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Daniel Fahrenheit Edit Profile

also known as Daniel Gabriel Fahrenheit

Engineer , glassblower , physicist , scientific instruments maker

Daniel Fahrenheit was a physicist and scientific instruments maker. Although he was born in Poland and spent most of his life in Amsterdam, he has a German origin. Fahrenheit is known for creating the first ever reliable thermometer that used mercury to measure temperature. He also devised a temperature scale that was so precise that it became a worldwide standard.


Fahrenheit was born into a reputable merchant family as the eldest of five children of his father, Daniel, and his mother, Concordia. His family moved to Danzig (the name Gdansk had at the time) in the seventeenth century and gained considerable wealth from the mercantile trade. He had three sisters and one brother.


A great tragedy marked Fahrenheit’s childhood. His both parents died in 1801 after eating poisonous mushrooms, leaving Daniel and his brothers and sisters orphaned. The City of Danzig appointed them legal guardians who believed that Daniel should continue the family business. However, young Daniel didn’t want this as he wasn’t attracted to sales at all. Although he was a great student with an enormous interest in science, he started getting into trouble.

His guardians decided to send him to Amsterdam to learn the mercantile trade and bookkeeping from the reputable family Van Beuningen. Daniel went to Amsterdam in 1702 and somehow managed to complete his four years of apprenticeship but not without making problems such as running away or stealing money from the family. However, some later discoveries suggest that he only borrowed the money for his experiments but wasn’t able to get it back, so it had to be paid from the inheritance he got from his parents.


While he was on his apprenticeship in Amsterdam, he encountered Florentine thermometers, the first ever temperature sensors made. The thermometer was in huge demand all over Europe and Fahrenheit was absolutely thrilled with it. However, he also recognized its flaws and knew that it was not very reliable or easy to manufacture and calibrate the temperature. Fascinated by meteorological instruments, he soon started attempting to create his own.

The guardians didn’t understand his ideas and were getting fed up with him and the troubles he was causing them. They wanted to send him overseas to the East Indies. By the time that the Mayor of Danzig authorized a warrant for Daniel’s arrest and deportation in 1707, Fahrenheit managed to run away yet again.

Fahrenheit knew he had to be on the move constantly, considering the warrant for his arrest had been issued. He heard that Ole Roemer, Danish astronomer, had created his own temperature scale and decided to visit him. In addition to being an astronomer, Roemer was also chief of the police in Copenhagen, which might be related to the fact that Fahrenheit’s arrest warrant was withdrawn shortly after.

Young and ambitious Fahrenheit knew what he wanted to make – a thermometer that will be easy to make and the one that could easily calibrate the temperature. Inspired by Roemer’s scale, he decided to improve it and make his own. He set up three fixed points of calibration – freezing brine, freezing water and body temperature (or “blood heat”). Unlike Roemer who used a factor of 7.5, Fahrenheit chose a factor of eight, subsequently dividing each degree into four. The result of multiplying four by eight is 32, which coincidentally made the freezing point on his scale 32 degrees.

Due to the need to make capillaries for his thermometers, Fahrenheit learned the skill of glassblowing. His contemporaries used wine-spirit, so he went with it for his early thermometers. His first major breakthrough came in 1714 when he made two thermometers that showed almost identical results despite the fact they were using different ranges.

However, Fahrenheit made the biggest discovery when he chose to put quick-silver (mercury) in a thermometer instead of alcohol later that year. Mercury had numerous advantages – contracting and expanding more evenly and being more accurate than alcohol when used at a wider range. This allowed people to take the temperature significantly below the freezing brine point and above the boiling water point. Fahrenheit knew that he succeeded – he created a thermometer that can be very accurate in showing the temperature.

In 1717, Fahrenheit decided to settle in Amsterdam and begin producing his mercury thermometers. They turned out to be a great hit and were highly appreciated but they were not the only products that Fahrenheit made. He also made “thermobarometers” used for measuring barometric pressure and a constant-weight hydrometer.

Fahrenheit published a collection of research papers that explained his scale in 1724. This scale was the primary temperature standard for the medical, climatic and industrial purposes in most of the English-speaking countries until the middle of the 20th century and is still used as the primary temperature scale in the United States.

The same year, Fahrenheit was admitted to the British Royal Society as an associate member, despite the fact he had no formal science education. This was not so unusual at the time, especially for the maker of scientific instruments, as they often made breakthroughs who were of great significance to the scientific community.

Fahrenheit continued producing his mercury thermometers and working on other scientific instruments. He was active until his death in 1936 when he was struck by a fever during his trip to The Hague.


  • Discovered that mercury is much more reliable to be used in thermometers than alcohol;

    Created and produced a very reliable mercury thermometer;

    Devised a temperature scale that was used as the primary scale int he most English-speaking areas until the middle of the 20th century;

    Joined British Royal Society as an associate member, despite he didn't have any formal scientific education;


Daniel Fahrenheit was baptized as a catholic in the St. Mary's Church in Gdansk on June 6, 1686.


As a man dedicated to his work, Fahrenheit never expressed any desire to be afiiliated with any political party. The only connection that can be made with politics was at the time when Fahrenheit had lost his parents and the Mayor of Danzig had to appoint him and his siblings legal guardians, who Fahrenheit wasn't thrilled with.


Fahrenheit was fascinated by science ever since his childhood. Even when he suffered a family tragedy and lost his parents as a teenager, that fascination didn’t leave him. It was what kept him going and caused him a lot of troubles with the legal guardians that were assigned to him. They didn’t understand Fahrenheit and his desire to study science and work on making scientific instruments and this led to numerous disagreements until he definitely left Danzig in 1807.

When he first encountered the Florentine thermometers, Fahrenheit became somewhat obsessed with making an improved version of the instrument. He knew the importance of conducting experiments and pursuing his dreams. He virtually stopped at nothing, he borrowed money (some even suggest that he also stole it) to finance the experiments, he learned all the necessary skills that could help him with achieving his goal (glassblowing) and he invested a lot of time. In the end, his belief in his idea paid off.


Fahrenheit cause a lot of troubles for his guardians after he lost his parents but this was only because he was trying to pursue his interest in science, so it is wrong to depict that he had a troublesome personality. On the contrary, he was very dedicated to his work and active until the day he died.


  • Philosophers & Thinkers

    Ole Roemer, Galileo Galilei, Guillaume Amontons

  • Politicians

    Ferdinando II de’ Medici

  • Other Interests



Fahrenheit never married and had no kids of his own. He had three younger sisters and one, also younger, brother.

Daniel Fahrenheit - merchant

Fahrenheit's both parents died when he was 15, leaving Daniel and four other children as orphans

Ole Rømer - Denmark - astronomer
Ole Rømer - colleague of Daniel Fahrenheit

The temperature scale that Roemer devised served Fahrenheit as an inspiration for his own