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Vendredi, 16 Septembre 2011 12:00

Sept. 16, 1736: One Degree of Separation ? Fahrenheit Dies

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mercury_680x1736: German physicist and instrument maker Gabriel Daniel Fahrenheit dies in the Netherlands. His pioneering work on thermometers means he will live on, to a degree.

Fahrenheit (Daniel Gabriel Fahrenheit in some accounts) was born in the Royal Prussian city of Danzig (now the Polish city of Gdansk) on May 14, 1686. His dad was a prosperous merchant, and his mom came from a whole family of well-heeled businessmen.

That wasn’t enough to keep them from eating poisonous mushrooms, and both parents died on the same day in 1701. Orphan Gabriel was then apprenticed to a merchant who took him to Amsterdam as a bookkeeper.

It was in Amsterdam that Fahrenheit found fabulous Florentine thermometers (or thermoscopes, as they were then known). He got so interested in tinkering with them that he skipped out on his apprenticeship. A career counselor might have thought that a good move, but a lawyer most certainly wouldn’t.

Fahrenheit was about to be arrested by Dutch police and sent into exile in India, so he went on the lam, traveling around Holland, Germany, Denmark, Sweden and Poland until he became a legal adult at age 24.

Galileo had created a water-based thermometer as early as 1593, and Santorio Santorio introduced a numerically graduated model in Florence in the mid-17th century. The Florentine models used the expansion of an alcohol solution to register changes in temperature. But no two of the instruments were exactly alike, usually marked only with the coldest and hottest days in Florence in the year they were made.

Running Hot and Cold

Gabriel Fahrenheit’s
Temperature estimates
Often would fail.

He thought out the problem
And by degrees he came
Up with his scale.

With instruments like that, you could compare the temperature in your own house or garden from one day to the next, or even one year to the next, but not to the temperature anywhere else. Isaac Newton had thought it might be possible to make standardized thermometers by marking universal points that didn’t vary, say, between England and Italy. But Newton had other things on his mind that he didn’t want to drop, so he never followed up on this idea.

Fahrenheit, however, wanted to standardize the thermometer. First, he produced two thermometers in 1714 that gave identical readings, a major accomplishment for the time. He went on to substitute mercury for alcohol as the measuring medium that would expand and contract. And he introduced the cylindrical shape, replacing the spherical bulbs that had been used previously.

He introduced the scale that bears his name and that’s still used to measure temperature — if only in the metric-averse United States. Folklorically, zero was the coldest day of the winter he created the scale, and 32 degrees the freezing point of water, which resulted in 212 degrees for the boiling point of water at sea level (which, you will recall, is overhead in much of Holland).

But that’s not the way of a methodical scientist who wanted to standardize things. Zero was as cold as he could make a concentrated solution of ice, water and salt, and 96 was supposed to be human body temperature.

He was a little low on that, but he was striving for mathematical convenience: 96 = 3 x 32. In any event, water’s boiling point at 212 is 180 degrees opposite its freezing point at 32.

Fahrenheit also invented a hygrometer for measuring the moisture content of air. Remember that the next time you say, “It’s not the heat, it’s the humidity.”

Source: Various

Image: Quicksilver temperature service — mercury is pretty and poisonous, and it helped Fahrenheit standardize the thermometer.

Double-dactyl doggerel: By your blogger, in his college days.

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