Zahlen, bitte! Fahrenheit and the search for zero
Apart from the USA, only a few countries still use the Fahrenheit temperature scale. It was invented by German physicist Daniel Gabriel Fahrenheit.
The USA is the largest country in the world where daily temperatures are measured on the Fahrenheit scale. It ranges from 0 degrees Fahrenheit, the lowest temperature that Daniel Gabriel Fahrenheit was able to measure with "salted ice" around 1710, in 180 increments to 212 degrees, the boiling point of water. In addition to the USA, the Fahrenheit scale is still in use in some island states and in Liberia in Africa.
Great Britain is considered the mother country of this type of thermometry because Fahrenheit presented the thermometers he built and the measuring method in the Transactions of the Royal Society in 1724. In 1965, the conversion to the metric system and the use of Celsius degrees in science began there. Under US President Gerald Ford, the USA attempted the conversion in 1975 with the Metric Conversion Act, but his successor Ronald Reagan quickly dissolved the US Metric Board in 1982.
In addition to education, busy with meteorology
In 1702, Daniel Gabriel Fahrenheit from Danzig was sent to Amsterdam at the age of 16 to learn the ropes as a merchant in a trading office. His education bored him and he began to occupy himself with meteorological and physical questions. He specialized in the development of thermometers and drew on his parental inheritance to do so. His guardians tried to stop this with an arrest warrant in 1707, but Fahrenheit had already left by then.
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On his travels around the Baltic Sea, he visited the Danish astronomer Olav Rømer, known for the first calculation of the speed of light. Rømer himself had constructed thermometers and developed a temperature scale that ranged from the melting point of brine to the boiling point of water.
Subsequently, Fahrenheit, who was now of age, tried to determine Fahrenheid's zero point and reached it by measuring "salted ice", a mixture of ice and ammonium chloride at -17.8 degrees Celsius. At this fixed point, Fahrenheit set the freezing point of pure water of ice at 32 degrees and 96 degrees for human body temperature. This scale , which was discovered and published in 1714, made him famous above all because he returned to Amsterdam – and developed – thermometers that enabled comparative measurements to be made with great precision.
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Much-praised scale
They were particularly praised by the then influential scientist Christian Wolf. "For certain private reasons, he does not disclose the artifice by which he obtains the agreement; however, the effect has been observed by many people who have compared his thermometers and barometers," said Wolf. Fahrenheit wanted to make a living by manufacturing his thermometers.
When lower temperatures were measured, meaning Fahrenheit had to resort to negative values, he wrote to his friend, the chemist Hermann Boerhaave, in 1729: "...if we consider the large spaces between the celestial bodies, there must be the least heat, therefore the strongest cold, because the rays of the heat-emitting bodies have no 'reflections' and no 'revibrations'."
(Image:Â Mrmw, CC0)
Without knowledge of the third law of thermodynamics, Fahrenheit had the correct assumptions that finally enabled Lord Kelvin to determine absolute zero in 1848 and set it on his Kelvin scale, which later became the SI unit of temperature.
Fahrenheit was the first to use mercury instead of spirit of wine in his thermometers and to investigate the influence of the different types of glass (PDF) in his capillaries on the temperature measurement. The highlight of his career was his admission to the Royal Society in 1724, for which he traveled to London and gave a lecture. In that year, he published five papers in the Transactions of the Society, in which he presented a barometer and hydrometer he had developed and published on his investigations into the boiling point of various liquids.
Legal definition after Fahreneid's death
However, general recognition only came after his death, when the "Imperial Standard Yard" made of bronze and gold "at a temperature of 62 degrees Fahrenheit" was established by law in 1855.
The Fahrenheit scale became famous with a temperature that was not on Fahrenheit's original scale. Ray Bradbury's dystopia Fahrenheit 451 is based on the spontaneous combustion of paper and is emblematic of censorship attempts of all kinds. Bradbury's fire department does not extinguish fires, but burns books and thus acts as a state power that suppresses knowledge.
When the novel, written in the 1950s, was remade into a film in 2018, it was criticized for criticizing Trump's cultural policy. In the same year, Fahrenheit 11/9 was released, a documentary film in which Michael Moore critically examined the political situation in the USA after Trump's first election victory.
Conversion aids created between C° and F°
There are numerous calculators, tables and apps for converting Fahrenheit degrees to Celsius, as well as a mnemonic published by a mathematician. For 04, 16 and 28 degrees Celsius, it is sufficient to reverse the numbers. This gives you the temperatures for cold, cool, warm and hot days, as used by Daniel Fahrenheit when describing his scale to the English public.
Outside the USA, Fahrenheit is only used in a few countries: Belize, the Cayman Islands, the Bahamas and Liberia. The reasoning that these are warmer regions may be a little disconcerting. Could climate change lead to a revision of the Fahrenheit scale, as seen here? Or will it remain as Christian Morgenstern wrote in his gallows song cycle about the "crown pretenders"?
– "Ich bin der Graf von Réaumur
und Hass euch wie die Schande!
Dient nur dem Celsio fĂĽr und fĂĽr,
ihr Apostatenbande!"
Im Winkel König Fahrenheit
hat still sein Mus gegessen.
– "Ach Gott, sie war doch schön, die Zeit,
da man nach mir gemessen!"
Or in English:
– "I am the Count of Réaumur
And hate you like shame!
Serve only the Celsio for and for,
you band of apostates!"
In the corner King Fahrenheit
ate his mush in silence.
– "Oh God, it was a beautiful time,
when they measured after me!"
(dahe)
