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Daniel Fahrenheit is one of those physicists who have significantly influenced our lives, given these scientists’ important discoveries that led to creating instruments still commonly used today. Fahrenheit’s journey comes with a story behind, so take a read this article to find the 10 most interesting facts.

Unfortunate adolescence

Born in Danzig in 1686, Daniel Fahrenheit was the son of a wealthy merchant. While this might seem like an ideal setting for someone who is on the way to making important discoveries, the story has an unfortunate twist.

Fahrenheit lost both of his parents on the same day, in August 1701, when he was only fifteen. Following this event, he became an apprentice to a shopkeeper in Amsterdam where he was supposed to learn the needed business skills.


Passion for scientific instruments

It was in Amsterdam where he was first introduced to the somewhat specialized and small, but rapidly developing business of making scientific instruments. Given that he became fascinated by this topic, of course, he pursued it and started learning as much as possible about it.

Around 1707, Fahrenheit began his years of wandering, which helped him acquire the techniques needed for this trade by observing what the other scientists and instruments makers were doing and what their practices were. He traveled throughout many cities in Germany, including Berlin, Leipzig, and Dresden.


First thermometers completed in 1714

He completed the first two thermometers, that contained alcohol in their design, in 1714. The proof that they worked just fine is the fact that they perfectly agreed in readings, which means that he managed to produce two items so similar so as to leave little to no room for errors.

In 1717, he returned to Amsterdam and established himself as a maker of scientific instruments. That’s where he became acquainted with some of the greatest Dutch scientists, including Hermann Boerhaave, Pieter van Musschenbroek, and W. J. ’s Gravesande.


A member of the Royal Society

Although he lived most of his life in Amsterdam, he spent a lot of time in England and, in 1724, was admitted to the Royal Society, which is one of the oldest scientific institutions in the world. This only further proved the importance of his studies.

In the same year, he published his only scientific writings in the Philosophical Transactions, and these were five articles in Latin. In the early eighteenth century, it was acceptable for a person without scientific training to be admitted into the Royal Society.

Those who made scientific instruments were valuable because they often trespassed the limits of the accepted knowledge and defined universally useful constants on which to scale the instruments, and identified variables that could appear in this process.

Benefits for the scientific community

Because his instruments had to be reliable for the entire scientific community, Daniel Fahrenheit had to address and figure out a wide variety of scientific issues.

These included measuring the expansion of glass, describing the effects of atmospheric pressure on the boiling points of different liquids, and assessing the behavior of alcohol or mercury under different conditions.

Although his direct contributions can be seen as somewhat small compared to those of other scientists, the fact that he considerably improved the level of obtainable precision for many scientific observations had a profound impact on the course of experimental physics.

Without his studies maybe we would not be enjoying today reliable devices such as digital thermometers for babies.


His other inventions were significantly important

Daniel Fahrenheit knew that the boiling point of water was correlated with the atmospheric pressure. It was on this principle that he created a hypsometric thermometer – a device that allowed him to determine the atmospheric pressure by directly reading the boiling point of water.

Another one of his inventions was a hydrometer which later became a model for following developments and added to the know-how of the world of science.


The Fahrenheit scale was calibrated later

In 1714, when Fahrenheit completed the first two thermometers, the scale which was going to bear his name had not yet been defined and calibrated. He tried a number of other versions before settling on the one that made him famous.

He decided to replace the alcohol used in the first devices with mercury and completed a series of researches and investigations that were based on G. Amontons’ work. It was in these studies that he determined the boiling point of water and further studied the expansion properties of mercury.

He took into consideration the most intense cold obtainable artificially in a combination of water, ice, and ammonium chloride and the limit of heat found in the human body.

He then set as 0 the temperature of the frozen mixture, 32 as the temperature registered when the thermometer was placed in the cold water when ice was just forming, and 96 as the reference point when the instrument was placed under someone’s arm, or in the mouth.


180 is a convenient number

The Fahrenheit scale was later refined, and the freezing-to-boiling points interval was established at exactly 180 degrees. This is a highly composite number, which means that it can be evenly divided into many fractions.

Today’s underarm thermometers register the body’s temperature at 98.6 degrees because of this further development of the scale. On the original scale, the human body’s temperature was registered at 96 degrees.

He discovered supercooling

Fahrenheit has made yet another discovery that is still being used today, namely the phenomenon of supercooling. This takes place when the water is cooled below the freezing point without being converted to ice.

The principle is applied today for refrigeration. Some freezers are capable of cooling drinks to a supercooled level and when these are opened, they form a slush. Of course, this is used in other industries as well, such as the medical and technological ones.


Trade secrets

Fahrenheit’s instruments were highly esteemed during his time. He successfully used mercury because he developed a special cleaning technique, and he also introduced cylindrical bulbs instead of spherical ones.

Less known is the fact that his know-how for making thermometers was a trade secret and it was kept as such for about 18 years, showing that he also had business skills, besides his scientific knowledge.



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