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
Wedgwood scale The scale was divided into 240 equidistant parts. The unheated piece of clay would fit the 0.5-inch gap giving the zero temperature reading. After annealing, the clay cylinder would shrink and fit somewhere in between the left and right ends of the bars, and the temperature could be read from the scales on the bars. The origin (0°) on Wedgwood scale was set at the onset temperature of red heat, . The scale had 240 steps of and extended up to . Wedgwood tried to compare his scale with other scales by measuring the expansion of silver as a function