About Rømer
Ole Rømer made significant contributions to the field of temperature measurement.
He was a Danish astronomer known for his work in the late 17th century. The Rømer scale (also known as the Danish scale) was based on the freezing and boiling points of water as many temperature scales are. Rømer's scale used the freezing and boiling reference points as 0 degrees and 60 degrees respectively. While the Rømer scale is no longer used it played a role as an early precursor to the Celsius scale.
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.