JAMA: The Journal of the American Medical Association. 268 (12): 1578–80. doi:10.1001/jama.1992.03490120092034. PMID 1302471.
Elert, Glenn; Forsberg, C; Wahren, LK (2002). "Temperature of a Healthy Human (Body Temperature)". Scandinavian Journal of Caring Sciences. 16 (2): 122–8. doi:10.1046/j.1471-6712.2002.00069.x. PMID 12000664. Retrieved 4 December 2008.
Zimmermann, Kim Ann (24 September 2013). "Fahrenheit: Facts, History & Conversion Formulas". Live Science. Retrieved 16 September 2017.

External links

Letter from Daniel Gabriel Fahrenheit (scan) to Carl Linnaeus, 7 May 1736 n.s., (in German)
"Gabriel Daniel Fahrenheit" . Encyclopædia Britannica. Vol. VIII (9th ed.). 1878. p. 847.
Senese, Fred (2005). "Why isn't 0°F the lowest possible temperature for a salt/ice/water mixture?".
Fahrenheit's papers in the Royal Society Publishing (in Latin)

v t e Scientists whose names are used as units
SI base units	André-Marie Ampère (ampere) Lord Kelvin (kelvin)
SI derived units	Henri Becquerel (becquerel) Anders Celsius (degree Celsius) Charles-Augustin de Coulomb (coulomb) Michael Faraday (farad) Louis Harold Gray (gray) Joseph Henry (henry) Heinrich Hertz (hertz) James Prescott Joule (joule) Isaac Newton (newton) Georg Ohm (ohm) Blaise Pascal (pascal) Werner von Siemens (siemens) Rolf Maximilian Sievert (sievert) Nikola Tesla (tesla) Alessandro Volta (volt) James Watt (watt) Wilhelm Eduard Weber (weber)
Non-SI metric (cgs) units	Anders Jonas Ångström (angstrom) Peter Debye (debye) Loránd Eötvös (eotvos) Galileo Galilei (gal) Carl Friedrich Gauss (gauss) William Gilbert (gilbert) Heinrich Kayser (kayser) Johann Heinrich Lambert (lambert) Samuel Langley (langley) James Clerk Maxwell (maxwell) Hans Christian Ørsted (oersted) Jean Léonard Marie Poiseuille (poise) Sir George Stokes, 1st Baronet (stokes) John William Strutt, 3rd Baron Rayleigh (rayl)
Imperial and US customary units	Daniel Gabriel Fahrenheit (degree Fahrenheit) Johann Heinrich Lambert (foot-lambert) William John Macquorn Rankine (degree Rankine)
Non-systematic units	Alexander Graham Bell (bel) Marie Curie (curie) Pierre Curie (curie) John Dalton (dalton) Michael Faraday (faraday) Heinrich Mache (Mache) John Napier (neper) René Antoine Ferchault de Réaumur (degree Réaumur) Wilhelm Röntgen (roentgen) J. J. Thomson (thomson) Evangelista Torricelli (torr)
List of scientists whose names are used as units · Scientists whose names are used in physical constants · People whose names are used in chemical element names

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