Daniel Gabriel Fahrenheit was born on May 24, 1686 in Danzig in the Polish-Lithuanian Commonwealth. Fahrenheit came from a family of merchants, but in 1701, both of Fahrenheit's parents died from eating poisonous mushrooms. After this, Fahrenheit moved to Amsterdam to begin training to become a merchant himself.
While in Amsterdam, Fahrenheit became interested in natural science and began studying and experimenting in the field. Fahrenheit also began to travel throughout Northern and Central Europe. While travelling, Fahrenheit met many notable members of the scientific and Enlightenment communities, including Gottfried Leibniz, co-developer of infinitesimal calculus, and Ole Romer, who made the first quantitative measurements of the speed of light.
In 1717, Fahrenheit settled in The Hague as a glassblower who specialized in making barometers, altimeters, and thermometers. Fahrenheit also lectured in chemistry in Amsterdam. In 1724, Fahrenheit created a scale to record temperature based on three points. These three points were the lowest point on the thermometer, or 0 Fahrenheit (F), the freezing point of water, or 32 F, and body temperature, which he calculated to be 96 F. The system was later changed so that the difference between the freezing and boiling points of water was exactly 180 F.
Anders Celsius was born on November 27, 1701 in Uppsala, Sweden. Unlike Fahrenheit, Celsius came from a family of scientists. Celsius's father and maternal grandfather were astronomers, and Celsius's paternal grandfather was a mathematician. Celsius studied at the Uppsala University and in 1730, Celsius became a professor there.
Celsius published many works in several fields of study. In one study conducted, he was the first to suggest that there was a connection between the appearance of the aurora borealis and changes in the magnetic field of the Earth, which was later proved to be correct. He also was part of the 1736 expedition to Lapland to measure the length of a degree along the meridian. This expedition, when compared to similar measurements from Peru, proved Isaac Newton's theory that the Earth was ellipsoid, rather than completely round, and flattened at the poles. Celsius was also one of the first people to measure the magnitude, or brightness, of certain stars, and, even with the equipment he used, Celsius was quite accurate.
Celsius is most famous for his creation of the temperature system that was named after him. Celsius understood that the boiling point of liquids was not simply dependent on heat but on pressure as well, so using a standard pressure (the pressure at sea-level), Celsius created a thermometer. At the standard pressure, the thermometer would read 100 Celsius (C) at water's melting point and 0 C at its boiling point. A year after his death, the system was reversed so the 0 C would be freezing and 100 C would be boiling.
Fahrenheit died in The Hague on September 16, 1736 and is buried there at Cloister Church. Celsius died on April 25, 1744 of tuberculosis soon after co-founding the Royal Swedish Academy of Sciences. Fahrenheit's system of temperature measurement was widely accepted throughout the world and is still used by the general population of the United States, Belize, and in parts of the United Kingdom and Canada. Celsius's system, when published, replaced Fahrenheit's system in all but the above stated regions. The Celsius system has also become the standard measurement system for the majority of scientific studies, and the Kelvin System is based off of that of Celsius. Fahrenheit and Celsius are on our list because they create the first systems to measure temperature without just say "It's cold." or "It's hot."