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On May 24, 1686, Dutch-German-Polish physicist, engineer, and glass blower Daniel Gabriel Fahrenheit was born. He is is best known for his invention of the mercury-in-glass thermometer in 1714, and for developing a temperature scale that is now named after him.
During his apprenticeship in Amsterdam, Daniel Fahrenheit began building instruments and traveled through Europe, meeting and exchanging knowledge with contemporary instrument makers. By 1714, he built his first thermometers containing alcohol, which he later changed to mercury and already made use of a new scale standard even though it did not catch on in the scientific community yet. Furtherly, Daniel Fahrenheit began experimenting with the different properties of water. Based on previous works of Ole Rømer and his scale, he investigated the boiling point of water while changing the pressure. Also, he managed to discover the ability of supercooling water, meaning that water can be cooled below its freezing point without actually freezing.
With these new findings, Fahrenheit began to question the general reliability of freezing and boiling points of fluids and developed his temperature scale, ranging from 0 to 212. He noted that the zero point on his scale was the temperature of ice melting in a salt water solution and 32 degrees depicted the temperature of ice melting in clear water. Fahrenheit began building thermometers that became more and more popular. He decided that a cylinder shaped bulb would be more efficient and made further improvements, which he kept secret for almost 18 years.
Despite Daniel Fahrenheit's success with building and distributing thermometers as well as his research on the Fahrenheit scale, the Celsius scale named after the Swedish scientist Anders Celsius slowly replaced Fahrenheit's scale during the metrication process. It is still used in the U.S., some territories of Puerto Rico, and Belize in everyday life, while scientists throughout the world mostly use Celsius or Kelvin.