Daniel Gabriel Fahrenheit FRS was born on May 24, 1686, and died on September 16, 1736. He was a scientist, inventor, and maker of scientific instruments. He was born in Poland to a family of German origin, though he lived most of his life in the Dutch Republic. Fahrenheit made significant improvements to the design and production of thermometers. His thermometers were very accurate and reliable, allowing different people using their own Fahrenheit thermometers to compare temperature measurements consistently. Fahrenheit is also credited with creating the first successful thermometers that used mercury inside glass. These thermometers were more accurate than the spirit-filled thermometers used at the time and had a better overall design. The popularity of his thermometers led to the widespread use of the Fahrenheit scale, which came with his thermometers.
Biography
Daniel Gabriel Fahrenheit was born in Danzig, now known as Gdańsk, which was part of the Polish–Lithuanian Commonwealth. The Fahrenheit family was a German Hanse merchant family that had lived in several Hanseatic cities. Research suggests the family may have originated in Hildesheim. Daniel’s grandfather moved from Kneiphof in Königsberg (then in the Duchy of Prussia) to Danzig in 1650 and became a merchant there. Daniel’s father, also named Daniel Fahrenheit, married Concordia Schumann, a member of a well-known Danzig business family. Daniel was the oldest of five Fahrenheit children who survived childhood. His sister, Virginia Elisabeth Fahrenheit, married Benjamin Krüger, and they had a son named Benjamin Ephraim Krüger, who became a clergyman and playwright.
As a young adult, Fahrenheit showed a strong interest in learning and was scheduled to attend the Danzig Gymnasium. However, on August 14, 1701, his parents died after eating poisonous mushrooms. Fahrenheit and his siblings were placed under the care of guardians. In 1702, his guardians enrolled him in a bookkeeping course and sent him to a four-year merchant apprenticeship in Amsterdam.
After completing his apprenticeship, Fahrenheit ran away and began traveling through the Holy Roman Empire, Sweden, and Denmark in 1707. His guardians issued a warrant for his arrest, hoping to place him in the service of the Dutch East India Company.
By around 1706, Fahrenheit was making and selling barometers and thermometers using the Florentine temperature scale. In 1708, he met the mayor of Copenhagen and astronomer Ole Rømer, who introduced him to Rømer’s temperature scale and thermometer-making methods. Rømer noted that there was high demand for accurate thermometers, which inspired Fahrenheit to improve his own designs. Around the same time, the warrant for Fahrenheit’s arrest was dropped.
In 1709, Fahrenheit returned to Danzig and used his instruments to take observations. He traveled again in 1710 and returned to Danzig in 1711 to settle his parents’ estate. After additional trips to Königsberg and Mitau in 1711, he returned to Danzig in 1712 and stayed there for two years. During this time, he worked on solving technical issues with his thermometers.
Fahrenheit began experimenting with mercury thermometers in 1713. By this time, he was using a modified version of Rømer’s scale, which would later become his own Fahrenheit scale. In 1714, he moved to Berlin and Dresden to work with glass-blowers. That same year, Christian Wolff wrote about Fahrenheit’s thermometers in a journal, which helped raise his scientific reputation.
In addition to thermometers, Fahrenheit worked on ideas for a mercury clock, a perpetual motion machine, and a heliostat around 1715. He corresponded with Leibniz about these projects. From their letters, it is clear that Fahrenheit was struggling financially and asked Leibniz for help securing a paid position to 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, he had perfected the process of making and standardizing his thermometers. His mercury thermometers became more popular than alcohol-based ones, leading to the widespread use of his Fahrenheit scale.
Fahrenheit spent the rest of his life in Amsterdam. From 1718 onward, he taught chemistry there. He visited England in 1724 and was elected a Fellow of the Royal Society on May 5. That year, he published five papers in Latin for the Royal Society’s journal, Philosophical Transactions, on various topics. In his second paper, Experimenta et observationes de congelatione aquæ in vacuo factæ, he described his thermometers and the reference points he used for calibration. For two centuries, this document was the only record of Fahrenheit’s thermometer-making process. In the 20th century, Ernst Cohen discovered letters between Fahrenheit and Herman Boerhaave, which cast doubt on the accuracy of Fahrenheit’s description of his scale’s reference points. In his book, The History of the Thermometer and Its Use in Meteorology, W. E. Knowles Middleton writes,
— W. E. Knowles Middleton, The History of the Thermometer and Its Use in Meteorology
From August 1736 until his death, Fahrenheit lived in the home of Johannes Frisleven at Plein Square in The Hague while applying for a patent in the States of Holland and West Friesland. In early September, he became ill, and by September 7, his health had worsened to the point that he asked notary Willem Ruijsbroek to create his will. On September 11, the notary returned to make changes to the will. Five days later, Fahrenheit died at the age of 50. Four days after his death, he received a fourth-class funeral for someone classified as destitute at the Kloosterkerk in The Hague (the Cloister or Monastery Church).
Fahrenheit scale
In 1724, Fahrenheit created his temperature scale using three fixed points. The lowest temperature was found by mixing ice, water, and salt (such as ammonium chloride or sea salt) until the mixture reached a stable temperature. A thermometer was placed in this mixture, and the lowest temperature it reached was recorded as 0 °F. The second point was determined by placing the thermometer in water as ice began to form on its surface, which was marked as 30 °F. The third point was set by placing the thermometer under a person’s arm or in their mouth, which was recorded as 90 °F.
Fahrenheit noted that mercury boils at about 300 degrees on his scale. Later research showed that water boils 180 degrees above its freezing point. The Fahrenheit scale was later adjusted so that the range from freezing to boiling water was exactly 180 degrees. This number is useful because it can be divided evenly into many smaller parts. Because of this change, the average human body temperature is now 98.6 °F, whereas it was 96 °F on Fahrenheit’s original scale.
The Fahrenheit scale was widely used for weather, industry, and medicine in English-speaking countries until the 1970s. In 1963, the British Meteorological Office officially switched to the Celsius scale (also called Centigrade) but continued using Fahrenheit in public broadcasts until the 1980s. Today, most countries use the Celsius scale, except the United States, where temperatures are still reported in Fahrenheit.