About Réaumur
Réaumur was widely used in Europe in the past but is now rarely seen. The Réaumur scale was named after the French physicist René Antoine Ferchault de Réaumur who developed it in the early 18th century. The freezing point of water is 0°Ré and the boiling point 80°Ré. This scale has been almost completely replaced by the Celsius scale.
Despite the Réaumur scale no longer being used, it had a significant impact in the history of temperature measurement.
About Celsius
Celsius is the most commonly used temperature scale in the world. The Celsius scale (known as the centigrade in some instances) is named after the Swedish astronomer Anders Celsius. It is based on the freezing and boiling points of water at standard atmospheric pressure making 0°C the freezing point and 100°C the boiling point.
The Celsius scale is normally found in weather forecasts, household temperatures and cooking in most countries with the notable exception of the United States.