About Réaumur
The Réaumur scale (°Ré) was devised by the French physicist René Antoine Ferchault de Réaumur in 1730, with water freezing at 0°Ré and boiling at 80°Ré. It was widely used in Europe but 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 Rankine
Rankine is temperature unit normally used in thermodynamics. It is named after the Scottish engineer and physicist William John Macquorn Rankine, who is know for his work in thermodynamics. The Rankine scale is based on the Fahrenheit scale with degree increments identical but starting at absolute zero.
With the zero point at absolute zero (-459.67°F) it is easy to convert between Rankine and Fahrenheit: simply subtract 459.67.
The Rankine scale is not normally used in everyday life as it is an engineering unit particularly thermodynamics in the United States.