The total passion of a derailed merchant's son

Daniel Gabriel Fahrenheit (Danzig, May 24, 1686 – The Hague, September 16, 1736)

Many scientists worked on the development of the thermometer, but the man who first succeeded in getting two thermometers to indicate the same temperature identically, making series production possible, is undoubtedly Daniel Gabriel Fahrenheit.

Remarkably little has been published about Fahrenheit. Maybe because the Dutch see him as a German and the Germans see him as a Dutchman.

Fahrenheit was born in 1686 as the eldest of five children in a merchant family in the Prussian Hanseatic city of Danzig (now Gdansk). His grandfather had moved to Danzig from the Hanseatic city of Koningsbergen (Kaliningrad).

When he was fifteen, both his parents died suddenly at the same time after eating poisonous mushrooms. The city council placed the four younger children with foster families and Daniel, the eldest, had to be apprenticed to a merchant.

He taught the boy some bookkeeping and then sent him to Amsterdam to learn the trade at renowned trading houses.

There the boy became fascinated by physics, by the instruments that belonged to it and especially by the Florentine thermometers. No two of them were the same. One manufacturer took the coldest day in Florence as the lowest point and the warmest day of the year as the highest point. The young Fahrenheit developed a strange passion for the devices, learned how to blow the tubes himself and ignored his apprenticeship. That came to the attention of his guardian in Danzig.

The city council of Danzig immediately issued an arrest warrant against him and asked the Dutch authorities to put him to work on an East India Company ship as punishment. Fahrenheit fled and criss-crossed Europe for many years penniless.

He had to stay away from the Netherlands until the age of 24 because only then could he be registered as an adult.

Gradually his flight turned into a study trip that took him to England, Germany (Berlin, Halle, Leipzig, Dresden), Poland, Denmark and Sweden. Everywhere the young man sought out scientists who were busy with thermometers and barometers.

He refined his glassblowing technique and collected all available knowledge. Without being very aware of it, he became the most handsome man in Europe in his small discipline. According to him, thermometers were of no use if you could not compare the temperatures.

That was difficult because you had to have identical tubes and identically pure substances. His first thermometer with wine alcohol dates from 1709, three hundred years ago, the one with mercury from 1714. That year is also recorded as the year he invented the modern thermometer.

He was then 28.

Three years later, in 1717, he settled permanently in Amsterdam, the city that fascinated him most. He had a shop in which he sold blown glass instruments himself. At the same time he gave private lessons in statics and optics.
As the zero point, he chose the lowest temperature achievable at the time, namely a mixture of water, ice and certain salts. In this way he wanted to avoid minus degrees. And curiously enough, he opted for a 12-point scale of eight degrees each.

He set the melting point of ice at 32 degrees, his body heat (under the arm, or in the mouth) at 96 and the boiling point of water at 212 degrees.

The autodidact from Danzig has since corresponded with the greatest scholars of his time. In 1724 he even became a member of the Royal Society in London. In this way, his findings quickly spread throughout Europe.

He was the first to develop an hydrometer to measure the weight of liquid substances and, among other things, tinkered with a machine to drain flooded arable land. Polder machines, as it were.

After his death he left the machine to his highly learned friend Willem Jacob 's Gravesande, but he could not find out how it worked.

He died on September 16, 1736, barely fifty years old, in The Hague. For 18 guilders he was buried in a rented grave under the choir of the Kloosterkerk on the Lange Voorhout. For that amount he also received 'two times luijen', the bells were rung twice.

in the grave registers of the church

Ray Bradbury's well-known 1953 novel Fahrenheit 451 lists only owners of graves. Presumably no one has paid the rent afterwards, so his remains were removed centuries ago.

Although the inhabitants of The Hague have not forgotten him: in The Hague a street, a pharmacy and a magazine are named after him.

And on 6 June 2002, the The Hague-Warsaw Foundation for Urban Links and the Dutch Physics Association had a memorial plaque placed in the Kloosterkerk containing a working thermometer, of course with a fahrenheit scale.

Six years after his death, the Swedish astronomer Celsius proposed the scale of one hundred degrees. After the French Revolution, it fitted exactly into the decimal system.

The Americans in particular cherish to this day the bowl of Daniel Gabriel Fahrenheit, the inquisitive young man from Danzig who had found his second homeland in the Republic of the United Netherlands.

At the 1948 Conférence Générale des Poids et Mesures, congressmen radically opted for the Celsius scale. But well into the 1950s and 1960s, the Celsius and Fahrenheit scales continued to coexist in Flanders and the Netherlands.

Certainly in education, where teachers cherished converting the scales as a nice math exercise. The Fahrenheit scale was used for a long time to indicate warm summer temperatures. '80 degrees Fahrenheit' made more of an impression than '28 degrees Celsius'.

In winter, on the other hand, the minus-zero degrees of Celsius made the cold even colder. The fahrenheit scale slowly died out here.

In 1953, the fahrenheit scale in the United States was given a new meaning by Ray Bradbury's science fiction novel Fahrenheit 451, also made into a film in 1966 by François Truffaut.

It is a dystopia, the opposite of a utopia, in which books must be burned for the ideas they contain. At 451 degrees Fahrenheit, they catch fire on their own. Bradbury wrote the book in response to the witch hunts of the McCarthy era.

Michael Moore's 2004 film Fahrenheit 9/11 is a reference to it; 9/11 is then the temperature at which freedom goes up in flames. Ray Bradbury disagreed with that allusion and with Moore's title choice.