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 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.