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Fahrenheit: The Man and His Scale

In 1714 Daniel Gabriel Fahrenheit invented the mercury thermometer which is now familiar to most of the world. He created a scale that was adopted throughout the English speaking world, but is now only used in the United States. Fahrenheit needed a way to determine temperature based on an objective source. He chose the lowest temperature to which he could supercool water without it turning to ice as the beginning point or zero point for his scale. He set the freezing of non-supercooled water at 30°, and the temperature of the human body was set at 96°. On this scale boiling would be at 212°. He later decided that it would be convenient to change the scale so that there would be exactly 180 degrees between the freezing of water and the boiling point. So he changed the temperature of freezing to 32°. This had the effect of moving body temperature to 98.6°.

Drawing of Daniel Gabriel Fahrenheit

Fahrenheit was born in Gdansk, at the time a Polish province of Prussia. He was educated in business, but also trained in natural sciences, to which he took a great interest and liking. He worked in the fields of chemistry and engineering. In the 1710s he ventured to Amsterdam where he gave lectures in chemistry. In 1724 he became a member of the Royal Society in Great Britain.1

Yet before he became the great inventor of the mercury thermometer (other types of thermometers had been developed earlier, but none were as accurate or practical) he had lived an interesting existence. In 1701 his parents died of mushroom poisoning. He was apprenticed out as a bookkeeper by his guardians. Not particularly liking the work, he left, but a warrant was issued for him to return him to his work. He wandered from city to city. In the course of those roamings he visited the famous astronomer, Olaf Romer. It was here that he learned of the importance of precision temperature-measuring instruments in scientific work. It may have been at Romer's request that the order to arrest Fahrenheit was withdrawn.

Thought by many to be an adroit businessman, he manufactured barometers and thermometers and sold them to an eager public. Throughout his career he continued to invest in advancing his instruments and doing further research in science. Most of his discoveries he turned immediately to practical use. To further his work he became a deft engineer as well as an able glass blower.2 He did work on all manner of instruments, including clocks for navigation, the heliostat (a device that tracks the motion of the sun), telescopes, and efficient pumps.

After he settled in Amsterdam, Fahrenheit did quite a lot of scientific work and made many discoveries, including a method for supercooling of water, that the boiling point of water is dependent on barometric pressure, and the specific gravities of many elements. Fahrenheit died in 1736. He lived a life that proved that science and business could work hand-in-hand to improve the lives and lifestyles of the people.

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  1. Biography Base
  2. Fahrenheit's Letters, p2 of Introduction