because the term centigrade was also the spanish and french language name for a unit of angular...

8/9/2019 Because the Term Centigrade Was Also the Spanish and French Language Name for a Unit of Angular Measurement

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Celsius (known until 1948 as centigrade) is a temperature scale that is named after the Swedishastronomer Anders Celsius (17011744), who developed a similar temperature scale two years

before his death. The degree Celsius (C) can refer to a specific temperature on the Celsius scale aswell as a unit to indicate a temperature interval (a difference between two temperatures or anuncertainty).

From 1744 until 1954, 0 C was defined as the freezing point of water and 100 C was defined asthe boiling point of water, both at a pressure of one standard atmosphere.[citation needed] Althoughthese defining correlations are commonly taught in schools today, by international agreement theunit "degree Celsius" and the Celsius scale are currently defined by two different points: absolutezero, and the triple point of VSMOW (specially prepared water). This definition also preciselyrelates the Celsius scale to the Kelvin scale, which defines the SI base unit of thermodynamictemperature (symbol: K). Absolute zero, the hypothetical but unattainable temperature at whichmatter exhibits zero entropy, is defined as being precisely 0 K and 273.15 C. The temperaturevalue of the triple point of water is defined as being precisely 273.16 K and 0.01 C.[1]

This definition fixes the magnitude of both the degree Celsius and the kelvin as precisely 1 part in273.16 parts, the difference between absolute zero and the triple point of water. Thus, it sets themagnitude of one degree Celsius and that of one kelvin as exactly the same. Additionally, itestablishes the difference between the two scales' null points as being precisely 273.15 degreesCelsius (273.15 C = 0 K and 0 C = 273.15 K).[2]An illustration of Anders Celsius's original thermometer. Note the reversed scale, where 0 is the

boiling point of water and 100 is its freezing point.Contents[hide]

* 1 Historyo 1.1 Centigrade and Celsiuso 1.2 Common temperatures

* 2 Formattingo 2.1 The special Unicode degree Celsius character

* 3 Temperatures and intervals* 4 Why technical articles use a mix of kelvin and Celsius scales* 5 The melting point of ice and the boiling point of water* 6 Worldwide adoption* 7 See also* 8 Notes

* 9 External links[edit] History

In 1742 Swedish astronomer Anders Celsius (17011744) originally created a "reversed" version ofthe modern Celsius temperature scale whereby zero represented the boiling point of water and onehundred represented the freezing point of water. In his paper Observations of two persistent degreeson a thermometer, he recounted his experiments showing that ice's melting point was essentiallyunaffected by pressure. He also determined with remarkable precision how water's boiling pointvaried as a function of atmospheric pressure. He proposed that zero on his temperature scale(water's boiling point) would be calibrated at the mean barometric pressure at mean sea level. This

pressure is known as one standard atmosphere. (The BIPM's 10th CGPM later defined one standardatmosphere to equal precisely 1,013,250 dynes per square centimeter (101.325 kPa))


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In 1744, coincident with the death of Anders Celsius, the famous Swedish botanist CarolusLinnaeus (17071778) effectively reversed[3] Celsius's scale upon receipt of his first thermometerfeaturing a scale where zero represented the melting point of ice and 100 represented water's boiling

point. His custom-made "linnaeus-thermometer", for use in his greenhouses, was made by DanielEkstrm, Sweden's leading maker of scientific instruments at the time and whose workshop waslocated in the basement of the Stockholm observatory. As often happened in this age before modern

communications, numerous physicists, scientists, and instrument makers are credited with havingindependently developed this same scale;[4] among them were Pehr Elvius, the secretary of theRoyal Swedish Academy of Sciences (which had an instrument workshop) and with whomLinnaeus had been corresponding; Christian of Lyons; Daniel Ekstrm, the instrument maker; andMrten Strmer (17071770) who had studied astronomy under Anders Celsius.

The first known document[5] reporting temperatures in this modern "forward" Celsius scale is thepaper Hortus Upsaliensis dated 16 December 1745 that Linnaeus wrote to a student of his, SamuelNauclr. In it, Linnaeus recounted the temperatures inside the orangery at the Botanical Garden ofUppsala University:

"... since the caldarium (the hot part of the greenhouse) by the angle of the windows, merely fromthe rays of the sun, obtains such heat that the thermometer often reaches 30 degrees, although thekeen gardener usually takes care not to let it rise to more than 20 to 25 degrees, and in winter notunder 15 degrees ..."

[edit] Centigrade and Celsius

For the next 204 years, the scientific and thermometry communities worldwide referred to this scaleas the "centigrade scale". Temperatures on the centigrade scale were often reported simply as"degrees" or, when greater specificity was desired, "degrees centigrade". The symbol fortemperature values on this scale was C (in several formats over the years).

Because the term centigrade was also the Spanish and French language name for a unit of angularmeasurement (1/10,000 of a right angle) and had a similar connotation in other languages, the term"centesimal degree" was used when very precise, unambiguous language was required byinternational standards bodies such as the Bureau international des poids et mesures (BIPM). The9th CGPM (Confrence gnrale des poids et mesures) and the CIPM (Comit international des

poids et mesures) formally adopted "degree Celsius" (symbol: C) in 1948.[6][7] Some people stilluse the old term.[edit] Common temperatures

Some key temperatures relating the Celsius scale to other temperature scales are shown in the tablebelow.Key scale relations Kelvin Celsius FahrenheitAbsolute zero(precisely, by definition) 0 K 273.15 C 459.67 FMelting point of ice(approximate)[8] 273.15 K 0 C 32 FWater's triple point(precisely, by definition) 273.16 K 0.01 C 32.018 FWater's boiling point at 1 atm (101.325 kPa)(approximate: see Boiling point)[9] 373.1339 K 99.9839 C 211.9710 F

[edit] Formatting

The "degree Celsius" has been the only SI unit whose full unit name contains an uppercase letter


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since its SI base unit, the kelvin, became the proper name in 1967 for the obsolete term, the "degreeKelvin". The correct plural form is "degrees Celsius".

The general rule is that the numerical value always precedes the unit, and a space is always used toseparate the unit from the number, e.g., "23 C" (not "23C" or "23 C"). Thus the value of thequantity is the product of the number and the unit, the space being regarded as a multiplication sign

(just as a space between units implies multiplication). The only exceptions to this rule are for theunit symbols for degree, minute, and second for plane angle, , , and , respectively, for which nospace is left between the numerical value and the unit symbol.[10][edit] The special Unicode degree Celsius character

Unicode provides a compatibility character for the degree Celsius at U+2103 (decimal 8451), forcompatibility with CJK encodings that provide such a character (as such, in most fonts the width isthe same as for fullwidth characters). Its appearance is similar to the one synthesized byindividually typing its two components () and (C). Shown below is the degree Celsius characterfollowed immediately by the two-component version:

C

When viewed on computers that properly support Unicode, the above line may be similar to theimage in the line below (enlarged for clarity):

Unicode degree Centigrade comparison

The canonical decomposition is simply an ordinary degree sign and "C", so some browsers maysimply display "C" in its place due to Unicode normalization.[edit] Temperatures and intervals

The degree Celsius is a special name for the kelvin for use in expressing Celsius temperatures.[11]The degree Celsius is also subject to the same rules as the kelvin with regard to the use of its unitname and symbol. Thus, besides expressing specific temperatures along its scale (e.g. "Galliummelts at 29.7646 C" and "The temperature outside is 23 degrees Celsius"), the degree Celsius isalso suitable for expressing temperature intervals: differences between temperatures or theiruncertainties (e.g. "The output of the heat exchanger is hotter by 40 degrees Celsius", and "Ourstandard uncertainty is 3 C").[12] Because of this dual usage, one must not rely upon the unitname or its symbol to denote that a quantity is a temperature interval; it must be unambiguousthrough context or explicit statement that the quantity is an interval.[13] What is often confusedabout the Celsius measurement is that it follows an interval system but not a ratio system or it

follows a relative scale not an absolute scale. This is put simply by illustrating that while 10 C and20 C have the same interval difference as 20 C and 30 C the temperature 20 C is not twice theair heat energy as 10 C. As this example shows degrees Celsius is a useful interval measurement

but does not possess the characteristics of ratio measures like weight or distance.[14][edit] Why technical articles use a mix of kelvin and Celsius scales

In science (especially) and in engineering, the Celsius scale and the kelvin are often usedsimultaneously in the same article (e.g. "its measured value was 0.01023 C with an uncertaintyof 70 K"). This practice is permissible because:

1. the degree Celsius is a special name for the kelvin for use in expressing Celsius temperatures,

and2. the magnitude of the degree Celsius is precisely equal to that of the kelvin.


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Notwithstanding the official endorsement provided by decision #3 of Resolution 3 of the 13thCGPM, which stated "a temperature interval may also be expressed in degrees Celsius," the practiceof simultaneously using both "C" and "K" remains widespread throughout the scientific world asthe use of SI prefixed forms of the degree Celsius (such as "C" or "microdegrees Celsius") toexpress a temperature interval has not been well-adopted.

This practice should be avoided for literature directed to lower-level technical fields and in non-technical articles intended for the general public where both the kelvin and its symbol, K, are notwell recognised and could be confusing.[edit] The melting point of ice and the boiling point of water

One effect of defining the Celsius scale at the triple point of Vienna Standard Mean Ocean Water(VSMOW, 273.16 K and 0.01 C), and at absolute zero (0 K and 273.15 C), is that neither themelting and boiling point of water under one standard atmosphere (101.325 kPa) remain defining

points for the Celsius scale. In 1948 when the 9th General Conference on Weights and Measures(CGPM) in Resolution 3 first considered using the triple point of water as a defining point, thetriple point was so close to being 0.01 C greater than water's known melting point, it was simply

defined as precisely 0.01 C.[15] However, current measurements show that the triple and meltingpoints of VSMOW are actually very slightly (


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summer)[citation needed], for the benefit of generations born before 1960, and air-temperaturethermometers sold still show both scales for the same reason. Schools in the United Kingdom teachthe Celsius scale exclusively.[edit] See also

* Absolute zero

* ITS-90* Temperature* Temperature conversion* Thermodynamic temperature

[edit] Notes

1. ^ "SI brochure, section 2.1.1.5". International Bureau of Weights and Measures.http://www1.bipm.org/en/si/si_brochure/chapter2/2-1/2-1-1/kelvin.html. Retrieved 9 May 2008.

2. ^ "Essentials of the SI: Base & derived units". http://physics.nist.gov/cuu/Units/units.html.Retrieved 9 May 2008.

3. Citation: Uppsala University (Sweden), Linnaeus' thermometer4. ^ Citation for Daniel Ekstrm, Mrten Strmer, Christian of Lyons: The Physics

Hypertextbook, Temperature; citation for Christian of Lyons: Le Moyne College, Glossary, (Celsiusscale); citation for Linnaeus' connection with Pehr Elvius and Daniel Ekstrm: Uppsala University(Sweden), Linnaeus' thermometer; general citation: The Uppsala Astronomical Observatory, Historyof the Celsius temperature scale

5. ^ Citations: University of WisconsinMadison, Linnus & his Garden and; Uppsala University,Linnaeus' thermometer

6. ^ "CIPM, 1948 and 9th CGPM, 1948". International Bureau of Weights and Measures.http://www.bipm.org/en/committees/cipm/cipm-1948.html. Retrieved 9 May 2008.

7. According to The Oxford English Dictionary (OED), the term "Celsius' thermometer" hadbeen used at least as early as 1797. Further, the term "The Celsius or Centigrade thermometer" wasagain used in reference to a particular type of thermometer at least as early as 1850. The OED alsocites this 1928 reporting of a temperature: "My altitude was about 5,800 metres, the temperaturewas 28 Celsius." However, dictionaries seek to find the earliest use of a word or term and are not auseful resource as regards the terminology used throughout the history of science. According toseveral writings of Dr. Terry Quinn CBE FRS, Director of the BIPM (19882004), includingTemperature Scales from the early days of thermometry to the 21st century (herePDF (146 KiB)) aswell as Temperature (2nd Edition / 1990 / Academic Press / 0125696817), the term Celsius inconnection with the centigrade scale was not used whatsoever by the scientific or thermometrycommunities until after the CIPM and CGPM adopted the term in 1948. The BIPM was not even

aware that "degree Celsius" was in sporadic, non-scientific use before that time. It is alsonoteworthy that the twelve-volume, 1933 edition of OED didn't even have a listing for the wordCelsius (but did have listings for both centigrade and centesimal in the context of temperaturemeasurement). The 1948 adoption of Celsius accomplished three objectives:

1. All common temperature scales would have their units named after someone closelyassociated with them; namely, Kelvin, Celsius, Fahrenheit, Raumur and Rankine.

2. Notwithstanding the important contribution of Linnaeus who gave the Celsius scale itsmodern form, Celsius' name was the obvious choice because it began with the letter C. Thus, thesymbol C that for centuries had been used in association with the name centigrade could continueto be used and would simultaneously inherit an intuitive association with the new name.

3. The new name eliminated the ambiguity of the term "centigrade", freeing it to referexclusively to the French-language name for the unit of angular measurement.


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8. ^ The ice point of purified water has been measured to be 0.000 089(10) degrees Celsius - seeMagnum, B.W. (June 1995). "Reproducibility of the Temperature of the Ice Point in RoutineMeasurements" (PDF). Nist Technical Note 1411.http://www.cstl.nist.gov/div836/836.05/papers/magnum95icept.pdf. Retrieved 11 February 2007.

9. ^ For Vienna Standard Mean Ocean Water at one standard atmosphere (101.325 kPa) whencalibrated solely per the two-point definition of thermodynamic temperature. Older definitions of

the Celsius scale once defined the boiling point of water under one standard atmosphere as beingprecisely 100 C. However, the current definition results in a boiling point that is actually 16.1 mKless. For more about the actual boiling point of water, see VSMOW in temperature measurement.There is a different approximation using ITS-90 which approximate the temperature to 99.974 C

10. ^ For more information on conventions used in technical writing, see the informative SI Unitrules and style conventions by the NIST as well as the BIPM's SI brochure: Subsection 5.3.3,Formatting the value of a quantity.

11. ^ Note (e) of SI Brochure, Section, 2.2.2, Table 312. ^ Decision #3 of Resolution 3 of the 13th CGPM13. ^ In 1948, Resolution 7 of the 9th CGPM stated, "To indicate a temperature interval or

difference, rather than a temperature, the word 'degree' in full, or the abbreviation 'deg' must be

used." This resolution was abrogated in 1967/1968 by Resolution 3 of the 13th CGPM which statedthat ["The names "degree Kelvin" and "degree", the symbols "K" and "deg" and the rules for theiruse given in Resolution 7 of the 9th CGPM (1948),] and the designation of the unit to express aninterval or a difference of temperatures are abrogated, but the usages which derive from thesedecisions remain permissible for the time being." Consequently, there is now wide freedom in usageregarding how to indicate a temperature interval. The most important thing is that one's intentionmust be clear and the basic rule of the SI must be followed; namely that the unit name or its symbolmust not be relied upon to indicate the nature of the quantity. Thus, if a temperature interval is, say,10 K or 10 C (which may be written 10 kelvin or 10 degrees Celsius), it must be unambiguousthrough obvious context or explicit statement that the quantity is an interval. Rules governing theexpressing of temperatures and intervals are covered in the BIPM's SI Brochure, 8th edition([1]PDF (1.39 MiB)).

14. ^ This fact is demonstrated in the book 'Biostatistics: A Guide to Design, Analysis, andDiscovery' By Ronald N. Forthofer, Eun Sul Lee and Mike Hernandez

15. ^ "Resolution 3 of the 9th CGPM (1948)". International Bureau of Weights and Measures.http://www.bipm.org/en/CGPM/db/9/3/. Retrieved 9 May 2008.

16. ^ Citation: London South Bank University, Water Structure and Behavior, notes c1 and c217. ^ "Belize Weather Bureau". http://www.hydromet.gov.bz/. Retrieved 9 May 2008.

[edit] External linksSearch Wiktionary Look up celsius in Wiktionary, the free dictionary.

* NIST, Basic unit definitions: Kelvin* The Uppsala Astronomical Observatory, History of the Celsius temperature scale* London South Bank University, Water, scientific data* BIPM, SI brochure, section 2.1.1.5, Unit of thermodynamic temperature* TAMPILE, Comparison of temperature scales

[show]v d eTemperature scales

Celsius Fahrenheit Kelvin Rankine Delisle Leiden Newton Raumur RmerConversion formulas[show]


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v d eSI derived unitsDerived unitsradian steradian hertz newton pascal joule watt coulomb volt farad ohm henry siemens weber tesla degree Celsius lumen lux becquerel gray sievert katalBase units

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because the term centigrade was also the spanish and french language name for a unit of angular...

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