Scale of temperature the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale two years before his death. The degree Celsius (°C) can refer to a specific temperature on the Celsius scale as well as a unit to indicate a temperature "interval "(a difference between two temperatures or an uncertainty). From 1744 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere. Although these defining correlations are commonly taught in schools today, by international agreement the unit "degree Celsius" and
Wedgwood scale Wedgwood scale The Wedgwood scale (°W) is an obsolete temperature scale, which was used to measure temperatures above the boiling point of mercury of . The scale and associated measurement technique were proposed by the English potter Josiah Wedgwood in the 18th century. The measurement was based on the shrinking of clay when heated above red heat, and the shrinking was evaluated by comparing heated and unheated clay cylinders. The scale started at being 0° Wedgwood and had 240 steps of . Both the origin and the step were later found inaccurate. The boiling point of mercury limits the mercury-in-glass