Jean-Pierre Christin facts for kids
Jean-Pierre Christin (born May 31, 1683 – died January 19, 1755) was a French scientist who studied physics, mathematics, and astronomy. He was also a musician. Christin is best known for suggesting a new way to set up the Celsius thermometer scale in 1743. Before him, water boiled at 0 degrees and froze at 100 degrees. He flipped it, so 0 degrees became the freezing point of water and 100 degrees became the boiling point. This change was widely accepted and is still used today around the world.
Christin was born in the city of Lyon, France. He helped start the Academy of Sciences, Arts, and Literature of Lyon. He worked as its Permanent Secretary from 1713 until he passed away in 1755. His special thermometer was known in France as the "thermometer of Lyon." One of these original thermometers is kept at the Science Museum in London.
Christin's Thermometer Innovations
The first thermometers used in Lyon were based on ideas from René Antoine Ferchault de Réaumur. In 1730, Réaumur created an alcohol thermometer. It had a scale divided into 80 parts, with 0° for melting ice and 80° for boiling water.
After doing many experiments, Christin believed that mercury thermometers were better than alcohol ones. He shared his findings in a meeting on June 13, 1740. He noticed something interesting when he was researching. He saw that a small amount of mercury in a tube would shrink when it was very cold (like in crushed ice). Then, it would expand when it was heated by boiling water. The mercury's volume moved from 66 to 67 parts of the tube.
Christin thought it made sense to divide the space the mercury moved into 100 parts. He felt these smaller units would show temperature changes more accurately.
With this idea, in 1743, he created his own mercury-based "thermometer of Lyon." This new thermometer used a centigrade (meaning "100 parts") scale. On this scale, 0 degrees marked the temperature where water freezes, and 100 degrees marked where water boils. This is the Celsius scale we know today.
See also
In Spanish: Jean-Pierre Christin para niños
