Réaumur (°Ré)
Modern equivalent
1°Ré = 1.25°C
A scale devised by René Antoine Ferchault de Réaumur in 1730, setting the freezing point of water at 0 and its boiling point at 80.
Réaumur built his scale around a dilute alcohol thermometer, dividing the range between freezing and boiling water into eighty parts. The eighty-degree span gave convenient whole numbers for brewing, dairying and spirit distillation, and the scale dominated continental Europe through the eighteenth and much of the nineteenth century. British scientific and industrial writing of the period frequently quotes Réaumur figures alongside Fahrenheit, and Russian literature used it well into the twentieth century.