Rankine scale Rankine scale The Rankine scale () is an absolute scale of thermodynamic temperature named after the Glasgow University engineer and physicist William John Macquorn Rankine, who proposed it in 1859. (The Kelvin scale was first proposed in 1848.) It may be used in engineering systems where heat computations are done using degrees Fahrenheit. The symbol for degrees Rankine is °R (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). By analogy with kelvin, some authors term the unit "rankine", omitting the degree symbol. Zero on both the Kelvin and Rankine scales is absolute zero, but a
Absolute scale Absolute scale An absolute scale is a system of measurement that begins at a minimum, or zero point, and progresses in only one direction. An absolute scale differs from an arbitrary, or "relative," scale, which begins at some point selected by a person and can progress in both directions. An absolute scale begins at a natural minimum, leaving only one direction in which to progress. An absolute scale can only be applied to measurements in which a true minimum is known to exist. Time, for example, which does not have a clearly known beginning, is measured on a relative scale,