William Rankine was a Scottish engineer and physicist, inventor. In 1855 he became professor of engineering at Glasgow University, where he made valuable contributions to civil and mechanical engineering and thermodynamics. Rankine wrote manuals on these subjects and also devised the absolute temperature scale based on the degree Fahrenheit, known as the Rankine scale.

 

Rankine scale

 

Comparison of Kelvin, Celsius, Fahrenheit, and Rankine scales.

 

The Rankine scale is a temperature scale expressing absolute temperature in Fahrenheit degrees. It was devised by the Scottish engineer William Rankine (1820–1872). For Fahrenheit readings above zero, 460° is added. Thus, 72°F equals 460° plus 72°, or 532° absolute (532°R). If the Fahrenheit reading is below zero, it is subtracted from 460°. Thus, –40°F equals 460° minus 40°, or 420° absolute (420°R).